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Purpose: Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) is a novel, minimally invasive alternative to traditional open surgery corpus callosotomy (CC). We aim to compare both approaches in terms of time of hospitalization and surgical procedure, complications, and efficacy outcomes., Methods: A systematic search on PubMed, Embase, Web of Science, and Cochrane Library databases was performed for studies directly comparing MRgLITT and open surgery for refractory epilepsy in children., Results: A total of 240 patients from five studies were included. There was no statistically significant difference observed between the two groups regarding the favorable Engel outcome. (RR 0.89; 95 % CI 0.70-1.14; p = 0.36; I 2 =0 %) The mean hospital length of stay (LOS) was significantly shorter in the patients who underwent MRgLITT. (MD -2.84 days; 95 % CI [-3.17]-[-2.51] days; p < 0.00001; I 2 =90 %) The mean operation duration was significantly longer in the intervention group. (MD 1.38 h; 95 % CI 0.64- 2.12 h; p = 0.00002; I 2 =55 %). The mean blood loss was significantly lower in patients who underwent MRgLITT. (MD -75.15 ml; 95 % CI [-92.82]-[-57.48] ml; p < 0.00001; I 2 =0 %) CONCLUSION: CC is a valuable option for treating RE, especially in children. The open surgery bears the stigma of an invasive and complicated technique which might justify its underuse. MRgLITT is a great alternative and possibly a way to widen the use of callosotomy in children, however, its cost and availability may be a challenge., Competing Interests: Declaration of competing interest None of the authors has any conflict of interest to disclose., (Copyright © 2024. Published by Elsevier Ltd.)

Introduction: Post-operative complications of corpus callosotomy (CC) in children, prolonged hospitalization due to inactivity as acute disconnection syndrome is occasionally experienced. We aimed to clarify this issue and its risk factors with a hypothesis that electroencephalogram (EEG) findings as measures of functional lateralization may be among prognostic factors for post-operative recovery., Materials and Methods: Twenty-three patients with childhood-onset drug-resistant epilepsy who underwent total CC between April 2017 and December 2023 were included in the study and they were divided into two groups based on the duration of post-operative hospitalization as an indicator of recovery of daily living activity. We compared scalp EEG findings and the other factors including clinical characteristics between the two groups., Results: Of 22 patients (14 males) without specific complications, post-operative hospitalization clustered in 9-14 days in 15 patients (Group A) with range 16-118 days in seven patients (Group B). The ratios of patients with non-lateralized spikes on pre-operative EEG and that of patients with symmetric background activity on post-operative EEG were significantly greater in Group B (7/7, 100 %; 6/7, 86 %, respectively) than in Group A (8/15, 53 %; 4/15, 27 %, respectively) (p = 0.038; p = 0.020, respectively, by Fisher's exact test), while other factors were not significantly different between the two groups., Conclusions: Delayed recovery of living activity should be anticipated, especially in patients with non-lateralized epileptic discharges on pre-operative EEG., Competing Interests: Declaration of competing interest The authors have no other conflicts of interest to disclose., (Copyright © 2024. Published by Elsevier B.V.)

Background: The objective of frontal lobe disconnection (FD) is to isolate the frontal lobe without removing brain parenchyma, to achieve epilepsy outcomes comparable to those for frontal lobectomy but with fewer complications, since a large post-operative cavity is not created., Method: Main surgical steps include "Identification of the central sulcus" to ensure the preservation of motor function, and "Frontal lobe disconnection" comprising: 1) fronto-parietal disconnection; 2) fronto-basal disconnection; 3) anterior corpus callosotomy; and 4) insula and basal ganglia disconnection., Conclusion: In performing FD, consideration of the disconnection boundary based on an anatomical understanding of white matter tracts is essential., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Objective: Idiopathic normal pressure hydrocephalus (iNPH) is a disease characterized by gait disturbance, cognitive impairment, and urinary incontinence. For those patients who do not respond to shunt surgery, it lacks objective radiologic findings for the diagnosis of shunt malfunction. Here we aimed to evaluate whether the Evans index and callosal angle change during a prospective long-term follow-up of patients with iNPH submitted to shunt surgery., Methods: Clinical (NPH Japanese Scale) and radiologic (Evans index and callosal angle) data were collected pre- and postoperatively (3, 6, 12 and months) in 19 patients with iNPH. Imaging tests were evaluated by the same neuroradiologist during the follow-up., Results: Patients had lower scores on the NPH Japanese Scale over time (P < 0.001). There was no significant difference among Evans index values during the follow-up (P = 0.24). Preoperative average callosal angle was 72 ± 15, which increased to 91 ± 18 in 6 months (P = 0.003)., Conclusions: In this sample, patients with iNPH submitted to a programmable valve shunt had an increase in callosal angle concomitant to neurologic improvement. The Evans index did not change during follow-up., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: The transcallosal retroforniceal transchoroidal approach represents an advanced neurosurgical technique that allows access to lesions located within the posterior third ventricle and mesencephalon. It relies on a comprehensive understanding of microsurgical anatomy and embryology, integrating modern neurosurgical operative techniques to minimize retraction and injury to the normal neuronal structures., Methods: We report the cases of 2 patients undergoing treatment via this approach, one presenting with a thalamic cavernoma and the other with cystic low-grade glioma of the midbrain., Results: In these 2 cases, the decision to use the transcallosal approach was mainly due to improved trajectory, gravitational retraction of the hemisphere, and improved delivery of the lesion into the operative field by gravity alone., Conclusions: Through a detailed description of the surgical approach and anatomy, we illustrate the feasibility of the transcallosal retroforniceal transchoroidal approach for accessing lesions located deeply in the brain., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Hemispherotomy is a surgical procedure aimed at the treatment of hemispheric epilepsy. Hemispherotomy disconnects the commissural fibers, projecting fibers, and limbic system while preserving most of the brain parenchyma, unlike conventional hemispherectomy. 1 Hemispherotomy is one of most complicated operations currently used in epilepsy surgery and requires a high-level understanding of the intrinsic neuroanatomy. Generally, 2 main techniques are applied in hemispherotomy: lateral hemispherotomy and vertical hemispherotomy. 2 , 3 Vertical hemispherotomy was developed after the lateral technique. Despite a deeper, narrower surgical corridor, vertical hemispherotomy requires a smaller craniotomy and a shorter disconnection line and allows easier disconnection of the insula than the lateral approach. 1 In performing vertical hemispherotomy, 2 options are available: the interhemispheric approach 4 and the parasagittal approach. 3 With the parasagittal approach, the lateral ventricle is opened and entered via superior frontal gyrus. To ease the surgery and minimize the operation time, we apply "partial superior frontal gyrus removal." This procedure is useful to widen a shallower surgical field while skipping the need for interhemispheric dissection. Total callosotomy is then performed via the lateral ventricle. To disconnect limbic system, we used the technique following the falx and tentorial edge as a landmark. 5 Here, we present our surgical steps for parasagittal hemispherotomy in a 5-month-old girl diagnosed as hemimegalencephaly (Figures 1-8)., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The right-ear advantage (REA) for recalling dichotically presented auditory-verbal stimuli has been traditionally linked to the dominance of the left cerebral hemisphere for speech processing. Early studies on patients with callosotomy additionally found that the removal of the corpus callosum leads to a complete extinction of the left ear, and consequently the today widely used models to explain the REA assume a central role of callosal axons for recalling the left-ear stimulus in dichotic listening. However, later dichotic-listening studies on callosotomy patients challenge this interpretation, as many patients appear to be able to recall left-ear stimuli well above chance level, albeit with reduced accuracy. The aim of the present systematic review was to identify possible experimental and patient variables that explain the inconsistences found regarding the effect of split-brain surgery on dichotic listening. For this purpose, a systematic literature search was conducted (databases: Pubmed, Web of Knowledge, EBSChost, and Ovid) to identify all empirical studies on patients with surgical section of the corpus callosum (complete or partial) that used a verbal dichotic-listening paradigm. This search yielded k s  = 32 publications reporting patient data either on case or group level, and the data was analysed by comparing the case-level incidence of left-ear suppression, left-ear extinction, and right-ear enhancement narratively or statistically considering possible moderator variables (i.a., extent of the callosal surgery, stimulus material, response format, selective attention). The main finding was an increased incidence of left-ear suppression (odds ratio = 7.47, CI 95% : [1.21; 83.49], exact p = .02) and right-ear enhancement (odds ratio = 21.61, CI 95% : [4.40; 154.11], p < .01) when rhyming as compared with non-rhyming stimuli were used. Also, an increase in left-ear reports was apparent when a response by the right hemisphere was allowed (i.e., response with the left hand). While the present review is limited by the overall small number of cases and a lack of an appropriate control sample in most of the original studies, the findings nevertheless suggest an adjustment of the classical dichotic-listening models incorporating right-hemispheric processing abilities as well as the perceptual competition of the left- and right-ear stimuli for attention., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Purpose: Coherence analysis in electroencephalography (EEG) allows measurement of the degree of consistency of amplitude between pairs of electrodes. Theoretically, disconnective epilepsy surgery should decrease coherence between corresponding areas. The study aimed to evaluate postoperative changes in interhemispheric coherence values after corpus callosotomy (CC)., Methods: Non-lesional, drug-resistant, generalized epilepsy patients who underwent total CC were retrospectively collected. To evaluate coherence, we divided the scalp interictal EEG into "baseline" and "discharge" states after excluding periods with artifacts. Interhemispheric coherence values were obtained between eight pairs of symmetrically opposite scalp electrodes in six different frequency bands. We analyzed both pre- and postoperative EEG sessions and calculated the percentage of difference (POD) in coherence values., Results: We collected 13 patients and analyzed 2496 interhemispheric coherence values. Preoperative coherence values differed significantly between baseline and discharge states (p = 0.0003), but postoperative values did not (p = 0.11). For baseline state, coherence values were decreased after CC and median POD was - 22.3% (p < 0.0001). Delta frequency showed the most decreased POD (-44.3%, p = 0.0009). Median POD was lowest in the Fp1-Fp2 pair of electrodes. For discharge state, coherence values were decreased after CC and median POD was - 24.7% (p < 0.0001). Delta frequency again showed the most decreased POD (-55.9%, p = 0.0016). Median POD was lowest in the F7-F8 pair., Conclusion: After total CC, interhemispheric coherence decreased significantly in both baseline and discharge states. The most decreased frequency band was the delta band, which may be used as a representative frequency band in future studies., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Herein, we present the case of a 21-year-old man with a history of generalized tonic seizures since the age of 4 years. These seizures occurred either spontaneously or could be provoked by auditory stimuli such as the sounds of a vacuum cleaner or an electric shaver. Despite trials with 10 different anti-seizure medications, his seizures remained refractory. Interictal electroencephalography (EEG) revealed generalized epileptiform activity, whereas ictal EEG showed a generalized attenuation pattern. Magnetic resonance imaging revealed extensive chronic infarctions, predominantly in the bilateral cerebral watershed areas. At the age of 17, the patient underwent a one-stage complete callosotomy, which only achieved remission of auditory-provoked seizures. Based on this experience and published reports, we propose that the posterior corpus callosum, particularly the isthmus and anterior splenium, may be involved in seizures caused by unexpected sound stimuli., (© 2024 The Authors. Epileptic Disorders published by Wiley Periodicals LLC on behalf of International League Against Epilepsy.)

Two main surgical techniques are available for corpus callosotomy (CC): conventional microscopic CC and endoscopic CC. 1 Microscopic CC is more familiar to neurosurgeons and allows three-dimensional visualization, but it requires a larger craniotomy and has a narrower visual angle in the deep part. Endoscopic CC has only recently been introduced to epilepsy surgery, but it is gaining increasing interest among epilepsy surgeons. The endoscope provides two-dimensional visualization and requires a camera as an additional instrument inserted into the surgical corridor. The merits of endoscopic CC include the smaller craniotomy and smaller skin incision, potentially reducing invasiveness. 2 Bridging veins to the superior sagittal sinus are also less problematic because of the reduced need for brain retraction. The lack of need of arachnoid dissection is another advantage. Generally, an anterior approach is applied for CC, but this approach makes interhemispheric fissure dissection mandatory, especially at the cingulate gyri. In some cases, this procedure can take a long time. On the other hand, a posterior approach requires less interhemispheric arachnoid dissection, or sometimes none at all, due to the anatomy of the falx cerebri. These reasons have driven the development of a posterior approach for an endoscopic-alone technique. 3 Here, we present a 5-year-old girl with medically intractable epileptic spasms that were diagnosed as infantile epileptic spasms syndrome, who underwent endoscopic total CC via a posterior approach to control her seizures (Video 1)., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Purpose: To assess preferences and outcome expectations for vagus nerve stimulation (VNS) and corpus callosotomy (CC) surgeries in the treatment of atonic seizure in Lennox-Gastaut syndrome (LGS)., Methods: A total of 260 surveys were collected from patients are caregivers of LGS patients via Research Electronic Data Capture (REDCap)., Results: Respondents reported an average acceptable atonic seizure reduction rate of 55.9% following VNS and 74.7% following CC. 21.3% (n = 50) were willing to be randomized. Respondents reported low willingness for randomization and a higher seizure reduction expectation with CC., Conclusion: Our findings guide surgical approaches for clinicians to consider patient preference in order to design future studies comparing effectiveness between these two procedures., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objective: The aims of this study were to 1) assess and quantify white matter (WM) microstructural characteristics derived from diffusion tensor imaging (DTI) in children with cerebral palsy (CP) prior to selective dorsal rhizotomy (SDR), and 2) investigate potential associations between WM diffusion properties and gross motor function and spasticity in children with spastic CP who underwent SDR., Methods: This study is a multisite study based on DT images acquired prior to SDR as well as postoperative outcome data. DTI data collected from two sites were harmonized using the ComBat approach to minimize intersite scanner difference. The DTI abnormalities between children with spastic CP and controls were analyzed and correlated with the severity of impaired mobility based on the Gross Motor Function Classification System (GMFCS). The improvement in gross motor function and spasticity after SDR surgery was assessed utilizing the Gross Motor Function Measure-66 (GMFM-66), the Modified Tardieu Scale (MTS), and the modified Ashworth scale (MAS). Alterations in these outcome measures were quantified in association with DTI abnormalities., Results: Significant DTI alterations, including lower fractional anisotropy (FA) in the genu of the corpus callosum (gCC) and higher mean diffusivity (MD) in the gCC and posterior limb of the internal capsule (PLIC), were found in children in the SDR group when compared with the age-matched control group (all p < 0.05). Greater DTI alterations (FA in gCC and MD in gCC and PLIC) were associated with lower mobility levels as determined based on GMFCS level (p < 0.05). The pre- to post-SDR improvement in motor function based on GMFM-66 was statistically significant (p = 0.006 and 0.002 at 6-month and 12-month follow-ups, respectively). The SDR efficacy was also identified as improving spasticity in lower-extremity muscle groups assessed with the MTS and MAS. Partial correlation analysis presented a significant association between pre- to post-SDR MTS alteration and DTI abnormalities., Conclusions: The findings in the present study provided initial quantitative evidence to establish the WM microstructural characteristics in children with spastic CP prior to SDR surgery. The study generated data for the association between baseline DTI characteristics and mobility in children with CP prior to SDR surgery. The study also demonstrated SDR efficacy in improving motor function and spasticity based on the GMFM-66, MTS, and MAS, respectively, in association with DTI data.

Background: Endoscopic callosotomy has emerged as a promising and minimally invasive technique for the treatment of refractory epilepsy. This paper aims to review the clinical outcomes and advancements associated with endoscopic callosotomy as a therapeutic option., Materials and Methods: This study includes 14 Paediatric patients diagnosed and managed at Al-azhar university hospitals. Those 14 patients were studied over 2 years. All patients underwent a corpus callosotomy using the bimanual endoscopic technique., Results: Endoscopic anterior corpus callosotomy was done in 13 patients while one case underwent endoscopic complete callosotomy. The most frequent complication was transient disconnection syndrome followed by transient Urinary incontinence and one case had minor CSF leak. As regard seizure freedom outcome (Engel's Outcome Scale): 4 cases (28.6%) became seizure free (Engle class I), 5 cases (35.7%) with Engle class II, 1 case (7.1%) with Engle class III and 4 cases (28.6%) classify as Engle class IV., Conclusion: As a minimally invasive technique with a favorable impact on cognitive function, less complications and a significant reduction in seizure frequency and severity in the majority of paediatric patients, endoscopic corpus callosotomy offeres substantial benefits in managing refractory epilepsy in paediatric., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objectives: Corpus callosotomy (CC) is used to reduce seizures, primarily in patients with generalized drug-resistant epilepsy (DRE). The invasive nature of the procedure contributes to underutilization despite its potential superiority to other palliative procedures. The goal of this study was to use a multi-institutional epilepsy surgery database to characterize the use of CC across participating centers., Methods: Data were acquired from the Pediatric Epilepsy Research Consortium (PERC) Surgery Database, a prospective observational study collecting data on children 0-18 years referred for surgical evaluation of DRE across 22 U.S. pediatric epilepsy centers. Patient, epilepsy, and surgical characteristics were collected across multiple CC modalities. Outcomes and complications were recorded and analyzed statistically., Results: Eighty-three patients undergoing 85 CC procedures at 14 participating epilepsy centers met inclusion criteria. Mean age at seizure onset was 2.3 years (0-9.4); mean age for Phase I evaluation and surgical intervention were 9.45 (.1-20) and 10.46 (.2-20.6) years, respectively. Generalized seizure types were the most common (59%). Complete CC was performed in 88%. The majority of CC procedures (57%) were via open craniotomy, followed by laser interstitial thermal therapy (LiTT) (20%) and mini-craniotomy/endoscopic (mc/e) (22%). Mean operative times were significantly longer for LiTT, whereas mean estimated blood loss was greater in open cases. Complications occurred in 11 cases (13%) and differed significantly between surgical techniques (p < .001). There was no statistically significant difference in length of postoperative stay across approaches. Mean follow-up was 12.8 months (range 1-39). Favorable Engel outcomes were experienced by 37 (78.7%) of the patients who underwent craniotomy, 10 (58.8%) with LiTT, and 12 (63.2%) with mc/e; these differences were not statistically significant., Significance: CC is an effective surgical modality for children with DRE. Regardless of surgical modality, complication rates are acceptable and seizure outcomes generally favorable. Newer, less-invasive, surgical approaches may lead to increased adoption of this efficacious therapeutic option for pediatric DRE., (© 2023 International League Against Epilepsy.)

Objective: Corpus callosotomy (CC) is an important treatment for atonic seizures in patients with generalized or multifocal drug-resistant epilepsy (DRE). Traditionally, CC is performed via an open microsurgical approach, but more recently, MR-guided stereotactic laser interstitial thermal therapy (LITT) corpus callosum ablation (CCA) has been developed to leverage the safety and minimally invasive nature of LITT. Given the recent adoption of CCA at select centers, how CCA compares to CC is unknown. We aim to compare the clinical seizure outcomes of CCA and CC after extended follow-up., Methods: We performed a retrospective cohort study to compare the effectiveness and safety of CC to CCA from 1994 to 2022. The primary outcome was a 50% reduction in target seizure. Secondary outcome measures were postoperative length of stay, adverse events, and other effectiveness metrics. Comparative statistics were executed using Stata. Normality for continuous variables was assessed, and parametric statistics were utilized as needed. Frequency was compared with chi-squared or Fischer's exact tests, when applicable., Results: Data from 47 operations performed on 36 patients were included in this study, of which 13 (36%) patients underwent 17 CCA. Patients who received CCA had similar rates of meaningful reduction (>50%) of atonic seizures as their CC counterparts (55% vs 70% P = 0.15). Patients undergoing CCA had significantly shorter hospitalizations than those receiving CC (2.5 vs 6.0 days P < 0.001). There was no significant difference in rates of postoperative complications between the groups, although the magnitude of the complication rates was lower in the CCA cohort (12% vs 28%)., Significance: This early experience suggests CCA has similar outcomes to traditional CC, albeit with a shorter hospital stay. However, future studies are necessary to investigate the noninferiority between these two approaches. Large multicenter studies are necessary to investigate differences in adverse events and whether these findings generalize across other centers., (© 2023 The Authors. Epilepsia Open published by Wiley Periodicals LLC on behalf of International League Against Epilepsy.)

Background: Corpus callosum glioblastoma (ccGBM) is a specific type of GBM and has worse outcomes than other non-ccGBMs. We sought to identify whether en-bloc resection of ccGBMs based on T2-FLAIR imaging contributes to clinical outcomes and can achieve a satisfactory balance between maximal resection and preservation of neurological function., Methods: A total of 106 adult ccGBM patients (including astrocytoma, WHO grade 4, IDH mutation, and glioblastoma) were obtained from the Department of Neurosurgery in Nanfang Hospital between January 2008 and December 2018. The clinical data, including gender, age, symptoms, location of tumor, involvement of eloquent areas, extent of resection (EOR), pre- and postoperative Karnofsky Performance Status (KPS) scales, and National Institute of Health stroke scale (NIHSS) scores were collected. Propensity score matching (PSM) analysis was applied to control the confounders for analyzing the relationship between the en-bloc technique and EOR, and the change in the postoperative KPS scales and NIHSS scores., Results: Applying the en-bloc technique did not negatively affect the postoperative KPS scales compared to no-en-bloc resection (P = 0.851 for PSM analysis) but had a positive effect on preserving or improving the postoperative NIHSS scores (P = 0.004 for PSM analysis). A positive correlation between EOR and the en-bloc technique was identified (r = 0.483, P < 0.001; r = 0.720, P < 0.001 for PSM analysis), indicating that applying the en-bloc technique could contribute to enlarged maximal resection. Further survival analysis confirmed that applying the en-bloc technique and achieving supramaximal resection could significantly prolong OS and PFS, and multivariate analysis suggested that tumor location, pathology, EOR and the en-bloc technique could be regarded as independent prognostic indicators for OS in patients with ccGBMs, and pathology, EOR and the en-bloc technique were independently correlated with patient's PFS. Interestingly, the en-bloc technique also provided a marked reduction in the risk of tumor recurrence compared with the no-en-bloc technique in tumors undergoing TR, indicating that the essential role of the en-bloc technique in ccGBM surgery (HR: 0.712; 95% CI: 0.535-0.947; P = 0.02)., Conclusions: The en-bloc technique could contribute to achieving an enlarged maximal resection and could significantly prolong overall survival and progression-free survival in patients with ccGBMs., (© 2023. The Author(s).)

Intraventricular tumors of the lateral and third ventricles are relatively rare, accounting for 1-2% of all primary brain tumors in most large series [1-4]. They can be uniquely challenging to approach due to their deep location, propensity to become large before they are discovered, and association with hydrocephalus [5, 6]. The surgeon's goal is to develop a route to these deep lesions that will cause the least morbidity, provide adequate working space, and achieve a complete resection. This must be performed with minimal manipulation of the neural structures encircling the ventricles, avoiding functional cortical areas, and acquiring early control of feeding vessels [7, 8]., (© 2024. The Author(s), under exclusive license to Springer Nature Switzerland AG.)

Objective: Lennox-Gastaut syndrome (LGS) is a severe form of epileptic encephalopathy, presenting during the first years of life, and is very resistant to treatment. Once medical therapy has failed, palliative surgeries such as vagus nerve stimulation (VNS) or corpus callosotomy (CC) are considered. Although CC is more effective than VNS as the primary neurosurgical treatment for LGS-associated drop attacks, there are limited data regarding the added value of CC following VNS. This study aimed to assess the effectiveness of CC preceded by VNS., Methods: This multinational, multicenter retrospective study focuses on LGS children who underwent CC before the age of 18 years, following prior VNS, which failed to achieve satisfactory seizure control. Collected data included epilepsy characteristics, surgical details, epilepsy outcomes, and complications. The primary outcome of this study was a 50% reduction in drop attacks., Results: A total of 127 cases were reviewed (80 males). The median age at epilepsy onset was 6 months (interquartile range [IQR] = 3.12-22.75). The median age at VNS surgery was 7 years (IQR = 4-10), and CC was performed at a median age of 11 years (IQR = 8.76-15). The dominant seizure type was drop attacks (tonic or atonic) in 102 patients. Eighty-six patients underwent a single-stage complete CC, and 41 an anterior callosotomy. Ten patients who did not initially have a complete CC underwent a second surgery for completion of CC due to seizure persistence. Overall, there was at least a 50% reduction in drop attacks and other seizures in 83% and 60%, respectively. Permanent morbidity occurred in 1.5%, with no mortality., Significance: CC is vital in seizure control in children with LGS in whom VNS has failed. Surgical risks are low. A complete CC has a tendency toward better effectiveness than anterior CC for some seizure types., (© 2023 The Authors. Epilepsia published by Wiley Periodicals LLC on behalf of International League Against Epilepsy.)

The central role of the corpus callosum in integrating perception and cognition across the cerebral hemispheres makes it highly desirable for clinical and basic research to have a repertoire of experimental paradigms assessing callosal functioning. Here, the objective was to assess the validity of two such paradigms (Poffenberger, redundant-target paradigms) by conducting single-step meta-analyses on individual case data of callosotomy patients. Studies were identified by systematic literature search (source: Pubmed and WebOfKnowledge, date: 07.03.2022) and all studies were included that reported callosotomy case data for either paradigm. Twenty-two studies (38 unique cases) provided 116 observations of the crossed-uncrossed difference (CUD) for the Poffenberger paradigm, while ten studies (22 cases, 103 observations) provided bilateral redundancy gain (bRG) measures. Using linear-mixed models with "individual" and "experiment" as random-effects variable, the mean CUD was estimated at 60.6 ms (CI 95% : 45.3; 75.9) for commissurotomy, 43.5 ms (26.7; 60.2) for complete callosotomy, and 8.8 ms (1.1; 16.6) for partial anterior-medial callosotomy patients. The estimates of commissurotomy/callosotomy patients differed significantly from patients with partial callosotomy and healthy controls. The mean bRG min (minimum unilateral reference) was estimated at 42.8 ms (27.1;58.4) for patients with complete and 30.8 ms (16.8; 44.7) for patients with partial callosotomy, both differing significantly from controls. One limitation was that different formulas for bRG were used, making it necessary to split the sample and reducing test power of some analyses. Nevertheless, the present findings suggest that both paradigms assess interhemispheric callosal integration, confirming their construct validity, but likely test distinct callosal functions., (© 2022. The Author(s).)

Corpus callosotomy (CC) is a palliative treatment for drop seizures in patients with drug-resistant nonlocalizable epilepsy. We compared drop seizure outcomes between patients undergoing anterior CC versus complete CC and examined factors impacting outcomes for drop seizures including age at CC and duration of epilepsy. A retrospective review of patients who underwent CC between 2003 and 2022 with a minimum of 6 months postsurgical follow-up was included. Outcome measure for drop seizures included seizure reduction ≥50% from baseline as well as elimination of drop seizures. Thirty-eight patients were included. Overall, ≥50% reduction in drop seizures occurred in nearly 70% (23 out of 33) patients with complete elimination in 58% (19 out of 33). Compared with anterior CC (n = 13), patients undergoing complete CC (n = 25) had increased likelihood of ≥50% reduction (p = 0.006) or elimination (p = 0.024) of drop seizures. Regression analysis showed that complete CC was the primary predictor for improved drop seizure outcomes (elimination, p = 0.014 or ≥50% reduction, p = 0.006), while age at CC and duration of epilepsy did not impact the outcomes. Compared to anterior CC, complete CC was significantly more likely to lead to improvement/freedom from drop seizures. Age at CC or duration of epilepsy did not influence drop seizure outcomes., (© 2023 The Authors. Epilepsia Open published by Wiley Periodicals LLC on behalf of International League Against Epilepsy.)

Objective: The goal of this systematic review and meta-analysis was to provide an updated analysis of studies investigating outcomes, morbidity, and mortality associated with MR-guided laser interstitial thermal therapy (MRgLITT) corpus callosum ablation (CCA)., Methods: Study inclusion criteria for screening required that studies report on human subjects only, including patients aged 1-52 years diagnosed with drug-resistant epilepsy who underwent CCA. Sixteen articles published between 2016 and 2023 were included for the systematic review and analysis, including 4 case reports, 11 case series, and 1 case-control study. Altogether, 85 pediatric and adult patients undergoing CCA were included in the systematic review (46 patients younger and 39 patients older than 21 years). The main outcome of seizure freedom was measured using the decrease in the frequency of atonic seizures following surgery, percentage of atonic seizure freedom following surgery, and percentage of overall seizure freedom following surgery. These measurements were made using data from the last follow-up for patients with at least 6 months of follow-up post-CCA., Results: The extent of CCA differed across the pooled cohorts, including anterior two-thirds CCA (38.89%, n = 35) and posterior one-third CCA for completion of a prior partial CCA (22.22%, n = 20), complete CCA (27.78%, n = 25), or CCA of residual white matter in the case of subtotal initial ablation (5.56%, n = 5). Overall, 12.94% of the patients undergoing CCA experienced operational complications. The most common operative complications across 90 CCA operations were probe malpositioning (n = 6), hemorrhage (n = 5), off-target extension of splenium ablation to the thalamus (n = 1), infection (n = 1), and postoperative CSF leak (n = 1). Neurological deficits following CCA were reported as transient in 18.82% and permanent in 4.71% of patients across all studies. The most common neurological deficits were disconnection syndrome (n = 4) or transient hemiplegia (supplementary motor area-like syndrome; n = 4). The 6-month overall seizure freedom rate was 18.87% of 53 patients, and the atonic seizure freedom rate was 46.28% of 52 patients postoperatively. CCA resulted in an average decrease in atonic seizure rate from 8.30 to 1.65 atonic seizures per day (average decrease 80.12%)., Conclusions: CCA is associated with an acceptable complication profile, and most patients experience a meaningful reduction in target seizure semiologies. Accurate MRgLITT probe placement is likely important for maximizing CCA while avoiding collateral damage. Avoidable complications of CCA include off-target ablation (and associated deficits), hemorrhage, and future surgery for residual CCA to palliate continued seizures.

Purpose: To create a high-quality, cadaver-based, operatively oriented resource documenting the anterior transcortical and interhemispheric transcallosal approaches as corridors to the third ventricle targeted towards neurosurgical trainees at all levels., Methods: Two formalin-fixed, latex-injected specimens were dissected under microscopic magnification and endoscopic-assisted visualization. Dissections of the transcortical and transcallosal craniotomies with transforaminal, transchoroidal, and interforniceal transventricular approaches were performed. The dissections were documented in a stepwise fashion using three-dimensional photographic image acquisition techniques and supplemented with representative cases to highlight pertinent surgical principles., Results: The anterior transcortical and interhemispheric corridors afford excellent access to the anterior two-thirds of the third ventricle with varying risks associated with frontal lobe versus corpus callosum disruption, respectively. The transcortical approach offers a more direct, oblique view of the ipsilateral lateral ventricle, whereas the transcallosal approach readily establishes biventricular access through a paramedian corridor. Once inside the lateral ventricle, intraventricular angled endoscopy further enhances access to the extreme poles of the third ventricle from either open transcranial approach. Subsequent selection of either the transforaminal, transchoroidal, or interforniceal routes can be performed through either craniotomy and is ultimately dependent on individual deep venous anatomy, the epicenter of ventricular pathology, and the concomitant presence of hydrocephalus or embryologic cava. Key steps described include positioning and skin incision; scalp dissection; craniotomy flap elevation; durotomy; transcortical versus interhemispheric dissection with callosotomy; the aforementioned transventricular routes; and their relevant intraventricular landmarks., Conclusions: Approaches to the ventricular system for maximal safe resection of pediatric brain tumors are challenging to master yet represent foundational cranial surgical techniques. We present a comprehensive operatively oriented guide for neurosurgery residents that combines stepwise open and endoscopic cadaveric dissections with representative case studies to optimize familiarity with third ventricle approaches, mastery of relevant microsurgical anatomy, and preparation for operating room participation., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Objective: In this study, the authors describe their 10-year single-institution experience with single-step complete corpus callosotomy (CCC) for seizure management in pediatric and adult patients with catastrophic, medically refractory, nonlocalizing epilepsy at Advent Health Orlando., Methods: The authors conducted a retrospective observational study of patients aged 6 months to 49 years who underwent clinically indicated CCC for drug-resistant nonlocalizing epilepsy at Advent Health Orlando between July 2011 and July 2021. Follow-up ranged from 12 months to 10 years., Results: Of the 101 patients (57% of whom were male) who met eligibility criteria, 81 were pediatric patients and 20 were ≥ 18 years. All patients had seizures that appeared poorly lateralized on both electroencephalograms and clinical semiological studies. Of 54 patients with drop seizures before CCC, 29 (54%) achieved stable freedom from drop seizures after CCC. Of the 101 patients, 14 (13.9%) experienced stable resolution of all types of clinical seizures (International League Against Epilepsy classes 1 and 2). The most common postoperative neurological complication was a transient disconnection syndrome, observed in 50% of patients; of those patients, 73% experienced syndrome resolution within 2 months after surgery, and all resolved by the 2-year follow-up. Formal neuropsychological test results were stable in 13 patients assessed after CCC., Conclusions: CCC is an effective and well-tolerated palliative surgical technique. In this study, drop attacks were reduced after CCC but could recur for the first time as late as 44 months after surgery. Other seizure types were also reduced postoperatively but could recur for the first time as late as 28 months after surgery. Nearly 14% of patients achieved stable and complete freedom from seizures after CCC. Re-evaluation after CCC can reveal lateralized seizure onset in some patients.

Objective: Corpus callosotomy (CC) is a palliative surgical intervention for patients with medically refractory epilepsy that has evolved in recent years to include a less-invasive alternative with the use of laser interstitial thermal therapy (LITT). LITT works by heating a stereotactically placed laser fiber to ablative temperatures under real-time magnetic resonance imaging (MRI) thermometry. This study aims to (1) describe the surgical outcomes of CC in a large cohort of children with medically refractory epilepsy, (2) compare anterior and complete CC, and (3) review LITT as a surgical alternative to open craniotomy for CC., Methods: This retrospective cohort study included 103 patients <21 years of age with at least 1 year follow-up at a single institution between 2003 and 2021. Surgical outcomes and the comparative effectiveness of anterior vs complete and open versus LITT surgical approaches were assessed., Results: CC was the most common surgical disconnection (65%, n = 67) followed by anterior two-thirds (35%, n = 36), with a portion proceeding to posterior completion (28%, n = 10). The overall surgical complication rate was 6% (n = 6/103). Open craniotomy was the most common approach (87%, n = 90), with LITT used increasingly in recent years (13%, n = 13). Compared to open, LITT had shorter hospital stay (3 days [interquartile range (IQR) 2-5] vs 5 days [IQR 3-7]; p < .05). Modified Engel class I, II, III, and IV outcomes at last follow-up were 19.8% (n = 17/86), 19.8% (n = 17/86), 40.2% (n = 35/86), and 19.8% (n = 17/86). Of the 70 patients with preoperative drop seizures, 75% resolved postoperatively (n = 52/69)., Significance: No significant differences in seizure outcome between patients who underwent only anterior CC and complete CC were observed. LITT is a less-invasive surgical alternative to open craniotomy for CC, associated with similar seizure outcomes, lower blood loss, shorter hospital stays, and lower complication rates, but with longer operative times, when compared with the open craniotomy approach., (© 2023 International League Against Epilepsy.)

Objective: Open corpus callosotomy (CC) poses a higher risk of perioperative morbidity than does magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) for treatment of drop and generalized seizures without documented superiority. We present a single-institution comparison between open and MRgLITT CC., Methods: A 2-year retrospective review was performed of patients who underwent open and MRgLITT CC (January 2019-January 2021). Demographics, surgical outcome data, hospital costs, and interhemispheric connectivity with diffusion tensor imaging were compared., Results: The average age in years was 9.3 and 11.4 for CC (n = 4) and MRgLITT (n = 9), respectively. Preoperative drop seizure frequency was higher in CC (25 vs. 14.5 seizures/day; P = 0.59). At 10 months follow-up, the reduction in drop seizure frequency was better in open CC, but not statistically significant (93.8% vs. 64.3%; P = 0.21). The extent of CC ablation did not correlate with seizure reduction (Pearson coefficient = 0.09). An inverse correlation between interhemispheric connectivity change (diffusion tensor imaging analysis) and drop seizure frequency reduction was noted (Pearson coefficient = -0.97). Total hospital cost was significantly lower in MRgLITT ($67,754 vs. $107,111; P = 0.004), attributed to lower intensive care unit (1.1 vs. 4 days; P= 0.004) and total hospital stay (1.8 vs. 10.5 days; P = 0.0001). Postoperative hydrocephalus was present in 75% of patients in the CC group compared with zero in the MRgLITT group., Conclusions: Our middle-volume single-institution experience shows the safety, efficacy, and cost-effective benefit of MRgLITT compared with the traditional CC with therapeutic equipoise. This study is limited by the number of patients and, hence, further patient enrollment or multicenter study is warranted., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Background: Some patients suffering from intractable epileptic seizures, particularly drop attacks (DAs), are nonremediable by curative techniques. Palliative procedure carries a significant rate of surgical and neurological complications., Objective: To propose evaluation of safety and efficacy of Gamma Knife corpus callosotomy (GK-CC) as an alternative to microsurgical corpus callosotomy., Methods: This study included retrospective analysis of 19 patients who underwent GK-CC between 2005 and 2017., Results: Of the 19 patients, 13 (68%) had improvement in seizure control and 6 had no significant improvement. Of the 13/19 (68%) with improvement in seizures, 3 (16%) became completely seizure-free, 2 (11%) became free of DA and generalized tonic-clonic but with residual other seizures, 3 (16%) became free of DA only, and 5 (26%) had >50% reduction in frequency of all seizure types. In the 6 (31%) patients with no appreciable improvement, there were residual untreated commissural fibers and incomplete callosotomy rather than failure of Gamma Knife to disconnect. Seven patients showed a transient mild complication (37% of patients, 33% of the procedures). No permanent complication or neurological consequence was observed during the clinical and radiological workup with a mean of 89 (42-181) months, except 1 patient who had no improvement of epilepsy and then aggravation of the pre-existing cognitive and walking difficulties (Lennox-Gastaut). The median time of improvement after GK-CC was 3 (1-6) months., Conclusion: Gamma Knife callosotomy is safe and accurate with comparable efficacy to open callosotomy in this cohort of patients with intractable epilepsy suffering from severe drop attacks., (Copyright © Congress of Neurological Surgeons 2023. All rights reserved.)

Isolated lesions of the corpus callosum are rare and may represent permanent but also transient responses to various pathology termed "reversible splenial lesion syndrome" (RESLES) when in light of relevant clinical presentation. We present the first case of the RESLES after elective surgery for distant arteriovenous malformation (AVM), followed by a slight speech disturbance and MRI verified small, oval, well-circumscribed area of apparent cytotoxic edema in the center of the corpus callosum splenium, which completely resolved within 15 days. Surgery for AVM is followed by the complex adaptation to a new vascular pattern, RESLES might develop, and should be suspected., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Background: This report described the surgical nuance of a challenging deep-seated corpus callosum arteriovenous malformation (AVM) using a novel robotic digital microscope., Method: A 64-year-old male was admitted to treat a ruptured corpus callosum AVM. In order to facilitate surgical manipulation under the robotic digital microscope, a gravity-assisted supine position was utilized. Intraoperatively, identifying and preserving the transit and bystander artery is important while skeletonizing the anterior cerebral artery. The nidus was totally resected and the patient was discharged without sequella., Conclusion: It is feasible to perform complicated AVM resection under the robotic digital microscope with a rigorous surgical plan., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

The concept of a topographical map of the corpus callosum (CC), the main interhemispheric commissure, has emerged from human lesion studies and from anatomical tracing investigations in other mammals. Over the last few years, a rising number of researchers have been reporting functional magnetic resonance imaging (fMRI) activation in also the CC. This short review summarizes the functional and behavioral studies performed in groups of healthy subjects and in patients undergone to partial or total callosal resection, and it is focused on the work conducted by the authors. Functional data have been collected by diffusion tensor imaging and tractography (DTI and DTT) and functional magnetic resonance imaging (fMRI), both techniques allowing to expand and refine our knowledge of the commissure. Neuropsychological test were also administered, and simple behavioral task, as imitation perspective and mental rotation ability, were analyzed. These researches added new insight on the topographic organization of the human CC. By combining DTT and fMRI it was possible to observe that the callosal crossing points of interhemispheric fibers connecting homologous primary sensory cortices, correspond to the CC sites where the fMRI activation elicited by peripheral stimulation was detected. In addition, CC activation during imitation and mental rotation performance was also reported. These studies demonstrated the presence of specific callosal fiber tracts that cross the commissure in the genu, body, and splenium, at sites showing fMRI activation, consistently with cortical activated areas. Altogether, these findings lend further support to the notion that the CC displays a functional topographic organization, also related to specific behavior., Competing Interests: Declarations of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Purpose: To present the longitudinal MR imaging of 4 children with an acquired corpus callosum hump, in order to demonstrate graphically that this represents a dysmorphology caused through a constellation of pre-existing pathology, timing, and complications of treatment., Materials and Methods: Four cases with a corpus callosum hump were evaluated for common findings in the clinical history and on MRI scans. Those patients with available follow-up imaging were specifically evaluated for the presence of the hump on initial neonatal imaging and for evidence of development and progression of the deformity over time. Corpus callosum length was measured and compared against normal standards., Results and Conclusion: Congenital hydrocephalus, chronic ventricular over-shunting, white matter volume loss, and lateral ventricle communication were common to all cases. Corpus callosum length was above normal values. The corpus callosum hump term was previously described as dysplasia but was not present on initial scans in our cases. We conclude that the corpus callosum hump can be acquired as a complication of over-shunting in children with congenital hydrocephalus. Thus, we present our examples as "acquired hump of the corpus callosum," which differs from the prior example. We postulate that the lengthening of the stretched corpus callosum due to chronic hydrocephalus in the pre-myelinated state renders it unable to return to its normal shape when the ventricles are drained. Over-shunting of both lateral ventricles simultaneously in the absence of a septum pellucidum results in collapse and folding in of the corpus callosum on itself, resulting in the hump., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Corpus callosotomy (CC) is appropriate for patients with seizures of a bilateral or diffuse origin, or those with seizures of a unilateral origin with rapid spread to the contralateral cerebral hemisphere. The efficiency of CC in patients with drug-resistant epilepsy is a long-term concern because most articles reporting the surgical results of CC arise from small case series, and the durations of follow-up vary., Methods: PubMed, Embase, Cochrane Library, and Web of Science were searched to identify papers published before November 8, 2021. The systematic review was completed following PRISMA guidelines. Outcomes were analyzed by meta-analysis of the proportions., Results: A total of 1644 patients with drug-resistant epilepsy (49 retrospective or prospective case series studies) underwent CC, and the follow-up time of all patients was at least 1 year. The rate of complete seizure freedom (SF) was 12.38% (95% confidence interval [CI], 8.17%-17.21%). Meanwhile, the rate of complete SF from drop attacks was 61.86% (95% CI, 51.87%-71.41%). The rates of complete SF after total corpus callosotomy (TCC) and anterior corpus callosotomy (ACC) were 11.41% (95% CI, 5.33%-18.91%) and 6.75% (95% CI, 2.76%-11.85%), respectively. Additionally, the rate of complete SF from drop attacks after TCC was significantly higher than that after ACC (71.52%, 95% CI, 54.22%-86.35% vs. 57.11%, 95% CI, 42.17%-71.49%). The quality of evidence for the three outcomes by GRADE assessment was low to moderate., Conclusion: There was no significant difference in the rate of complete SF between TCC and ACC. TCC had a significantly higher rate of complete SF from drop attacks than did ACC. Furthermore, CC for the treatment of drug-resistant epilepsy remains an important problem for further investigation because there are no universally accepted standardized guidelines for the extent of CC and its benefit to patients. In future research, we will focus on this issue., (© 2023 The Authors. Brain and Behavior published by Wiley Periodicals LLC.)

Background: Recent neuroimaging studies on upper-limb amputation have revealed the reorganization of bilateral sensorimotor cortex after sensory deprivation, underpinning the assumption of changes in the interhemispheric connections. In the present study, using functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI), we aim to explore the alterations in the interhemispheric functional and structural connectivity after upper-limb amputation. Methods: Twenty-two upper-limb amputees and 15 age- and sex-matched healthy controls were recruited for MRI scanning. The amputees were further divided into subgroups by amputation side and residual limb pain (RLP). DTI metrics of corpus callosum (CC) subregions and resting-state functional connectivity (FC) between the bilateral sensorimotor cortices were measured for each participant. Linear mixed models were carried out to investigate the relationship of interhemispheric connectivity with the amputation, amputation side, and RLP. Results: Compared with healthy controls, upper-limb amputees showed lower axial diffusivity (AD) in CC subregions II and III. Subgroup analyses showed that the dominant hand amputation induced significant microstructural changes in CC subregion III. In addition, only amputees with RLP showed decreased fractional anisotropy and AD in CC, which was also correlated with the intensity of RLP. No significant changes in interhemispheric FC were found after upper-limb amputation. Conclusion: The present study demonstrated that the interhemispheric structural connectivity rather than FC degenerated after upper-limb amputation, and the degeneration of interhemispheric structural connectivity was shown to be relevant to the amputation side and the intensity of RLP. Impact statement Neuroimaging studies have revealed the functional reorganization of bilateral sensorimotor cortex after amputation, with expanded activation from the intact hemisphere to the deprived hemisphere. Our findings indicated a degeneration of interhemispheric white matter connections in upper-limb amputees, unveiling the underlying structural basis for bilateral functional reorganization after amputation.

Purpose: The cingulate gyrus is a potential surgical area to treat tumours, psychiatric diseases, intractable pain and vascular malformations. The aim of the study was to define the topographic anatomy and arterial supply of the cingulate gyrus located on the medial surface of the cerebral hemisphere., Methods: We studied thirty-six hemispheres, each hemisected in the midsagittal plane. The vertical thickness of the cingulate gyrus was measured at the anterior commissure (AC), posterior commissure (PC), and genu levels of the corpus callosum. The branches of the anterior and posterior cerebral arteries supplying each zone were noted separately. The arterial pathways were transformed to digital data in AutoCAD to identify the condensation and reduction areas., Results: The mean AC-PC distance was 27.17 ± 1.63 mm. The thinnest region was the genu level of the corpus callosum (10.29 mm). The superior internal parietal artery (SIPA), inferior internal parietal artery (IIPA) and pericallosal artery (PrCA) supplied all zones of the cingulate gyrus. The anterior zone received the greatest supply. The arterial condensation and reduction areas on both sides of cingulate gyrus and its x, y, and z coordinates specified., Conclusions: The target cingulotomy (TC) area was determined for anterior cingulotomy. The properties of the TC area are that the thinnest region of the cingulate gyrus is supplied relatively less than other areas and is close to the anterior cingulotomy areas in the literature. The arterial reduction area (ARA) was found to be suitable for corpus callosotomy in terms of avoiding haemorrhage., (© 2023. The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature.)

Introduction: Aneurysms of the A3 segment of the distal anterior cerebral artery (DACA), in relation to the genu of the corpus callosum, are specific sub-group which pose unique surgical challenges due to their discrete anatomical location. We describe a mini-anterior interhemispheric approach which can be safely utilised to clip these aneurysms rather than the traditional bifrontal approach., Methods: Retrospective analysis of the clinical and radiological data of ruptured DACA-A3 aneurysms operated between 2014 and 2021 at our institute. A curvilinear scalp incision within the hairline followed by raising small, unilateral, free frontal bone flap, avoiding the opening of frontal sinus. Superior sagittal sinus is displaced medially, inter-hemispheric dissection carried out with posterior trajectory and small callosotomy is performed. DACA is skeletonised, proximal control is established, and the A3 aneurysm is dissected and clipped., Result: Our cohort of 18 patients had a definite female preponderance (F:M::2:1) with mean age of 55.6 years. On admission three patients were categorized as WFNS Grade I, thirteen in Grade II, and two in Grade III for subarachnoid haemorrhage. All the patients had evidence of blood in the interhemispheric fissure; intraparenchymal haemorrhage was seen in seven, with intraventricular haemorrhage in six patients. Within the A3 segment six aneurysms were infragenu (inferior), eight were at the genu (anterior) and four were supragenu (superior). Two (11.1%) elderly patients succumbed post-surgery following ischemic infarcts and associated complications. At the time of follow-up at 3 months of the remaining sixteen (72.2%) patients, thirteen had a good outcome (mRS 0-3) and three (16.7%) had a poor outcome (mRS > 3)., Conclusion: The mini anterior interhemispheric is an effective minimally invasive alternative for A3 segments aneurysms and helps to avoid the complications of the conventional bifrontal interhemispheric approach., Competing Interests: Conflict of interest None., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Background: The interhemispheric transcallosal approach is widely used to remove intraventricular lesions. Corpus callosotomy gives immediate access to the ventricular chambers but is invasive in nature. Loss of callosal fibers, although normally tolerate, may cause disturbances ranging from a classical disconnection syndrome up to minor neuropsychological changes., Objective: To open an operative window in the corpus callosum through separation rather than disconnection of the white matter fibers., Methods: In 7 patients undergoing the interhemispheric transcallosal approach for intraventricular lesions, lying around or below the foramen of Monro, a stoma was created within the corpus callosum by using a 4F Fogarty catheter. The series included 3 colloid of the third ventricle, 2 thalamic cavernomas, 1 subependymoma, and 1 ependymoma of the foramen of Monro. We illustrate the technique and the clinico-radiological outcome, focusing on the size of callosotomy as seen on postoperative MRI., Results: The balloon-assisted corpus callosotomy provided a circular, smooth-walled access to the ventricular chambers, which allowed uncomplicated removal of the lesions. On postoperative MRI, the size of the callosotomy shrinked compared with surgery (2.8-6.4 mm at follow-up vs 6-9 mm as measured intraoperatively). No signs of disconnection syndrome or new permanent deficits were observed in this series., Conclusion: The balloon-assisted technique produces a small callosotomy, without clinical consequences, showing a self-closing trend on postoperative MRI. This technique is a rewarding tool to reduce the impact of callosotomy while keeping the advantages of microsurgical interhemispheric approaches., (Copyright © Congress of Neurological Surgeons 2022. All rights reserved.)

Background: Corpus callosotomy (CC) is a surgical palliative procedure done for a selected group of patients with drug resistant epilepsy (DRE) to stop drop attacks and prevent falls., Methods: We performed a retrospective chart review of consecutive patients who underwent CC for DRE with drop attacks at our center between 2015 and 2019. Clinical, imaging details and surgical findings were noted. Clinical outcomes and functional status were evaluated., Results: During the study period, 17 patients underwent corpus callosotomy (Male: Female 14:3). The mean age at surgery was 10.3 years (standard deviation - 5.85, interquartile range [IQR] = 6.5). The mean age at onset of seizure was 2.23 years (standard deviation - 3.42, IQR = 1.5). Preoperative seizure frequency ranged from 2 to 60 attacks per day (median: 20, IQR= 36). All patients had atonic seizures/drop attacks. One patient underwent anterior CC and 16 underwent complete CC. Three patients had complications in the postoperative period. The median follow-up was 26 months. All patients had cessation of drop attacks immediately following surgery. One patient with anterior CC had a recurrence of drop attacks for which she underwent completion CC. Another patient had recurrent drop attacks 3 years later and was found to have a residual callosal connection. Three patients had complete seizure freedom and 4 patients had a <50% reduction in seizure frequency., Conclusions: Our study lends additional support to the efficacy of CC in patients with DRE, with the cessation of drop attacks. It also provided a reasonable reduction in seizure frequency. Complete CC led to better control of drop attacks., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: Corpus callosotomy (CC) is a palliative neurosurgical procedure for patients with intractable epilepsy and without resectable focal epileptogenic lesions. Anterior commissurotomy (AC) has been historically performed with CC. However, the efficacy and safety of adding AC to CC remain unknown., Objective: To describe the surgical technique of extraventricular AC and retrospectively investigate its clinical efficacy and safety by assessing patients who underwent CC with and without AC., Methods: AC has been added to CC at our institution since 2018. Fifty-five consecutive patients who received total callosotomy from 2016 to 2020 were included and categorized into 2 groups: 26 patients with additional AC and 29 patients without additional AC. Seizure outcome 1 year after surgery were compared between groups for assessing the efficacy of adding AC. The perioperative factors were compared for assessing the safety and feasibility., Results: Seizure reduction rate (50% and 60%; P = .60) and disappearance of drop attacks (42% and 58%; P = .25) were not significantly different between CC and CC + AC groups. No statistical group differences were found in intraoperative estimated blood loss, number of days to first oral intake, duration of postoperative intravenous hydration, and length of hospital stay., Conclusion: Disconnection of the anterior commissure is a feasible and relatively safe procedure. This study failed to show the significant efficacy of adding AC to CC. However, further investigation is needed to prove its efficacy in ameliorating epilepsy., (Copyright © Congress of Neurological Surgeons 2022. All rights reserved.)

Callosotomy is widely used today as a treatment option for medically refractory epilepsy in patients with generalized or unknown-onset seizures. Other surgical indications include bilaterally distributed, most often synchronous, epileptiform discharges on EEG and some epilepsy syndromes, including Lennox-Gastaut syndrome and infantile spasms/West syndrome. Patients with drop attacks, mainly caused by epileptic spasms or atonic seizures, are most likely to benefit from this procedure. A more favorable seizure outcome was observed after a one-stage total callosal section in pediatric patients. For older children and adults, anterior callosotomy should initially be applied, and staged complete sections should be considered if the seizure outcome is insufficient. In terms of complications, most surgically associated brain and vascular injuries are avoidable in this era of microsurgery, and some less invasive newer methods, including endoscopic and stereotactic methods, are being explored. Disconnection syndrome is an unavoidable condition. However, it is usually transient in most cases and does not outweigh the improvement in symptoms of epilepsy in most patients, particularly in children who have compensatory functions or plasticity of the developing brain.

Corpus callosotomy (CC) is an effective surgical treatment for medically resistant generalized or multifocal epilepsy (MRE). The premise of CC extrapolates from the observation that the corpus callosum is the predominant commissural pathway that allows spread and synchroneity of epileptogenic activity between the hemispheres. Candidacy for CC is typically reserved for patients seeking palliative epilepsy treatment with the goal of reducing the frequency of drop attacks, although reduction of other seizure semiologies (absence, complex partial seizures, and tonic-clonic) has been observed. A reduction in morbidity affiliated with evolution of surgical techniques to perform CC has improved the safety profile of the procedure without necessarily sacrificing efficacy., (© 2023. The Author(s), under exclusive license to Springer Nature Switzerland AG.)

Objective: Surgical resection of gliomas involving the supplementary motor area (SMA) frequently results in SMA syndrome, a symptom complex characterized by transient akinesia and mutism. Because the factors influencing patient functional outcomes after surgery remain elusive, the authors investigated network-based predictors in a multicentric cohort of glioma patients., Methods: The participants were 50 patients treated for glioma located in the SMA at one of the three centers participating in the study. Postoperative functional outcomes (motor deficits, mutism) and duration of symptoms were assessed during hospitalization. Long-term outcome was assessed 3 months after surgery. MRI-based lesion-symptom mapping was performed to estimate the severity of gray matter damage and white matter disconnection., Results: The median duration of acute symptoms was 3 days (range 1-42 days). Long-term deficits involving fine motor movements and speech were found at follow-up in 27 patients (54%). Disconnection of the central callosal fibers was associated with prolonged acute symptoms (p < 0.05). Postoperative mutism was significantly related to disconnection severity of the left frontopontine tract, frontal aslant tract, cingulum, and corticostriatal tract (p < 0.05). Disconnection of midposterior callosal fibers and lesion loads within the left medial Brodmann area 4 were associated with long-term motor deficits (p < 0.05)., Conclusions: This study provides evidence for the pathophysiology and predictive factors of postoperative SMA syndrome by demonstrating the relation of the disconnection of callosal fibers with prolonged symptom duration (central segment) and long-term motor deficits (midposterior segment). These data may be useful for presurgical risk assessment and adequate consultation for patients prior to undergoing resection of glioma located within the SMA region.

Purpose: To explore the relationships between clinical-radiological features and surgical outcomes in subjects with interhemispheric cysts (IHC) and corpus callosum anomalies., Methods: We reviewed the clinico-radiological and neurosurgical data of 38 patients surgically treated with endoscopic fenestration, shunting, or combined approaches from 2000 to 2018 (24 males, median age 9 years). Pre- and postoperative changes in IHC volume were calculated. Outcome assessment was based on clinico-radiological data. Group comparisons were performed using χ 2 , Fisher exact, Mann-Whitney U, and Kruskal-Wallis tests., Results: Median age at first surgery was 4 months (mean follow-up 8.3 years). Eighteen individuals (47.3%) required > 1 intervention due to IHC regrowth and/or shunt malfunction. Larger preoperative IHC volume (P = .008) and younger age at surgery (P = .016) were associated with cyst regrowth. At last follow-up, mean cystic volume was 307.8 cm 3 , with IHC volume reduction > 66% in 19/38 (50%) subjects. The neurological outcome was good in 14/38 subjects (36.8%), fair in 18/38 (47.3%), and poor in 6/38 (15.7%). There were no differences in the postoperative cyst volume with respect to either the type of first surgery or overall surgery type. Higher absolute postoperative IHC reduction was observed in subjects who underwent both IHC fenestration and shunting procedures (P < .0001). No differences in neurological outcome were found according to patient age at surgery or degree of IHC reduction., Conclusion: Endoscopic fenestration and shunting approaches are both effective but often require multiple procedures especially in younger patients. Larger IHC are more frequently complicated by cyst regrowth after surgery., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objective: This retrospective study was designed to observe differences in ictal movements of epileptic spasm (ES) before and after corpus callosotomy (CC). We hypothesized that asymmetric expression of ES is more clarified after CC and would be a good indicator for the epileptic hemisphere., Methods: We selected 16 patients with intractable ES in West syndrome who were seizure-free after CC and subsequent resection or disconnective surgery of the unilateral hemisphere. We retrospectively reviewed their behavioral ES recorded at video-electroencephalography monitoring before and after CC. Asymmetric neck flexion (NF) and involuntary muscular contraction of the upper and lower extremities (MCU and MCL, respectively) were primarily described correlating their laterality and the responsible hemisphere proved by surgical resection., Results: Asymmetric NF, MCU, and MCL could be found both before and after CC. However, the percentage of those movements to the total number of ES increased after CC; asymmetric NF, 82.9% vs. 20.1%; unilaterally predominant MCU, 81% vs. 39.3%; and unilaterally predominant MCL, 77.6% vs. 29.9%. Regarding asymmetric NF, the direction in which the neck flexed or the head turned was significantly ipsilateral to the responsible hemisphere in 9 of 12 patients after CC (75%). The predominant side of MCU and MCL were significantly contralateral to the responsible hemisphere in 11 of 11 and 7 of 9 patients (100% and 77.8%, respectively)., Significance: Asymmetric NF, MCU, and MCL were clarified in patients with ES who were successfully treated with CC and subsequent surgery. Those changes in ictal behaviors after CC may indicate the lateralization of epileptic activity and encourage more curative surgical treatment., (© 2022 The Authors. Epilepsia Open published by Wiley Periodicals LLC on behalf of International League Against Epilepsy.)

Background: Epilepsy surgery has an important role in the treatment of patients with medically intractable seizures. Various authors have proposed an endoscopic technique to perform disconnective procedures. A detailed description of intracerebral anatomy seen through an endoscopic transcallosal corridor has not been reported. The aim of this study was to present a cadaveric step-by-step anatomical demonstration of endoscopic transcallosal hemispherotomy using a dedicated three-dimensional model., Methods: Anatomical dissections were performed on 6 cadaveric heads (12 hemispheres), and the disconnective procedure was performed using an endoscopic transcallosal approach. A dedicated three-dimensional model was used to better illustrate each step. A simulation of the disconnective procedure was performed by recreating the surgical steps on a subject from the Human Connectome Project dataset, and a calculation of the fiber tracts intersected was performed., Results: Analyzing data extracted from the three-dimensional model and tractography simulation, 100% of the fibers (streamlines) of corpus callosum, corticopontine tracts, corticospinal tract, and inferior fronto-occipital fascicle were transected. Moreover, a satisfactory number of fibers (>95%) of the thalamocortical tracts, corticostriatal tracts, corona radiata, fornix, and uncinate fascicle were disconnected., Conclusions: This anatomical study described the relevant neurovascular structures to enable prediction of feasibility and control of the surgical procedure using the endoscopic transcallosal approach. The quantitative analysis permitted estimation of the theoretical efficacy of the procedure, confirming its relevant role in disconnective surgery., (Copyright © 2022 The Author(s). Published by Elsevier Inc. All rights reserved.)

Purpose: Patients with pharmacoresistant refractory epilepsy may require epilepsy surgery to prevent future seizure occurrences. Conventional surgery consists of a large craniotomy with straight rigid tools with associated outcomes of morbidity, large tissue resections, and long post-operative recovery times. Concentric tube robots have recently been developed as a promising application to neurosurgery due to their nonlinear form and small diameter. The authors present a concept study to explore the feasibility of performing minimally invasive hemispherotomy with concentric tube robots., Methods: A model simulation was used to achieve the optimal design and surgical path planning parameters of the concentric tube robot for corpus callosotomy and temporal lobectomy. A single medial burr hole was chosen to access the lateral ventricles for both white matter disconnections., Results: The concentric tube robot was able to accurately reach the designated surgical paths on the corpus callosum and the temporal lobe., Conclusion: In a model simulation, the authors demonstrated the feasibility of performing corpus callosotomy and temporal lobectomy using concentric tube robots. Further advancements in the technology may increase the applicability of this technique for epilepsy surgery to better patient outcomes., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Recovery time after corpus callosotomy (CC) is known to be longer in elderly than in younger patients., Objective: To evaluate the relationship between patient age and recovery time of activities of daily living (ADL) after 1-stage complete CC., Methods: This study included 41 patients (22 women; aged 13 months-34 years, median 7 years) who underwent 1-stage complete CC for medically intractable seizures with drop attacks, infantile spasms, and/or bilaterally synchronized electroencephalographic discharges between August 2009 and April 2019. The timing of restart of competence in 5 ADL categories and surgical outcomes were recorded., Results: Patients (1) restarted speech at 2.2 ± 1.3 (mean ± 2 standard deviations; range 1-5) days, (2) restarted replying with their own name on request at 5.5 ± 8.6 (2-33) days, (3) restarted oral intake at 1.6 ± 1.7 (1-11) days, (5) discontinued intravenous feeding at 6.0 ± 3.0 (2-16) days, and (5) restarted ambulation or wheelchair movement at 5.8 ± 3.4 (2-10) days. Younger patients showed significantly (P < .0223) earlier recovery of ambulation or wheelchair movement, but no age difference was found in the other 4 ADL categories. Overall seizure freedom was achieved in 5 patients, excellent (>80%) seizure reduction in 11, good (50%-80%) seizure reduction in 5, and poor (<50%) seizure reduction in 20., Conclusion: Early ADL recovery after 1-stage complete CC is favorable in both young and adult patients. These findings, with good surgical outcomes, will encourage more positive consideration of 1-stage complete CC in both pediatric and adult patients., (Copyright © Congress of Neurological Surgeons 2022. All rights reserved.)

Objective: To perform measurements in normal brain imaging studies from the free edge of the falx cerebri to the genu and the body of the corpus callosum and perform a statistical analysis based on age, type of study, and sex highlighting potential surgical implication of these measurements., Methods: In 193 normal brain imaging studies, 3 anatomical points of the corpus callosum were used to measure the distance to the falx cerebri. Horos and RadiAnt DICOM Viewer software were used to perform the measurements. Statistical analysis of data was performed with Minitab18 software., Results: The results obtained in computed tomography (CT) studies were: distance A, mean 2.1065 cm; distance B, mean 2.2677 cm; distance C, mean 1.765 cm. The results obtained in magnetic resonance imaging studies were: distance A, mean 1.7148 cm; distance B, mean 2.1197 cm; distance C, mean 1.5321 cm. Statistically significant differences were obtained in measurements related to the type of study and in measurements made in CT studies related to age., Conclusions: There is a distance from the free edge of the falx cerebri to the genu and body of the corpus callosum of at least 1 cm in both CT and magnetic resonance imaging studies of normal brains. Statistically significant differences were found in the measurements in relation to the type of study and in relation to age in the measurements made in CT studies. These measurements could be important in determining the extent of bone resection in certain types of decompressive craniectomies., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Purpose: Scaphocephaly is the premature closure of the sagittal suture. The treatment strategies mainly focus on correcting the shape of the head, but there are very limited studies examining changes in brain structure. This study aimed to investigate shape differences in the shape of corpus callosum regarding the pre-treatment and post-treatment term at scaphocephaly patients., Methods: Cranium shape data were collected from the two-dimensional digital images. The generalized Procrustes analysis was used to obtain mean shapes in the pre- and postoperative phases. The shape deformation of the corpus callosum from the pre- to postoperative phases was evaluated using the thin plate spline method., Results: There is an enlargement of the splenium part of corpus callosum in the late group. In the early group, corpus callosum genu and body enlargement were observed in the postoperative period compared to the preoperative period, followed by a narrowing of the isthmus region., Conclusion: This study showed structural deformations in the corpus callosum in scaphocephaly patients using head shape with the landmark-based geometric morphometric method by taking into consideration the topographic distribution. An enlargement at the splenium part of corpus callosum exposes after the cranial vault expansion depending on time., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)