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Background: MR-guided stereotaxy has emerged as a viable alternative to CT-guided frame-based or frameless approaches. By offering direct MR-guided navigation, this technique addresses most limitations inherent to CT navigation, enabling submillimeter precision. Method: We detail the workflow of using the ClearPoint® MR navigation system for laser catheter placement in the treatment of a hypothalamic hamartoma. Conclusion: MR-guided navigation is a precise and effective stereotactic method for laser ablation of targets with high demands for accuracy. However, compared to standard stereotactic techniques, MR-guided navigation is more time-consuming and costly. [ABSTRACT FROM AUTHOR]

• Corpus callosotomy is underutilized due to the potential complications. • However, MRgLITT mitigates the concerns associated with open surgery. • The minimally invasive approach is associated with lower hospital length of stay and complications. • It is also associated with a longer time of surgery and costs, reducing its widespread use. • No particular procedure is preferred and individualization of each case is needed. 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. 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. 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; I2=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; I2=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; I2=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; I2=0 %) 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. [Display omitted] [ABSTRACT FROM AUTHOR]

MR-guided Laser Interstitial Thermal Therapy (MRgLITT) is a minimally invasive neurosurgical technique increasingly used for the treatment of drug-resistant epilepsy and brain tumors. Utilizing near-infrared light energy delivery guided by real-time MRI thermometry, MRgLITT enables precise ablation of targeted brain tissues, resulting in limited corridor-related morbidity and expedited postoperative recovery. Since receiving CE marking in 2018, the adoption of MRgLITT has expanded to more than 40 neurosurgical centers across Europe. In epilepsy treatment, MRgLITT can be applied to various types of focal lesional epilepsy, including mesial temporal lobe epilepsy, hypothalamic hamartoma, focal cortical dysplasias, periventricular heterotopias, cavernous malformations, dysembryoplastic neuroepithelial tumors (DNET), low-grade gliomas, tuberous sclerosis, and in disconnective surgeries. In neuro-oncology, MRgLITT is used for treating newly diagnosed and recurrent primary brain tumors, brain metastases, and radiation necrosis. This comprehensive review presents an overview of the current evidence and technical considerations for the use of MRgLITT in treating various pathologies associated with drug-resistant epilepsy and brain tumors. [ABSTRACT FROM AUTHOR]

Magnetic resonance–guided laser interstitial thermal therapy (MRgLITT) is a new minimally invasive treatment for tuberous sclerosis complex (TSC)-associated epilepsy in children. This video describes a case of a 17-year-old girl with TSC-associated drug-resistant epilepsy treated with robotic-assisted MRgLITT. In our case, MRgLITT was safe and effective in simultaneous targeting of multiple epileptic tubers in 1 single procedure, leading to a marked decrease in seizure frequency. MRgLITT could be a promising and more appealing treatment option for children who may need multiple surgeries over their lifetime as a result of the progressive nature of TSC. [ABSTRACT FROM AUTHOR]

There is an emerging role for minimally invasive magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) in the treatment of pediatric epilepsy refractory to medication. To date, predictors of MRgLITT success have not been established in a sizeable singular experience. Correspondingly, the aim of this study was to elucidate if previous surgical history predicts MRgLITT success in this setting. A retrospective review was conducted of our MRgLITT procedures for pediatric (patient age <19 years) epilepsy from 2011 to 2020 with documented seizure outcomes at 1 and 2 years after procedure. Categorical and continuous data were compared using χ2 and Student's t test, respectively. A total of 41 patients satisfied all criteria with 16 (39%) female and 25 (61%) male patients. Following MRgLITT, seizure-freedom at 1-year was achieved in 15 (37%) patients. In the cohort, there were 14 (34%) patients who had undergone previous open surgery for epilepsy at mean age of 9.4 ± 5.5 years. Patients with a previous open surgery history were found to statistically experience longer length of hospitalization after MRgLITT (P = 0.04) with a statistically lower proportion of seizure-freedom at 1-year after MRgLITT (14% vs. 48%, P = 0.03). However, there was no difference in the rate of seizure-freedom at 2 years (29% vs. 41%, P = 0.44), as well as no difference in subsequent surgical interventions for seizure management between groups. Based on our institutional experience, patients with previous open surgery history may experience longer length of hospitalization after MRgLITT for pediatric epilepsy and lesser response in seizure-freedom within the first year but with non-inferior seizure freedom by the second year. [ABSTRACT FROM AUTHOR]

Abstract Background To describe and report the efficacy and safety of MR-guided laser interstitial thermal therapy (MRgLITT) in the treatment of drug-resistant epilepsy. Methods A retrospective review of all MRgLITT procedures in our hospital was performed. All procedures were performed using a surgical laser ablation system. Demographic and outcome data were compiled and analyzed. Results A total of 19 patients underwent MRgLITT procedures from June 2021 to November 2021. The average age at surgery was 18.1 years (3–61.4 years). The average length of hospitalization post-surgery was 4.95 days (4–7 days). Surgical substrates included 8 patients with hypothalamic hamartomas, 5 with medial temporal lobe epilepsy, 3 with deep focal cortical dysplasia, 1 with tuberous sclerosis, 1 with a cavernous malformation, and 1 with Lennox–Gastaut syndrome who underwent anterior corpus callosotomy. Complications occurred in three patients. After an average follow-up of 1 year, 6 patients were seizure-free (Engel I, 31.6%), 1 had significant seizure control (Engel II, 5.3%), 7 had seizure control (Engel III, 36.8%), and 5 had no improvement in their seizures (Engel IV, 26.3%). Fisher’s exact tests did not reveal statistical significance for the association between Engel class outcome and epileptic disease. Conclusion This study confirmed that MRgLITT, as a method for treating drug-resistant epilepsy, is minimally invasive, safe, and efficient and that it can reduce the incidence of surgery-related complications.

Background: To describe and report the efficacy and safety of MR-guided laser interstitial thermal therapy (MRgLITT) in the treatment of drug-resistant epilepsy. Methods: A retrospective review of all MRgLITT procedures in our hospital was performed. All procedures were performed using a surgical laser ablation system. Demographic and outcome data were compiled and analyzed. Results: A total of 19 patients underwent MRgLITT procedures from June 2021 to November 2021. The average age at surgery was 18.1 years (3–61.4 years). The average length of hospitalization post-surgery was 4.95 days (4–7 days). Surgical substrates included 8 patients with hypothalamic hamartomas, 5 with medial temporal lobe epilepsy, 3 with deep focal cortical dysplasia, 1 with tuberous sclerosis, 1 with a cavernous malformation, and 1 with Lennox–Gastaut syndrome who underwent anterior corpus callosotomy. Complications occurred in three patients. After an average follow-up of 1 year, 6 patients were seizure-free (Engel I, 31.6%), 1 had significant seizure control (Engel II, 5.3%), 7 had seizure control (Engel III, 36.8%), and 5 had no improvement in their seizures (Engel IV, 26.3%). Fisher's exact tests did not reveal statistical significance for the association between Engel class outcome and epileptic disease. Conclusion: This study confirmed that MRgLITT, as a method for treating drug-resistant epilepsy, is minimally invasive, safe, and efficient and that it can reduce the incidence of surgery-related complications. [ABSTRACT FROM AUTHOR]

Magnetic resonance–guided laser interstitial thermal therapy (MRgLITT) is a commonly used clinical method of destroying intracranial brain foci. Our objective was to correlate the thermal damage estimate transition zone with cognitive outcomes in MRgLITT of a pediatric hypothalamic hamartoma. Uncomplicated MRgLITT was used to disconnect an 8-mm left Delalande grade II hypothalamic hamartoma (HH) revealed on neuroimaging of a 17-year-old male patient with drug-resistant epilepsy and a "gelastic +" semiology including both gelastic and tonic-clonic seizures. Despite meticulous planning, submillimetric stereotactic accuracy, and reassuring intraoperative thermography, the patient experienced transient, but profound, global amnesia. Retroactively, we applied a new iteration of thermographic software that overlays a magenta-colored transition zone (TZ) around the necrotic zone defined by the orange-pigmented thermal damage estimate (TDE). Clear involvement of the bilateral mesial circuits was demonstrated by the overlay of the TZ on the TDE. Involvement of the bilateral mesial circuits visualized with TDE and TZ could account for the neurocognitive outcomes of our patient. We highlight this case as our understanding of thermography analysis evolves, emphasizing principles of technique and trajectory planning, as well as considerations during thermablation to help inform surgical decision-making. [ABSTRACT FROM AUTHOR]

To understand if unexplained signal artifacts in MRg-LITT proton resonance frequency- (PRF-) shift thermometry images are caused by air bubbles or hemorrhages, and to characterize their effects on temperature measurements. Retrospective image data from an IRB-approved clinical trial of intracranial MRg-LITT were inspected for asymmetric distortions observed in phase data during ablations, which have been previously reported as likely hemorrhages. A total of eight patient cases were selected: seven with artifact occurrence and one without. Mathematical image models for air bubbles or hemorrhages were implemented to estimate the size of the air bubble or hemorrhage needed to explain the clinically observed phase artifacts. Correlations and Bland-Altman analyses were used to determine if an air bubble model or a hemorrhage model was better correlated to the clinical data. The model was used to inject bubbles into clean PRF phase data without artifacts to examine how temperature profile distortions change with slice orientation. The simulated air-bubble injected data were compared to clinical data containing artifacts to examine the bubbles' effects on temperature and thermal damage estimates. The model demonstrated that air bubbles up to approximately 1 cm in diameter could explain the clinically observed phase artifacts. The bubble model predicts that a hemorrhage would have to be 2.2 times as large as an air bubble in order to explain the same extent of phase distortion observed in clinical data. Air bubbles had 16% percent higher correlations to the clinical PRF phase data than hemorrhages, even after rescaling the hemorrhage phases to better match the data. The air bubble model also explains how the phase artifacts lead to both large positive and large negative temperature errors, up to ±100 °C, which could cascade to damage estimate errors of several millimeters. Results showed that the artifacts are likely caused by air bubbles rather than hemorrhages, which may be introduced before heating or appear during heating. Manufacturers and users of devices that rely upon PRF-shift thermometry should be aware these phase distortions from bubble artifacts can result in large temperature errors. [ABSTRACT FROM AUTHOR]

Laser ablation for treatment of hypothalamic hamartoma (HH) is a minimally invasive and effective technique used to destroy hamartomatous tissue and disconnect it from the functioning brain. Currently, the gold standard to evaluate the amount of tissue being "burned" is the use of heat maps during the ablation procedure. However, these maps have low spatial resolution and can be misleading in terms of extension of the tissue damage. The aim of this study is to use different MRI sequences immediately after each laser ablation and correlate the extension of signal changes with the volume of malacic changes in a long-term follow-up scan. During the laser ablation procedure, we imaged the hypothalamic region with high-resolution axial diffusion-weighted images (DWI) and T2-weighted images (T2WI) after each ablation. At the end of the procedure, we also added a post-contrast T1-weighted image (T1WI) of the same region. We then correlated the product of the maximum diameters on axial showing signal changes (acute oedema on T2WI, DWI restriction rim, DWI hypointense core and post-contrast T1WI rim) with the product of the maximum diameters on axial T2WI of the malacic changes in the follow-up scan, both as a fraction of the total area of the hamartoma. The area of the hypointense core on DWI acquired immediately after the laser ablation statistically correlated better with the final area of encephalomalacia, while the T2WI, hyperintense oedema, DWI rim and T1WI rim of enhancement tended to overestimate the encephalomalacic damage. In conclusion, the use of intraoperative sequences (in particular DWI) during laser ablation can give surgeons valuable information in real time about the effective heating damage on the hamartomatous tissue, with better spatial resolution in comparison to the thermal maps. [ABSTRACT FROM AUTHOR]

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. 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. 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. 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. [ABSTRACT FROM AUTHOR]

Abstract Objective Corpus callosotomy is a safe and effective procedure for reducing the frequency of drop attacks. MR‐guided laser interstitial thermal therapy (MRgLITT) offers a minimally invasive alternative to conventional open craniotomy for callosotomy. We hypothesized that MRgLITT callosotomy could be safely performed in pediatric patients with similar seizure control. Methods We present an institutional case series of 11 procedures in 10 patients for the treatment of drop attacks in drug‐refractory primary generalized epilepsy. MRgLITT was used for complete callosotomy, anterior two‐thirds, posterior, or ablation of residual callosal fibers following prior callosotomy (open or MRgLITT). We retrospectively reviewed clinical course, operative details, radiographic imaging, clinical outcomes, and complications. Results Operative time ranged from 4‐8 hours, and median hospitalization was 2 days. No complications were encountered. Among the 7 patients with at least 3 months of follow‐up, 71% experienced freedom from drop attacks at longest follow‐up and 57% of cases showed improvement in their other seizure semiologies as well (Engel Class II: 28%, Class III: 28%, Class IV: 43%). Significance MR‐guided LITT callosotomy is safe and effective modality in the management of pediatric patients with medically intractable epilepsy characterized by drop attacks. While this is among the largest pediatric series to date, further studies are required to delineate its safety and efficacy among such patients.

Background: The surgical treatment of insular lesions has been historically associated with high morbidity. Laser interstitial thermal therapy (LITT) has been increasingly used in the treatment of insular lesions, commonly neoplastic or epileptogenic. Stereotaxis is used to guide laser probes to the insula where real-time magnetic resonance thermometry defines lesion creation. There is an absence of previously published reviews on insular LITT, despite a rapid uptake in use, making further study imperative. Methods: Here we present a systematic review of the PubMed and Scopus databases, examining the reported clinical indications, outcomes, and adverse effects of insular LITT. Results: A review of the literature revealed 10 retrospective studies reporting on 53 patients (43 pediatric and 10 adults) that were treated with insular LITT. 87% of cases were for the treatment of epilepsy, with 89% of patients achieving seizure outcomes of Engle I-III following treatment. The other 13% of cases reported on insular tumors and radiological improvement was seen in all cases following treatment. All but one study reported adverse events following LITT with a rate of 37%. The most common adverse events were transient hemiparesis (29%) and transient aphasia (6%). One patient experienced an intracerebral hemorrhage, which required a decompressive hemicraniectomy, with subsequent full recovery. Conclusion: This systematic review highlights the suitability of LITT for the treatment of both insular seizure foci and insular tumors. Despite the growing use of this technique, prospective studies remain absent in the literature. Future work should directly evaluate the effcacy of LITT with randomized and controlled trials. [ABSTRACT FROM AUTHOR]

Hypothalamic hamartoma (HH) is a rare lesion consisting of normal neurons and neuroglia arranged in an abnormal pattern which usually causes gelastic seizures (GS). Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) has been developed as a minimally invasive approach to treat HH and gradually become a first-line treatment. In total, this study enrolled 47 consecutive HH patients that underwent one round of ablation. Patients were followed for at least one year. Patients' medical records and surgical information were carefully reviewed, and univariate analyses were performed. Of the treated patients, 72.3% remained GS-free in this study, with an overall Engel class I rate of 68.1%. Long-term postoperative complications occurred in six patients. Factors associated with GS prognosis included Delalande classification (p = 0.033), HH volume (p = 0.01), and the ablation rate of the HH body (p = 0.035). The disconnection rate was 0.73 ± 0.14 in the Engel class Ia group as compared to 0.62 ± 0.13 in the Engel Ib–Engel IV group (p = 0.046). MRgLITT represents a safe and effective surgical procedure. Patients with larger or Delalande type IV HH may require multiple rounds of ablation. In addition to assessing the degree of disconnection, ablation volume should also be carefully considered for patients undergoing this procedure. [ABSTRACT FROM AUTHOR]

Background : About 65 million people worldwide are affected by epilepsy, with temporal lobe epilepsy being the most common type resistant to drugs and often requiring surgical treatment. Although open surgical approaches, such as temporal lobectomy, have been the method of choice for decades, minimally invasive MRgLITT has demonstrated promising results. However, it remains unknown whether patients who underwent one of these two approaches would show better performance on vestibulo-spatial tasks. Methods : Twenty-seven patients were included in three different groups: (1) MRgLITT (37.0 ± 15.1 years, two females), (2) R-OP (44 ± 15.7 years, five females) and (3) No-OP (43 ± 11.2 years, three females)-with no significant differences in age, disease duration and number of medications. Groups were compared on their performance in three vestibular-dependent tests: (1) clinical balance test (CBT), (2) triangle completion test (TCT) and (3) rotational memory (RM) test. Results : Significantly better performance of MRgLITT patients, in comparison to the other two groups (R-OP and No-OP), was found for the TCT. The other tests revealed no significant differences between the groups. Conclusions : Patients who underwent MRgLITT performed significantly better on the vestibular-dependent spatial orientation task (TCT) compared to those who underwent temporal lobectomy (R-OP) and non-operated patients. Speculations about reasons for such an effect-including minimal invasiveness with less "collateral damage", influence of operated side, timing of surgery, sample heterogeneity and others-need to be assessed in detail in larger-scale, prospective longitudinal studies.

BackgroundThe surgical treatment of insular lesions has been historically associated with high morbidity. Laser interstitial thermal therapy (LITT) has been increasingly used in the treatment of insular lesions, commonly neoplastic or epileptogenic. Stereotaxis is used to guide laser probes to the insula where real-time magnetic resonance thermometry defines lesion creation. There is an absence of previously published reviews on insular LITT, despite a rapid uptake in use, making further study imperative.MethodsHere we present a systematic review of the PubMed and Scopus databases, examining the reported clinical indications, outcomes, and adverse effects of insular LITT.ResultsA review of the literature revealed 10 retrospective studies reporting on 53 patients (43 pediatric and 10 adults) that were treated with insular LITT. 87% of cases were for the treatment of epilepsy, with 89% of patients achieving seizure outcomes of Engle I-III following treatment. The other 13% of cases reported on insular tumors and radiological improvement was seen in all cases following treatment. All but one study reported adverse events following LITT with a rate of 37%. The most common adverse events were transient hemiparesis (29%) and transient aphasia (6%). One patient experienced an intracerebral hemorrhage, which required a decompressive hemicraniectomy, with subsequent full recovery.ConclusionThis systematic review highlights the suitability of LITT for the treatment of both insular seizure foci and insular tumors. Despite the growing use of this technique, prospective studies remain absent in the literature. Future work should directly evaluate the efficacy of LITT with randomized and controlled trials.

Laser ablation for treatment of hypothalamic hamartoma (HH) is a minimally invasive and effective technique used to destroy hamartomatous tissue and disconnect it from the functioning brain. Currently, the gold standard to evaluate the amount of tissue being “burned” is the use of heat maps during the ablation procedure. However, these maps have low spatial resolution and can be misleading in terms of extension of the tissue damage. The aim of this study is to use different MRI sequences immediately after each laser ablation and correlate the extension of signal changes with the volume of malacic changes in a long-term follow-up scan. During the laser ablation procedure, we imaged the hypothalamic region with high-resolution axial diffusion-weighted images (DWI) and T2-weighted images (T2WI) after each ablation. At the end of the procedure, we also added a post-contrast T1-weighted image (T1WI) of the same region. We then correlated the product of the maximum diameters on axial showing signal changes (acute oedema on T2WI, DWI restriction rim, DWI hypointense core and post-contrast T1WI rim) with the product of the maximum diameters on axial T2WI of the malacic changes in the follow-up scan, both as a fraction of the total area of the hamartoma. The area of the hypointense core on DWI acquired immediately after the laser ablation statistically correlated better with the final area of encephalomalacia, while the T2WI, hyperintense oedema, DWI rim and T1WI rim of enhancement tended to overestimate the encephalomalacic damage. In conclusion, the use of intraoperative sequences (in particular DWI) during laser ablation can give surgeons valuable information in real time about the effective heating damage on the hamartomatous tissue, with better spatial resolution in comparison to the thermal maps.

Magnetic resonance-guided laser interstitial thermal therapy (MRg-LITT) is a promising new technique to ablate epileptic foci in patients with hypothalamic hamartoma (HH). We aim to systematically synthesize all available evidence and determine the effectiveness of MRg-LITT in reducing seizures in patients with HH. We systematically searched MEDLINE (PubMed), Embase (Ovid), Scopus, and Google Scholar for all relevant articles. We used Open[Meta]Analyst to pool the number of seizure-free patients after MRg-LITT treatment in a random-effects model. Risk ratios were calculated, and subgroups were analyzed. Comprehensive meta-analysis was used to assess publication bias via funnel plots, Egger's regression test, and Begg's correlation test. This review complies with the Preferred Reporting Items for Systematic Review and Meta-Analyses guidelines. After screening the titles, abstracts, and full texts, we included 17 articles in our meta-analysis, which revealed a 77.1% rate of seizure freedom (95% confidence interval 0.696–0.837, P < 0.001), with moderate heterogeneity (I2 = 49.46%). Subgroup analysis by study design and sensitivity analyses excluding 1 study at a time did not impact the results substantially, and we found no evidence of publication bias. Adverse effects included electrolyte imbalances, weight gain, and transient neurologic disturbances. MRg-LITT might be a feasible and effective technique for ablation of epileptic foci, leading to seizure freedom in a large proportion of patients with HH. However, there is a paucity of literature on the topic, and prospective clinical trials with larger number of participants comparing MRg-LITT to open surgery are needed. [ABSTRACT FROM AUTHOR]

Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) is a minimally invasive and effective treatment option that can potentially treat deep-seated pathologies in cases without safe open surgical corridors. In the present report, we have described our experience using MRgLITT for brainstem pathologies. A retrospective medical record review and analysis were conducted for all patients who had undergone MRgLITT for pathologies within or closely surrounding the brainstem between 2011 and 2020. The patients had undergone stereotactic laser placement in the operating suite and were transported to the magnetic resonance imaging suite for laser ablation with real-time monitoring. The demographics, operative parameters, and complications were recorded. A total of 12 patients had undergone MRgLITT for brainstem pathologies. The average age of the patients was 47.6 years (range, 4–75 years). The pathologies included both primary and metastatic intracranial tumors. The average preablation volume of the targets was 2.4 ± 0.50 cm3. The average ablation time was 324.3 ± 60.7 seconds, and the average postablation volume was 2.92 ± 0.53 cm3. One perioperative mortality was directly related to the procedure and 7 patients developed postoperative deficits. Two patients had experienced a recurrence after MRgLITT and opted to undergo additional alternative treatment. The brainstem represents formidable territory even for minimally invasive procedures. The overall morbidity and mortality has remained high, and the probability of achieving a meaningful outcome must be carefully assessed. [ABSTRACT FROM AUTHOR]

Objective: Corpus callosotomy is a safe and effective procedure for reducing the frequency of drop attacks. MR‐guided laser interstitial thermal therapy (MRgLITT) offers a minimally invasive alternative to conventional open craniotomy for callosotomy. We hypothesized that MRgLITT callosotomy could be safely performed in pediatric patients with similar seizure control. Methods: We present an institutional case series of 11 procedures in 10 patients for the treatment of drop attacks in drug‐refractory primary generalized epilepsy. MRgLITT was used for complete callosotomy, anterior two‐thirds, posterior, or ablation of residual callosal fibers following prior callosotomy (open or MRgLITT). We retrospectively reviewed clinical course, operative details, radiographic imaging, clinical outcomes, and complications. Results: Operative time ranged from 4‐8 hours, and median hospitalization was 2 days. No complications were encountered. Among the 7 patients with at least 3 months of follow‐up, 71% experienced freedom from drop attacks at longest follow‐up and 57% of cases showed improvement in their other seizure semiologies as well (Engel Class II: 28%, Class III: 28%, Class IV: 43%). Significance: MR‐guided LITT callosotomy is safe and effective modality in the management of pediatric patients with medically intractable epilepsy characterized by drop attacks. While this is among the largest pediatric series to date, further studies are required to delineate its safety and efficacy among such patients. [ABSTRACT FROM AUTHOR]

BACKGROUND AND PURPOSE: Magnetic resonance‐guided laser interstitial thermal therapy (MRgLITT) is a minimally invasive procedure that produces real‐time thermal damage estimates (TDEs) of ablation. Currently, MRgLITT software provides limited quantitative parameters for intraoperative monitoring, but orthogonal TDE‐MRI slices can be utilized to mathematically estimate ablation volume. The objective of this study was to model TDE volumes and validate using post‐24 hours MRI ablative volumes. METHODS: Ablations were performed with the Visualase Laser Ablation System (Medtronic). Using ellipsoidal parameters determined for dual‐TDEs from orthogonal MRI planes, TDE volumes were calculated by two definite integral methods (A and B) implemented in Matlab (MathWorks). Post‐24 hours MRI ablative volumes were measured in OsiriX (Pixmeo) by two‐blinded raters and compared to TDE volumes via paired t‐test and Pearson's correlations. RESULTS: Twenty‐two ablations for 20 patients with various intracranial pathologies were included. Average TDE volume calculated with method A was 3.44 ± 1.96 cm3 and with method B was 4.83 ± 1.53 cm3. Method A TDE volumes were significantly different than post‐24 hours volumes (P <.001). Method B TDE volumes were not significantly different than post‐24 hours volumes (P =.39) and strongly correlated with each other (r =.85, R2 =.72, P <.0001). A total of eight of 22 (36%) method A versus 17 of 22 (77%) method B TDE volumes were within 25% of the post‐24 hours ablative volume. CONCLUSION: We present a viable mathematical method integrating dual‐plane TDEs to calculate volumes. Future algorithmic iterations will incorporate additional calculated variables that improve ablative volume estimations. [ABSTRACT FROM AUTHOR]

Objective: Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) is a minimally invasive procedure that produces real-time thermal damage estimates (TDE) in orthogonal MRI-planes. The current system does not allow the user to quantify the TDE during the ablation process. We aim to characterize TDE dimensional expansion via a validated semi-automated algorithm. Methods: Selection criteria included single-laser catheter use, performed with the Visualase MRI-Guided Laser Ablation System. TDE lengths and widths relative to the laser path were calculated using a developed algorithm and validated with two raters’ manual measurements. MATLAB Blob Analysis was used to approximate TDE ellipsoidal major-minor axes. TDE length–width expansion was characterized by the power law f(x) = axk. Results: For analyses of 40 TDEs across 20 patients, minimal measurement differences, 0.2). No significant differences were observed between ratios of major-minor axes vs length–width (P = 0.19). For dynamic studies, 60 MRI planes across 30 patients were analyzed for linear regressions (R^2 = 0.70–0.99) from log-log plots of TDE dimensions vs time. Constant “a” for width (0.38 ± 0.17) was larger than length (0.28 ± 0.16) (P

Pediatric low-grade gliomas (LGGs) are found in approximately 1–3% of patients with childhood epilepsy that is often medically refractory. Magnetic resonance guided laser interstitial thermal therapy (MRgLITT) is a minimal access technique FDA-approved since 2007 to ablate soft tissue lesions including brain tumors and seizure foci in children. The authors describe the case of an 11-year-old boy who presented with focal right-sided seizures and was found to have a growing left insular mass determined to be a WHO grade II diffuse astrocytoma. After the initial open resection using frontotemporal craniotomy with transsylvian approach, gross total resection was achieved; however, the tumor recurred, as did the seizures. Six months postoperatively, the patient underwent laser ablation with MRgLITT for the recurrent tumor with complete removal. At both 1- and 6-months post re-operation, he has remained seizure free. MRgLITT management of LGG allows for both successfully reducing tumor burden and the amelioration of secondary seizures. [ABSTRACT FROM AUTHOR]

Introduction: Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) is a new technology that provides a clinically efficacious and minimally invasive alternative to conventional microsurgical resection. However, little data exist on how costs compare to traditional open surgery. The goal of this paper is to investigate the cost-effectiveness of MRgLITT in the treatment of pediatric epilepsy. Methods: We retrospectively analyzed the medical records of pediatric patients who underwent MRgLITT via the Visualase® thermal therapy system (Medtronic, Inc., Minneapolis, MN, USA) between December 2013 and September 2017. Direct costs associated with preoperative, operative, and follow-up care were extracted. Benefit was calculated in quality-adjusted life years (QALYs), and the cost-effectiveness was derived from the discounted total direct costs over QALY. Sensitivity analysis on 4 variables was utilized to assess the validity of our results. Results: Twelve consecutive pediatric patients with medically refractory epilepsy underwent MRgLITT procedures. At the last postoperative follow-up, 8 patients were seizure free (Engel I, 66.7%), 2 demonstrated significant improvement (Engel II, 16.7%), and 2 patients showed worthwhile improvement (Engel III, 16.7%). The average cumulative discounted QALY was 2.11 over the lifetime of a patient. Adjusting for inflation, MRgLITT procedures had a cost-effectiveness of USD 22,211 per QALY. Our sensitivity analysis of cost variables is robust and supports the procedure to be cost--effective. Conclusion: Our data suggests that MRgLITT may be a cost-effective alternative to traditional surgical resection in pediatric epilepsy surgery. [ABSTRACT FROM AUTHOR]

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Navika D Shukla, Allen L Ho, Arjun V Pendharkar, Eric S Sussman, Casey H Halpern Department of Neurosurgery, Stanford University, Stanford, CA, USA Abstract: Medically intractable epilepsy is associated with increased morbidity and mortality. For those with focal epilepsy and correlated electrophysiological or radiographic features, open surgical resection can achieve high rates of seizure control, but can be associated with neurologic deficits and cognitive effects. Recent innovations have allowed for more minimally invasive methods of surgical seizure control such as magnetic resonance-guided laser interstitial therapy (MRgLITT). MRgLITT achieves the goal of ablating seizure foci while preserving neuropsychological function and offering real-time feedback and monitoring of tissue ablation. This review summarizes the utilization of MRgLITT for mesial temporal lobe epilepsy and other seizure disorders. Overall, the efficacy of MRgLITT is comparable to that of open surgery and offers a less invasive approach in patients with significantly less morbidity. Keywords: laser ablation, MRgLITT, mesial temporal lobe epilepsy, epilepsy surgery, corpus callostomy

Objective: MRI-guided laser interstitial thermal therapy (MRgLITT) has recently gained interest as an ablative stereotactic procedure for intractable epilepsy, movement disorders, and brain tumors. Conventionally, a LITT system consists of a laser generator and cooled laser applicator, which is a fiber optic core surrounded by a sheath through which cooled fluid is pumped. However, this footprint can make the system bulky and nonmobile, limit the maximum depth of targeting, and increase the chances of breakdown. Herein, the authors conduct a preclinical assessment of a noncooled MRgLITT system in a porcine model., Methods: Three-tesla MRI was used to guide the in vivo placement of noncooled laser applicators in the porcine brain. The study consisted of a survival arm and terminal arm. The laser was activated at a power of 4-7 W for ≤ 180 seconds. Temperature changes were monitored using the MR thermometry software ThermoGuide in the survival arm (n = 5) or both ThermoGuide software and adjacently inserted thermal probes in the terminal arm (n = 3). Thermal damage was determined by the software using the temperature-time relationship of cumulative equivalent minutes at 43°C (CEM43). Temperatures calculated by the software were compared with those recorded by the temperature probes. The dimensions of thermal damage thresholds (TDTs; 2-9, 10-59, 60-239, ≥ 240 CEM43 isolines) given by MR thermometry were compared with the dimensions of irreversible damage on histopathological analysis., Results: There was a strong correlation between temperature recordings by ThermoGuide and those by thermal probes at both 4 mm (r = 0.96) and 8 mm (r = 0.80), with a mean absolute error of 0.76°C ± 2.13°C and 0.17°C ± 1.65°C at 4 and 8 mm, respectively. The area of 2-9 CEM43 was larger than the area of irreversible damage seen on histopathological analysis. The dimensions of the 10 and 60 CEM43 correlated well with dimensions of the lesion on histopathological analysis. A well-defined border (≤ 1 mm) was observed between the area of irreversible damage and healthy brain tissue., Conclusions: This preclinical assessment showed that the noncooled LITT system was able to precisely reach the target and create well-defined lesions within a margin of safety, without any adverse effects. MR thermometry software provided an accurate near-real-time temperature of the brain tissue, and dimensions of the lesion as visualized by the software correlated well with histopathological findings. Further studies to test the system's efficacy and safety in human subjects are in progress.

Purpose: Tuberous sclerosis (TSC) is a well-known cause of medically refractory epilepsy (MRE). Stereoencephalography-directed magnetic resonance-guided laser interstitial thermal therapy (SEEG-directed MRgLITT) is an emerging minimally invasive technique that appears aptly suited for the surgical management of TSC. Our aims are to present our experiences with patients who had undergone SEEG-directed MRgLITT to identify and treat cortical tubers responsible for clinical seizures and to perform an in-depth analysis of volumetric and thermal dynamic factors that may be related to seizure outcomes. Methods: We studied all pediatric patients with MRE due to TSC who underwent SEEG-directed MRgLITT, investigating seizure outcomes in relation to thermal dynamic and volumetric factors. Results: Eight cortical tubers from three pediatric patients were analyzed. Two of three patients had Engel I outcomes at last follow-up (median 18 months). Average A/T (ablation volume/tuber volume) ratio for Engel I outcomes was 1.28 (variance, 0.16) and 0.84 (variance, < 0.01) for all other outcomes (P = 0.035). There was a moderate positive correlation when comparing ablation energy to ablation volume (R2 = 0.65) in cortical tuber tissue. When the calcified tuber is excluded, the correlation is stronger (R2 = 0.77). Thus, the calculated energy needed to ablate 1 cm3 of cortical tuber tissue is 1263.6 J (calcified tuber) or 1089.5 J (non-calcified tuber). Conclusions: SEEG-directed MRgLITT appears to be a safe and effective technique in the management of pediatric patients with MRE due to TSC. The A/T ratio may be a useful indicator in predicting seizure outcomes. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the safety and efficacy of stereoelectroencephalography (sEEG) directed magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) in medically refractory insular epilepsy in pediatric patients, define the relationship between ablation volumes and seizure control, and analyze the relationship between thermal energy and ablation volumes.Methods: A single-institution, retrospective review of pediatric patients with insular epilepsy who underwent sEEG directed MRgLITT over a 10-month period was performed. Perioperative, imaging, and outcome data were analyzed. Seizure outcomes were determined based on Engel score (Engel I versus Engel II-IV). Insula and ablation volumes were measured, and the proportion of insula volume ablated was calculated. Thermal energy was calculated in joules.Results: Four patients underwent sEEG directed MRgLITT of insular epileptogenic foci. The ablation volume was higher in patients with Engel I outcome (3.93 cm3) compared to Engel II-IV outcome (1.02 cm3). The proportion of ablation to insula volume was lowest in patients with Engel II-IV outcome (25.09%). The mean energy requirement to create a unit volume of ablation in the insula is 1205.86 J. A linear trend was noted between thermal ablation energy and ablation volume (R2 = 0.884). Over a mean follow-up period of 104 days, three patients were seizure-free (Engel I), and one patient saw significant improvement in seizure frequency (Engel III).Conclusions: The proportion of insula ablated, as well as the volume of ablation, are related to seizure outcome with increasing ablation volumes corresponding to improved seizure control. Further analysis of insula laser ablation thermal dynamics and volumes is needed. [ABSTRACT FROM AUTHOR]

Introduction Magnetic resonance–guided laser interstitial thermal therapy (MRgLITT) and stereotactic radiosurgery (SRS) are 2 emerging minimally invasive procedures being increasingly used for surgical intervention in cases of medically intractable temporal lobe epilepsy (TLE). To date, no comparative analyses of these 2 procedures have been made. In the current study, we synthesized pooled data from existing studies in an attempt to present a systematic review and meta-analysis of seizure and clinical outcomes of the 2 procedures in patients with TLE. Methods The Population, Intervention, Comparator, and Outcome (PICO) approach and Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines were followed to perform an indirect meta-analysis of seizure and clinical outcomes between MRgLITT and SRS. Only studies reporting outcomes for patients with TLE were included in the current review. Results A total of 19 studies were included in the final analysis, giving a total of 415 TLE patients. Of those studies, 9 were on MRgLITT, with a total of 250 patients (60%), and 10 were on SRS, with a total of 165 patients (40%). We found that the overall seizure freedom rate was comparable between the 2 procedures (MRgLITT 50%, 95% confidence interval [CI] 44% to 56%, vs. SRS 42%, 95% CI 27% to 59%, P = 0.39). Similarly, among patients with lesional pathologic conditions only, the seizure freedom rate was comparable between the 2 procedures (MRgLITT 62%, 95% CI 48% to 74%, vs. SRS 50%, 95% CI 37% to 64%, P = 0.23). Compared with SRS, MRgLITT was associated with lower complication rates (MRgLITT 20%, 95% CI 14% to 26% vs. SRS 32%, 95% CI 20% to 46%, P = 0.06) but similar reoperation rates (15%, 95% CI 9% to 22% vs. 27%, 95% CI 12% to 46%, P = 0.31). Conclusions As minimally invasive procedures continue to gain popularity for use in surgery for epilepsy, it is imperative to evaluate their efficacy and safety outcomes. In this study we pooled the data from existing studies to compare the seizure and clinical outcomes in patients with TLE undergoing MRgLITT and SRS. We found similar outcomes and complications between the 2 procedures. Highlights • MRgLITT and SRS are 2 emerging minimally invasive surgical techniques for epilepsy surgeries. • The 2 procedures may have comparable rates of postoperative seizure freedom and reoperation. • MRgLITT may be associated with a lower complication rate. [ABSTRACT FROM AUTHOR]

Purpose: Magnetic resonance-guided laser-induced thermal therapy (MRgLITT) is a minimally invasive procedure used to treat various intracranial pathologies. This study investigated the effects of variable power on maximal estimated thermal damage during ablation and duration required to reach maximal ablation. Materials/Methods: All ablations were performed using the Visualase Thermal Therapy System (Medtronic Inc., Minneapolis, Minnesota), which uses a 980 nm diffusing tip diode laser. Cases were stratified into low, medium and high power. Maximal thermal damage estimate (TDEmax) achieved in a single plane and time to reach maximal damage (ttdemax) were measured and compared between groups using a 2×3 Fixed Factor Analysis of Covariance. Ablation area change for cases in which an initial thermal dose was followed by a subsequent dose, with increased power, was also assessed. Results: We used real-time ablation data from 93 patients across various intracranial pathologies. ttdemax (mean ± SEM) decreased linearly as power increased (low: 139.2 ± 10.4 s, medium: 127.5 ± 4.3 s, high: 103.7 ± 5.8 s). In cases where a second thermal dose was delivered at higher power, the TDE expanded an average of 51.4 mm2 beyond the initial TDE generated by the first ablation, with the second ablation approaching TDEmax at a higher rate than the initial ablation. Conclusion: Increased power results in a larger TDEmax and an increased ablation rate. In cases where an initial thermal dose does not fully ablate the target lesion, a second ablation at higher power can increase the area of ablation with an increased ablation rate. [ABSTRACT FROM AUTHOR]

Hypothalamic hamartoma is an archetypal example of subcortical epilepsy that can be associated with intractable gelastic epilepsy, secondary epilepsy, and epileptic encephalopathy. The history of its surgical treatment is fraught with mislocalization of the seizure focus, modest efficacy and a high complication rate. Many minimally invasive techniques have been described to mitigate this high complication profile of which MR-guided laser ablation is one. The technology combines instant effect of thermal coagulation with stereotactic precision and guidance with real time MR thermography. This article presents a series of 71 hypothalamic hamartoma patients operated with laser ablation. Ninety-three percent (93%) were free of gelastic seizures at one year with 23% of the patients requiring more than one ablation. One patient experienced a significant memory deficit and one patient experienced worsening diabetes insipidus. Stereotactic laser ablation appears to be a safe and effective surgical option in the treatment of hypothalamic hamartoma. [ABSTRACT FROM AUTHOR]

Copyright of Zeitschrift für Epileptologie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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.

Surgical treatment of focal epilepsy in the presence of periventricular nodular heterotopia (PVNH) poses a challenge, as the relative roles of the nodular tissue and the overlying cortex in the generation of seizures can be complex and variable. Here, we review the literature on chronic invasive EEG recordings in humans with this substrate and present two illustrative cases from our practice. We found that while inter-ictal spiking from nodules is common, clinical seizures rarely arise solely from nodular tissue. More typically, ictal onset is simultaneous with overlying neocortex or mesial temporal structures. Surgical outcome is more favorable in cases with unilateral (as opposed to bilateral) PVNH, and when a substantial or complete ablation of PVNH is performed. In rare cases, nodular ablation alone may be sufficient, as may be completed by MRI-guided laser interstitial thermal therapy. The mechanism(s) by which PNVH interacts with overlying cortex are not fully understood, but we suggest that PVNH either orchestrates or amplifies local network epileptogenicity. At present, invasive recordings with penetrating depth electrodes are required prior to surgical therapy, as illustrated in our cases. [ABSTRACT FROM AUTHOR]

Pre-operative scalp shaving is conventionally thought to simplify postoperative cranial wound care, lower the rate of wound infections, and ease optimal incision localization. Over the past few decades, some neurosurgeons have refrained from scalp shaving in order to improve patient satisfaction with brain surgery. However, this hair-sparing approach has not yet been explored in the growing field of magnetic resonance-guided laser interstitial thermal therapy (MRgLITT). This study investigated the initial impact of a no-shave technique on post-operative wound infection rate as well as on entry and target accuracy in MRgLITT for mesial temporal epilepsy. Eighteen patients selected by the Stanford Comprehensive Epilepsy Program between November 2015 and August 2017 were included in the study. All patients underwent functional selective amygdalohippocampotomies using MRgLITT entirely within a diagnostic MRI suite. No hair was removed and no additional precautions were taken for hair or scalp care. Otherwise, routine protocols for surgical preparations and wound closure were followed. The study was performed under approval from Stanford University’s Internal Review Board (IRB-37830). No post-operative wound infections or erosions occurred for any patient. The mean entry point error was 2.87 ± 1.3 mm and the mean target error was 1.0 ± 0.9 mm. There have been no other complications associated with this hair-sparing approach. The study’s results suggest that hair sparing in MRgLITT surgery for temporal epilepsy does not increase the risk of wound complications or compromise accuracy. This preferred cosmetic approach may thus appeal to epilepsy patients considering such interventions. [ABSTRACT FROM AUTHOR]

Purpose To evaluate a novel imaging sequence termed crushed rephased orthogonal slice selection (CROSS) that uses the available time in long echo time (TE) gradient echo (GRE) imaging-as employed for proton resonance frequency (PRF) shift thermometry-to simultaneously acquire two orthogonal magnetic resonance imaging (MRI) temperature maps around the target region. Materials and Methods The CROSS sequence encodes a second orthogonal slice between excitation and data readout in long-TE imaging and applies dedicated crusher (CR) gradients to separate the signals from the two slices. Numerical simulations of the Bloch equations and phantom experiments were performed to analyze the MR signal. In phantom and in vivo experiments with two domestic pigs, the applicability of the CROSS sequence for temperature mapping of thermal therapies with focused ultrasound and laser was studied. Results A successful separation of the signals from the two slices was achieved for CR dephasing lengths approaching the in-plane resolution. In the two animal experiments, CROSS temperature mapping could be successfully demonstrated at a temporal resolution of 2-3 seconds and a temperature uncertainty of 3-4K. Conclusion At the expense of a reduced signal in the overlap of the two slices, the CROSS sequence achieves an improvement of temporal resolution by 50%, without requiring further acceleration techniques such as parallel imaging, over conventional sequential GRE sequences employing the same repetition time as the CROSS sequence acquires two slices within one repetition interval. J. Magn. Reson. Imaging 2013;38:1510-1520. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

• Seizure outcomes following ablation of hypothalamic hamartomas are heterogeneous. • Differences in surgical targeting contribute to variability in postoperative outcomes. • A preoperative high-resolution hypothalamic atlas can inform surgical targeting. Large hypothalamic hamartomas (HH) are often associated with difficult-to-treat, refractory seizures. Although magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) has emerged as a useful tool to treat these challenging lesions, postoperative outcomes are variable and potentially related to differences in surgical targeting. We sought to identify differences in the anatomic localization of laser ablations that either did or did not result in seizure freedom. Four children who underwent MRgLITT for large HH (3 seizure-free and 1 not seizure-free) were included in the analysis. Ablation volumes were segmented, normalized, and overlaid on a high-resolution hypothalamic atlas. For each lesion, the size, spatial extent, and degree of overlap with key hypothalamic nuclei and surrounding brain regions were computed and compared between ablations that did and did not result in seizure freedom. Ablation masks that resulted in seizure freedom were smaller and located more centrally than the ablation mask that did not. In addition, ablation masks that resulted in seizure freedom overlapped with regions including the paraventricular nucleus, the posterior hypothalamus and the zona incerta, fornix, and mammillothalamic tract, whereas the single non-seizure-free ablation did not. Differences in the size, position, and anatomical localization of ablation volumes may be a potential contributor to the variability in postoperative outcomes of large HH treated with MRgLITT. A novel, high-resolution MRI atlas of the hypothalamus identifies a number of regions at the interface of large HH that are preferentially disconnected in seizure-free patients. This method of anatomical localization not only serves as a potential clinical tool for surgical targeting but may also provide novel insights into the mechanisms of epileptogenesis in hypothalamic hamartomas. [ABSTRACT FROM AUTHOR]

Laser interstitial thermal therapy (LITT) is increasingly used as a surgical option for the treatment of epilepsy. Placement of the laser fibers relies on stereotactic navigation with cranial fixation pins. In addition, the laser fiber is stabilized in the cranium during the ablation using a cranial bolt that assumes maturity of the skull. Therefore, younger infants (< 2 years of age) have traditionally not been considered as candidates for LITT. However, LITT is an appealing option for patients with familial epilepsy syndromes, such as tuberous sclerosis complex (TSC), due to the multiplicity of lesions and the likely need for multiple procedures. A 4-month-old infant with TSC presented with refractory focal seizures despite receiving escalating doses of 5 antiepileptic medications. Electrographic and clinical seizures occurred numerous times daily. Noninvasive evaluations, including MRI, magnetoencephalography, scalp EEG, and SPECT, localized the ictal onset to a left frontal cortical tuber in the premotor area. In this paper, the authors report a novel technique to overcome the challenges of performing LITT in an infant with an immature skull by repurposing the Navigus biopsy skull mount for stereotactic placement of a laser fiber using electromagnetic-based navigation. The patient underwent successful ablation of the tuber and remained seizure free 4 months postoperatively. To the authors' knowledge, this is the youngest reported patient to undergo LITT. A safe method is described to perform LITT in an infant using commonly available tools without dedicated instrumentation beyond standard stereotactic navigation, a biopsy platform, and the Visualase system.