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Purpose The definition of chronic adult hydrocephalus encompasses different pathological entities with overlapping characteristics, including long-standing overt ventriculomegaly in adults (LOVA), late-onset idiopathic aqueductal stenosis (LIAS) and idiopathic normal pressure hydrocephalus (iNPH). The aim of our study was to identify preoperative clinical and radiological features peculiar of these diseases providing some pathophysiology inferences on these forms of hydrocephalus. Methods Clinical and radiological preoperative records, type of surgical treatment and clinical outcome of patients with chronic adult hydrocephalus who were surgically treated between 2013 and 2019 were retrospectively reviewed. Univariate and multivariate analyses were performed to evaluate the contribution of each variable to the differential diagnosis. Results In total, 105 patients were included: 18 with LOVA, 23 with LIAS and 64 with iNPH. On multivariate analysis, an enlarged cisterna magna and a more severe ventriculomegaly were associated with the diagnosis of LOVA, while an older age and DESH with iNPH. LIAS patients tend to have an higher prevalence of raised ICP symptoms. Based on that, a clinical and radiological scoring system was developed to distinguish between iNPH and no iNPH cases. A precise cut-off value with a sensitivity of 95.1% and a specificity of 90.6% was identified. Conclusions LOVA, LIAS and iNPH are different forms of chronic adulthood hydrocephalus and present different and peculiar clinical and radiological features, with an impact on the treatment and outcome prediction. The implementation of a clinical-radiological score for differential diagnosis may help the differentiation. Further studies are warranted.

We describe a patient with focal epilepsy characterized by ictal asystole episodes and low-grade tumour over the left temporal neocortex. Non-invasive pre-surgical evaluation showed an epileptogenic zone extended beyond the low-grade tumour. This extension was confirmed by intraoperative electrocorticography. One-stage surgery with anterior temporal lobe resection was performed. The patient was seizure-free after one year of follow-up. Detailed electroclinical and therapeutic reasoning with hypotheses defining epileptogenic and symptomatogenic networks are discussed.

BackgroundPathological brain processes may induce adaptive cortical reorganization, however, the mechanisms underlying neuroplasticity that occurs in the presence of lesions in eloquent areas are not fully explained. The aim of this study was to evaluate functional compensatory cortical activations in patients with frontal brain gliomas during a phonemic fluency task and to explore correlations with cognitive performance, white matter tracts microstructural alterations, and tumor histopathological and molecular characterization.MethodsFifteen patients with frontal glioma were preoperatively investigated with an MRI study on a 3T scanner and a subgroup underwent an extensive neuropsychological assessment. The hemispheric laterality index (LI) was calculated through phonemic fluency task functional MRI (fMRI) activations in the frontal, parietal, and temporal lobe parcellations. Diffusion-weighted images were acquired for all patients and for a group of 24 matched healthy volunteers. Arcuate Fasciculus (AF) and Frontal Aslant Tract (FAT) tractography was performed using constrained spherical deconvolution diffusivity modeling and probabilistic fiber tracking. All patients were operated on with a resective aim and underwent adjuvant therapies, depending on the final diagnosis.ResultsAll patients during the phonemic fluency task fMRI showed left hemispheric dominance in temporal and parietal regions. Regarding frontal regions (i.e., frontal operculum) we found right hemispheric dominance that increases when considering only those patients with tumors located on the left side. These latter activations positively correlate with verbal and visuo-spatial short-term memory, and executive functions. No correlations were found between the left frontal operculum and cognitive performance. Furthermore, patients with IDH-1 mutation and without TERT mutation, showed higher rightward frontal operculum fMRI activations and better cognitive performance in tests measuring general cognitive abilities, semantic fluency, verbal short-term memory, and executive functions. As for white matter tracts, we found left and right AF and FAT microstructural alterations in patients with, respectively, left-sided and right-side glioma compared to controls.ConclusionsCompensatory cortical activation of the corresponding region in the non-dominant hemisphere and its association with better cognitive performance and more favorable histopathological and molecular tumor characteristics shed light on the neuroplasticity mechanisms that occur in the presence of a tumor, helping to predict the rate of post-operative deficit, with the final goal of improving patients'quality of life.

ObjectiveThe aim of the present study is to evaluate a neurocognitive outcome in patients affected by late-onset idiopathic aqueductal stenosis (LIAS) who underwent endoscopic third ventriculostomy (ETV).Materials and MethodsA prospective study was conducted between January 2015 and December 2017 in a series of 10 consecutive adult patients referred to the Neurosurgery Department of IRCCS Istituto delle Scienze Neurologiche di Bologna, Bologna, Italy. All the adult patients admitted with absence of CSF flow through the aqueduct in phase-contrast (PC)—MRI sequences or a turbulence void signal in T2—weighted images in midsagittal thin-slice MR sequences underwent a specific neuroradiological, neurological, and neurocognitive assessment pre- and postoperatively.ResultsAll patients affected by gait and sphincter disturbances improved after ETV. Attentive and executive functions as well as visuo-spatial memory and verbal executive functions improved in several patients. Similarly, the affective and behavioral scales improved in almost 50% of the patients. No major complications have been recorded, and no patients required a second surgery for shunt placement.ConclusionEndoscopic third ventriculostomy represents a safe and effective surgical procedure for the treatment of LIAS. In addition to neurological improvement, we demonstrated also postoperative neurocognitive improvement mainly in attentive and executive functions, visuo-spatial memory, verbal executive functions, and behavioral and affective domains.

Radiofrequency thermocoagulation (RF-TC) is a wide-used procedure for drug-resistant epilepsy. The technique is considered safe with an overall risk of 1.1% of permanent complications, mainly focal neurological deficits. We report the case of a patient with drug-resistant epilepsy who complained of immediate seizure worsening and an unexpected event seven months following RF-TC. A 35-year-old male with drug-resistant epilepsy from the age of 18years underwent stereoelectroencephalography (SEEG) implantation for a right peri-silvian polymicrogyria. He was excluded from surgery due to extent of the epileptogenic zone and the risk of visual field deficits. RF-TC was attempted to ablate the most epileptogenic zone identified by SEEG. After RF-TC, the patient reported an increase in seizure severity/frequency and experienced episodes of postictal psychosis. Off-label cannabidiol treatment led to improved seizure control and resolution of postictal psychosis. Patients with polymicrogyria (PwP) may present with a disruption of normal anatomy and the co-existence between epileptogenic zone and eloquent cortex within the malformation. RF-TC should be considered in PwP when they are excluded from surgery for prognostic and palliative purposes. However, given the complex interplay between pathological and electrophysiological networks in these patients, the remote possibility of clinical exacerbation after RF-TC should also be taken into account.

Background: Tractography has been widely adopted to improve brain gliomas' surgical planning and guide their resection. This study aimed to evaluate state-of-the-art of arcuate fasciculus (AF) tractography for surgical planning and explore the role of along-tract analyses in vivo for characterizing tumor histopathology.Methods: High angular resolution diffusion imaging (HARDI) images were acquired for nine patients with tumors located in or near language areas (age: 41 ± 14 years, mean ± standard deviation; five males) and 32 healthy volunteers (age: 39 ± 16 years; 16 males). Phonemic fluency task fMRI was acquired preoperatively for patients. AF tractography was performed using constrained spherical deconvolution diffusivity modeling and probabilistic fiber tracking. Along-tract analyses were performed, dividing the AF into 15 segments along the length of the tract defined using the Laplacian operator. For each AF segment, diffusion tensor imaging (DTI) measures were compared with those obtained in healthy controls (HCs). The hemispheric laterality index (LI) was calculated from language task fMRI activations in the frontal, parietal, and temporal lobe parcellations. Tumors were grouped into low/high grade (LG/HG).Results: Four tumors were LG gliomas (one dysembryoplastic neuroepithelial tumor and three glioma grade II) and five HG gliomas (two grade III and three grade IV). For LG tumors, gross total removal was achieved in all but one case, for HG in two patients. Tractography identified the AF trajectory in all cases. Four along-tract DTI measures potentially discriminated LG and HG tumor patients (false discovery rate < 0.1): the number of abnormal MD and RD segments, median AD, and MD measures. Both a higher number of abnormal AF segments and a higher AD and MD measures were associated with HG tumor patients. Moreover, correlations (unadjusted p < 0.05) were found between the parietal lobe LI and the DTI measures, which discriminated between LG and HG tumor patients. In particular, a more rightward parietal lobe activation (LI < 0) correlated with a higher number of abnormal MD segments (R = −0.732) and RD segments (R = −0.724).Conclusions: AF tractography allows to detect the course of the tract, favoring the safer-as-possible tumor resection. Our preliminary study shows that along-tract DTI metrics can provide useful information for differentiating LG and HG tumors during pre-surgical tumor characterization.

Recently, endoscopic approaches for orbital lesions have been proposed. Their results seem promising; however, orbital surgery remains challenging with possible significant morbidity, mostly because of orbital structures manipulation. Ultrasonography is an innovative intraoperative imaging technique that can assist the surgeon in these approaches.To assess the role of intraoperative ultrasound (IOUS) in endoscopic orbital surgery.All consecutive patients with orbital tumors operated in our institution through an endoscopic approach with IOUS have been prospectively collected from 2019 to May 2021.Fifteen patients were included. Based on tumor location, evaluated on preoperative MRI, the endoscopic endonasal approach was preferred in 7 tumors in medial quadrants while the endoscopic transpalpebral in 8 lateral ones. During surgery, IOUS allowed us to identify the tumors and the most relevant anatomic structures in all cases. Time spent for IOUS preparation before the first scan was 8 ± 6 minutes on average, and each intraoperative scan took approximately 30 to 120 seconds. Gross tumor removal was achieved in 8 patients, subtotal in 3, while in 4 patients, surgery was limited to a biopsy. No surgical complications were observed.IOUS has allowed us to localize the lesion and to identify the straighter surgical corridor and assess the tumor resection, effectively helping the surgeon and potentially reducing operative complications. This tool provides a real-time image, not affected by the orbital structures shift, which can be dynamically assessed multiple times during surgery. However, it is hampered by the need of specific training and possible artifacts.

BACKGROUND: Glioblastoma with multiple localizations (mGBMs) can be defined as multifocal, where enhancing lesions present a connection visible on magnetic resonance imaging fluid-attenuated inversion recovery imaging, or multicentric, in the absence of a clear dissemination pathway. OBJECTIVE: To evaluate the role of the extent of resection (EOR) in the treatment of mGBMs and its correlation with overall survival (OS) and progression free survival (PFS). METHODS: One hundred patients with mGBMs were treated at our Institution between 2009 and 2019. Clinical, radiological, and follow-up data were collected. EOR of the contrast-enhancing part of lesions was classified as gross total resection (GTR, absence of tumor remnant), subtotal resection (STR, residual tumor30%of the initial mass), and needle or open biopsy (residual tumor>75%of the initial mass). RESULTS: Approximately 15% of patients underwent GTR, 14% STR, 32% PR, and 39% biopsy. Median OS was 17 mo for GTR, 11 mo for STR, 7 mo for PR, and 5 mo for biopsy. Greater EOR was associated with a significantly longer OS than biopsy. GTR and STR were associated with a longer PFS in Kaplan-Meier survival analyses. After adjusting for age, Karnofsky performance status (KPS), number of lesions, and adjunctive therapy in multivariable Cox regression analyses, GTR, STR, and PR were still associated with OS, but only GTR remained associated with PFS. CONCLUSION: Our study suggests that EOR may positively influence survival of patients with mGBM. Surgical resection can be a reasonable option when performance and access to adjuvant treatment can be preserved.

Objective: We describe a multicenter experience with VNS implantation in pediatric patients with epileptic encephalopathy. Our goal was to assess VNS efficacy and identify potential predictors of favorable outcome. Methods: This was a retrospective study. Inclusion criteria were: ≤18 years at the time of VNS implantation and at least one year of follow-up. All patients were non-candidates for excisional procedures. Favorable clinical outcome and effective VNS therapy were defined as seizure reduction >50%. Outcome data were reviewed at one, two, three and five years after VNS implantation. Fisher's exact test, Kaplan-Meier and multiple logistic regression analysis were employed. Results: Twenty-seven patients met inclusion criteria. Responder rate (seizure frequency reduction ≥ 50%) at one-year follow-up was 25.9%, and 15.3% at last follow-up visit. The only variable significantly predicting favorable outcome was time to VNS implantation, with the best outcome achieved when VNS implantation was performed within five years of seizure onset (overall response rate of 83.3% at one year of follow-up and 100% at five years). In total, 63% of patients evidenced improved QOL at last follow-up visit. Only one patient exited the study due to an adverse event at two years from implantation. Significance: Early VNS implantation within five years of seizure onset was the only predictor of favorable clinical outcome in pediatric patients with epileptic encephalopathy. Improved QOL and a very low incidence of adverse events were observed.

Objectives The Leucine-rich glioma inactivated 1 (LGI1) protein is thought to be implicated in malignant progression of glioma tumors, and mutations in the encoding gene, LGI1, cause autosomal dominant lateral temporal epilepsy, a genetic focal epilepsy syndrome. The aim of this study was to investigate the possible involvement of LGI1 in high-grade glioma-associated epilepsy by analyzing its expression in tumor specimens of patients with and without epilepsy and by searching for LGI1 autoantibodies in the sera these patients. Patients and methods We examined tumor tissue samples from 24 patients with high-grade gliomas (12 with and 12 without epilepsy) by immunoblot and detected variable amounts of LGI1 in tumor tissues from 9/24 (37%) patients. Results LGI1 was detected in 7/12 (58%) patients with epilepsy and in 2/12 (16%) patients without epilepsy (p = 0.0894; Fisher’s exact test). Moreover, testing blood sera of five patients for antibodies against LGI1 revealed LGI1 autoantibodies in two patients, both suffering from epilepsy and expressing LGI1 in tumor tissue. Conclusion Our findings suggest that there may be a preferential expression of LGI1 in high-grade glioma tumors of patients with epilepsy. We also unveil the presence of serum LGI1 autoantibodies in some patients with high-grade gliomas, where they might play an epileptogenic role.

Patients with hypothalamic hamartomas (HHs) located at the level of the mammillary bodies may present with a peculiar epileptic syndrome characterized by gelastic seizures and, commonly, falls.(1-4) Associated symptoms can include developmental delay, cognitive deterioration, psychiatric disorders, central precocious puberty, and sleep disturbances.(1,4-6) Here, we report the case of an adult patient with HH and excessive daytime sleepiness (EDS) in whom CSF analysis disclosed low levels of hypocretin-1, a finding consistently observed in patients with type 1 narcolepsy.(7)

Focal cortical dysplasia (FCD) type IIb is a frequent cause of pharmacoresistant epilepsy. However, intraoperative identification of the pathological tissue still remains a challenge despite the use of neuronavigation, particularly when it lies in eloquent areas. We here report a case of intraoperative identification of a right frontal FCD type IIB through ultrasound assisted neuronavigation during awake surgery in a patient with drug-resistant epilepsy. Intraoperative ultrasound may have a role in focal cortical dysplasia localization optimizing its resection. In selected patient submitted to epilepsy surgery the integration of disposable technologies (i.e. brain neuronavigation, fMRI and iUS) with awake surgery could improve FCD identification preventing unacceptable neurological morbidity.

Background During surgery in the posterior fossa in the prone position, blood can sometimes fill the surgical field, due both to the less efficient venous drainage compared to the sitting position and the horizontally positioned surgical field itself. In some cases, blood clots can wedge into the cerebral aqueduct and the third ventricle, and potentially cause acute hydrocephalus during the postoperative course. Objective To illustrate a technique that can be used in these cases: the use of a flexible scope introduced through the opened roof of the fourth ventricle with a freehand technique allows the navigation of the fourth ventricle, the cerebral aqueduct, and the third ventricle in order to explore the cerebrospinal fluid pathways and eventually aspirate blood clots and surgical debris. Methods We report on one patient affected by an ependymoma of the fourth ventricle, for whom we used a flexible neuroendoscope to explore and clear blood clots from the cerebral aqueduct and the third ventricle after the resection of the tumor in the prone position. Blood is aspirated with a syringe using the working channel of the scope as a sucker. Results A large blood clot that was lying on the roof of the third ventricle was aspirated, setting the ventricle completely free. Other clots were aspirated from the right foramen of Monro and from the optic recess. Conclusion We describe this novel technique, which represents a safe and efficient way to clear the surgical field at the end of posterior fossa surgery in the prone position. The unusual endoscopic visual perspective and instrument maneuvers are easily handled with proper neuroendoscopic training.

Background Hippocampal sclerosis (HS) is the most common cause of drug-resistant medial temporal lobe epilepsy (MTLE). Structural abnormalities such as HS, granule cell pathology (GCP), and focal cortical dysplasia (FCD) have been classified histopathologically, possibly allowing a more accurate assessment of prognostic seizure and neuropsychologic outcomes. We correlated seizure outcome with comprehensive temporal lobe pathologic findings, identified according to the most recent classification systems of HS, GCP, and FCD. Methods All the 83 patients who underwent anterior temporal lobectomy (ATL) for drug-resistant MTLE and with a proven diagnosis of HS between April 2001 and May 2014 were collected. Patients were divided in 2 main groups: 1) isolated HS with/without GCP (HS +/- GCP); and 2) HS associated with FCD with/without GCP (HS+FCD +/- GCP). Patients were followed up at least 1 year, and seizure outcome was reported in accordance with Engel classification. Results Group I: HS +/- GCP: Statistical analysis confirmed a better outcome in HS + GCP patients than in HS-no GCP (P < 0.05). Moreover, a better outcome for the patients affected by GCP type I was observed (P < 0.05). Group II: HS+FCD +/- GCP: Patients with HS variant type I presented a better seizure outcome than the patients with HS type II (Engel class IA HS type I vs. type II: 69% vs. 40%). Conclusions A pathology-based approach to epilepsy surgery might improve the interpretation of the results, could predict which cases will enjoy a better seizure outcome, and could help to the comprehension of the causes of failures.

The aim of this study was to verify the presence of BRAF mutations in a series of six patients affected by drug-resistant focal epilepsy associated with neocortical posterior temporal gangliogliomas (GG) who were subjected to lesionectomy between June 2008 and November 2013. GG are an increasingly recognized cause of epilepsy and represent the most common tumor in young patients undergoing surgery for intractable focal epilepsy. BRAF mutations have been identified in up to 50% of GG. Interestingly, these six patients shared a specific anatomical posterior temporal site. In all patients, histological examination confirmed the diagnosis of GG, and two were also associated with a focal cortical dysplasia (FCD) type IIa. BRAF mutations were found in four out of six GG (66.6%). Furthermore, dysplastic tissue of Patient 2 showed a concomitant BRAF V600E mutation. All patients but one (83.3%) achieved Engel Class Ia seizure control. The patient carrying a concomitant BRAF mutation in GG and FCD fell into Engel Class II. Further analyses will be required in order to better understand the meaning of BRAF mutations in epilepsy-associated tumors and FCD and their possible role as a prognostic seizure outcome and tumor behavior marker.

none 28 no Objective: To analyze the attitude and results of Italian epilepsy surgery centers in the surgical management of “low grade epilepsy associated neuroepithelial tumors” (LEATs). Methods: We conducted a retrospective study enrolling 339 consecutive patients with LEATs who underwent surgery between January 2009 and June 2015 at eight Italian epilepsy surgery centers. We compared demographic, clinical, pathologic, and surgical features of patients with favorable (Engel class I) and unfavorable (Engel class II, III, and IV) seizure outcome. In addition, we compared patients with tumor-associated focal cortical dysplasia (FCD) and patients with solitary tumors to identify factors correlated with FCD diagnosis. Results: Fifty-five (98.2%) of 56 patients with medically controlled epilepsy were seizure-free after surgery, compared to 249 (88.0%) of 283 patients with refractory epilepsy. At multivariate analysis, three variables independently predict unfavorable seizure outcome in the drug-resistant group. Age at surgery is largely the most significant (p = 0.001), with an odds ratio (OR) of 1.04. This means that the probability of seizure recurrence grows by 4% for every waited year. The resection site is also significant (p = 0.039), with a relative risk (RR) of 1.99 for extratemporal tumors. Finally, the completeness of tumor resection has a trend toward significance (p = 0.092), with an RR of 1.82 for incomplete resection. Among pediatric patients, a longer duration of epilepsy was significantly associated with preoperative neuropsychological deficits (pÂ

Both temporal lobe meningoencephalocele (TE) and hippocampal sclerosis (HS) are causes of drug-resistant temporal lobe epilepsy. Spontaneous TE constitutes a rare but well-known and increasingly recognised cause of refractory epilepsy. It is well known that HS may be associated with another neocortical lesion (dual pathology). Here we report for the first time a new type of dual pathology; namely, the coexistence of temporal pole meningoencephalocele and HS.

Left-handers have a more bilateral language representation than right-handers. Therefore, in left-handers with a low-grade glioma (LGG) in the left hemisphere (LH), one could hypothesize that the right hemisphere (RH) might allow language compensation, at least partly, with no or only a minor persistent role of the LH in speech. However, although LGG induces language reorganization in right-handed patients, little is known in left-handers. Here, we report the first series of left-handers who underwent awake surgery for a left LGG using intraoperative mapping, in order to investigate whether there was still an involvement of LH in language. Ten consecutive left-handed patients were operated for a left LGG (three frontal, four paralimbic, one parietal, one temporal, one parieto-temporal tumor) using an awake procedure with intraoperative electrical language mapping. Intraoperative language disorders were elicited in all cases but one by electrostimulation in the LH. Cortical language sites were detected in nine cases. Subcortical stimulation also demonstrated the crucial role of left white matter pathways in language, including the inferior occipital-frontal fascicle, arcuate fascicle, lateral segment of the superior longitudinal fascicle and fibers from the ventral premotor cortex. Moreover, stimulation of deep gray nuclei generated language disturbances in four patients. These nine patients experienced transient postoperative language worsening, supporting the persistent critical role of LH in speech. In only one patient, no language deficit was evoked intraoperatively and postoperatively. The ten patients returned to a normal life. Total or subtotal resection was achieved in all cases but one. Our results suggest that, even though the RH may participate in language compensation, the LH in left-handers still plays a crucial role, despite a left slow-growing LGG. Thus, we propose to routinely consider awake surgery for left LGG removal in left-handers patients, to optimize the extent of resection while preserving language.

Objective Focal cortical dysplasias (FCDs) represent a common architectural cortical disorder underlying pharmacoresistant focal epilepsy. The recent ILAE classification defines different types of FCDs based on their histopathological features, MRI imaging, and presumed pathogenesis; however, their clinical features and their prognostic significance are still incompletely defined. In addition, the combination of different histopathological abnormalities can represent “unusual” subtypes that can be difficult to classify. The aim of our study was to analyze the incidence and the significance of these “unusual” subtypes of FCDs in drug-resistant mesial temporal lobe epilepsy (MTLE). Methods We retrospectively analyzed 133 patients consecutively submitted to tailored anteromesial temporal lobe resection for pharmacoresistant MTLE. Seizure onset, seizure duration, age at surgery, and postoperative seizure outcome were evaluated in relation to the different neuropathological groups defined according to the new ILAE classification. Results Focal cortical dysplasias were found in 80 out of 133 patients. Six patients were affected by isolated FCD type I, 12 patients by FCD type II, and 44 patients by FCD type III. Furthermore, we found 18 “atypical” cases (20.5% of all FCD cases and 26.6% of FCDs associated with a principal lesion): 10 cases of associated FCD type II–hippocampal sclerosis (HS) and 8 cases associated with FCD II–epilepsy-associated tumors (EATs). Conclusion Our results indicate that “unusual” subtypes of FCDs, in particular associated FCD type II, are not uncommon findings, suggesting that they deserve a classification recognition. Similarities in seizure outcome and immunohistochemical and molecular evidences, shared by FCD type II + EATs and EATs, suggest a common pathogenic link. The choice to create a specific unifying class or, on the contrary, to also include “associated FCD type II” in the definition of the new unifying class FCD type III should be further discussed.

Dysembryoplastic neuroepithelial tumors (DNTs) are usually located within the supratentorial cortex, often in the temporal lobe and they are frequently associated with intractable complex partial seizures. DNTs in extracortical sites are rare. Thus far, 21 cases of 36 DNT-lesions occurring in these areas have been reported; only 8 out of them had epilepsy. We report a case of a 39-year-old woman who had pharmacoresistant epilepsy associated to a DNT in the caudate nucleus-periventricular area treated by lesionectomy. During a 4-year follow-up period, the patient was seizure free and the tumor did not recur. We discuss the hypothetical epileptogenic mechanism involved and we review the pertinent literature.

BRAF alterations, namely BRAF fusion and BRAF V600E mutation, have been recently reported in low-grade epilepsy-associated tumors. Twenty low-grade epilepsy-associated tumors were retrieved to evaluate the BRAF mutational status. BRAF mutations were present in 10 tumors and concomitantly in associated dysplastic tissue of three patients. We here show for the first time that BRAF mutations are present not only in low-grade epilepsy-associated tumors but, in some cases, also in the associated focal cortical dysplasia.

Marco Giulioni *, Laura Licchetta , Francesca Bisulli , Guido Rubboli , Barbara Mostacci , Gianluca Marucci , Matteo Martinoni , Lorenzo Ferri , Lilia Volpi , Fabio Calbucci , Agostino Baruzzi , Paolo Tinuper b,c a IRCCS Istituto delle Scienze Neurologiche di Bologna, Division of Neurosurgery, AUSL di Bologna, Italy b IRCCS Istituto delle Scienze Neurologiche di Bologna, AUSL di Bologna, Italy Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy d IRCCS Istituto delle Scienze Neurologiche di Bologna, Division of Neurology, AUSL di Bologna, Italy Danish Epilepsy Center, Epilepsihospitalet, Dianalund, Denmark f Section of Pathology ‘‘M. Malpighi’’ at Bellaria Hospital, Department of Biomedical and Neuro Motor Sciences, University of Bologna, Bologna, Italy

Magnetic resonance imaging (MRI) is mandatory to identify the epileptogenic zone in refractory temporal lobe epilepsy (TLE). The correct identification of lesions is essential to obtain good post-surgery seizure control. Low grade tumours (LGT) and focal cortical dysplasia (FCD) are common findings in symptomatic TLE, and frequently coexist. The aim of this study was to identify the MRI characteristics in the diagnosis of FCD associated with LGT. We analyzed 24 subjects with TLE who underwent tailored surgery. They all had LGTs. Two expert neuroradiologists analyzed the imaging data and compared them with histological results, hypothesizing the causes of diagnostic errors in the identification of FCD. We selected three exemplary cases to report the most important causes of errors. In the diagnosis of FCD we reported false positives and false negatives due to different causes. An incomplete MRI protocol, the large dimensions of the tumour, infiltration and related oedema were the most important factors limiting MRI accuracy. MRI can be limited by an incomplete protocol. In addition, the presence of an LGT may limit the neuroradiological diagnosis of FCD in the temporal lobe. Advanced MRI techniques could help reveal subtle lesions that eluded a previous imaging inspection.

BACKGROUND AND IMPORTANCE Arachnoid cysts within the fourth ventricle have rarely been reported in the literature. Different procedures have been performed to restore a normal cerebrospinal fluid dynamic or pressure, including shunting and partial or complete excision of the cyst by open microsurgery. Cerebrospinal fluid shunts give only partial improvement of symptoms and are prone to malfunctions. The microsurgical excision of the cyst seems to offer the best chance of success. CLINICAL PRESENTATION We report the case of a fourth ventricle arachnoid cyst successfully treated with a complete endoscopic cerebral procedure via the third ventricle. CONCLUSION Endoscopic fenestration of fourth ventricle arachnoid cysts may be considered an effective neurosurgical treatment.

Unfortunately, the affiliation of the author name, Antonella Bacci, was incorrectly listed as Antonella Bacci(1) instead of Antonella Bacci(3), and the affiliations were incorrectly listed as (1) Department of Neurosurgery, IRCCS Neurological Research Hospital; Bologna, Italy - (2) Section of Pathology "M. Malpighi", Bellaria Hospital, Azienda USL of Bologna, Bologna, Italy instead of (1) Department of Neurosurgery, (3) Department of Neuroradiology, IRCCS Neurological Research Hospital; Bologna, Italy. (2) Section of Pathology "M. Malpighi", Bellaria Hospital, Azienda USL of Bologna, Bologna, Italy in the original publication of this paper.

The number of implanted vagal nerve stimulators is growing and the need for removal or revision of the devices will become even more frequent. A significant concern about Vagus Nerve Stimulation (VNS) therapy is the presence of the spiral stimulating electrodes, wrapped around the nerve, once treatment is considered ineffective or is no longer desired. Our purpose is to demonstrate the feasibility of complete removal and replacement of the vagal nerve stimulator electrodes using microsurgical technique even after a long period, without damaging the nerve. We attempted removal and replacement of spiral stimulating electrodes from a patient who received a 10-year long VNS therapy for drug-resistant epilepsy. Our results indicate that the spiral electrodes may be safely removed from the vagus nerve, even after several years. The reversibility of lead implantation may enhance the attractiveness of VNS therapy. Furthermore, with a correct microsurgical technique, it is possible to respect the normal anatomy and functionality of vagal nerve and to reimplant a new VNS system with all its components, maintaining the same therapeutic efficacy after many years.

Dear Editor, We have read with great interest the exhaustive paper of Seifman et al. about “Postoperative intracranial haemorrhage: a review” published inNeurosurgical Review January 2011 [10]. However, we think that the chapter “remote intracranial haemorrhage” particularly the emerging field of “remote cerebellar hemorrhage” deserves further elaboration and attempts to highlight and clarify the pathogenetic mechanisms. Cerebellar haemorrhage after supratentorial craniotomy has been reported in 0.6–4.9% of all supratentorial craniotomies particularly after unruptured aneurysms surgery, epilepsy surgery and spinal surgery with opening of the dura [1–7, 9, 10, 12]. Although its venous origin has been recognised, the pathogenesis of cerebellar haemorrhage is unclear. Haemorrhage is often characterised by a typical, streaky bleeding pattern due to blood spreading in the upper cerebellar vermis and foliae (“Zebra sign”) [1]. The proposed pathogenetic mechanisms include: (a) increase of venous and venular transmural pressure due to the reduction of intracranial pressure caused by removal of a space-occupying mass and enhanced by CSF drainage; (b) increase of venous pressure as a consequence of head position; (c) tearing of superior vermian veins due to mechanical shifting of the cerebellum which results from intraoperative and or postoperative CSF withdrawal; and (d) transtentorial pressure gradient between the supratentorial and infratentorial venous system due to withdrawal of CSF [1, 8, 11, 12]. In our opinion, cerebellar haemorrhage may be caused by an increase in transmural venous pressure (intravascular venous pressure minus extravascular pressure; that is, in normal status, equal to intracranial pressure) related either to venous pressure rise favoured by head position or to intracranial pressure decrease determined by CSF withdrawal or through the concomitance of both factors. We suggest that the main decisive critical factor for this peculiar complication is a “normal” intracranial pressure [5]. This feeling originates from the fact that surgery for unruptured aneurysms, drug-resistant temporal lobe epilepsy and spine pathology shares a condition of normal intracranial pressure. A state of normal intracranial pressure makes transmural pressure forces balance at level of venous–venular system more sensitive to changes related either to an increase of venous pressure and/or to CSF withdrawal. The rare occurrence of cerebellar haemorrhage when surgery is performed in conditions of high intracranial pressure, such as in ruptured aneurysms, also supports our point of view. Therefore, in order to avoid remote cerebellar haemorrhage, above all when surgery is performed in state of likely normal intracranial pressure, special attention should be paid, during the pre-, intraand postoperative management, to the factors related to the increase of transmural venous pressure such as head position, CSF withdrawal and drugs that reduce intracranial pressure [5].

Various subtypes of intracerebral hamartomas, associated with seizure disorders, have long been described. We describe a cerebral hamartoma placed in the left frontal lobe, associated with drug-resistant epilepsy, composed exclusively of mature oligodendroglial cells. The patient was a 27-year-old right-handed male presenting with severe epileptic encephalopathy and symptoms of behavior dysfunction (disinhibition, rage attacks) associated with a left frontal lesion. Magnetic resonance imaging revealed a small area iso-hypointense compared to the gray matter in T1-weighted sequences not enhancing after gadolinium contrast injection in the left frontal site. On histology, a cortical lesion composed of large aggregates of oligodendroglial cells, with round central nuclei and clear perinuclear halos, was observed. Neither mitotic figures nor necrosis were present. Reactivity for Ki67 and P53 was not found. The lesion was well demarcated from the adjacent brain parenchyma and perineuronal satellitosis was not observed in the cortex. In conclusion, albeit extremely rare, recognition of oligodendroglial hamartoma and its distinction from other epileptogenic lesions as dysembryoplastic neuroepithelial tumor or above all oligodendroglioma have important therapeutic and prognostic implications.

We describe a 17-year-old boy with a left extraventricular temporo-mesial neurocytoma associated with cortical dysplasia causing focal pharmacoresistant temporal lobe epilepsy. He presented with a long history of medically refractory, temporal complex partial seizures. MRI showed a left temporo-mesial lesion suspect to be a low-grade tumor. Based on the pre-operative non-invasive neurophysiological studies, the patient underwent a left tailored temporal antero-mesial resection. Histopathological examination showed an extraventricular neurocytoma associated with architectural dysplasia (Type 1a) of the temporal pole. The patient was seizure-free at 2 years follow-up. Extraventricular neurocytomas must be considered in the differential diagnosis of the plethora of low-grade tumors associated with focal epilepsy that typically involve the temporal lobe, and are frequently associated with focal cortical dysplasia.

Unfortunately, the affiliation of the author name, Antonella Bacci, was incorrectly listed as Antonella Bacci(1) instead of Antonella Bacci(3), and the affiliations were incorrectly listed as (1) Department of Neurosurgery, IRCCS Neurological Research Hospital; Bologna, Italy - (2) Section of Pathology "M. Malpighi", Bellaria Hospital, Azienda USL of Bologna, Bologna, Italy instead of (1) Department of Neurosurgery, (3) Department of Neuroradiology, IRCCS Neurological Research Hospital; Bologna, Italy. (2) Section of Pathology "M. Malpighi", Bellaria Hospital, Azienda USL of Bologna, Bologna, Italy in the original publication of this paper.

Sir, We read with great interest the paper by Barba et al. (2015), recently published in Brain . This study is an effort to investigate deeper those patients who ‘fail’ anterior temporal lobectomy for intractable epilepsy associated with hippocampal sclerosis or ‘normal’ MRI. We congratulate the authors for their excellent analysis of factors involved in temporal lobe epilepsy surgery failures. They demonstrated four predictors of seizure relapse: temporal plus epilepsy ( P < 0.001), postoperative hippocampal remnant ( P = 0.001), past history of traumatic or infectious brain insult ( P = 0.022), and secondary generalized tonic-clonic seizures ( P = 0.023). Risk of temporal lobe surgery failure was 5.06 (95% confidence interval (CI): 2.36–10.382) greater in patients with temporal plus epilepsy than in those with unilateral temporal lobe epilepsy. We agree with the authors about the importance to identify factors predicting seizures outcome, to better understand causes of epilepsy surgery ‘failure’. However there is a noteworthy limitation in this study, as the authors do not mention the histological diagnoses of the resected specimens. In our opinion, more attention should be paid to referring …