Characteristics and management of the offending veins in microvascular decompression surgery for trigeminal neuralgia.

The optimal technique of microvascular decompression (MVD) for trigeminal neuralgia (TN) caused by venous conflict remains unclear. The objectives of this study are to characterize the offending veins identified during MVD for TN and to evaluate intraoperative technique applied for their management. From 2007 till 2019, 308 MVD surgeries were performed in 288 consecutive patients with TN, and in 58 of them, pure venous conflict was identified. In 44 patients, the offending vein was interrupted, as was done for small veins arising from the cisternal trigeminal nerve (CN V) or its root entry zone (REZ) causing their stretching (19 cases), small veins on the surface of REZ (9 cases), transverse pontine vein (TPV) compressing REZ or distal CN V (12 cases), and superior petrosal vein (SPV) using flow conversion technique (4 cases). In 14 other cases, the offending vein was relocated, as was done for the SPV or the vein of cerebellopontine fissure (8 cases), TPV (3 cases), and the vein of middle cerebellar peduncle (3 cases). Complete pain relief after surgery was noted in 49 patients (84%). No one patient experienced major neurological deterioration. Postoperative facial numbness developed in 14 patients (24%), and in 8 of them, it was permanent. In 14 patients, MRI demonstrated venous infarction of the middle cerebellar peduncle, which was associated with the presence of any (P = 0.0180) and permanent (P = 0.0002) facial numbness. Ten patients experienced pain recurrence. Thus, 39 patients (67%) sustained complete pain relief at the last follow-up (median, 48 months), which was significantly associated with the presence of any (P = 0.0228) and permanent (P = 0.0427) postoperative facial numbness. In conclusion, in cases of TN, small offending veins arising from REZ and/or distal CN V and causing their stretching may be coagulated and cut. In many cases, TPV can be also interrupted safely or considered as collateral way for blood outflow. The main complication of such procedures is facial numbness, which is associated with the venous infarction of middle cerebellar peduncle and long-term complete pain relief.

[A Case of Segmental Arterial Mediolysis:Subarachnoid Hemorrhage Followed by Abdominal Bleeding].

We describe a case involving subarachnoid and intraperitoneal hemorrhage due to segmental arterial mediolysis(SAM). A 77-year-old female patient with sudden subarachnoid hemorrhage was immediately transferred to our institution. The hemorrhage was classified as grade 2 according to the World Federation of Neurosurgical Societies system. The patient was a non-smoker and did not drink alcohol regularly. A right internal carotid aneurysm was detected using CT angiography and was clipped during frontotemporal craniotomy. Bleeding was observed from the anterior wall of the internal carotid artery, and the tear was clipped. The patient had an uneventful postoperative course until sudden cardiopulmonary arrest eight days after craniotomy. She died of massive intraperitoneal hemorrhage. Autopsy revealed that the hemorrhage was due to dissection of the celiac artery. Tunica media denaturation was observed not only in the celiac artery, but also in the splenic and internal carotid arteries, which exhibited ruptured aneurysms, and the patient was diagnosed with segmental arterial mediolysis(SAM). SAM is an arterial degenerative disease affecting the medial layer of the arterial and dissecting walls. Multiple lesions are sometimes found. Radiographic imaging findings of SAM are similar to those of dissecting aneurysms, which are characterized by a single continuous dissection of the medial layer. As observed in this case, abdominal bleeding caused by SAM can occur after intracranial bleeding. When surgeons encounter unusual intracranial dissecting aneurysms, SAM should be considered as a differential diagnosis.

[Two Cases of Primary Intracranial Solitary Fibrous Tumor:Genetic Examination of NAB2-STAT6 Fusion and Its Association with Hemangiopericytoma].

Using whole exome and transcriptome sequencing, NAB2-STAT6 gene fusions have recently been identified in patients with solitary fibrous tumors (SFT). We report two cases of SFT in which NAB2-STAT6 fusions were identified. The patients were a 32-year-old man with a parasagittal tumor involving the superior sagittal sinus, and a 40-year-old man with a cerebellar convexity tumor partially involving the transverse sinus. Their tumors were gross totally resected and diagnosed to be SFT according to the following pathological findings:the tumors were composed of spindle cells with a patternless architecture, with prominent stromal collagen and staghorn vessels. An immunohistochemical study yielded positive results for CD34, CD99, and Bcl-2 and negative results for EMA, GFAP, and S100. The MIB-1 indexes were 13 and 7%, respectively. NAB2-STAT6 fusions were detected in both cases with a common fusion variant, NAB2ex6-STAT6ex16/17. We also identified NAB2-STAT6 fusions in two hemangiopericytomas diagnosed in the past with a common variant of NAB2ex6-STAT6ex16/17. These findings suggest that solitary fibrous tumor and hemangiopericytoma may be diagnosed based on the presence of NAB2-STAT6 fusion, and not classified separately because of the same genetic background.

[Clinical features of bilateral trigeminal neuralgia].

Among 238 patients with bilateral trigeminal neuralgia(TN)who visited our hospital between April 2007 and June 2014, 5(2%)were surgically treated by microvascular decompression(MVD). The initial symptom was on the right side in four and on both sides in one patient. Intervals between the initial and second onset on the other side(left)were two months, and four, six, and eight years. None of the patients showed involvement of the first branch of the trigeminal nerve. The patients with bilateral TN were younger than the 154 patients with unilateral TN who were treated surgically by MVD in this period(45 vs. 65 years), and the bilateral TN patients predominantly were women(4/5 vs. 99/154). In the surgical field, the trigeminal nerve and root entry zone were compressed more by veins in the bi lateral TN patients than in the unilateral TN(4/5 vs. 60/154, respectively)patients. We could not identify any differences in MRI CISS before versus after the onset of left trigeminal neuralgia, suggesting that compression is not the sole cause of the symptom.

[A case of cavernous sinus epidermoid: anatomical classification and surgical approach].

Epidermoid rarely appears in the cavernous sinus. We encountered a 41-year-old man with left abducens nerve palsy. A round-shaped, low-density lesion on CT was located lateral to the left cavernous sinus with a compressed and thinned lateral wall of the sphenoid sinus. We could not identify cranial nerves in the cavernous sinus, which was found to be packed with a non-enhanced, high-intensity tumor on both T1 and T2 MRI. Part of the tumor capsule and its pearly contents were removed with an intradural subtemporal approach, and an inner membranous layer with cranial nerves and a tumor capsule were seen at the bottom of the tumor cavity. Postoperatively, complete cure was achieved. Reviewing similar cases, we found 18 cavernous sinus epidermoids:extracavernous type in 5;interdural in 10;and intracavernous in 3. The interdural type could be further divided into two subtypes:superficial cavernous sinus and inner membranous types. The present case belongs to the former. Frontotemporal and subtemporal procedures via both intra- and extradural approaches are relatively safe for lesions except for the intracavernous type, because cranial nerves are not located in the lateral wall of the tumor. MRI provides more useful information on cranial nerves and aid in choosing a better treatment strategy.

[Trigeminal neuralgia caused by cerebellopontine angle lipoma:a case report and review of the literature].

A 59-year-old man presented with right trigeminal neuralgia of the second branch, which had been treated with carbamazepine. The pain could not be controlled adequately because of side effects. CT and MRI revealed a 2-cm lesion in the right cerebellopontine angle. Retrosigmoid lateral suboccipital craniectomy was performed, and a soft yellowish mass was found to be associated with the 5th, 7th, and 8th cranial nerves, anterior inferior cerebellar artery, and small vessels. The lipoma was partially resected from around the root entry zone(REZ)of the 5th nerve and small vessels were coagulated around the REZ. After surgery, there was no trigeminal neuralgia, but facial numbness and cerebellar signs were noted. Postoperative MRI showed decompression of the trigeminal nerve and venous infarction in the middle cerebellar peduncle. Reviewing similar cases, we found 19 lipoma patients presenting with trigeminal neuralgia. Symptoms of involvement of other cranial nerves were also present in 11 patients, and 14 were younger than 30 years old. Of 17 surgical cases, total resection was not attempted apart from one case. Although pain relief was achieved in all surgical cases, complications developed in 11. Surgery should be performed only in patients with disabling and uncontrolled symptoms.

Usefulness of Robotic Stereotactic Assistance (ROSA®) Device for Stereoelectroencephalography Electrode Implantation: A Systematic Review and Meta-analysis.

The aim of this study was to systematically review and meta-analyze the efficiency and safety of using the Robotic Stereotactic Assistance (ROSA®) device (Zimmer Biomet; Warsaw, IN, USA) for stereoelectroencephalography (SEEG) electrode implantation in patients with drug-resistant epilepsy. Based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, a literature search was carried out. Overall, 855 nonduplicate relevant articles were determined, and 15 of them were selected for analysis. The benefits of the ROSA® device use in terms of electrode placement accuracy, as well as operative time length, perioperative complications, and seizure outcomes, were evaluated. Studies that were included reported on a total of 11,257 SEEG electrode implantations. The limited number of comparative studies hindered the comprehensive evaluation of the electrode implantation accuracy. Compared with frame-based or navigation-assisted techniques, ROSA®-assisted SEEG electrode implantation provided significant benefits for reduction of both overall operative time (mean difference [MD], -63.45 min; 95% confidence interval [CI] from -88.73 to -38.17 min; P < 0.00001) and operative time per implanted electrode (MD, -8.79 min; 95% CI from -14.37 to -3.21 min; P = 0.002). No significant differences existed in perioperative complications and seizure outcomes after the application of the ROSA® device and other techniques for electrode implantation. To conclude, the available evidence shows that the ROSA® device is an effective and safe surgical tool for trajectory-guided SEEG electrode implantation in patients with drug-resistant epilepsy, offering benefits for saving operative time and neither increasing the risk of perioperative complications nor negatively impacting seizure outcomes.

Nonconvulsive status epilepticus as sign of tumor recurrence.

Status epilepticus (SE) can be a sign of brain tumor progression or recurrence, but there are few reports of nonconvulsive status epilepticus (NCSE) being a sign of tumor progression or recurrence. Moreover, much remains to be elucidated about its clinical course, and outcome. This is the first report of NCSE associated with the progression of a metastatic brain tumor treated by surgical excision of the tumor. The patient was 74-year-old woman. She had a history of craniotomy for tumor resection and gamma knife treatment for multiple metastatic brain tumors originating from breast cancer. She suddenly developed dysarthria and right hemiparesis, followed by convulsive seizures in the right side of her body. Magnetic resonance imaging showed tumor recurrence in the left parietal lobe and worsening edematous changes around the tumor. Antiseizure medication was initiated, however her seizures did not improve; therefore, tumor resection was performed. Postoperatively, her consciousness, seizures, and electroencephalogram findings improved. NCSE caused by brain tumors may be refractory to treatment with antiseizure medications, and early surgical treatment may be useful for seizure control.

Drug-resistant temporal lobe epilepsy due to middle fossa meningoencephalocele in a child: A surgical case report.

BACKGROUND: Meningoencephalocele (ME) of the temporal lobe through a bone defect in the middle cranial fossa is a rare known cause of refractory temporal lobe epilepsy (TLE). ME-induced drug-resistant TLE has been described in adults; however, its incidence in children is very rare. CASE REPORT: A 7-year-old girl presented at our hospital with brief episodes of impaired consciousness and enuresis. Initial brain MRI results were interpreted as normal. Her seizures could not be controlled even with multiple anti-seizure medications. She was diagnosed with drug-resistant TLE, which presented with prolonged impaired awareness seizures for 30-60 s and secondary bilateral tonic seizures. At 9 years of age, brain MRI revealed a left temporal anteroinferior ME with a congenital bone defect in the left middle cranial fossa. She was referred for presurgical epilepsy evaluation. Long-term video electroencephalography (EEG) failed to reveal regional abnormality in the left temporal lobe; invasive evaluation using stereoelectroencephalography (SEEG) was thus indicated. Ictal onset SEEG was identified in the temporal pole near the ME which was rapidly propagated to the mesial temporal structures and other cortical regions. The left temporal pole including the ME was micro-surgically disconnected while preserving the hippocampus and amygdala. The patient's seizures have been completely controlled for 1 year and 6 months post-operatively. CONCLUSION: SEEG revealed rapid propagation of ictal activity in this patient's case, confirming that the ME was epileptogenic. Since the majority of patients with refractory epilepsy caused by ME have favorable postoperative seizure outcomes, it is important to carefully check for ME in drug-resistant TLE patients with apparently normal MRI.

Appropriate treatment within 13 hours after onset may improve outcome in patients with high-grade aneurysmal subarachnoid hemorrhage.

OBJECTIVE: This retrospective study evaluated whether earlier timing of appropriate treatment of high-grade aneurysmal subarachnoid hemorrhage (aSAH), defined as management of ruptured intracranial aneurysm (RIA) combined with required additional surgical measures for control of increased intracranial pressure (ICP), is associated with more favorable outcomes. METHODS: The study cohort comprised 253 patients with high-grade aSAH. Modified Rankin Scale score of 0-3 at 3-month follow-up after the ictus was considered as favorable outcome. RESULTS: Appropriate treatment of aSAH was completed in 205 patients (81 %), and included clipping or coiling of RIA without (64 cases) and with (141 cases) additional surgical measures for control of increased ICP (evacuation of intracranial hematoma, decompressive craniotomy, and/or cerebrospinal fluid drainage). Favorable outcome was noted significantly more often if appropriate treatment was completed within 13 h after aSAH than between 13 and 72 h (37 % vs. 17 %; adjusted P = 0.0475), which was confirmed by evaluation in the multivariate model along with other prognostic factors. Subgroup analysis revealed that completion of the appropriate treatment within 13 h was associated with more favorable outcome in those patients, who underwent management of RIA in combination with additional surgical measures for control of increased ICP (P = 0.0023), and in those, who felt into poor outcome predicting group (P = 0.0046). CONCLUSIONS: Appropriate treatment of high-grade aSAH with management of RIA in combination with required additional surgical measures for control of increased ICP, may be associated with more favorable outcomes if completed within 13 h after the ictus.

Venous Flow Conversion Technique for Sacrificing the Superior Petrosal Vein During Microvascular Decompression for Trigeminal Neuralgia.

BACKGROUND: Microvascular decompression for trigeminal neuralgia (TN) may require sacrifice of the superior petrosal vein (SPV), with potential risks of ischemia and hemorrhagic complications due to impaired venous return. OBJECTIVE: To investigate methods for safely sacrificing the SPV. METHODS: We retrospectively reviewed 21 cases in 346 consecutive microvascular decompression surgeries for TN. They were intraoperatively identified as SPV and its tributaries being the offending vessels causing TN and were intentionally sacrificed. RESULTS: The transverse pontine vein (TPV) was sacrificed in 10 patients. The main trunk of the SPV was sacrificed using the TPV as a collateral flow pathway in 10 patients. No complications occurred related to impaired venous return. CONCLUSION: The venous flow conversion technique can be applied to safely sacrificing the SPV and its tributaries with the TPV acting as a collateral blood flow pathway to prevent postoperative impaired venous return.

Clinical features of herpes simplex virus reactivation after microvascular decompression for trigeminal neuralgia: Experience of 200 patients and a literature review.

Background: Herpes simplex virus (HSV) reactivation occasionally develops in the early postoperative period after microvascular decompression (MVD) for trigeminal neuralgia (TN). Therefore, the present study investigated the clinical features of this phenomenon. Methods: The study cohort comprised 200 patients with 125 women aged between 17 and 90 years (median age, 66 years) who underwent MVD for TN between January 2010 and December 2020. Characteristics were compared between patients with and without HSV reactivation and clinical features were analyzed. Results: Twenty patients had HSV reactivation: herpes labialis in 18 and herpes zoster (final diagnosis) in 2. A multivariate analysis revealed independent correlations between postoperative HV reactivation and a previous history of herpes labialis (odds ratios [OR]: 6.32, P = 0.0003) and reoperation for recurrent or persistent pain (OR: 5.06, P = 0.0211). No significant differences were observed in pain relief, postoperative facial numbness, or Barrow Neurological Institute Pain Intensity/Facial Numbness Scores in the past follow-up between patients with and without HSV reactivation. HSV reactivation manifested at a median of the 4th postoperative day (1-10 days) and its location was not related to the preoperative distribution of facial pain. All patients were treated with local acyclovir and were completely cured within 1-2 weeks. Conclusion: HSV reactivation occurred in 10% of patients after MVD including 1% of herpes zoster. A previous history of herpes labialis and reoperation was identified as risk factors for reactivation. Symptoms were completely cured by antiviral drugs within 1-2 weeks. It is important to note that cases of herpes zoster may be confused with cases of HSV after MVD.

Low EEG Gamma Entropy and Glucose Hypometabolism After Corpus Callosotomy Predicts Seizure Outcome After Subsequent Surgery.

Background: Patients with generalized epilepsy who had lateralized EEG abnormalities after corpus callosotomy (CC) occasionally undergo subsequent surgeries to control intractable epilepsy. Objectives: This study evaluated retrospectively the combination of EEG multiscale entropy (MSE) and FDG-PET for identifying lateralization of the epileptogenic zone after CC. Methods: This study included 14 patients with pharmacoresistant epilepsy who underwent curative epilepsy surgery after CC. Interictal scalp EEG and FDG-PET obtained after CC were investigated to determine (1) whether the MSE calculated from the EEG and FDG-PET findings was lateralized to the surgical side, and (2) whether the lateralization was associated with seizure outcomes. Results: Seizure reduction rate was higher in patients with lateralized findings to the surgical side than those without (MSE: p < 0.05, FDG-PET: p < 0.05, both: p < 0.01). Seizure free rate was higher in patients with lateralized findings in both MSE and FDG-PET than in those without (p < 0.05). Conclusions: This study demonstrated that patients with lateralization of MSE and FDG-PET to the surgical side had better seizure outcomes. The combination of MSE and conventional FDG-PET may help to select surgical candidates for additional surgery after CC with good postoperative seizure outcomes.

Predictors of Seizure Outcome after Repeat Pediatric Epilepsy Surgery: Reasons for Failure, Sex, Electrophysiology, and Temporal Lobe Surgery.

Considering that seizure freedom is one of the most important goals in the treatment of epilepsy, repeat epilepsy surgery could be considered for patients who continue to experience drug-resistant seizures after epilepsy surgery. However, the chance of seizure freedom is reported to be below 50% after reoperation for failed epilepsy surgery. This study aimed to elucidate the predictive factors for seizure outcomes after repeat pediatric epilepsy surgery. In all, 39 pediatric patients who underwent repeat curative epilepsy surgery between 2008 and 2020 at our institution were retrospectively studied. The relationship between preoperative clinical factors and postoperative seizure freedom at the last follow-up was statistically evaluated. The mean age at the first surgery was 5.5 years (0-16). The etiology of epilepsy was malformation of cortical development in 33 patients. The average time to seizure recurrence after the first surgery was 6.4 months (range, 0-26 months). In all, 16 patients (41.0%) achieved seizure freedom after the second surgery. Seven patients underwent a third surgery, and three (42.9%) achieved seizure freedom. Overall, 19 patients achieved seizure freedom after repeat epilepsy surgery (48.7%). Female sex, surgical failure due to technical limitations, congruent electroencephalography (EEG) findings, lesional magnetic resonance imaging (MRI) and Rt-sided surgery were predictive of seizure freedom, and surgery limited to the temporal lobe was predictive of residual seizures, as determined in the multivariate analysis. The reoperation of failed epilepsy surgery is challenging. Consideration of the above predictive factors can be helpful in deciding whether to reoperate on pediatric patients whose initial surgical intervention failed.

Volume-Based Radiofrequency Thermocoagulation for Pediatric Insulo-Opercular Epilepsy: A Feasibility Study.

BACKGROUND: Stereotactic ablation surgeries including radiofrequency thermocoagulation (RFTC) and laser interstitial thermal therapy are recent less invasive treatment methods for insular epilepsy. Volume-based RFTC after stereoelectroencephalography was first proposed by a French group as a more effective method for seizure relief in insular epilepsy patients than stereoelectroencephalography-guided RFTC. OBJECTIVE: To describe the feasibility and technical details about volume-based RFTC in patients with insulo-opercular epilepsy. METHODS: We successfully treated 3- and 6-year-old patients with medically refractory insulo-opercular epilepsy with volume-based RFTC, in which the target volume of coagulation was flexibly designed by combining multiple spherical models of 5-mm diameter which is smaller than reported previously. RESULTS: The insula was targeted by oblique trajectory from the frontoparietal area in one case, and the opercular cortex was targeted by perpendicular trajectories from the perisylvian cortex in the other case. The use of the small sphere model required more trajectories and manipulations but enabled more exhaustive coagulation of the epileptogenic zone, with 70% to 78% of the planned target volume coagulated without complications, and daily seizures disappeared after RFTC in both patients. CONCLUSION: Volume-based RFTC planned with small multiple sphere models may improve the completeness of lesioning for patients with insulo-opercular epilepsy. Careful planning is necessary to reduce the risks of vascular injuries.

Is Hippocampal Resection Necessary for Low-Grade Epilepsy-Associated Tumors in the Temporal Lobe?

Low-grade epilepsy-associated tumors (LEATs) are common in the temporal lobe and can cause drug-resistant epilepsy. Complete resection of LEATs is sufficient for seizure relief. However, hippocampal resection might result in postoperative cognitive impairment. This study aimed to clarify the necessity of hippocampal resection for seizure and cognitive outcomes in patients with temporal lobe LEATs and a normal hippocampus. The study included 32 patients with temporal lobe LEATs and without hippocampal abnormalities. All patients underwent gross total resection as treatment for drug-resistant epilepsy at our tertiary epilepsy center from 2005 to 2020, followed by at least a 12-month follow-up period. Seizure and cognitive outcomes were compared between patients who underwent additional hippocampal resection (Resected group) and those who did not (Preserved group). Among the participants, 14 underwent additional hippocampal resection and 28 (87.5%) achieved seizure freedom irrespective of hippocampal resection. The seizure-free periods were not different between the two groups. Additional hippocampal resection resulted in a significantly negative impact on the postoperative verbal index. In conclusion, additional hippocampal resection in patients with temporal lobe LEATs without hippocampal abnormalities is unnecessary because lesionectomy alone results in good seizure control. Additional hippocampal resection may instead adversely affect the postoperative language function.

Single-Institutional Experience of Chronic Intracranial Electroencephalography Based on the Combined Usage of Subdural and Depth Electrodes.

Implantation of subdural electrodes on the brain surface is still widely performed as one of the "gold standard methods" for the presurgical evaluation of epilepsy. Stereotactic insertion of depth electrodes to the brain can be added to detect brain activities in deep-seated lesions to which surface electrodes are insensitive. This study tried to clarify the efficacy and limitations of combined implantation of subdural and depth electrodes in intractable epilepsy patients. Fifty-three patients with drug-resistant epilepsy underwent combined implantation of subdural and depth electrodes for long-term intracranial electroencephalography (iEEG) before epilepsy surgery. The detectability of early ictal iEEG change (EIIC) were compared between the subdural and depth electrodes. We also examined clinical factors including resection of MRI lesion and EIIC with seizure freedom. Detectability of EIIC showed no significant difference between subdural and depth electrodes. However, the additional depth electrode was useful for detecting EIIC from apparently deep locations, such as the insula and mesial temporal structures, but not in detecting EIIC in patients with ulegyria (glial scar). Total removal of MRI lesion was associated with seizure freedom. Depth electrodes should be carefully used after consideration of the suspected etiology to avoid injudicious usage.

Deep Brain Stimulation for Refractory Tourette Syndrome: Electrode Position and Clinical Outcome.

The efficacy of deep brain stimulation (DBS) for refractory Tourette syndrome (TS) is accepted, but whether the efficacy of DBS treatment in the Japanese population is equivalent to those reported internationally and whether adverse effects are comparable are not yet known. This study evaluated the clinical practice and outcome of DBS for TS in a Japanese institution. This study included 25 consecutive patients with refractory TS treated with thalamic centromedian-parafascicular nucleus DBS. The severity of tics was evaluated with the Yale Global Tic Severity Scale (YGTSS) before surgery, at 1 year after surgery, and at the last follow-up of 3 years or more after surgery. The occurrence of adverse events, active contact locations, and stimulation conditions were also evaluated. YGTSS tic severity score decreased by average 45.2% at 1 year, and by 56.6% at the last follow-up. The reduction was significant for all aspects of the scores including motor tics, phonic tics, and impairment. The mean coordinates of active contacts were 7.62 mm lateral to the midline, 3.28 mm posterior to the midcommissural point, and 3.41 mm above anterior commissure-posterior commissure plane. Efficacy and stimulation conditions were equivalent to international reports. The stimulation-induced side effects included dysarthria (32.0%) and paresthesia (12.0%). Device infection occurred in three patients (12.0%) as a surgical complication. The DBS device was removed because of infection in two patients. DBS is an effective treatment for refractory TS, although careful indication is necessary because of the surgical risks and unknown long-term outcome.

Corpus callosotomy in pediatric patients with non-lesional epileptic encephalopathy with electrical status epilepticus during sleep.

Epileptic encephalopathy with electrical status epilepticus during sleep (ESES) is often refractory to medical treatment and leads to poor cognitive outcomes. Corpus callosotomy may be an effective treatment option for drug-resistant ESES with no focal etiology. We retrospectively identified three patients who underwent corpus callosotomy for drug-resistant ESES in our institution. Electroencephalography (EEG) findings and cognitive functions were evaluated before surgery, at 3 months, 6 months, 1 year, and 2 years after surgery. Age at surgery was 6 years 10 months, 7 years 9 months, and 8 years 4 months, respectively. Period between the diagnosis of ESES and surgery ranged from 7 to 25 months. All patients had no obvious structural abnormalities and presented with cognitive decline despite multiple antiseizure medications and steroid therapies. One patient showed complete resolution of ESES and an improvement of intelligence quotient after surgery. Epileptiform EEG was lateralized to one hemisphere after surgery and spike wave index (SWI) was decreased with moderate improvement in development and seizures in the other 2 patients. SWI re-exacerbated from 6 months after surgery, but without subsequent developmental regression in these 2 patients. Corpus callosotomy may become an important treatment option for drug-resistant ESES in patients with no structural abnormalities.

Hemifacial Spasm Caused by Veins Confirmed by Intraoperative Monitoring of Abnormal Muscle Response.

BACKGROUND: Hemifacial spasm (HFS) is a benign disease caused by the hyper excitement of facial nerves owing to vessel compression. The offending vessels are usually arteries, such as anterior and posterior inferior cerebellar or vertebral arteries, but there are few reports of vein involvement cases. OBJECTIVE: The aim of this study was to investigate veins as offending vessels in patients with HFS confirmed by abnormal muscle response (AMR). METHODS: We analyzed 5 patients with HFS caused by veins among 78 patients with HFS over the past 10 years. All patients underwent microvascular decompression (MVD) with AMR monitoring, whereas 3 of them underwent a second MVD. The mean follow-up time was 97 months. RESULTS: Arteries were thoroughly decompressed in 3 patients with a failed first MVD surgery who received a second surgery, during which veins at the root exit point (RExP) were decompressed with the disappearance or a significant decrease in the amplitude of AMR. Two patients showed spasm resolution after the first surgery when veins were decompressed together with the disappearance of AMR. The location of veins was RExP and the cisternal portion. All patients had excellent outcomes within 3 months, and no complications were observed. CONCLUSIONS: Veins can be offending vessels in HFS patients. AMR is useful to determine the endpoint in these cases. Once arteries are decompressed thoroughly with residual AMR, surrounding veins at unusual sites, such as the RExP or the cisternal portion, must be checked to prevent persistent HFS. Complete decompression of veins leads to a good clinical outcome.