Surgical outcome of corpus callosotomy in patients with drop attacks

Disconnection Methods in the Surgical Treatment of Epilepsy

Disconnection procedures in epilepsy surgery have become an important tool for the management of multifocal drug-resistant epilepsy. In this chapter, we will review their indications, describe the technical procedures, and review outcome data in the literature. Among the curative approaches, anterior quadrant disconnection, posterior quadrant (PQ) disconnection, and functional hemispherectomy can be performed for patients whose epileptic focus resides in one hemisphere or one quadrant. Seizure freedom rates from these procedures range from 50 to 81% for anterior quadrant disconnections, 50 to 92% for PQ disconnections, and 43 to 93% for hemispherectomy. Although typically performed in the pediatric population, data suggest that carefully selected adult patients could also benefit from a disconnection procedure. Of the palliative approaches, corpus callosotomy has been shown to be effective for drop attacks, resulting in significant improvement in seizure frequency, severity, and quality of life. Minimally invasive alternatives to standard open corpus callosotomies with laser interstitial thermal therapy (LITT) have been proposed. Overall, surgical disconnection procedures are an effective way of treating multifocal epilepsy, with good outcomes that can improve the quality of life for these patients.

Efficacy and safety of pharmacological and non-pharmacological therapies in Lennox-Gastaut syndrome: a systematic review and network meta-analysis

Objective

This study aimed to evaluate the efficacy and safety of antiepileptic drugs and non-pharmacological treatments in patients with Lennox-Gastaut syndrome (LGS).

Methods

We conducted a systematic search of the PubMed, Embase, Cochrane, and Web of Science databases for randomized controlled trials (RCTs) evaluating both pharmacological and non-pharmacological interventions for LGS. The treatments assessed included cannabidiol, fenfluramine, clobazam, rufinamide, felbamate, lamotrigine, topiramate, deep brain stimulation, and anterior corpus callosotomy. The primary efficacy outcome was defined as a reduction of at least 50% in the frequency of drop seizures during treatment compared to baseline levels. The secondary efficacy outcome was measured as the median percentage reduction in monthly drop seizure frequency throughout the treatment period. Safety assessments were based on the incidence of adverse events and serious adverse events. All outcomes were ranked according to their surface under the cumulative ranking curve (SUCRA).

Result

This network meta-analysis encompassed 12 RCTs involving a total of 1,445 patients. The SUCRA indicated that clobazam 1 mg/kg/day, anterior corpus callosotomy, and rufinamide were the three most effective interventions for achieving a reduction of at least 50% in drop seizures. In terms of median percentage reduction in drop seizure frequency, clobazam 1 mg/kg/day ranked highest, followed by clobazam 0.5 mg/kg/day and rufinamide. Regarding safety profiles, SUCRA analysis revealed that cannabidiol 20 mg/kg/day had the highest likelihood of inducing adverse events, followed closely by fenfluramine 0.7 mg/kg/day. Lamotrigine was found to be most likely to cause serious adverse reactions, with cannabidiol 10 mg/kg/day following closely behind.

Conclusion

Clobazam 1 mg/kg/day, anterior corpus callosotomy, and rufinamide manifested the most optimal efficacy in seizure control among LGS patients. Caution should be exercised when administering cannabidiol, lamotrigine, and fenfluramine 0.7 mg/kg/day in clinical practice to mitigate safety concerns associated with drug-related side effects.

Complete Corpus Callosotomy Brings Worthwhile Seizure Reduction in Both Pediatric and Adult Patients

BACKGROUND AND OBJECTIVES

The influence of the age at which complete corpus callosotomy (CC) surgery is performed on seizure outcomes remains unclear. This study aimed to evaluate the age-dependent aspects of long-term seizure outcomes after complete CC.

METHODS

We reviewed 41 patients who underwent one-stage complete CC. Seizure outcomes were analyzed for age at epilepsy onset and at complete CC, focal MRI abnormality, and etiology.

RESULTS

The median age was 7 months at epilepsy onset and 93 months at complete CC. The median follow-up duration was 67 months. Sixteen patients had focal MRI lesions and 4 had only general atrophy. Etiology was identified in 20 patients. For overall seizure outcomes (N = 41), complete seizure freedom was achieved in 5 patients, excellent seizure reduction (>80%) in 11, good (50%-80%) in 5, and poor (<50%) in 20. Freedom was correlated with younger age at complete CC and unknown etiology ( P ≤ .05). Freedom was only achieved in patients aged younger than 7 years. Worthwhile (≥50%, freedom, excellent, and good) and not worthwhile (<50%, poor) overall seizure reduction showed no statistical difference in age at complete CC. No related factor was found for worthwhile overall seizure reduction. For drop attack outcomes (N = 31), freedom was achieved in 22 cases, excellent in 5, and poor in 4. Freedom was correlated with younger age at complete CC ( P < .05) although freedom was achieved in 4 of 7 patients older than 20 years. Age at complete CC showed no statistical difference between worthwhile (≥50%) and not worthwhile (<50%) drop attack reduction. Worthwhile drop attack reduction was correlated with unknown etiology ( P < .05). Complications were mild and transient.

CONCLUSION

Complete CC is an excellent surgical option based on favorable seizure outcomes and acceptable complications in our present study.

A retrospective study on post-operative recovery of daily living activity after total corpus callosotomy

INTRODUCTION

Post-operative complications of corpus callosotomy (CC) in children, prolonged hospitalization due to inactivity as acute disconnection syndrome is occasionally experienced. We aimed to clarify this issue and its risk factors with a hypothesis that electroencephalogram (EEG) findings as measures of functional lateralization may be among prognostic factors for post-operative recovery.

MATERIALS AND METHODS

Twenty-three patients with childhood-onset drug-resistant epilepsy who underwent total CC between April 2017 and December 2023 were included in the study and they were divided into two groups based on the duration of post-operative hospitalization as an indicator of recovery of daily living activity. We compared scalp EEG findings and the other factors including clinical characteristics between the two groups.

RESULTS

Of 22 patients (14 males) without specific complications, post-operative hospitalization clustered in 9-14 days in 15 patients (Group A) with range 16-118 days in seven patients (Group B). The ratios of patients with non-lateralized spikes on pre-operative EEG and that of patients with symmetric background activity on post-operative EEG were significantly greater in Group B (7/7, 100 %; 6/7, 86 %, respectively) than in Group A (8/15, 53 %; 4/15, 27 %, respectively) (p = 0.038; p = 0.020, respectively, by Fisher's exact test), while other factors were not significantly different between the two groups.

CONCLUSIONS

Delayed recovery of living activity should be anticipated, especially in patients with non-lateralized epileptic discharges on pre-operative EEG.

Use of an Endoscope Reduces the Size of Craniotomy Without Increasing Operative Time Compared With Conventional Microscopic Corpus Callosotomy

BACKGROUND AND OBJECTIVES

Corpus callosotomy (CC) is an epilepsy surgery that disconnects the commissural fibers at the corpus callosum, a structure that often plays a key role in propagating seizure activity. CC is particularly beneficial in patients with drop attacks. Less invasive endoscopic surgeries have recently been introduced to some fields of neurosurgery but have not yet become common in epilepsy surgery. Endoscopic surgeries offer better visualization and require a smaller corridor than conventional microscopic surgeries. Here, we presented a case series comparing endoscopic CC with microscopic CC.

METHODS

This 2-center retrospective study involved patients who underwent all types of CC (anterior, total, or posterior CC [pCC]) between January 2014 and May 2022. We excluded patients who underwent additional craniotomy for electrocorticography rather than CC, prior craniotomy, or CC without craniotomy. The primary outcomes were comparing size of craniotomy, operative time, and surgical complications between endoscopic CC and microscopic CC.

RESULTS

We included 14 CCs in 11 patients in the endoscopic group and 58 CCs in 55 patients in the microscopic group. No significant difference in age was seen between groups. Craniotomies were significantly smaller in the endoscopic group for anterior (13.36 ± 1.31 cm 2 vs 27.55 ± 3.78 cm 2 ; P = .001), total (14.07 ± 2.54 cm 2 vs 26.63 ± 6.97 cm 2 ; P = .001), and pCC (9.44 ± 1.18 cm 2 vs 30.23 ± 10.76 cm 2 ; P = .002). Moreover, no significant differences in operative time (anterior CC [261 ± 53.11 min vs 298.73 ± 81.08 min, P = .226], total CC [339.5 ± 48.2 min vs 321.39 ± 65.98 min, P = .452], pCC [198 ± 24.73 min vs 242.5 ± 59.12 min, P = .240]), or complication rate were seen.

CONCLUSION

Endoscopic CC is a promising technique requiring a smaller craniotomy than microscopic CC, without significantly increasing operative time or complication rate compared with microscopic CC.

Influence of extent and age at corpus callosotomy on seizure outcomes. A single center experience

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

Radiosurgical Corpus Callosotomy for Intractable Epilepsy: Retrospective Long-Term Safety and Efficacy Assessment in 19 Patients an Review of the Literature

BACKGROUND

Some patients suffering from intractable epileptic seizures, particularly drop attacks (DAs), are nonremediable by curative techniques. Palliative procedure carries a significant rate of surgical and neurological complications.

OBJECTIVE

To propose evaluation of safety and efficacy of Gamma Knife corpus callosotomy (GK-CC) as an alternative to microsurgical corpus callosotomy.

METHODS

This study included retrospective analysis of 19 patients who underwent GK-CC between 2005 and 2017.

RESULTS

Of the 19 patients, 13 (68%) had improvement in seizure control and 6 had no significant improvement. Of the 13/19 (68%) with improvement in seizures, 3 (16%) became completely seizure-free, 2 (11%) became free of DA and generalized tonic-clonic but with residual other seizures, 3 (16%) became free of DA only, and 5 (26%) had >50% reduction in frequency of all seizure types. In the 6 (31%) patients with no appreciable improvement, there were residual untreated commissural fibers and incomplete callosotomy rather than failure of Gamma Knife to disconnect. Seven patients showed a transient mild complication (37% of patients, 33% of the procedures). No permanent complication or neurological consequence was observed during the clinical and radiological workup with a mean of 89 (42-181) months, except 1 patient who had no improvement of epilepsy and then aggravation of the pre-existing cognitive and walking difficulties (Lennox-Gastaut). The median time of improvement after GK-CC was 3 (1-6) months.

CONCLUSION

Gamma Knife callosotomy is safe and accurate with comparable efficacy to open callosotomy in this cohort of patients with intractable epilepsy suffering from severe drop attacks.

Corpus Callosotomy for Non-Localizing Drug Resistant Epilepsy with Drop Attacks

BACKGROUND

Corpus callosotomy (CC) is a surgical palliative procedure done for a selected group of patients with drug resistant epilepsy (DRE) to stop drop attacks and prevent falls.

METHODS

We performed a retrospective chart review of consecutive patients who underwent CC for DRE with drop attacks at our center between 2015 and 2019. Clinical, imaging details and surgical findings were noted. Clinical outcomes and functional status were evaluated.

RESULTS

During the study period, 17 patients underwent corpus callosotomy (Male: Female 14:3). The mean age at surgery was 10.3 years (standard deviation - 5.85, interquartile range [IQR] = 6.5). The mean age at onset of seizure was 2.23 years (standard deviation - 3.42, IQR = 1.5). Preoperative seizure frequency ranged from 2 to 60 attacks per day (median: 20, IQR= 36). All patients had atonic seizures/drop attacks. One patient underwent anterior CC and 16 underwent complete CC. Three patients had complications in the postoperative period. The median follow-up was 26 months. All patients had cessation of drop attacks immediately following surgery. One patient with anterior CC had a recurrence of drop attacks for which she underwent completion CC. Another patient had recurrent drop attacks 3 years later and was found to have a residual callosal connection. Three patients had complete seizure freedom and 4 patients had a <50% reduction in seizure frequency.

CONCLUSIONS

Our study lends additional support to the efficacy of CC in patients with DRE, with the cessation of drop attacks. It also provided a reasonable reduction in seizure frequency. Complete CC led to better control of drop attacks.

Corpus Callosotomy Is a Safe and Effective Procedure for Medically Resistant Epilepsy

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

Stereotactic laser interstitial thermal therapy for the treatment of pediatric drug-resistant epilepsy: indications, techniques, and safety

BACKGROUND

MRI-guided laser interstitial thermal therapy (MRgLITT) is a promising alternative to open surgery for treatment of drug-resistant epilepsy, offering significant advantages over traditional approaches for candidate patients, including minimally invasive approach, shorter hospitalization, and decreased patient post-operative discomfort. LITT uses a stereotactically placed fiber optic laser probe to ablate tissue under real-time MR thermometry.

METHODS

Retrospective chart review of intraoperative and perioperative characteristics was performed for 28 cases of MRgLITT in 25 pediatric patients, ages 4-21 years old, at our institution between 2019 and 2021. MRgLITT ablation of the mesial temporal lobe was performed in 8 cases, extratemporal epileptogenic foci in 9 cases, and for corpus callosotomy in 11 cases.

RESULTS

At 1 year of follow-up, 53% of all patients experienced improvement in seizure frequency (Engel I or II) (class I: 38%, class II: 15%, class III: 17%, class IV: 31%), including 37% of MTL ablations and 80% extratemporal SOZ ablations. After MRgLITT corpus callosotomy, 71% of patients were free from atonic seizures at most recent follow-up. Median length of hospitalization was 2 days (1-3), including a median ICU stay of 1 day (1-2).

CONCLUSION

This series demonstrates the safety of MRgLITT as an approach for seizure control in drug-resistant epilepsy. We provide additional evidence that MRgLITT is an effective procedure that is well-tolerated by pediatric patients and is accompanied by an acceptable rate of complications and relatively short hospital stay.

Complete Corpus Callosotomy for Refractory Epilepsy in Children

Corpus callosotomy is an interhemispheric disconnection by callosal commissural fiber ablation. Its rationale is the disruption of ictal spread to prevent seizure generalization. The objective pursued is alleviation of intractable, debilitating, and injurious manifestations of generalized epilepsy.¹ Eight decades of experience support this procedure's safety and effectiveness for appropriately selected patients with drug-resistant epilepsy not amenable to optimal resection; particularly, favorable outcomes for tonic or atonic seizures with drop attacks have been reported.^2,3 Children may benefit more than adults from callosotomy for improved daily function, psychosocial adjustment, and family satisfaction.⁴ A meta-analysis found a better seizure reduction from total than partial callosotomy (88.2% vs. 58.6% of worthwhile reduction) comprising drop-attacks (77.8% vs. 45.4%) with an increased but transient (i.e., resolution within 6 weeks) risk of significant disconnection syndromes (12.5% vs. none).⁵ Here, we present the illustrative case of a 4-year-old boy with Lennox-Gastaut syndrome who underwent open single-stage complete callosotomy. Video 1 shows the microscope-assisted interhemispheric approach aided by stereotactic navigation. We showcase critical steps such as dissection of cingulate gyri and anterior and then posterior callosotomy while highlighting crucial anatomic landmarks. This procedure may be accessible for epilepsy surgeons worldwide in resource-constrained environments⁶ while serving as a basis for promising high-technology development (e.g., endoscopic, radiosurgical, laser interstitial thermal therapy, or magnetic resonance-guided focused ultrasound callosotomies). In this video article, we aim to provide a streamlined and stepwise approach to this rare but important epilepsy surgery.

Surgical nuances in corpus callosotomy as a palliative epilepsy surgery

Background:

Corpus callosotomy is a well-established palliative procedure in selected patients with drug resistant epilepsy (DRE). It has a beneficial role in ameliorating generalized seizures mainly drop attacks. Here, we present some technical tips for performing callosotomy depending on the anatomical basis, to minimize craniotomy size and guard against inadvertently entering the lateral ventricles.

Methods:

This study was a retrospective review of patients who received corpus callosotomy at our institute as a palliative epilepsy surgery. We present our experience and surgical tips with the extraventricular technique of corpus callosotomy with comparison of surgery-related complications and operative time between extraventricular and conventional techniques in selected patients with DRE.

Results:

Our study included 34 patients. First group of patients included 14 patients who received conventional approach, while the extraventricular approach was done in 20 patients. Extraventricular approach showed significantly lower wound complications rate of 10% compared to 78% in intraventricular approach (P < 0.001). Mean operative time was significantly lower in extraventricular versus conventional technique with 52 min versus 94 min, respectively (P < 0.001). Planned extent of corpus callosotomy resection was achieved in all our patients using both approaches.

Conclusion:

The cleft of the septum pellucidum offers a natural pursuit to section corpus callosum strictly midline and completely extraventricular in well selected patients of DRE candidate for callosotomy. Performing corpus callosotomy in extraventricular approach provided better patients outcomes regarding surgery and wound-related complications when compared to conventional approach.

Age-Related Recovery of Daily Living Activity After 1-Stage Complete Corpus Callosotomy: A Retrospective Analysis of 41 Cases

BACKGROUND

Recovery time after corpus callosotomy (CC) is known to be longer in elderly than in younger patients.

OBJECTIVE

To evaluate the relationship between patient age and recovery time of activities of daily living (ADL) after 1-stage complete CC.

METHODS

This study included 41 patients (22 women; aged 13 months-34 years, median 7 years) who underwent 1-stage complete CC for medically intractable seizures with drop attacks, infantile spasms, and/or bilaterally synchronized electroencephalographic discharges between August 2009 and April 2019. The timing of restart of competence in 5 ADL categories and surgical outcomes were recorded.

RESULTS

Patients (1) restarted speech at 2.2 ± 1.3 (mean ± 2 standard deviations; range 1-5) days, (2) restarted replying with their own name on request at 5.5 ± 8.6 (2-33) days, (3) restarted oral intake at 1.6 ± 1.7 (1-11) days, (5) discontinued intravenous feeding at 6.0 ± 3.0 (2-16) days, and (5) restarted ambulation or wheelchair movement at 5.8 ± 3.4 (2-10) days. Younger patients showed significantly (P < .0223) earlier recovery of ambulation or wheelchair movement, but no age difference was found in the other 4 ADL categories. Overall seizure freedom was achieved in 5 patients, excellent (>80%) seizure reduction in 11, good (50%-80%) seizure reduction in 5, and poor (<50%) seizure reduction in 20.

CONCLUSION

Early ADL recovery after 1-stage complete CC is favorable in both young and adult patients. These findings, with good surgical outcomes, will encourage more positive consideration of 1-stage complete CC in both pediatric and adult patients.

Corpus Callosotomy for Controlling Epileptic Spasms: A Proposal for Surgical Selection

In 1940, van Wagenen and Herren first proposed the corpus callosotomy (CC) as a surgical procedure for epilepsy. CC has been mainly used to treat drop attacks, which are classified as generalized tonic or atonic seizures. Epileptic spasms (ESs) are a type of epileptic seizure characterized as brief muscle contractions with ictal polyphasic slow waves on an electroencephalogram and a main feature of West syndrome. Resection surgeries, including frontal/posterior disconnections and hemispherotomy, have been established for the treatment of medically intractable ES in patients with unilaterally localized epileptogenic regions. However, CC has also been adopted for ES treatment, with studies involving CC to treat ES having increased since 2010. In those studies, patients without lesions observed on magnetic resonance imaging or equally bilateral lesions predominated, in contrast to studies on resection surgeries. Here, we present a review of relevant literature concerning CC and relevant adaptations. We discuss history and adaptations of CC, and patient selection for epilepsy surgeries due to medically intractable ES, and compared resection surgeries with CC. We propose a surgical selection flow involving resection surgery or CC as first-line treatment for patients with ES who have been assessed as suitable candidates for surgery.

Stereotactic laser interstitial thermal therapy corpus callosotomy for the treatment of pediatric drug-resistant epilepsy

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.

Corpus Callosotomy in 3 Cavalier King Charles Spaniel Dogs with Drug-Resistant Epilepsy

Corpus callosotomy (CC) is an established palliative surgery for human patients with drug-resistant epilepsy (DRE), especially those with generalized seizures and multiple or unknown epileptogenic focus. However, there are no reports to describe CC in canine patients with epilepsy. Three client-owned Cavalier King Charles Spaniels with DRE are included in this case series. In presurgical evaluations, an apparent epileptogenic zone was not detected in each dog and CC was conducted. Total CC was performed in one dog, whereas the other two received partial CC. One dog recovered from surgery without any complications, but died suddenly by an unknown cause at 10 h after surgery. For the other two dogs, postoperative evaluations including seizure outcomes, complications, and quality of life of the dogs and owners were assessed for at least 12 months. Both dogs showed a remarkable decrease in seizure frequency (averaged 80.3% reduction) and severity after surgery. The antiseizure medications were maintained, and not only the mentation and activity of the dogs, but also the quality of life of dogs and owners were improved postoperatively. Although technical improvement and more large-scale studies are needed, CC is a treatment option for dogs with DRE in veterinary medicine.

Palliative Epilepsy Surgery Procedures in Children

Surgical treatment of epilepsy typically focuses on identification of a seizure focus with subsequent resection and/or disconnection to "cure" the patient's epilepsy and achieve seizure freedom. Palliative epilepsy surgery modalities are efficacious in improving seizure frequency, severity, and quality of life. In this paper, we review palliative epilepsy surgical options for children: vagus nerve stimulation, responsive neurostimulation, deep brain stimulation, hemispherotomy, corpus callosotomy, lobectomy and/or lesionectomy and multiple subpial transection. Reoperation after surgical resection should also be considered. If curative resection is not a viable option for seizure freedom, these methods should be considered with equal emphasis and urgency in the treatment of drug-resistant epilepsy.

The Curious Case of Lennox-Gastaut Syndrome: Treatment-Resistant Seizures in a Patient With Autism Spectrum Disease With Lennox-Gastaut Syndrome

Lennox-Gastaut syndrome (LGS) is a childhood epilepsy disorder seen between the ages of one to eight years with the electroencephalogram (EEG) changes showing slow spiked-wave complex bursts or paroxysms of generalized fast activity and intellectual disability and often needing multiple lines of treatment. Autism spectrum disease (ASD) is rare but catastrophic comorbidity seen in a patient with LGS. We report an eight-year-old boy presenting to the emergency department with seizures and mental retardation. His first seizure was at the age of five months but was symptomatically treated without any specific diagnosis. On further investigation, the patient was diagnosed with LGS with concomitant ASD. The patient has successfully been treated for his treatment-resistant seizures and is now on regular follow-ups. This article aims to highlight this rare combination of LGS along with ASD and understand the disease course.

Comparison of seizure outcomes and ADL recovery period after total or anterior corpus callosotomy in adolescent and young adults with drop attacks and severe mental retardation

PURPOSE

The aim of this study was to evaluate seizure outcomes and postoperative neurologic complications, with an emphasis on the recovery period of activities of daily living (ADL) between anterior partial corpus callosotomy (ACC) and total corpus callosotomy (TCC) in adolescent and young adults with drop attacks and severe mental retardation.

METHODS

We retrospectively reviewed the clinical records of consecutive patients with intractable epilepsy who underwent corpus callosotomy (CC) for drop attacks between 2010 and 2019 in the Department of Neurosurgery, Hiroshima University hospital, with a minimum follow-up of one year. Inclusion criteria of this study were 1) age at surgery: 11-39 years, 2) preoperative intelligence quotient <35, and 3) preoperative Barthel index (BI) ≥30. Postoperative full ADL recovery was defined as complete recovery to the preoperative BI score. We compared the postoperative days required for 1) recovery of oral intake ability, 2) discharge from our hospital, 3) returning home from any hospital, 4) returning home with full ADL recovery, and 5) seizure outcomes in patients with ACC versus those with one-stage TCC.

RESULTS

Ten patients with ACC and 14 patients with one-stage TCC met the inclusion criteria. The period for returning home with full ADL recovery was a median of 15 days (range 9-45 days) after ACC, while the median was 21.5 days (range 10-62 days) after one-stage TCC (p = 0.2904). Although there was a tendency for the ADL recovery period to be longer after one-stage TCC, there were no statistically significant differences in any category of ADL recovery period. Eleven of 14 (78.6 %) patients who received a one-stage TCC showed favorable seizure outcomes, with drop attack cessation, which was significantly better than 1 of 10 (10 %) patients with ACC (p = 0.0009).

CONCLUSIONS

From the viewpoint of postoperative seizure outcomes and ADL recovery period, one-stage TCC is preferred to ACC for adolescent and young adults with severe mental retardation.

Higher intelligence may be a risk factor for postoperative transient disturbance of consciousness after corpus callosotomy

INTRODUCTION

Corpus callosotomy (CC) is an established surgical option for palliative treatment of medically intractable epilepsy, especially for seizures with drop attacks. We postulated that specific risk factors for post-CC transient disturbance of consciousness (pCTDC) are associated with CC. The purpose of this study was to review patients with intractable epilepsy who underwent CC and to statistically analyze risk factors for pCTDC.

METHODS

Inclusion criteria for patients who underwent CC between January 2009 and November 2019 were: (1) ≥2 years old and (2) followed up for more than 8 months. The state of consciousness before and after CC was evaluated with the Glasgow coma scale. We statistically assessed predictors for pCTDC as the primary outcome.

RESULTS

Fifty-six patients (19 females, 37 males) were enrolled, and the age range was 2-57 years old. Thirty-seven (66.1%) patients developed pCTDC. The mean period from the beginning of the state of pCTDC to recovery to their baseline conscious level was 4.9 days (range: 2-25 days). All three (100%) normal intelligence level patients, 13 (81%) of 16 patients with a moderately impaired level of intelligence, and 21 (57%) of 37 patients with a severely impaired level of intelligence exhibited pCTDC. Univariate (p = 0.044) and multivariate (p = 0.006) logistic regression analyses for predictors of pCTDC showed that intellectual function was statistically significant.

CONCLUSION

Two-thirds of patients developed pCTDC. One risk factor for pCTDC may be higher intellectual function.

Phase Lag Analyses on Ictal Scalp Electroencephalography May Predict Outcomes of Corpus Callosotomy for Epileptic Spasms

Objective: We aimed to clarify the patterns of ictal power and phase lag among bilateral hemispheres on scalp electroencephalography (EEG) recorded pre-operatively during epileptic spasms (ESs) and the correlation with the outcomes following corpus callosotomy. Methods: We enrolled 17 patients who underwent corpus callosotomy for ESs before 20 years of age. After corpus callosotomy, seven patients did not experience further ESs (favorable outcome group), and the remaining 10 patients had ongoing ESs (unfavorable outcome group). We used pre-operative scalp EEG data from monopolar montages using the average reference. The relative power spectrum (PS), ictal power laterality (IPL) among the hemispheres, and phase lag, calculated by the cross-power spectrum (CPS) among symmetrical electrodes (i.e., F3 and F4), were analyzed in the EEG data of ESs from 143 pre-operative scalp video-EEG records. Analyses were conducted separately in each frequency band from the delta, theta, alpha, beta, and gamma range. We compared the means of those data in each patient between favorable and unfavorable outcome groups. Results: Among all frequency bands, no significant differences were seen in the individual mean relative PSs in the favorable and unfavorable outcome group. Although the mean IPLs in each patient tended to be high in the unfavorable outcome group, no significant differences were found. The mean CPSs in the delta, theta, and gamma frequency bands were significantly higher in the unfavorable than in the favorable outcome group. Using the Youden index, the optimal cutoff points of those mean CPS values for unfavorable outcomes were 64.00 in the delta band (sensitivity: 100%, specificity: 80%), 74.20 in the theta band (100, 80%), and 82.05 in the gamma band (100, 80%). Subanalyses indicated that those CPS differences originated from pairs of symmetrical electrodes in the bilateral frontal and temporal areas. Significance: Ictal power and laterality of the ictal power in each frequency band were not associated with the outcomes of CC; however, the phase lags seen in the delta, theta, and gamma frequency bands were larger in the unfavorable than in the favorable outcome group. The phase lags may predict outcomes of CC for ESs on pre-surgical scalp-ictal EEGs.

Control of drop attacks with selective posterior callosotomy: Anatomical and prognostic data

OBJECTIVE

In a previous proof of concept study, selective posterior callosotomy achieved similar degree of control of drop attacks as total callosotomy, while sparing prefrontal interconnectivity. The present study aims to confirm this finding in a larger cohort and to provide anatomical and prognostic data.

METHODS

Fifty-one patients with refractory drop attacks had selective posterior callosotomy and prospective follow up for a mean of 6.4 years. Twenty-seven patients had post-operative magnetic resonance imaging (MRI) and 18 had tractography (DTI) of remaining callosal fibers. Pre and postoperative falls were quantified and correlated with demographic, clinical and imaging data.

RESULTS

Mean monthly frequency of drop attacks had a 95 % reduction, from 297 before to 16 after the procedure. Forty- one patients (80 %) had either complete or greater than 90 % control of the epileptic falls. Age and duration of epilepsy at surgery correlated with outcome (p values, respectively, 0.042 and 0.005). Mean index of callosal section along the posterior-to-anterior axis was 53.5 %. Extending the posterior section anterior to the midbody of the corpus callosum did not correlate with seizure control (p 0.91), providing fibers interconnecting the primary motor (M1) and caudal supplementary motor areas (SMA) were sectioned. Only one patient had a notable surgical complication which resolved in two days.

CONCLUSIONS

This level III cohort study with objective outcome assessment confirms that selective posterior callosotomy is safe and effective to control epileptic falls. Younger patients with smaller duration of epilepsy have better results. A posterior section contemplating the splenium, isthmus and posterior half of the body (posterior midbody) seems sufficient to achieve complete or almost complete control of drop attacks.

Secondary epileptogenesis on gradient magnetic-field topography correlates with seizure outcomes after vagus nerve stimulation

OBJECTIVE

To determine the correlation between secondary unilateral or bilateral spreading on gradient magnetic-field topography (GMFT) before and after vagus nerve stimulation (VNS), and postoperative seizure outcomes.

METHODS

We analyzed pre- and post-VNS magnetoencephalography (MEG) in 15 patients with VNS implants. We applied McHugh classification to evaluate seizure outcomes. GMFT visualized the spatiotemporal spread of the gradient magnetic field from MEG (>300 fT/cm) before and after the spike peak. We compared the proportion of bilaterally spreading (PBS) MEG spikes and seizure outcomes. We also compared the interhemispheric time difference (ITD) between patients with and without corpus callosotomy.

RESULTS

We allocated patients with favorable seizure outcomes of class I and II to group A (9 patients) and poor outcomes of class III-V to group B (6 patients). The number of post-VNS MEG spikes was significantly reduced compared to pre-VNS MEG spikes in group A, but not in group B. Group A showed significantly higher preoperative PBS than group B. Postoperative ITD significantly decreased in 5 patients who underwent corpus callosotomy compared to 10 patients without.

CONCLUSION

GMFT can detect the inter- and intrahemispheric spreading of spikes with high spatiotemporal resolution on the brain surface. Frequent interictal MEG spikes propagating bilaterally on GMFT may reflect a favorable seizure outcome after VNS. GMFT can identify dependent secondary epileptogenic spikes responding to VNS, which may be used to control generalized seizures in a subset of patients with pharmaco-resistant epilepsy.

Insufficient Efficacy of Corpus Callosotomy for Epileptic Spasms With Biphasic Muscular Contractions

Corpus callosotomy (CC) is the surgical strategy for drug-resistant epileptic seizures including epileptic spasms (ES). In this study we report a subtype of ES which is accompanied by two consecutive muscular contractions. This subtype has not been previously classified and may emerge via a complex epileptic network. We named these seizures “epileptic spasms with biphasic muscular contractions (ES-BMC)” and analyzed the association between them and CC outcomes. We enrolled 17 patients with ES who underwent CC before 20 years of age, and analyzed the records of long-term video-electroencephalogram (EEG) recordings. The outcomes of CC were ES-free (Engel's classification I) in 7 and residual ES (II to IV) in 10 patients. We statistically analyzed the associations between the presence of preoperative ES-BMC and the outcomes. Ages at CC ranged from 17 to 237 months. We analyzed 4–44 ictal EEGs for each patient. Five patients presented with ES-BMC with 6–40% of their whole ES on the presurgical video-EEG recordings, and all of them exhibited residual ES outcomes following CC. A Fisher's exact test revealed a significant positive correlation between the presence of preoperative ES-BMC and persistence of ES following CC (p = 0.044, odds ratio = 15.0, risk ratio = 2.0). The presence of ES-BMC may be useful in the presurgical prediction of CC outcomes in patients with ES.

Morphometric Analysis of the Corpus Callosum Using Cadaveric Brain: An Anatomical Study

Purpose:

The present study was conducted to measure the longitudinal and vertical lengths of the brain hemisphere, longitudinal length of the corpus callosum (CC), and distances of CC from the frontal and occipital poles, in order to define its topographic location within the brain hemispheres.

Materials and Methods:

Fifty formalin-fixed human brains were dissected in the midsagittal plane. The parameters measured were as follows: (i) straight distance between frontal and occipital pole (AB); (ii) vertical distance (height) between the upper and lower surface of the brain hemisphere (CD); (iii) frontal pole to anterior-most point of CC (EG); (iv) occipital pole to posterior-most point of CC (ZO); (v) anterior-most point to posterior-most point of CC (EZ); and (v) anterior edge of genu to the upper end of lamina terminalis (EF).

Results:

The mean value of AB, CD, EG, ZO, EZ, and EF was 15.47 ± 0.94 cm, 9.48 ± 0.83 cm, 3.31 ± 0.29 cm, 5.65 ± 0.54 cm, 6.96 ± 0.55 cm, and 2.1 ± 0.39 cm, respectively. AB had the strongest positive correlation with ZO (0.79), whereas CD (height) had it with EZ (0.59). Both AB and CD had a strong positive correlation with EZ. The ratios EZ/AB = 0.45 (P = 0.001) and EZ/CD = 0.73 (P = 0.003) illustrated a steady and significant proportions, present in all the brains studied. Although the mean values of all the parameters were greater in males than in females, only two parameters (ZO and EZ) showed statistically significant (P < 0.05) gender differences.

Conclusion:

The precise anatomical knowledge regarding the morphometry of CC will provide baseline data for the diagnosis and progression of disease affecting it.

Endoscopic Interhemispheric Disconnection for Intractable Multifocal Epilepsy: Surgical Technique and Functional Neuroanatomy

BACKGROUND

Callosotomy represents a palliative procedure for intractable multifocal epilepsy. The extent of callosotomy and the benefits of adding anterior and posterior commissurotomy are debated.

OBJECTIVE

To describe a new technique of a purely endoscopic procedure to disconnect the corpus callosum, the anterior, posterior, and habenular commissures through the use of a single burr hole via a transfrontal transventricular route.

METHODS

Our surgical series was retrospectively reviewed in terms of seizure control (Engel's class) and complication rate. Five cadaveric specimens were used to demonstrate the surgical anatomy of commissural fibers and third ventricle.

RESULTS

The procedure may be divided into 3 steps: (1) endoscopic transventricular transforaminal anterior commissure disconnection; (2) disconnection of posterior and habenular commissures; and (3) total callosotomy. Fifty-seven patients were included in the analysis. A favorable outcome in terms of epilepsy control (Engel class 1 to 3) was found in 71.4% of patients undergoing callosotomy coupled with anterior, posterior, and habenular commissure disconnection against 53% of patients with isolated callosotomy (P = .26). Patients with drop attacks had better epilepsy outcome independently from the surgical procedure used.

CONCLUSION

The full endoscopic callosotomy coupled with disconnection of anterior, posterior and habenular commissures is a safe alternative to treat multifocal refractory epilepsy. A gain in seizure outcome might be present in this cohort of patients treated with total interhemispheric disconnection when compared with isolated callosotomy. Larger studies are required to confirm these findings.

Symmetry of ictal slow waves may predict the outcomes of corpus callosotomy for epileptic spasms

We aimed to analyse the ictal electrographic changes on scalp electroencephalography (EEG), focusing on high-voltage slow waves (HVSs) in children with epileptic spasms (ES) and tonic spasms (TS) and then identified factors associated with corpus callosotomy (CC) outcomes. We enrolled 17 patients with ES/TS who underwent CC before 20 years of age. Post-CC Engel’s classification was as follows: I in 7 patients, II in 2, III in 4, and IV in 4. Welch’s t-test was used to analyse the correlation between ictal HVSs and CC outcomes based on the following three symmetrical indices: (1) negative peak delay: interhemispheric delay between negative peaks; (2) amplitude ratio: interhemispheric ratio of amplitude values for the highest positive peaks; and (3) duration ratio: interhemispheric ratio of slow wave duration. Ages at CC ranged from 17–237 months. Four to 15 ictal EEGs were analysed for each patient. The negative peak delay, amplitude ratio and duration ratio ranged from 0–530 ms, 1.00–7.40 and 1.00–2.74, respectively. The negative peak delay, amplitude ratio and duration ratio were significantly higher in the seizure residual group (p = 0.017, <0.001, <0.001, respectively). Symmetry of ictal HVSs may predict favourable outcomes following CC for ES/TS.

Corpus callosotomy for drug-resistant spasms associated with tuberous sclerosis complex

BACKGROUND

Corpus callosotomy (CC) has recently been adopted for the treatment of drug-resistant epileptic spasms and tonic spasms. In the present study, we investigated CC outcomes among patients with drug-resistant epileptic spasms or tonic spasms associated with tuberous sclerosis complex (TSC).

METHODS

We retrospectively collected data from seven patients (3 women, 4 men) with diagnosed TSC and who were treated using CC at Seirei Hamamatsu General Hospital in Japan. All patients had experienced drug-resistant epileptic spasms (<3 s of muscular contraction) or tonic spasms (>3 s) prior to CC, which were confirmed via video-electroencephalogram monitoring.

RESULTS

All patients exhibited multiple bilateral cortical tubers on brain magnetic resonance imaging. The main seizure types were epileptic spasms in four, tonic spasms in one, and both seizure types in two patients. Patients underwent total CC between the ages of 25 months and 21.5 years. Additional resection or disconnection was performed in two patients. The follow-up period after CC ranged between 9 months and 3.5 years. Three patients achieved remission from spasms following CC alone. Two other patients became free from spasms several months after CC but required an additional focus disconnection or medical treatment. The remaining two patients continued to show spasms or asymmetrical tonic seizures.

CONCLUSION

Total CC resulted in freedom from drug-resistant epileptic or tonic spasms in several patients with TSC. Stepwise progression from CC to additional resection or disconnection surgery may aid in the treatment of spasms secondary to TSC.

Rates and predictors of seizure outcome after corpus callosotomy for drug-resistant epilepsy: a meta-analysis

OBJECTIVE

Corpus callosotomy is a palliative surgery for drug-resistant epilepsy that reduces the severity and frequency of generalized seizures by disconnecting the two cerebral hemispheres. Unlike with resection, seizure outcomes remain poorly understood. The authors systematically reviewed the literature and performed a meta-analysis to investigate rates and predictors of complete seizure freedom and freedom from drop attacks after corpus callosotomy.

METHODS

PubMed, Web of Science, and Scopus were queried for primary studies examining seizure outcomes after corpus callosotomy published over 30 years. Rates of complete seizure freedom or drop attack freedom were recorded. Variables showing a potential relationship to seizure outcome on preliminary analysis were subjected to formal meta-analysis.

RESULTS

The authors identified 1742 eligible patients from 58 included studies. Overall, the rates of complete seizure freedom and drop attack freedom after corpus callosotomy were 18.8% and 55.3%, respectively. Complete seizure freedom was significantly predicted by the presence of infantile spasms (OR 3.86, 95% CI 1.13-13.23), normal MRI findings (OR 4.63, 95% CI 1.75-12.25), and shorter epilepsy duration (OR 2.57, 95% CI 1.23-5.38). Freedom from drop attacks was predicted by complete over partial callosotomy (OR 2.90, 95% CI 1.07-7.83) and idiopathic over known epilepsy etiology (OR 2.84, 95% CI 1.35-5.99).

CONCLUSIONS

The authors report the first systematic review and meta-analysis of seizure outcomes in both adults and children after corpus callosotomy for epilepsy. Approximately one-half of patients become free from drop attacks, and one-fifth achieve complete seizure freedom after surgery. Some predictors of favorable outcome differ from those in resective epilepsy surgery.

Successful corpus callosotomy for post-encephalopathic refractory epilepsy in a patient with MECP2 duplication syndrome

BACKGROUND

Patients with MECP2 duplication syndrome present with distinct facial anomalies and clinical features such as global developmental delay, recurrent respiratory infections, and epileptic seizures. Approximately half of all patients develop epileptic seizures which are refractory in most cases despite active medical management. Furthermore, no previous reports have discussed the efficacy of surgical treatment for seizures in patients with MECP2 duplication syndrome.

CASE REPORT

In the present report, we describe a case of MECP2 duplication syndrome in a 15-year-old boy who developed epileptic seizures following influenza-associated acute encephalitis. His frequent epileptic spasms, tonic, atonic, and partial seizures were refractory to multiple antiepileptic medications. Electroencephalography revealed continuous diffuse epileptic discharge, resulting in regression. A total corpus callosotomy (CC) was performed at the age of 14 years and 7 months. His seizures markedly decreased following CC, although he continued to experience brief partial seizures approximately once per month. Post-operative examination revealed that his epileptic discharges had disappeared, and that his developmental state had returned to pre-encephalopathy levels.

CONCLUSION

Our findings indicate that CC may represent a valuable surgical option for children with medically refractory generalized seizures following acute encephalopathy, irrespective of genetic disorders such as MECP2 duplication syndrome.

Neurosurgical approaches to pediatric epilepsy: Indications, techniques, and outcomes of common surgical procedures

Epilepsy is a common pediatric neurological condition, and approximately one-third of children with epilepsy are refractory to medical management. For these children neurosurgery may be indicated, but operative success is dependent on complete delineation of the epileptogenic zone. In this review, surgical techniques for pediatric epilepsy are considered. First, potentially-curative operations are discussed and broadly divided into resections and disconnections. Then, two palliative approaches to seizure control are reviewed. Finally, future neurosurgical approaches to epilepsy are considered.

Callosotomy in children - Parental experiences reported at long-term follow-up

Callosotomy is a palliative surgery method for selected individuals with severe, drug-resistant epilepsy. The aim of this retrospective study was to explore parental experiences of the family's life situation before and long after their child had undergone callosotomy. Semistructured interviews of the parents of 12 children were analyzed using a combination of inductive and deductive qualitative content analysis. Before surgery, parents felt that they lived in a chaotic bubble with an unbearable situation; their child had severe and frequent seizures and had to be looked after constantly. Most parents were both satisfied and dissatisfied with the given support and information. However, if the child did not improve after surgery, parents often felt that the information before surgery had not been adequate. After surgery, they found a glimpse of hope. They felt that the family got a new life; the reduced seizure severity led to a better life situation for the family. The support was described as both good and poor. The family life situation was complex, and even if they were partly satisfied with the support, it was still not enough. However, the life situation was also very stressful because of remaining seizures, behavioral problems, and sometimes, adverse effects of surgery. The families lived in disappointment and difficulty and had to fight for their rights. This indicates that these families need more information and social service coordination both before and long after surgery. They need not only tools to manage the child's disabilities but also substantial help to care for the child and to receive the social support they need.

Anterior corpus callosotomy in patients with drug-resistant epilepsy: Invasive EEG findings and seizure outcomes

Corpus callosotomy (CC) is used in patients with drug-resistant seizures who are not candidates for excisional surgery and failed neurostimulation. We examined ictal scalp and intracranial electroencephalogram (iEEG) recordings in 16 patients being evaluated for anterior CC alone or CC in combination with focal resection, to determine the role of the iEEG in predicting postoperative seizure outcomes. In our cohort, CC improved generalized atonic seizures and focal seizures with impaired awareness but did not alter outcomes for generalized tonic–clonic or tonic seizures. Invasive EEG prior to CC did not refine the prediction of postsurgical seizure outcomes in patients with inconclusive scalp EEG.

•

Patients with drug-resistant epilepsy achieved a significant reduction of generalized atonic and focal seizures with impaired awareness following corpus callosotomy.

•

The age at epilepsy diagnosis or structural pathology identified on the imaging did not predict postoperative seizure status.

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The ictal findings on invasive EEG prior to corpus callosotomy improved lateralization of seizure onset but did not predict seizure outcomes.

Surgical Resection of Anterior and Posterior Butterfly Glioblastoma

BACKGROUND

Evidence suggests a survival benefit for patients with glioblastoma who undergo maximal safe surgical resection. Not all glioblastomas are amenable to surgical resection and anatomic location is one potentially limiting factor. Glioblastomas that invade the corpus callosum and cross midline to the contralateral hemisphere-butterfly glioblastomas (bGBMs)-are one subgroup of tumors traditionally deemed inoperable.

METHODS

We evaluate the management of bGBMs at our institution to assess whether surgical resection is feasible, safe, and more effective than biopsy. We retrospectively reviewed our institutional brain tumor registry for all adult patients treated for glioblastoma (World Health Organization grade IV) between 2004 and 2016 to identify all bGBMs.

RESULTS

Survival between biopsy and resection was assessed using the Kaplan-Meier model. Twenty-nine (3.8%) of 764 newly diagnosed GBMs were identified as bGBM. Of these, 9 patients (31.0%) underwent surgical resection and 20 patients (69.0%) underwent biopsy. Five patients (55.6%) in the surgical resection group had 98% extent of resection or greater. Median survival of our entire cohort of patients was 3.3 months. Median survival was higher in the surgical resection groups (7.8 vs. 2.8 months; P = 0.0019). Increased age is independently associated with increased risk of death, and adjuvant therapy is independently associated with prolonged survival.

CONCLUSIONS

Surgical resection of butterfly glioblastoma prolongs survival without increased risk of permanent neurologic deficit. Both anterior and posterior bGBMs can be resected safely.

Successful corpus callosotomy for Doose syndrome

Doose syndrome (epilepsy with myoclonic-atonic seizures) is an epilepsy syndrome with an incidence of approximately 1-2% of childhood-onset epilepsies. Although this syndrome is associated with multiple types of generalized seizures, the diagnosis is based on the presence of myoclonic-atonic seizures. Eighteen percent of patients have refractory seizures and intellectual disabilities. There have, however, been a few reports on the efficacy of surgical treatment for Doose syndrome. We describe a case of Doose syndrome in a 10-year-old boy. He developed generalized tonic-clonic seizures at 3years 8months of age and subsequently developed myoclonic-atonic, myoclonic, and tonic seizures. The frequent myoclonic seizures were refractory to multiple antiepileptic medications. His cognitive development was moderately delayed. Anterior four fifths corpus callosotomy was performed at 8years 5months of age. His seizures, especially myoclonic seizures, were markedly reduced. He was given vagus nerve stimulation therapy at 9years and 1month of age, which led to complete resolution of the myoclonic seizures. Corpus callosotomy can be a good treatment strategy in patients with Doose syndrome with medically refractory generalized seizures.

Corpus Callosotomy for Intractable Epilepsy Revisited: The Children's Hospital of Michigan Series

Corpus callosotomy is a palliative procedure performed to reduce the severity of drug-resistant epilepsy. The authors assessed its efficacy on different seizure types in 20 subjects (age range 5-19 years); 8 with active vagus nerve stimulator. Fifteen had complete callosotomy, 3 had anterior 2/3, and 2 had anterior 2/3 followed later by complete callosotomy. Ten had endoscopic approach. In all, 65% had ≥ 50% reduction of generalized seizures leading to falls (atonic, tonic, myoclonic); 35% became seizure-free (follow-up period: 6 months to 9 years; mean 3 years). Seizure outcome distribution was better for generalized than for partial seizures ( P = .003). Endoscopic approach was as effective as transcranial approach. Seven subjects who failed vagus nerve stimulator therapy responded with ≥50% seizure reduction. Corpus callosotomy is an effective treatment for intractable generalized epilepsy leading to falls with significant seizure reduction or even elimination of seizures, in the majority of children.

Total corpus callosotomy for epileptic spasms after acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) in a case with tuberous sclerosis complex

Corpus callosotomy is a palliative therapy for refractory epilepsy, including West syndrome, without a resectable epileptic focus. The surgical outcome of corpus callosotomy is relatively favorable in cryptogenic (non-lesional) West syndrome. Tuberous sclerosis complex (TSC) is a disorder that frequently leads to the development of refractory seizures by multiple cortical tubers. The multiple cortical tubers cause multiple or wide epileptic networks in these cases. Most of West syndrome cases in TSC with multiple tubers need additional resective surgery after corpus callosotomy. We describe a case of TSC in a boy aged 4years and 8months. He had multiple cortical tubers on his brain and developed epileptic spasms. The seizures were controlled with valproate. At the age of 1year and 4months, he presented with acute encephalopathy with biphasic seizures and late reduced diffusion (AESD), and had relapsed epileptic spasms one month after the onset of the encephalopathy. The seizures were refractory to multiple antiepileptic drugs. A total corpus callosotomy was performed at the age of 3years and 8months. The patient did not show any seizures after the surgery. During 12months of the follow-up, the patient was free from any seizures. Even in cases of symptomatic WS with multiple lesions, total corpus callosotomy may be a good strategy if the patients have secondary diffuse brain insults.

Treatment-resistant Lennox-Gastaut syndrome: therapeutic trends, challenges and future directions

Lennox-Gastaut syndrome is a severe, childhood-onset electroclinical syndrome comprised of multiple seizure types, intellectual and behavioral disturbances and characteristic findings on electroencephalogram of slow spike and wave complexes and paroxysmal fast frequency activity. Profound morbidity often accompanies a common and severe seizure type, the drop attack. Seizures often remain refractory, or initial treatment efficacy fades. Few individuals are seizure free despite the development of multiple generations of antiseizure medications over decades and high-level evidence on several choices. Approved medications such as lamotrigine, topiramate, rufinamide, felbamate and clobazam have demonstrated efficacy in reducing seizure burden. Cannabidiol has emerged as a promising investigational therapy with vast social interest yet lacks a standard, approved formulation. Palliative surgical procedures, such as vagal nerve stimulation and corpus callosotomy may provide reduction in total seizures and drop attacks. Emerging evidence suggests that complete callosotomy provides greater improvement in seizures without additional side effects. Etiologies such as dysplasia or hypothalamic hamartoma may be amenable for focal resection and thus offer potential to reverse this devastating epileptic encephalopathy.

Efficacy and safety of corpus callosotomy after vagal nerve stimulation in patients with drug-resistant epilepsy

OBJECTIVE Vagal nerve stimulation (VNS) and corpus callosotomy (CC) have both been shown to be of benefit in the treatment of medically refractory epilepsy. Recent case series have reviewed the efficacy of VNS in patients who have undergone CC, with encouraging results. There are few data, however, on the use of CC following VNS therapy. METHODS The records of all patients at the authors' center who underwent CC following VNS between 1998 and 2015 were reviewed. Patient baseline characteristics, operative details, and postoperative outcomes were analyzed. RESULTS Ten patients met inclusion criteria. The median follow-up was 72 months, with a minimum follow-up of 12 months (range 12-109 months). The mean time between VNS and CC was 53.7 months. The most common reason for CC was progression of seizures after VNS. Seven patients had anterior CC, and 3 patients returned to the operating room for a completion of the procedure. All patients had a decrease in the rate of falls and drop seizures; 7 patients experienced elimination of drop seizures. Nine patients had an Engel Class III outcome, and 1 patient had a Class IV outcome. There were 3 immediate postoperative complications and 1 delayed complication. One patient developed pneumonia, 1 developed transient mutism, and 1 had persistent weakness in the nondominant foot. One patient presented with a wound infection. CONCLUSIONS The authors demonstrate that CC can help reduce seizures in patients with medically refractory epilepsy following VNS, particularly with respect to drop attacks.

Corpus Callosotomy for Patients With Intractable Seizures: An Insight Into the Rapid Relapse

It is well known that corpus callosotomy (CC) can bring a favorable seizure control outcome for disabling generalized seizures, but the complete remission rate achieved by CC is rarely reported, and the postoperative relapse pattern is still not clear. In this study, the authors reviewed patients with medically refractory epilepsy who were suffering disabling seizures, including drop attacks, generalized tonic-clonic seizures (GTCS), tonic seizures, atonic seizures, atypical absences, and complex partial seizures. The patients underwent anterior two third or complete CC in our hospital. Seizure control outcome was evaluated postoperatively at 2 weeks, 1 month, 3 months, 6 months, thereafter, at yearly intervals. Seizure-free or >90% reduction was considered to be satisfactory. There were 14 patients with mean age 11.00 ± 6.34 at surgery. Of all the patients, 6 patients underwent anterior two third CC, and the other 8 patients underwent complete CC. All the patients were postoperatively followed up for at least 1 year. Four patients (28.57%) were free of all seizure types in the first year after surgery. Among the 9 patients with follow-up longer than 3 years, 2 patients (22.22%) were free of all seizure types. In the first 3 months after surgery, more than half of the seizure free patients (55.56%) relapsed with the same seizure types as preoperatively. Although after that, there was only 1 patient relapsed. Of all the seizure types, CC achieved the most favorable seizure outcome in drop attacks. In conclusion, CC could achieve complete seizure remission in a small portion of selected candidates. Exploration of the relapse mechanism will contribute to improve the seizure outcome following CC.

Preoperative evaluation and surgical decision-making in pediatric epilepsy surgery

Epilepsy is a common disease in the pediatric population, and the majority of cases are controlled with medications and lifestyle modification. For the children whose seizures are pharmacoresistant, continued epileptic activity can have a severely detrimental impact on cognitive development. Early referral of children with drug-resistant seizures to a pediatric epilepsy surgery center for evaluation is critical to achieving optimal patient outcomes. There are several components to a thorough presurgical evaluation, including a detailed medical history and physical examination, noninvasive testing including electroencephalogram, magnetic resonance imaging (MRI) of the brain, and often metabolic imaging. When necessary, invasive diagnostic testing using intracranial monitoring can be used. The identification of an epileptic focus may allow resection or disconnection from normal brain structures, with the ultimate goal of complete seizure remission. Additional operative measures can decrease seizure frequency and/or intensity if a clear epileptic focus cannot be identified. In this review, we will discuss the nuances of presurgical evaluation and decision-making in the management of children with drug-resistant epilepsy (DRE).

Seizure outcomes in nonresective epilepsy surgery: an update

In approximately 30 % of patients with epilepsy, seizures are refractory to medical therapy, leading to significant morbidity and increased mortality. Substantial evidence has demonstrated the benefit of surgical resection in patients with drug-resistant focal epilepsy, and in the present journal, we recently reviewed seizure outcomes in resective epilepsy surgery. However, not all patients are candidates for or amenable to open surgical resection for epilepsy. Fortunately, several nonresective surgical options are now available at various epilepsy centers, including novel therapies which have been pioneered in recent years. Ablative procedures such as stereotactic laser ablation and stereotactic radiosurgery offer minimally invasive alternatives to open surgery with relatively favorable seizure outcomes, particularly in patients with mesial temporal lobe epilepsy. For certain individuals who are not candidates for ablation or resection, palliative neuromodulation procedures such as vagus nerve stimulation, deep brain stimulation, or responsive neurostimulation may result in a significant decrease in seizure frequency and improved quality of life. Finally, disconnection procedures such as multiple subpial transections and corpus callosotomy continue to play a role in select patients with an eloquent epileptogenic zone or intractable atonic seizures, respectively. Overall, open surgical resection remains the gold standard treatment for drug-resistant epilepsy, although it is significantly underutilized. While nonresective epilepsy procedures have not replaced the need for resection, there is hope that these additional surgical options will increase the number of patients who receive treatment for this devastating disorder-particularly individuals who are not candidates for or who have failed resection.

Surgical versus medical treatment for children with epileptic encephalopathy in infancy and early childhood: Results of an international multicenter cohort study in Far-East Asia (the FACE study)

OBJECTIVE

To compare the seizure and developmental outcomes in infants and young children with epileptic encephalopathy who have undergone surgical and medical treatments.

METHODS

An international, multicenter, observational cohort study was undertaken. A total of 317 children aged <6 years, who had frequent disabling seizures despite intensive medical treatments, were registered. Among the enrolled children, 250 were treated medically (medical group), 31 underwent resective surgery (resective group), and 36 underwent palliative surgery [callosotomy (n=30) or vagal nerve stimulation (n=6); palliative group] on admission. Seizure and developmental outcomes were obtained for 230 children during the 3-year follow-up period. Cox proportional hazard model was used to adjust for clinical backgrounds among treatment groups when comparing the seizure-free survival rates.

RESULTS

At the 3-year follow-up, seizure-free survival was 15.7%, 32.1%, and 52.4% in the medical, palliative, and resective groups, respectively. The adjusted hazard ratios for seizure recurrence in the resective and palliative groups versus the medical group were 0.43 (95% CI, 0.21-0.87, P=0.019) and 0.82 (95% CI, 0.46-1.46, P=0.50), respectively; the former was statistically significant. Regarding the developmental outcome, the mean DQs in the resective group increased significantly compared to those in the medical group during the follow-up (P<0.01). As for subgroup analysis, better seizure and development outcomes were demonstrated in the resective group compared to the medical group in children with nonsyndromic epilepsies (those to which no known epilepsy syndromes were applicable).

SIGNIFICANCE

These results suggest that surgical treatments, particularly resective surgeries, are associated with better seizure and developmental outcomes compared with successive medical treatment. The present observations may facilitate the identification of infants and young children with epileptic encephalopathy who could benefit from surgery.

Callosotopy: leg motor connections illustrated by fiber dissection

Precise anatomical knowledge of the structure of the corpus callosum is important in split-brain research and during neurosurgical procedures sectioning the callosum. According to the classic literature, commissural fibers connecting the motor cortex are situated in the anterior part of the corpus callosum. On the other hand, more recent imaging studies using diffusion tensor imaging indicate a more posterior topography of callosal fibers connecting motor areas. Topographical knowledge is especially critical when performing disconnective callosotomies in epilepsy patients who experience sudden loss of leg motor control, so-called epileptic drop attacks. In the current study, we aim to precisely delineate the topography of the leg motor connections of the corpus callosum. Of 20 hemispheres obtained at autopsy, 16 were dissected according to Klingler's fiber dissection technique to study the course and topography of callosal fibers connecting the most medial part of the precentral gyrus. Fibers originating from the anterior bank of the central sulcus were invariably found to be located in the isthmus of the corpus callosum, and no leg motor fibers were found in the anterior part of the callosum. The current results suggest that the disconnection of the pre-splenial fibers, located in the posterior one-third of the corpus callosum, is paramount in obtaining a good outcome after callosotomy.