Magnetic resonance-guided laser interstitial thermal therapy versus open surgical corpus callosotomy for pediatric refractory epilepsy: A systematic review and meta-analysis

PURPOSE

Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) is a novel, minimally invasive alternative to traditional open surgery corpus callosotomy (CC). We aim to compare both approaches in terms of time of hospitalization and surgical procedure, complications, and efficacy outcomes.

METHODS

A systematic search on PubMed, Embase, Web of Science, and Cochrane Library databases was performed for studies directly comparing MRgLITT and open surgery for refractory epilepsy in children.

RESULTS

A total of 240 patients from five studies were included. There was no statistically significant difference observed between the two groups regarding the favorable Engel outcome. (RR 0.89; 95 % CI 0.70-1.14; p = 0.36; I2=0 %) The mean hospital length of stay (LOS) was significantly shorter in the patients who underwent MRgLITT. (MD -2.84 days; 95 % CI [-3.17]-[-2.51] days; p < 0.00001; I2=90 %) The mean operation duration was significantly longer in the intervention group. (MD 1.38 h; 95 % CI 0.64- 2.12 h; p = 0.00002; I2=55 %). The mean blood loss was significantly lower in patients who underwent MRgLITT. (MD -75.15 ml; 95 % CI [-92.82]-[-57.48] ml; p < 0.00001; I2=0 %) CONCLUSION: CC is a valuable option for treating RE, especially in children. The open surgery bears the stigma of an invasive and complicated technique which might justify its underuse. MRgLITT is a great alternative and possibly a way to widen the use of callosotomy in children, however, its cost and availability may be a challenge.

Pediatric Palliative Epilepsy Surgery: A Report From the Pediatric Epilepsy Research Consortium (PERC) Surgery Database

BACKGROUND

Epilepsy surgery is an underutilized resource for children with drug-resistant epilepsy. Palliative and definitive surgical options can reduce seizure burden and improve quality of life. Palliative epilepsy surgery is often seen as a "last resort" compared to definitive surgical options. We compare patient characteristics between palliative and definitive epilepsy surgical patients and present palliative surgical outcomes from the Pediatric Epilepsy Research Consortium surgical database.

METHODS

The Pediatric Epilepsy Research Consortium Epilepsy Surgery database is a prospective registry of patients aged 0-18 years undergoing evaluation for epilepsy surgery at 20 pediatric epilepsy centers. We included all children with completed surgical therapy characterized as definitive or palliative. Demographics, epilepsy type, age of onset, age at referral, etiology of epilepsy, treatment history, time-to-referral/evaluation, number of failed anti-seizure medications (ASMs), imaging results, type of surgery, and postoperative outcome were acquired.

RESULTS

Six hundred forty patients undergoing epilepsy surgery were identified. Patients undergoing palliative procedures were younger at seizure onset (median: 2.1 vs 4 years, P= 0.0008), failed more ASM trials before referral for presurgical evaluation (P=<0.0001), and had longer duration of epilepsy before referral for surgery (P=<0.0001). During presurgical evaluation, patients undergoing palliative surgery had shorter median duration of video-EEG data collected (P=0.007) but number of cases where ictal data were acquired was similar between groups. The most commonly performed palliative procedure was corpus callosotmy (31%), followed by lobectomy (21%) and neuromodulation (82% responsive neurostimulation vs 18% deep brain stimulation). Palliative patients were further categorized into traditionally palliative procedures vs traditionally definitive procedures. The majority of palliative patients had 50% reduction or better in seizure burden. Seizure free outcomes were significantly higher among those with traditional definitive surgeries, 41% (95% confidence interval: 26% to 57%) compared with traditional palliative surgeries and 9% (95% confidence interval: 2% to 17%). Rate of seizure freedom was 46% at 24 months or greater of follow-up in the traditional definitive group.

CONCLUSIONS

Patients receiving palliative epilepsy surgery trialed more ASMs, were referred later after becoming drug resistant, and had longer gaps between drug resistance and epilepsy surgery compared with patients undergoing definitive epilepsy surgery. The extent of surgical evaluation is impacted if surgery is thought to be palliative. A majority of palliative surgery patients achieved >50% seizure reduction at follow-up, both in groups that received traditionally palliative and traditionally definitive surgical procedures. Palliative surgical patients can achieve greater seizure control and should be referred to an epilepsy surgery center promptly after failing two appropriate anti-seizure medications.

Current state of hemispherectomy and callosotomy for pediatric refractory epilepsy in Denmark

OBJECTIVE

To evaluate outcomes from hemispherectomy and callosotomy related to the need for anti-seizure medication (ASM), seizure frequency, and cognition.

METHODS

A review of the medical charts of all Danish pediatric patients who underwent hemispherectomy or callosotomy from January 1996 to December 2019 for preoperative and postoperative ASM use, seizure frequency, and cognitive data.

RESULTS

The median age of epilepsy onset was two years (interquartile range (IQR): 0.0-5.3) for the hemispherectomy patients (n = 16) and one year (IQR: 0.6-1.7) for callosotomy patients (n = 5). Median time from onset to final surgery was 3.4 years for hemispherectomy and 10.2 years for callosotomy, while the median follow-up time was 6.9 years and 9.0 years, respectively. Preoperatively, all patients had daily seizures and were treated with ≥ 2 ASM. Hemispherectomy resulted in a reduction in seizure frequency in 87.5 % of patients, with 78.6 % achieving seizure freedom. Furthermore, 81.3 % experienced a reduction in ASM use and 56.3 % stopped all ASM. Median IQ/developmental quotient (IQ/DQ) was low preoperatively (44.0 [IQR: 40.0-55.0]) and remained unchanged postoperatively (IQ change: 0.0 [IQR: -10.0-+4.0]). Callosotomy resulted in a seizure reduction of 86-99 % in four patients, and ASM could be reduced in three patients. Median IQ/DQ was 20.0 preoperatively (IQR: 20.0-30.0) and remained unchanged postoperatively (IQ change: 0.0 [IQR: 0.0]).

CONCLUSION

Hemispherectomy and callosotomy result in a substantial reduction in seizure frequency and ASM use without deterioration of IQ. Extensive epilepsy surgery should be considered early in children with drug-resistant epilepsy.

A multi-center comparison of surgical techniques for corpus Callosotomy in pediatric drug-resistant epilepsy

OBJECTIVES

Corpus callosotomy (CC) is used to reduce seizures, primarily in patients with generalized drug-resistant epilepsy (DRE). The invasive nature of the procedure contributes to underutilization despite its potential superiority to other palliative procedures. The goal of this study was to use a multi-institutional epilepsy surgery database to characterize the use of CC across participating centers.

METHODS

Data were acquired from the Pediatric Epilepsy Research Consortium (PERC) Surgery Database, a prospective observational study collecting data on children 0-18 years referred for surgical evaluation of DRE across 22 U.S. pediatric epilepsy centers. Patient, epilepsy, and surgical characteristics were collected across multiple CC modalities. Outcomes and complications were recorded and analyzed statistically.

RESULTS

Eighty-three patients undergoing 85 CC procedures at 14 participating epilepsy centers met inclusion criteria. Mean age at seizure onset was 2.3 years (0-9.4); mean age for Phase I evaluation and surgical intervention were 9.45 (.1-20) and 10.46 (.2-20.6) years, respectively. Generalized seizure types were the most common (59%). Complete CC was performed in 88%. The majority of CC procedures (57%) were via open craniotomy, followed by laser interstitial thermal therapy (LiTT) (20%) and mini-craniotomy/endoscopic (mc/e) (22%). Mean operative times were significantly longer for LiTT, whereas mean estimated blood loss was greater in open cases. Complications occurred in 11 cases (13%) and differed significantly between surgical techniques (p < .001). There was no statistically significant difference in length of postoperative stay across approaches. Mean follow-up was 12.8 months (range 1-39). Favorable Engel outcomes were experienced by 37 (78.7%) of the patients who underwent craniotomy, 10 (58.8%) with LiTT, and 12 (63.2%) with mc/e; these differences were not statistically significant.

SIGNIFICANCE

CC is an effective surgical modality for children with DRE. Regardless of surgical modality, complication rates are acceptable and seizure outcomes generally favorable. Newer, less-invasive, surgical approaches may lead to increased adoption of this efficacious therapeutic option for pediatric DRE.

The clinical features of patients with seizure freedom and failure after total corpus callosotomy for childhood-onset refractory epilepsy

BACKGROUND

Corpus callosotomy is a palliative surgery for medically refractory epilepsy. We aim to analyze the clinical features of patients with seizure freedom and failure after total corpus callosotomy for childhood-onset refractory epilepsy.

METHODS

We retrospectively reviewed the clinical courses of patients with childhood-onset refractory epilepsy undergoing total corpus callosotomy between May 2009 and March 2019. Seizure outcome at the last follow-up was the primary outcome. The clinical features of patients with seizure freedom and failure after callosotomy were compared.

RESULTS

Eighty patients with childhood-onset refractory epilepsy underwent total corpus callosotomy; 15 (18.8%) obtained freedom from all seizures and 19 (23.8%) had unworthwhile improvement and failure. The mean ages at seizure onset in patients with seizure freedom and failure after callosotomy were 5.7 and 5.9 years; and mean seizure durations were 9.4 and 11.5 years, respectively. Univariate analysis found epilepsy syndrome (p = 0.047), mental retardation (p = 0.007), previous medical history (p = 0.004), ≥10 seizures per day (p = 0.024), theta waves in the background electroencephalogram (p = 0.024), and acute postoperative seizure (p = 0.000) were associated with failure after callosotomy. Seizure freedom after callosotomy was more common among patients with less than 10 seizures per day.

CONCLUSIONS

Total corpus callosotomy is an effective palliative procedure for childhood-onset refractory epilepsy, particularly for patients with specific clinical characteristics. Callosotomy has a high seizure-free rate in well-selected patients.

Surgical outcomes of open and laser interstitial thermal therapy approaches for corpus callosotomy in pediatric epilepsy

OBJECTIVE

Corpus callosotomy (CC) is a palliative surgical intervention for patients with medically refractory epilepsy that has evolved in recent years to include a less-invasive alternative with the use of laser interstitial thermal therapy (LITT). LITT works by heating a stereotactically placed laser fiber to ablative temperatures under real-time magnetic resonance imaging (MRI) thermometry. This study aims to (1) describe the surgical outcomes of CC in a large cohort of children with medically refractory epilepsy, (2) compare anterior and complete CC, and (3) review LITT as a surgical alternative to open craniotomy for CC.

METHODS

This retrospective cohort study included 103 patients <21 years of age with at least 1 year follow-up at a single institution between 2003 and 2021. Surgical outcomes and the comparative effectiveness of anterior vs complete and open versus LITT surgical approaches were assessed.

RESULTS

CC was the most common surgical disconnection (65%, n = 67) followed by anterior two-thirds (35%, n = 36), with a portion proceeding to posterior completion (28%, n = 10). The overall surgical complication rate was 6% (n = 6/103). Open craniotomy was the most common approach (87%, n = 90), with LITT used increasingly in recent years (13%, n = 13). Compared to open, LITT had shorter hospital stay (3 days [interquartile range (IQR) 2-5] vs 5 days [IQR 3-7]; p < .05). Modified Engel class I, II, III, and IV outcomes at last follow-up were 19.8% (n = 17/86), 19.8% (n = 17/86), 40.2% (n = 35/86), and 19.8% (n = 17/86). Of the 70 patients with preoperative drop seizures, 75% resolved postoperatively (n = 52/69).

SIGNIFICANCE

No significant differences in seizure outcome between patients who underwent only anterior CC and complete CC were observed. LITT is a less-invasive surgical alternative to open craniotomy for CC, associated with similar seizure outcomes, lower blood loss, shorter hospital stays, and lower complication rates, but with longer operative times, when compared with the open craniotomy approach.

Comparing late-onset epileptic spasm outcomes after corpus callosotomy and subsequent disconnection surgery between post-encephalitis/encephalopathy and non-encephalitis/encephalopathy

OBJECTIVE

We aimed to analyze the efficiency of corpus callosotomy (CC) and subsequent disconnection surgeries in patients with late-onset epileptic spasms (LOES) by comparing post-encephalitis/encephalopathy (PE) and non-encephalitis/encephalopathy (NE). We hypothesized these surgeries can control potential focal onset epileptic spasms (ES) in the NE group but not in the PE group.

METHODS

We retrospectively included 23 patients (12 with PE and 11 with NE) who initially underwent CC and subsequent disconnection surgeries (five NE). We compared the clinical courses, seizure types, MRI, video-EEG, epilepsy surgery, and seizure outcomes between the two groups.

RESULTS

The median age of LOES onset in the PE group was 2.8 (range 1.0-10.1 years) and 2.9 years (range 1.1-12.6) in the NE group. Bilateral MRI abnormalities were observed in both groups (PE, n = 12; NE, n = 3; P < 0.05). The PE group presented ES alone (n = 2), ES + focal seizures (FS) (n = 3), ES + generalized seizures (GS) (n = 3), and ES + FS + GS (n = 4) in addition to stimulus-induced startle seizures (SS) (n = 8) (mean 3.1 seizure types/patient). The NE group presented ES alone (n = 1), ES + FS (n = 2), and ES + FS + GS (n = 8) (mean 2.7 seizure types/patient). In the PE group, CC stopped ES (n = 1) and SS (n = 1) and achieved <50% SS (n = 3). In the NE group, CC achieved immediate ES-free status (n = 2) and < 50% ES (n = 1), and additional disconnection surgeries subsided all seizure types (n = 3) based on lateralized interictal/ictal EEG findings. LOES was significantly remitted by surgery in the NE group (6/11 [55%]) compared with the PE group (1/12 [8%]) (P < 0.05).

SIGNIFICANCE

LOES is a drug-resistant, focal/generalized/unknown onset ES. Lateralization of ES in NE could be achieved after CC and eliminated by further disconnection surgeries because of potential focal onset ES. LOES in PE had little benefit from CC for generalized onset ES. However, CC might reduce SS in patients in the PE group with multiple seizure types.

Long-term follow-up seizure outcomes after corpus callosotomy: A systematic review with meta-analysis

BACKGROUND

Corpus callosotomy (CC) is appropriate for patients with seizures of a bilateral or diffuse origin, or those with seizures of a unilateral origin with rapid spread to the contralateral cerebral hemisphere. The efficiency of CC in patients with drug-resistant epilepsy is a long-term concern because most articles reporting the surgical results of CC arise from small case series, and the durations of follow-up vary.

METHODS

PubMed, Embase, Cochrane Library, and Web of Science were searched to identify papers published before November 8, 2021. The systematic review was completed following PRISMA guidelines. Outcomes were analyzed by meta-analysis of the proportions.

RESULTS

A total of 1644 patients with drug-resistant epilepsy (49 retrospective or prospective case series studies) underwent CC, and the follow-up time of all patients was at least 1 year. The rate of complete seizure freedom (SF) was 12.38% (95% confidence interval [CI], 8.17%-17.21%). Meanwhile, the rate of complete SF from drop attacks was 61.86% (95% CI, 51.87%-71.41%). The rates of complete SF after total corpus callosotomy (TCC) and anterior corpus callosotomy (ACC) were 11.41% (95% CI, 5.33%-18.91%) and 6.75% (95% CI, 2.76%-11.85%), respectively. Additionally, the rate of complete SF from drop attacks after TCC was significantly higher than that after ACC (71.52%, 95% CI, 54.22%-86.35% vs. 57.11%, 95% CI, 42.17%-71.49%). The quality of evidence for the three outcomes by GRADE assessment was low to moderate.

CONCLUSION

There was no significant difference in the rate of complete SF between TCC and ACC. TCC had a significantly higher rate of complete SF from drop attacks than did ACC. Furthermore, CC for the treatment of drug-resistant epilepsy remains an important problem for further investigation because there are no universally accepted standardized guidelines for the extent of CC and its benefit to patients. In future research, we will focus on this issue.

Complete corpus callosotomy using a frameless navigation probe through a minicraniotomy in children with medically refractory epilepsy: A case series and technical note

Background

Medically refractory epilepsy constitutes up to one-third of the epilepsy pediatric patients. Corpus callosotomy (CC) has been used for the treatment of medically refractory epilepsy in children with atonic seizures and generalized tonic-clonic (GTC) seizures. In this case series study, we are describing a novel technique for CC using the frameless navigation probe through a minicraniotomy.

Methods

Thirteen pediatric patients with the diagnosis of medically refractory epilepsy predominantly GTC with drop attack who underwent extensive Phase I. An L-shape was done, then through a 4 × 3 cm craniotomy, we were able to open the interhemispheric fissure until the corpus callosum is visualized. The Stealth probe is then used to go down to the midline raphe which is followed anteriorly then traced posteriorly to the anterior border of the vein of Galen. Finally, the Stealth probe is used to confirm the completeness of the callosotomy.

Results

The procedure was accomplished successfully with no intraoperative complications; mean surgical time is 3 h:07 m. The mean follow-up was 31.5 months. All patients achieved significant seizure control. No patients experienced worsening of their atonic seizures after surgery compared with their preoperative state; however, six patients achieved Engel Class I, four patients achieved Engel Class II, and three patients achieved Engel Class III.

Conclusion

Complete CC using a frameless navigation probe is a novel and effective technique for the treatment of medically refractory epilepsy with a very good surgical and seizure outcomes, minimal neurological morbidity, minimal blood loss, and short OR time.

Magnetic resonance imaging-guided laser interstitial thermal therapy for complete corpus callosotomy: technique and 1-year outcomes. Patient series

BACKGROUND

Magnetic resonance imaging (MRI)-guided stereotactic laser interstitial thermal therapy (LITT) is a minimally invasive technique that has been described for the treatment of certain forms of epilepsy through partial or complete callosotomy, with few cases describing single-stage complete LITT callosotomy. The authors aimed to demonstrate this technique's feasibility and efficacy through description of the technique and 1-year outcomes in 3 cases of single-stage complete LITT callosotomy in patients with anatomically normal corpa callosa (CCs).

OBSERVATIONS

The patients were aged 14-27 years and experienced atonic seizures. Completeness of callosotomy was determined from MRI scans obtained >3 months after LITT procedures. The estimated ablations of the CC were 94%, 89%, and 100%, respectively. The second patient had a catheter breach the lateral ventricle, resulting in the lowest estimated percentage of ablation in this series (89%), with minimal atonic seizure reduction. The first patient had significant reduction in atonic seizure frequency, and the third patient had complete resolution of atonic seizures. None of the patients experienced any long-term complications. Intensive care length of stay was 1 night for each patient, and total length of stay was between 2 and 7 nights. Postoperative follow-up was between 14 and 18 months.

LESSONS

Complete laser callosotomy is achievable and is a safe alternative to microsurgical or endoscopic approaches.

Surgical Treatment of Drug-Resistant Generalized Epilepsy

PURPOSE OF REVIEW

To summarize current evidence and recent developments in the surgical treatment of drug-resistant generalized epilepsy.

RECENT FINDINGS

Current surgical treatments of drug-resistant generalized epilepsy include vagus nerve stimulation (VNS), deep brain stimulation (DBS) and corpus callosotomy (CC). Neurostimulation with VNS and/or DBS has been shown to be effective in reducing seizure frequency in patients with generalized epilepsy. DBS for generalized epilepsy is primarily consisted of open-loop stimulation directed at the centromedian (CM) nucleus in the thalamus, though closed-loop stimulation and additional targets are being explored. CC can be effective in treating some seizure types and can be performed using traditional surgical techniques or with the less invasive methods of laser ablation and radiosurgery. This current literature supports the use of VNS, DBS and CC, alone or in combination, as palliative treatments of drug-resistant generalized epilepsy.

The role of neurosurgery in the management of tuberous sclerosis complex–associated epilepsy: a systematic review

OBJECTIVE

Tuberous sclerosis complex (TSC) is an autosomal dominant, multisystem neurocutaneous disorder associated with cortical tubers, brain lesions seen in nearly all patients with TSC, which are frequently epileptogenic. Seizures are often the earliest clinical manifestation of TSC, leading to epilepsy in over 70% of patients. Medical management with antiepileptic drugs constitutes early therapy, but over 50% develop medically refractory epilepsy, necessitating surgical evaluation and treatment. The objective of this study was to summarize the literature and report seizure outcomes following surgical treatment for TSC-associated epilepsy.

METHODS

A systematic literature review was performed in accordance with the PRISMA guidelines. The PubMed and Embase databases were searched for journal articles reporting seizure outcomes following epilepsy surgery in TSC patients. Included studies were placed into one of two groups based on the surgical technique used. Excellent and worthwhile seizure reductions were defined for each group as outcomes and extracted from each study.

RESULTS

A total of 46 studies were included. Forty of these studies reported seizure outcomes following any combination of resection, disconnection, and ablation on a collective 1157 patients. Excellent and worthwhile seizure reductions were achieved in 59% (683/1157) and 85% (450/528) of patients, respectively. Six of these studies reported seizure outcomes following treatment with neuromodulation. Excellent and worthwhile seizure reductions were achieved in 34% (24/70) and 76% (53/70) of patients, respectively.

CONCLUSIONS

Surgery effectively controls seizures in select patients with TSC-associated epilepsy, but outcomes vary. Further understanding of TSC-associated epilepsy, improving localization strategies, and emerging surgical techniques represent promising avenues for improving surgical outcomes.

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.

Corpus Callosotomy in the Modern Era: Origins, Efficacy, Technical Variations, Complications, and Indications

Corpus callosotomy is among the oldest surgeries performed for drug-resistant epilepsy (DRE). First performed in 1940, various studies have since assessed its outcomes in various patient populations in addition to describing different extents of sectioning and emerging technologies (i.e. endoscopic, laser interstitial thermal therapy, and radiosurgery). In order to capture the current state and offer a reappraisal, we comprehensively review corpus callosotomy's origins, efficacy for various seizure types, technical variations, complications, and indications and compare the procedure to vagus nerve stimulation therapy which has similar indications. We consider corpus callosotomy to be a safe and efficacious procedure that should be considered by clinicians when appropriate. Furthermore, it can also play an important role in treating patients with DRE in low-to-middle-income countries where resources are limited.

One-Year Cost-Effectiveness of Callosotomy Versus Vagus Nerve Stimulation for Drug-Resistant Seizures in Lennox-Gastaut Syndrome: A Decision Analytic Model

Objective

Palliative epilepsy surgery via corpus callosotomy (CC) or vagus nerve stimulation (VNS) is commonly employed for drug‐resistant seizures in Lennox‐Gastaut Syndrome (LGS). VNS is less effective at reducing seizures but has fewer adverse events, CC is more effective for seizure control, particularly atonic seizures, but can be associated with serious adverse events, and yet their relative cost‐effectiveness remains unknown.

Methods

To determine which option is most cost‐effective, a decision analytic model was developed to evaluate the risks and benefits of CC and VNS at 1 year based on costs in the United States. Our primary outcome measure was positive seizure outcomes, defined as >50% seizure reduction without procedural complications.

Results

CC had a 15% greater likelihood of a positive seizure outcome, but per patient costs were $68 147 more than VNS, or $451 952 per positive seizure outcome gained. One‐way sensitivity analyses demonstrate that probabilities of seizure freedom or reduction by VNS or CC and CC cost were most influential on results. When considering atonic seizures, CC had a 27% greater positive outcome likelihood than VNS, the same incremental cost, and cost $250 556 per positive seizure outcome gained.

Significance

This exploratory model suggests that VNS is more cost‐effective relative to CC at 1 year.

An observational report of swallowing outcomes following corpus callosotomy

AIM

Determine swallowing outcomes following corpus callosotomy (CC) surgery.

METHODS

Retrospective chart review of patients undergoing CC between July 2016 and November 2018 at a large, urban children's hospital.

RESULTS

Of the 18 patients without prior history of dysphagia who underwent CC, 15 received speech pathology consults for bedside swallowing evaluation (BSE). Four patients were referred for a videofluroscopic swallow study (VFSS), and 3 showed no signs of difficulty and were advanced to regular diets with thin liquids. One patient demonstrated swallowing difficulties during the VFSS and was placed on a regular diet with nectar thick liquids. Following a repeat swallow study 17 days post-surgery, the patient was advanced to thin liquids.

INTERPRETATION

Postoperative dysphagia following CC is an uncommon and transient complication. Patients undergoing CC should have their swallowing evaluated prior to advancing their postoperative diet but are likely to return to normal diet and thin liquids by discharge.

MRI-guided stereotactic laser corpus callosotomy for epilepsy: distinct methods and outcomes

OBJECTIVE

Several small series have described stereotactic MRI-guided laser interstitial thermal therapy for partial callosotomy of astatic and generalized tonic-clonic (GTC) seizures, especially in association with Lennox-Gastaut syndrome. Larger case series and comparison of distinct stereotactic methods for stereotactic laser corpus callosotomy (SLCC), however, are currently lacking. The objective of this study was to report seizure outcomes in a series of adult patients with epilepsy following anterior, posterior, and complete SLCC procedures and to compare the results achieved with a frameless stereotactic surgical robot versus direct MRI guidance frames.

METHODS

The authors retrospectively reviewed sequential adult epilepsy surgery patients who underwent SLCC procedures at a single institution. They describe workflows, stereotactic errors, percentage disconnection, hospitalization durations, adverse events, and seizure outcomes after performing anterior, posterior, and complete SLCC procedures using a frameless stereotactic surgical robot versus direct MRI guidance platforms.

RESULTS

Thirteen patients underwent 15 SLCC procedures. The median age at surgery was 29 years (range 20-49 years), the median duration of epilepsy was 21 years (range 9-48 years), and median postablation follow-up was 20 months (range 4-44 months). Ten patients underwent anterior SLCC with a median 73% (range 33%-80%) midsagittal length of callosum acutely ablated. Following anterior SLCC, 6 of 10 patients achieved meaningful (> 50%) reduction of target seizures. Four patients underwent posterior (completion) SLCC following prior anterior callosotomy, and 1 patient underwent complete SLCC as a single procedure; 3 of these 5 patients experienced meaningful reduction of target seizures. Overall, 8 of 10 patients in whom astatic seizures were targeted and treated by anterior and/or posterior SLCC experienced meaningful improvement. SLCC procedures with direct MRI guidance (n = 7) versus a frameless surgical robot (n = 8) yielded median radial accuracies of 1.1 mm (range 0.2-2.0 mm) versus 2.4 mm (range 0.6-6.1 mm; p = 0.0011). The most serious adverse event was a clinically significant intraparenchymal hemorrhage in a patient who underwent the robotic technique.

CONCLUSIONS

This is the largest reported series of SLCC for epilepsy to date. SLCC provides seizure outcomes comparable to open surgery outcomes reported in the literature. Direct MRI guidance is more accurate, which has the potential to reduce the risks of SLCC. Methodological advancements and larger studies are needed.

Using a Robotic-Assisted Approach for Stereotactic Laser Ablation Corpus Callosotomy: A Technical Report

BACKGROUND

Corpus callosotomy for medically intractable epilepsy is an effective ablative procedure traditionally achieved using either standard open craniotomy or with less-invasive approaches. Advances in robotic-assisted stereotactic guidance for neurosurgery can be applied for LITT for corpus callosotomy.

CLINICAL PRESENTATIONS

Two patients were included in this study. One was a 25-year-old female patient with extensive bi-hemispheric malformations of cortical development and medically refractory epilepsy, and the other was an 18-year-old male with medically refractory epilepsy and atonic seizures, who underwent a complete corpus callosotomy using robotic-assisted stereotactic guidance for LITT.

RESULTS

Both patients underwent successful intended corpus callosotomy with volumetric analysis demonstrating a length disconnection of 74% and a volume disconnection of 55% for patient 1 and a length disconnection of 83% and a volume disconnection of 33% for patient 2. Postoperatively, both patients had clinical reductions in seizure.

CONCLUSION

Our experience demonstrates that robotic guidance systems can safely and effectively be adapted for minimally invasive LITT corpus callosotomy.

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.

Developmental outcome after corpus callosotomy for infants and young children with drug-resistant epilepsy

AIM

To examine the developmental and seizure outcomes after corpus callosotomy (CC) in early childhood.

METHODS

We retrospectively identified 106 patients who underwent CC for drug-resistant epilepsy before the age of 6 years, at the Nagasaki Medical Center, between July 2002 and July 2016. Patients' developmental outcomes were evaluated one year after CC using the Kinder Infant Development Scale.

RESULTS

The mean preoperative developmental quotient (DQ) was 25.0 (standard deviation [SD], 20.8), and the mean difference between preoperative DQ and one-year postoperative DQ was -1.6 points (SD, 11.6). However, 42.5% of patients had a mean DQ increase of 6.5 points (SD, 6.4), one year after CC from that before surgery. Factors related to the improvement in postoperative DQ were 'low preoperative DQ', 'developmental gain 1 month postoperatively', and 'postoperative seizure-free state'. Approximately 21.7% of patients were seizure-free 1 year after CC.

INTERPRETATION

Performing CC, in infancy and early childhood for patients with drug-resistant epilepsy and severe developmental impairment, was associated with improved development in 42.5% of patients. Remission of seizures, even if only for a short period, contributed to developmental improvement. From a developmental perspective, CC for drug-resistant epilepsy in early childhood is an effective treatment.

Retrospective analysis of open surgical versus laser interstitial thermal therapy callosotomy in pediatric patients with refractory epilepsy

OBJECTIVE

Corpus callosotomy remains an established surgical treatment for certain types of medically refractory epilepsy in pediatric patients. While the traditional surgical approach is often well tolerated, the advent of MR-guided laser interstitial thermal therapy (LITT) provides a new opportunity to ablate the callosal body in a minimally invasive fashion and minimize the risks associated with an open interhemispheric approach. However, the literature is sparse regarding the comparative efficacy and safety profiles of open corpus callosotomy (OCC) and LITT callosotomy. To this end, the authors present a novel retrospective analysis comparing the efficacy and safety of these methods.

METHODS

Patients who underwent OCC and LITT callosotomy during the period from 2005 to 2018 were included in a single-center retrospective analysis. Patient demographic and procedural variables were collected, including length of stay, procedural blood loss, corticosteroid requirements, postsurgical complications, and postoperative disposition. Pre- and postoperative seizure frequency (according to seizure type) were recorded.

RESULTS

In total, 19 patients, who underwent 24 interventions (16 OCC and 8 LITT), were included in the analysis. The mean follow-up durations for the OCC and LITT cohorts were 83.5 months and 12.3 months, respectively. Both groups experienced reduced frequencies of seizure and drop attack frequency postoperatively. Additionally, LITT callosotomy was associated with a significant decrease in estimated blood loss and decreased length of pediatric ICU stay, with a trend of shorter length of hospitalization.

CONCLUSIONS

Longer-term follow-up and a larger population are required to further delineate the comparative efficacies of LITT callosotomy and OCC for the treatment of pediatric medically refractory epilepsy. However, the authors' data demonstrate that LITT shows promise as a safe and effective alternative to OCC.

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.

Atonic seizures in children: a meta-analysis comparing corpus callosotomy to vagus nerve stimulation

PURPOSE

Atonic seizures are associated with a particularly poor response to medical treatment. We performed a systematic review and meta-analysis to compare the efficacy of corpus callosotomy (CC) and vagus nerve stimulation (VNS) in the management of atonic seizures in the pediatric population.

METHODS

A literature search was performed in compliance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and recommendations, focusing on atonic seizures, CC, and VNS in pediatric populations. Pertinent clinical data were extracted and analyzed. Pooled effects between groups were calculated as standardized error (SE) with 95% confidence intervals (CIs). To assess for statistical significance, the Z-test was performed, using the pooled effect size (ES) and 95% CI for each intervention.

RESULTS

A total of 31 studies met the inclusion criteria, with 24 studies encompassing 425 children treated with CC and 7 studies encompassing 108 children treated with VNS. Twenty-four studies were included in a meta-analysis. There was a statistically significant difference in the primary outcome of atonic seizure control in favor of CC (overall effect size (ES) 0.73, 95% CI 0.69-0.77 for CC, ES 0.4, 95% CI 0.28-0.51 for VNS, p = 0.003). There was a higher rate of complications requiring reoperation in the CC cohort (6.6% vs. 3.8%) and a 14% rate of symptomatic disconnection syndrome.

CONCLUSIONS

While both techniques are safe, CC provides a much higher chance of effectively managing this morbid seizure type albeit with a higher risk of re-operation and disconnection syndrome.

Corpus callosotomy performed with laser interstitial thermal therapy

OBJECTIVE

Corpus callosotomy is a palliative procedure that is effective at reducing seizure burden in patients with medically refractory epilepsy. The procedure is traditionally performed via open craniotomy with interhemispheric microdissection to divide the corpus callosum. Concerns for morbidity associated with craniotomy can be a deterrent to patients, families, and referring physicians for surgical treatment of epilepsy. Laser interstitial thermal therapy (LITT) is a less invasive procedure that has been widely adopted in neurosurgery for the treatment of tumors. In this study, the authors investigated LITT as a less invasive approach for corpus callosotomy.

METHODS

The authors retrospectively reviewed all patients treated for medically refractory epilepsy by corpus callosotomy, either partial or completion, with LITT. Chart records were analyzed to summarize procedural metrics, length of stay, adverse events, seizure outcomes, and time to follow-up. In select cases, resting-state functional MRI was performed to qualitatively support effective functional disconnection of the cerebral hemispheres.

RESULTS

Ten patients underwent 11 LITT procedures. Five patients received an anterior two-thirds LITT callosotomy as their first procedure. One patient returned after LITT partial callosotomy for completion of callosotomy by LITT. The median hospital stay was 2 days (IQR 1.5-3 days), and the mean follow-up time was 1.0 year (range 1 month to 2.86 years). Functional outcomes are similar to those of open callosotomy, with the greatest effect in patients with a significant component of drop attacks in their seizure semiology. One patient achieved an Engel class II outcome after anterior two-thirds callosotomy resulting in only rare seizures at the 18-month follow-up. Four others were in Engel class III and 5 were Engel class IV. Hemorrhage occurred in 1 patient at the time of removal of the laser fiber, which was placed through the bone flap of a prior open partial callosotomy.

CONCLUSIONS

LITT appears to be a safe and effective means for performing corpus callosotomy. Additional data are needed to confirm equipoise between open craniotomy and LITT for corpus callosotomy.

Treatment of Multi-Focal Epilepsy With Resective Surgery Plus Responsive Neurostimulation (RNS): One Institution's Experience

Objective: Patients with medically refractory focal epilepsy can be difficult to treat surgically, especially if invasive monitoring reveals multiple ictal onset zones. Possible therapeutic options may include resection, neurostimulation, laser ablation, or a combination of these surgical modalities. To date, no study has examined outcomes associated with resection plus responsive neurostimulation (RNS, Neuropace, Inc., Mountain View, CA) implantation and we describe our initial experience in patients with multifocal epilepsy undergoing this combination therapy.

Methods: A total of 43 responsive neurostimulation (RNS) devices were implanted at UCI from 2015 to 2019. We retrospectively reviewed charts of patients from the same time period who underwent both resection and RNS implantation. Patients were required to have independent or multifocal onset, undergo resection and RNS implantation, and have a minimum of six-months for follow-up to be included in the study. Demographics, location of ictal onset, location of surgery, complications, and seizure outcome were collected.

Results: Ten patients met inclusion criteria for the study, and seven underwent both procedures in the same setting. The average age was 36. All patients had multifocal ictal onset on video electroencephalogram or invasive EEG with four patients undergoing subdural grid placement and four patients undergoing bilateral sEEG prior to the definitive surgery. Five patients underwent resection plus ipsilateral RNS placement and the remainder underwent resection with contralateral RNS placement. Two minor complications were encountered in this group. At six months follow up, there was an average of 81% ± 9 reduction in seizures, while four patients experienced complete seizure freedom at 1 year.

Conclusion: Patients with multifocal epilepsy can be treated with partial resection plus RNS. The complication rates are low with potential for worthwhile seizure reduction.

Surgical Treatments of Epilepsy

Nearly 30% of epilepsy patients are refractory to medical therapy. Surgical management of epilepsy is an increasingly viable option for these patients. Although surgery has historically been used as a palliative option, improvements in technology and outcomes show its potential in certain subsets of patients. This article reviews the two main categories of surgical epilepsy treatment-resective surgery and neuromodulation. Resective surgery includes temporal lobe resections, extratemporal resections, laser interstitial thermal therapy, and disconnection procedures. We discuss the three main types of neuromodulation-vagal nerve stimulation, responsive neurostimulation, and deep brain stimulation for epilepsy. The history and indications are explored for each type of treatment. Given the myriad types of resection and neuromodulation techniques, patient selection is reviewed in detail, with a discussion on which patients are most likely to benefit from different treatment strategies. We also discuss outcomes with examples of the pertinent landmark trials and their results. Finally, complications and surgical technique are reviewed. As new indications emerge and patient selection is refined, surgical management will continue to evolve as an adjuvant therapy for epileptic patients.

The Evolution of Corpus Callosotomy for Epilepsy Management

Corpus callosotomy, first used in the management of epilepsy by William P. van Wagenen in 1940, was for years a contentious procedure. Two decades later, Nobel Laureate Roger W. Sperry's split-brain studies inspired surgeons to reexamine the role of corpus callosotomy in the control of epileptic seizures. In 1962, Joseph Bogen and Philip Vogel performed complete corpus callosotomies in patients with a history of generalized seizures. The identification of a set of postsurgical disconnection symptoms and other neurologic deficits begged the improvement of the surgical technique. Modifications to the operation, including anterior callosotomy, posterior callosotomy, partial callosotomy, staged callosotomy, microsurgical techniques, and radiosurgical techniques, continue to refine the procedure.

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.

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.

Total Corpus Callosotomy for Medically Refractory Status Epilepticus Due to Progressive Myoclonic Epilepsy: A Clinically Challenging Case

BACKGROUND

Progressive myoclonic epilepsy (PME) is a syndrome characterized by development of progressive myoclonus, cognitive impairment, and other neurologic deficits. Despite major advances in medical treatment of epilepsy, some PME patients remain refractory to antiepileptic drugs. This may further accentuate cognitive impairment and deteriorate functional capacity. Corpus callosotomy (CC) is used in patients with drug-resistant epilepsy who are not candidates for either excisional epilepsy surgery or neurostimulation. We report the application of the standard complete callosotomy to control medically refractory status epilepticus in a patient with PME.

CASE DESCRIPTION

A 16-year-old boy was referred to the emergency department with generalized tonic-clonic seizures. He was known to have PME since 5 years earlier, with frequent generalized seizures requiring hospitalization and reloading of the drugs. The patient was discussed by the epilepsy surgery working group, and corpus callosotomy was considered as a last resort to control the refractory status epilepticus. The patient experienced no generalized seizures during the 3-month postoperative period (Engel class IIIB).

CONCLUSIONS

Inasmuch as surgery was the last resort to control severe disabling status epilepticus, because most of the epileptogenic discharges were originating from the parieto-occipital regions and profound cognitive impairment was present, we decided to perform a complete rather than just an anterior callosotomy. CC may be considered to prevent secondary generalized seizures as the most disabling attacks in patients with certain epilepsy syndromes. Nevertheless, the impact of palliative surgical intervention on the overall disease course of patients with an underlying diffuse pathologic state remains to be determined.

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.

Intractable Generalized Epilepsy: Therapeutic Approaches

PURPOSE OF REVIEW

To summarize recent developments in therapeutic options, both medical and surgical, for patients with drug-resistant generalized epilepsy syndromes, which continue to be a multifaceted challenge for patients and physicians.

RECENT FINDINGS

Newer generation pharmaceutical options are now available, such as brivaracetam, rufinamide, lacosamide, perampanel, and cannabidiol. Less restrictive dietary options appear to be nearly as effective as classic ketogenic diet for amelioration of seizures. The latest implantable devices include responsive neurostimulation and deep brain stimulation. Corpus callosotomy is an effective treatment for some seizure types, and newer and less invasive approaches are being explored. Resective surgical options have demonstrated success in carefully selected patients despite generalized electrographic findings on electroencephalogram. The current literature reflects a widening range of clinical experience with newer anticonvulsant medications including cannabinoids, dietary therapies, surgical approaches, and neurostimulation devices for patients with intractable generalized epilepsy.

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.

Interstitial Stereotactic Laser Anterior Corpus Callosotomy: A Report of 2 Cases with Operative Technique and Effectiveness

BACKGROUND AND IMPORTANCE

Corpus callosotomy is an effective palliative treatment for medically intractable Lennox–Gastaut syndrome (LGS) that disrupts the interhemispheric synchronization of epileptiform discharges. However, traditional open corpus callosotomy carries a significant risk of surgical complications associated with craniotomy and a parafalcine approach to the corpus callosum. Here, we report 2 cases of anterior corpus callosotomy using MRI-guided stereotactic laser interstitial thermal therapy (LITT) as a minimally invasive technique for mitigating the risks of craniotomy while achieving favorable outcomes.

CLINICAL PRESENTATION

Two patients with medically intractable LGS underwent stereotactic laser anterior corpus callosotomy using a 2 laser-fiber approach. Ablation of 70%-80% of the corpus callosum was confirmed by postoperative MRI diffusion tensor imaging and volumetric analysis. Marked reduction of epileptiform activity was observed in both patients during postoperative video-EEG studies as compared to preoperative video-EEG studies. Freedom from disabling seizures including drop attacks was achieved in 1 patient for 18 mo, and more than a 90% reduction of disabling seizures was achieved in the other patient for 7 mo with cognitive improvement and without surgical complications.

CONCLUSION

These early data demonstrate the technical feasibility, safety, and favorable outcomes of MRI-guided stereotactic laser anterior corpus callosotomy in patients with LGS, making it a potentially safe and effective alternative to traditional open corpus callosotomy and other stereotactic methods including radiofrequency ablation and radiosurgery due to the ability to monitor the ablation in real time with MRI.

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.

Electroencephalography Network Effects of Corpus Callosotomy in Patients with Lennox-Gastaut Syndrome

OBJECTIVES

This study aimed to investigate the functional network effects of corpus callosotomy (CC), a well-recognized palliative surgical therapy for patients with Lennox-Gastaut syndrome (LGS). Specifically, we sought to gain insight into the effects of CC on LGS remission, based on brain networks in LGS by calculating network metrics and evaluating by network measures before and after surgery.

METHODS

Electroencephalographic recordings made during preoperative and 3-month postoperative states in 14 patients with LGS who had undergone successful CC were retrospectively analyzed. First, undirected correlation matrices were constituted for the mathematical expression of functional networks. Then, we plotted these networks to analyze the effects of CC on connectivity. In addition, conventional local and global network measures were applied to evaluate differences in network topology between preoperative and postoperative states.

RESULTS

In the preoperative state, hubs were mainly distributed around the paramedian regions. After CC, the hubs moved from the paramedian regions to the dual-hemisphere and even the lateral regions. Thus, the general connectivity state became more homogeneous, which was verified by network plots and statistical analysis of local measures. The results of global network measures indicated a decreased clustering coefficient in the delta band, decreased characteristic path length in both the delta and gamma bands, and increased global efficiency in the gamma band.

CONCLUSION

Our results showed a consistent variation in the global brain network that converted to a small-world topology with an optimal balance of functional integration and segregation of the network. Such changes were positively correlated with satisfactory surgery results, which could be interpreted as being indicative of LGS recovery process after CC. For patients with refractory LGS along with no focal epileptogenic zone findings, which were not suitable for the resective surgical therapy, our results verified that CC could work as an effective surgical treatment option.

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.

Minimally Invasive Robotic Laser Corpus Callosotomy: A Proof of Concept

Introduction

We describe the feasibility of using minimally invasive robotic laser interstitial thermotherapy (LITT) for achieving an anterior two-thirds as well as a complete corpus callosotomy.

Methods

Ten probe trajectories were plotted on normal magentic resonance imaging (MRI) scans using the Brainlab Stereotactic Planning Software (Brainlab, Munich, Germany). The NeuroBlate® System (Monteris Medical, MN, USA) was used to conform the thermal burn to the corpus callosum along the trajectory of the probe. The distance of the ideal entry site from either the coronal suture and the torcula or nasion and the midline was calculated. The distance of the probe tip from the dorsal and ventral limits of the callosotomy in the sagittal plane were also calculated.

Results

Anterior two-thirds callosotomy was possible in all patients using a posterior parieto-occipital paramedian trajectory through the non-dominant lobe. The average entry point was 3.64 cm from the midline, 10.6 cm behind the coronal suture, and 9.2 cm above the torcula. The probe tip was an average of 1.4 cm from the anterior commissure. For a total callosotomy, an additional contralaterally placed frontal probe was used to target the posterior one-third of the corpus callosum. The average entry site was 3.3 cm from the midline and 9.1 cm above the nasion. The average distance of the probe tip from the base of the splenium was 0.94 cm.

Conclusion

The directional thermoablation capability of the NeuroBlate® system allows for targeted lesioning of the corpus callosum, to achieve a two-thirds or complete corpus callosotomy. A laser distance of < 2 cm is sufficient to reach the entire corpus callosum through one trajectory for an anterior two-thirds callosotomy and two trajectories for a complete callosotomy.

Surgical Management of Pediatric Epilepsy: Decision-Making and Outcomes

First-line treatment for epilepsy is antiepileptic drug and requires an interdisciplinary approach and enduring commitment and adherence from the patient and family for successful outcome. Despite adherence to antiepileptic drugs, refractory epilepsy occurs in approximately 30% of children with epilepsy, and surgical treatment is an important intervention to consider. Surgical management of pediatric epilepsy is highly effective in selected patients with refractory epilepsy; however, an evidence-based protocol, including best methods of presurgical imaging assessments, and neurodevelopmental and/or behavioral health assessments, is not currently available for clinicians. Surgical treatment of epilepsy can be critical to avoid negative outcomes in functional, cognitive, and behavioral health status. Furthermore, it is often the only method to achieve seizure freedom in refractory epilepsy. Although a large literature base can be found for adults with refractory epilepsy undergoing surgical treatment, less is known about how surgical management affects outcomes in children with epilepsy. The purpose of the review was fourfold: (1) to evaluate the available literature regarding presurgical assessment and postsurgical outcomes in children with medically refractory epilepsy, (2) to identify gaps in our knowledge of surgical treatment and its outcomes in children with epilepsy, (3) to pose questions for further research, and (4) to advocate for a more unified presurgical evaluation protocol including earlier referral for surgical candidacy of pediatric patients with refractory epilepsy. Despite its effectiveness, epilepsy surgery remains an underutilized but evidence-based approach that could lead to positive short- and long-term outcomes for children with refractory epilepsy.

Surgical strategies for pediatric epilepsy

Pediatric epilepsy is a debilitating condition that impacts millions of patients throughout the world. Approximately 20-30% of children with recurrent seizures have drug-resistant epilepsy (DRE). For these patients, surgery offers the possibility of not just seizure freedom but significantly improved neurocognitive and behavioral outcomes. The spectrum of surgical options is vast, ranging from outpatient procedures such as vagus nerve stimulation to radical interventions including hemispherectomy. The thread connecting all of these interventions is a common goal-seizure freedom, an outcome that can be achieved safely and durably in a large proportion of patients. In this review, we discuss many of the most commonly performed surgical interventions and describe the indications, complications, and outcomes specific to each.

Microsurgical endoscopy-assisted anterior corpus callosotomy for drug-resistant epilepsy in an adult unresponsive to vagus nerve stimulation

Because most of the corpus callosotomy (CC) series available in literature were published before the advent of vagus nerve stimulation (VNS), the efficacy of CC in patients with inadequate response to VNS remains unclear, especially in adult patients. We present the case of a 21-year-old female with medically refractory drop attacks that began at the age of 8 years, which resulted in the patient being progressively unresponsive to vagus nerve stimulation implanted at the age of 14 years. Corpus callosotomy was recommended to reduce the number of drop attacks. However, the patient had only mild cognitive impairments and no neurological deficits. For this reason, we were forced to plan a surgical approach able to maximize the disconnection for good seizure control while, at the same time, minimizing sequelae from disconnection syndromes and neurosurgical complications because in such cases of long-lasting epilepsy the gyri cinguli and the arteries can be tenaciously adherent and dislocated with all the normal anatomy altered. In this scenario, we opted for a microsurgical endoscopy-assisted anterior two-thirds corpus callosotomy. The endoscopic minimally invasive approach proved to be quite adequate in this technically demanding case and confirmed that CC may offer advantages, with good results, even in adult patients with drop attacks who have had inadequate response to VNS.

Corpus callosotomy

BACKGROUND

Corpus callosotomy is an effective, relatively low-risk, palliative procedure for a selected population of patients with medically intractable epilepsy. Here we describe this technique.

METHOD

An interhemispheric microsurgical approach is performed. Neuronavigation facilitates orientation. The callosal body is transected through to the roof of the ipsilateral ventricle using an ultrasonic aspirator; the genu and rostrum are then identified and also split. If a total callosotomy is performed, transection of the splenium is performed with care given to preserve the crus of the fornix.

CONCLUSIONS

Meticulous microsurgical technique and knowledge of the limbic system's anatomy is essential to keeping this procedure safe and effective.

Reappraisal of corpus callosotomy

PURPOSE OF REVIEW

Corpus callosotomy is a palliative surgical treatment modality that has gone in and out of favor. The purpose of this review is to summarize the studies of callosotomy in the past years as a treatment for severe drug-resistant epilepsy with traumatizing drop attacks, mostly in children and also in some adults. The aim is also to discuss knowledge gaps and suggest how these could be addressed.

RECENT FINDINGS

Lately, a number of callosotomy series, mostly retrospective and single center, have included 289 operated patients. A few series have included nonoperated controls; one prospective long-term series is national and population based. Seizure outcome is shown to be comparable to that earlier reported, with best effect against drop attacks. There is no consensus on whether anterior or complete callosotomy is to be preferred. In a meta-analysis of callosotomy versus vagal nerve stimulation, callosotomy led to better seizure outcome. Diffusion tensor imaging may be a promising tool to analyze the completeness of the procedure.

SUMMARY

Callosotomy remains an effective palliative procedure. Many unresolved issues, such as prognostic indicators, nonseizure-related outcomes, whether to choose anterior or complete callosotomy, and outcomes and adverse effects in adults, need to be studied in prospective, preferably multicenter studies.