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

Comparison of magnetic resonance-guided laser interstitial thermal therapy corpus callosum ablation to open microsurgical corpus callosotomy: A single-center retrospective cohort study

OBJECTIVE

Corpus callosotomy (CC) is an important treatment for atonic seizures in patients with generalized or multifocal drug-resistant epilepsy (DRE). Traditionally, CC is performed via an open microsurgical approach, but more recently, MR-guided stereotactic laser interstitial thermal therapy (LITT) corpus callosum ablation (CCA) has been developed to leverage the safety and minimally invasive nature of LITT. Given the recent adoption of CCA at select centers, how CCA compares to CC is unknown. We aim to compare the clinical seizure outcomes of CCA and CC after extended follow-up.

METHODS

We performed a retrospective cohort study to compare the effectiveness and safety of CC to CCA from 1994 to 2022. The primary outcome was a 50% reduction in target seizure. Secondary outcome measures were postoperative length of stay, adverse events, and other effectiveness metrics. Comparative statistics were executed using Stata. Normality for continuous variables was assessed, and parametric statistics were utilized as needed. Frequency was compared with chi-squared or Fischer's exact tests, when applicable.

RESULTS

Data from 47 operations performed on 36 patients were included in this study, of which 13 (36%) patients underwent 17 CCA. Patients who received CCA had similar rates of meaningful reduction (>50%) of atonic seizures as their CC counterparts (55% vs 70% P = 0.15). Patients undergoing CCA had significantly shorter hospitalizations than those receiving CC (2.5 vs 6.0 days P < 0.001). There was no significant difference in rates of postoperative complications between the groups, although the magnitude of the complication rates was lower in the CCA cohort (12% vs 28%).

SIGNIFICANCE

This early experience suggests CCA has similar outcomes to traditional CC, albeit with a shorter hospital stay. However, future studies are necessary to investigate the noninferiority between these two approaches. Large multicenter studies are necessary to investigate differences in adverse events and whether these findings generalize across other centers.

Demographic and clinical characteristics, seizure disorders, and antiepileptic drug usage in different types of corpus callosum disorders: a comparative study in children

BACKGROUND

This study aimed to investigate the demographic and clinical characteristics, types of seizure disorders, and antiepileptic drug usage among individuals with different types of corpus callosum disorders.

METHODS

A total of 73 individuals were included in the study and divided into three groups based on the type of corpus callosum abnormality: hypoplasia (H), agenesis (A), and dysgenesis (D). Demographic data, including gender and preterm birth, as well as clinical characteristics such as seizure disorders, attention deficit hyperactivity disorder (ADHD), severe developmental delay/intellectual disability, and other brain malformations, were analyzed. The types of seizure disorders and antiepileptic drugs used were also examined.

RESULTS

The H group had the highest number of participants (n = 47), followed by the A group (n = 11) and the D group (n = 15). The A group had the highest percentage of males and preterm births, while the D group had the highest percentage of seizure disorders, other brain malformations, and severe developmental delay/intellectual disability. The A group also had the highest percentage of ADHD. Focal seizures were observed in all three groups, with the highest proportion in the A group. Focal impaired awareness seizures (FIAS) were present in all groups, with the highest proportion in the D group. Generalized tonic-clonic seizures (GTCS) were observed in all groups, with the highest proportion in the H group. Different types of antiepileptic drugs were used among the groups, with variations in usage rates for each drug.

CONCLUSION

This study provided insights into the demographic and clinical characteristics, seizure disorders, and antiepileptic drug usage among individuals with different types of corpus callosum disorders. Significant differences were found between the groups, indicating the need for tailored management approaches. However, the study has limitations, including a small sample size and a cross-sectional design. Further research with larger sample sizes and longitudinal designs is warranted to validate these findings and explore the relationship between corpus callosum abnormality severity and clinical outcomes.

Ictogenesis proceeds through discrete phases in hippocampal CA1 seizures in mice

Epilepsy is characterized by spontaneous non-provoked seizures, yet the mechanisms that trigger a seizure and allow its evolution remain underexplored. To dissect out phases of ictogenesis, we evoked hypersynchronous activity with optogenetic stimulation. Focal optogenetic activation of putative excitatory neurons in the mouse hippocampal CA1 reliably evoked convulsive seizures in awake mice. A time-vs-time pulsogram plot characterized the evolution of the EEG pulse response from a light evoked response to induced seizure activity. Our results depict ictogenesis as a stepwise process comprised of three distinctive phases demarcated by two transition points. The induction phase undergoes the first transition to reverberant phase activity, followed by the second transition into the paroxysmal phase or a seizure. Non-seizure responses are confined to either induction or reverberant phases. The pulsogram was then constructed in seizures recorded from a murine model of temporal lobe epilepsy and it depicted a similar reverberance preceding spontaneous seizures. The discovery of these distinct phases of ictogenesis may offer means to abort a seizure before it develops.

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.

Minimally Invasive Destructive, Ablative, and Disconnective Epilepsy Surgery

Conventional epilepsy surgery performed by microsurgical dissection typically requires large cranial working windows created with high-speed drills and lengthy incisions. In the past few decades, minimally invasive techniques have been developed with smaller incisions, comparable efficacy, shorter hospitalizations, and better safety profiles. These minimally invasive alternatives utilize stereotactic, ultrasonic, radiotherapeutic, and endoscopic techniques. Although not able to completely replace conventional surgery for all etiologies of epilepsy, these minimally invasive techniques have revolutionized modern epilepsy surgery and have been an invaluable asset to the neurosurgeon's repertoire. The endoscope has allowed for surgeons to have adequate visualization during resective and disconnective epilepsy surgeries using keyhole or miniature craniotomies. Modern stereotactic techniques such as laser interstitial thermal therapy and radiofrequency ablation can be used as viable alternatives for mesial temporal lobe epilepsy and can destroy lesional tissue deep areas without the approach-related morbidity of microsurgery such as with hypothalamic hamartomas. These stereotactic techniques do not preclude future surgery in the settings of treatment failure and have been used successfully after failed conventional surgery. Multiple ablation corridors can be performed in a single procedure that can be used for lesioning of large targets or to simplify treating multifocal epilepsies. These stereotactic techniques have even been used successfully to perform disconnective procedures such as hemispherotomies and corpus callosotomies. In patients unable to tolerate surgery, stereotactic radiosurgery is a minimally invasive option that can result in improved seizure control with minimal procedural risks. Advances in minimally invasive neurosurgery provide viable treatment options for drug-resistant epilepsy with quicker recovery, less injury to functional brain, and for patients that may otherwise not choose conventional surgery.

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.

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.

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.

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.

Efficacy and safety of corpus callosotomy and ketogenic diet in children with Lennox Gastaut syndrome: a systematic review and meta-analysis

BACKGROUND

Both corpus callosotomy (CC) and the ketogenic diet (KD) are commonly used in patients with Lennox Gastaut syndrome (LGS), as a significant proportion of these patients develop pharmacoresistant epilepsy. But no systematic review has yet compared the efficacy and safety of these two measures.

METHODS

We conducted a systematic search on various databases to collating all available literature until 30th November 2020 with a primary objective to compare the efficacy of KD and CC in terms of the proportion of patients with complete seizure freedom, at least 75% and 50% reduction in seizure frequency at various time points after the institution of these modalities. We also attempted to compare the proportion and nature of adverse effects, impact on EEG, cognition, and behavior with these modalities. We only included original articles enrolling at least 10 patients with CC or KD for quantitative synthesis to determine a pooled estimate. We used a fixed or random effects model, depending on the degree of heterogeneity.

RESULTS

We selected 23 and 7 articles describing the efficacy of CC and KD in 436 and 185 LGS patients out of 217 search items, but none of the studies compared directly these two entities. The indirect comparison between the pooled estimate of all patients with individual modalities revealed more patients with CC had seizure freedom, at least 75% and 50% reduction in seizure frequency (p=0.0001, 0.01, and 0.04 respectively). The proportion of patients with adverse effects was also higher for CC patients (p=0.01), although the proportion with serious adverse effects was not significantly different between the two modalities. Patients selected for CC were older, had higher seizure burden, more lag time after the onset of seizures, and received more number of antiseizure medications previously. Due to the availability of limited data, a firm conclusion could not be determined regarding the effect on EEG, cognition, and behavior with CC and KD.

CONCLUSION

CC is more efficacious than KD in reducing seizure frequency in patients with LGS, although it has relatively more adverse effects during the immediate perioperative period.

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.

Four-dimensional tractography animates propagations of neural activation via distinct interhemispheric pathways

OBJECTIVE

To visualize and validate the dynamics of interhemispheric neural propagations induced by single-pulse electrical stimulation (SPES).

METHODS

This methodological study included three patients with drug-resistant focal epilepsy who underwent measurement of cortico-cortical spectral responses (CCSRs) during bilateral stereo-electroencephalography recording. We delivered SPES to 83 electrode pairs and analyzed CCSRs recorded at 268 nonepileptic electrode sites. Diffusion-weighted imaging (DWI) tractography localized the interhemispheric white matter pathways as streamlines directly connecting two electrode sites. We localized and visualized the putative SPES-related fiber activation, at each 1-ms time window, based on the propagation velocity defined as the DWI-based streamline length divided by the early CCSR peak latency.

RESULTS

The resulting movie, herein referred to as four-dimensional tractography, delineated the spatiotemporal dynamics of fiber activation via the corpus callosum and anterior commissure. Longer streamline length was associated with delayed peak latency and smaller amplitude of CCSRs. The cortical regions adjacent to each fiber activation site indeed exhibited CCSRs at the same time window.

CONCLUSIONS

Our four-dimensional tractography successfully animated neural propagations via distinct interhemispheric pathways.

SIGNIFICANCE

Our novel animation method has the potential to help investigators in addressing the mechanistic significance of the interhemispheric network dynamics supporting physiological function.

Prolonged functional cerebral asymmetry as a consequence of dysfunctional parvocellular paraventricular hypothalamic nucleus signaling: An integrative model for the pathophysiology of bipolar disorder

Approximately 45 million people worldwide are diagnosed with bipolar disorder (BD). While there are many known risk factors and models of the pathologic processes influencing BD, the exact neurologic underpinnings of BD are unknown. We attempt to integrate the existing literature and create a unifying hypothesis regarding the pathophysiology of BD with the hope that a concrete model may potentially facilitate more specific diagnosis, prevention, and treatment of BD in the future. We hypothesize that dysfunctional signaling from the parvocellular neurons of the paraventricular hypothalamic nucleus (PVN) results in the clinical presentation of BD. Functional damage to this nucleus and its signaling pathways may be mediated by myriad factors (e.g. immune dysregulation and auto-immune processes, polygenetic variation, dysfunctional interhemispheric connections, and impaired or overactivated hypothalamic axes) which could help explain the wide variety of clinical presentations along the BD spectrum. The neurons of the PVN regulate ultradian rhythms, which are observed in cyclic variations in healthy individuals, and mediate changes in functional hemispheric lateralization. Theoretically, dysfunctional PVN signaling results in prolonged functional hemispheric dominance. In this model, prolonged right hemispheric dominance leads to depressive symptoms, whereas left hemispheric dominance correlated to the clinical picture of mania. Subsequently, physiologic processes that increase signaling through the PVN (hypothalamic-pituitaryadrenal axis, hypothalamic- pituitary-gonadal axis, and hypothalamic-pituitary-thyroid axis activity, suprachiasmatic nucleus pathways) as well as, neuro-endocrine induced excito-toxicity, auto-immune and inflammatory flairs may induce mood episodes in susceptible individuals. Potentially, ultradian rhythms slowing with age, in combination with changes in hypothalamic axes and maturation of neural circuitry, accounts for BD clinically presenting more frequently in young adulthood than later in life.

Magnetic Resonance Imaging-Guided Laser Interstitial Thermal Therapy for Epilepsy: Systematic Review of Technique, Indications, and Outcomes

BACKGROUND

For patients with focal drug-resistant epilepsy (DRE), surgical resection of the epileptogenic zone (EZ) may offer seizure freedom and benefits for quality of life. Yet, concerns remain regarding invasiveness, morbidity, and neurocognitive side effects. Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) has emerged as a less invasive option for stereotactic ablation rather than resection of the EZ.

OBJECTIVE

To provide an introduction to MRgLITT for epilepsy, including historical development, surgical technique, and role in therapy.

METHODS

The development of MRgLITT is briefly recounted. A systematic review identified reported techniques and indication-specific outcomes of MRgLITT for DRE in human studies regardless of sample size or follow-up duration. Potential advantages and disadvantages compared to available alternatives for each indication are assessed in an unstructured review.

RESULTS

Techniques and outcomes are reported for mesial temporal lobe epilepsy, hypothalamic hamartoma, focal cortical dysplasia, nonlesional epilepsy, tuberous sclerosis, periventricular nodular heterotopia, cerebral cavernous malformations, poststroke epilepsy, temporal encephalocele, and corpus callosotomy.

CONCLUSION

MRgLITT offers access to foci virtually anywhere in the brain with minimal disruption of the overlying cortex and white matter, promising fewer neurological side effects and less surgical morbidity and pain. Compared to other ablative techniques, MRgLITT offers immediate, discrete lesions with real-time monitoring of temperature beyond the fiber tip for damage estimates and off-target injury prevention. Applications of MRgLITT for epilepsy are growing rapidly and, although more evidence of safety and efficacy is needed, there are potential advantages for some patients.

Challenges of Epilepsy Surgery

Though frequently effective in the management of medically refractory seizures, epilepsy surgery presents numerous challenges. Selection of the appropriate candidate patients who are likely to benefit from surgery is critical to achieving seizure freedom and avoiding neurocognitive morbidity. Identifying the seizure focus and mapping epileptogenic networks involves an interdisciplinary team dedicated to formulating a safe and effective surgical plan. Various strategies can be employed either to eliminate the epileptic focus or to modulate network activity, including resection of the focus with open surgery or laser interstitial thermal therapy; modulation of epileptogenic firing patterns with responsive neurostimulation, deep brain stimulation, or vagus nerve stimulation; or non-invasive disconnection of epileptic circuits with focused ultrasound, which is also discussed in greater detail in the subsequent chapter in our series. We review several challenges of epilepsy surgery that must be thoughtfully addressed in order to ensure its success.

Seizure Outcomes in Patients with Complete versus Anterior Corpus Callosotomy: Analysis of Outcome

Introduction

Corpus callosotomy (CCT) is a palliative procedure to treat injurious drop attacks or multifocal/generalized seizures in which resection of the epileptogenic focus is not feasible. We are presenting our experience in treating intractable epilepsy patients by CCT procedures.

Methods

We observed 16 patients who underwent callosotomy (male to female ratio 7:9; adult to pediatric ratio 3:13). Initial seizure frequency was reported ranged from 1 to 2 attacks daily to very often (more than 20 episodes daily).

Results

Our observation showed that among patients with drop attacks, complete and >90% seizure freedom was reported by 4 and 6 of 13 patients, respectively (76.9% combined).

Conclusion

Our observation showed that corpus callosotomy yielded good outcome in patients with intractable epilepsy in Indonesia. Our observation showed total callosotomy achieved complete seizure freedom better compared to partial callosotomy patients.

Corpus callosotomy for treatment of drug-resistant epilepsy: a review of 16 pediatric cases in northern Vietnam

OBJECTIVE

The aim of this study was to evaluate postoperative seizure outcome in children with drug-resistant epilepsy not eligible for focal resection who underwent corpus callosotomy.

METHODS

The study included 16 patients undergoing corpus callosotomy between September 2015 and May 2018. Seizure semiology and frequency, psychomotor status, and video electroencephalography and imaging findings were evaluated for all patients.

RESULTS

Of the 16 patients who underwent callosotomy during the study period, 11 underwent complete callosotomy and 5 underwent anterior only. Seizure improvement greater than 75% was achieved in 37.5% of patients, and another 50% of patients had seizure improvement of 50%-75%. No sustained neurological deficits were observed in these patients. There were no significant complications. Duration of postoperative follow-up ranged from 12 to 44 months.

CONCLUSIONS

Corpus callosotomy is an effective treatment for selected patients with drug-resistant epilepsy not eligible for focal resection in resource-limited settings. Fostering and developing international epilepsy surgery centers should remain a high priority for the neurosurgical community at large.

PTEN in Autism and Neurodevelopmental Disorders

Phosphatase and tensin homolog (PTEN) is a classical tumor suppressor that antagonizes phosphatidylinositol 3-phosphate kinase (PI3K)/AKT signaling. Although there is a strong association of PTEN germline mutations with cancer syndromes, they have also been described in a subset of patients with autism spectrum disorders with macrocephaly characterized by impairments in social interactions and communication, repetitive behavior and, occasionally, epilepsy. To investigate PTEN's role during neurodevelopment and its implication for autism, several conditional Pten knockout mouse models have been generated. These models are valuable tools to understand PTEN's spatiotemporal roles during neurodevelopment. In this review, we will highlight the anatomical and phenotypic results from animal studies and link them to cellular and molecular findings.

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.

Effectiveness of total corpus callosotomy for diffuse bilateral polymicrogyria: Report of three pediatric cases

PURPOSE

Polymicrogyria, a malformation of the cerebral cortex, frequently causes epilepsy. Diffuse bilateral polymicrogyria (DBP) is related to poor epilepsy prognosis, but most patients with DBP are not good candidates for resective epilepsy surgery and effectiveness of corpus callosotomy (CC), a palliative surgery, for patients without resective epileptogenic cortices, has not been established in DBP. Because CC might be effective against DBP-related epilepsy, we conducted total CC in three pediatric DBP cases.

METHODS

Case 1. A girl developed epilepsy at 3 months of age, with focal versive seizures and epileptic spasms. The electroencephalogram (EEG) showed a suppression-burst pattern. Total CC was performed at 6 months of age. Case 2. A female infant developed epilepsy on the day of birth, exhibiting epileptic spasms, generalized tonic-clonic seizures, and eye-deviating seizures. She had a history of clusters of tonic seizures. Total CC was performed at 1 year and 2 months of age. After CC, the epileptic focus of the tonic seizures was identified; a secondary resective surgery was conducted. Case 3. A girl developed multiple types of seizures at 3 years of age. Frequent atypical absence status was refractory to antiepileptic drugs. Total CC was conducted at 8 years of age.

RESULTS

Case 1: Frequencies of both seizure types decreased. The background EEG changed to continuous high-voltage slow waves. Case 2: Clusters of tonic seizures were well-controlled. Case 3: Atypical absence seizures completely disappeared.

CONCLUSION

CC could be effective for patients with DBP, whose habitual seizures include epileptic spasms and absence seizures.

Safety and effectiveness of surgery for epilepsy in children. Experience of a tertiary hospital in Ecuador

INTRODUCTION

There is sufficient evidence on the usefulness of surgery as a therapeutic alternative for patients with drug-resistant epilepsy; however this treatment is underutilized, especially in developing countries.

METHODS

We describe the outcomes of epilepsy surgery in 27 paediatric patients at Hospital Baca Ortiz in Quito, Ecuador. Our analysis considered the following variables: reduction in seizure frequency, surgery outcome according to the Engel classification, improvement in quality of life, and serious complications due to surgery.

RESULTS

21 corpus callosotomies and 6 resective surgeries were performed. The mean seizure frequency decreased from 465 per month before surgery to 37.2 per month thereafter (p<.001); quality of life scale scores increased from 12.6 to 37.2 (p<.001), and quality of life improved in 72.7% of patients. Regarding resective surgery, 2 patients with temporal lobe epilepsy and one with posterior quadrant epilepsy achieved Engel class IA, and one patient undergoing hemispherotomy due to Rasmussen encephalitis achieved Engel class IIA. Two patients underwent surgery for hypothalamic hamartoma: one achieved Engel III and the other, Engel IA; however, the latter patient died in the medium term due to a postoperative complication. The other major complication was a case of hydrocephalus, which led to the death of a patient with refractory infantile spasms who underwent corpus callosotomy.

CONCLUSIONS

Favourable outcomes were observed in 92.5% of patients.

Elimination of medically intractable epileptic drop attacks following endoscopic total corpus callosotomy in Rett syndrome

INTRODUCTION

Rett syndrome is a neurodevelopmental genetic disorder, characterized by developmental delay, hand stereotypies, abnormal gait, and acquired microcephaly. Epilepsy is very common in Rett syndrome and can be medically intractable. It remains uncertain if a patient with epileptic drop attacks associated with this genetic disease can benefit from corpus callosotomy.

CASE REPORT

We report an 8-year-old girl with Rett syndrome and medically intractable epileptic drop attacks who underwent endoscopic total corpus callosotomy without any complications that led to the successful elimination of her seizures.

CONCLUSION

Total corpus callosotomy is a feasible treatment option for medically intractable epileptic drop attacks in Rett syndrome and should not be considered as a contraindication in this condition. This is the first reported case of corpus callosotomy in Rett syndrome.