Endoscopic posterior interhemispheric complete corpus callosotomy

Total Corpus Callosotomy via Posterior Approach with Endoscopic-Alone Technique

Two main surgical techniques are available for corpus callosotomy (CC): conventional microscopic CC and endoscopic CC.1 Microscopic CC is more familiar to neurosurgeons and allows three-dimensional visualization, but it requires a larger craniotomy and has a narrower visual angle in the deep part. Endoscopic CC has only recently been introduced to epilepsy surgery, but it is gaining increasing interest among epilepsy surgeons. The endoscope provides two-dimensional visualization and requires a camera as an additional instrument inserted into the surgical corridor. The merits of endoscopic CC include the smaller craniotomy and smaller skin incision, potentially reducing invasiveness.2 Bridging veins to the superior sagittal sinus are also less problematic because of the reduced need for brain retraction. The lack of need of arachnoid dissection is another advantage. Generally, an anterior approach is applied for CC, but this approach makes interhemispheric fissure dissection mandatory, especially at the cingulate gyri. In some cases, this procedure can take a long time. On the other hand, a posterior approach requires less interhemispheric arachnoid dissection, or sometimes none at all, due to the anatomy of the falx cerebri. These reasons have driven the development of a posterior approach for an endoscopic-alone technique.3 Here, we present a 5-year-old girl with medically intractable epileptic spasms that were diagnosed as infantile epileptic spasms syndrome, who underwent endoscopic total CC via a posterior approach to control her seizures (Video 1).

Pediatric Neurostimulation and Practice Evolution

Since the late nineteenth century, the prevailing view of epilepsy surgery has been to identify a seizure focus in a medically refractory patient and eradicate it. Sadly, only a select number of the many who suffer from uncontrolled seizures benefit from this approach. With the development of safe, efficient stereotactic methods and targeted surgical therapies that can affect deep structures and modulate broad networks in diverse disorders, epilepsy surgery in children has undergone a paradigmatic evolutionary change. With modern diagnostic techniques such as stereo electroencephalography combined with closed loop neuromodulatory systems, pediatric epilepsy surgery can reach a much broader population of underserved patients.

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

BACKGROUND AND OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

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

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 Aspects of Corpus Callosotomy

Corpus callosotomy (CC) is one of the options in epilepsy surgeries to palliate patient seizures, and is typically applied for drop attacks. The mechanisms of seizure palliation involve disrupting the propagation of epileptic activity to the contralateral side of the brain. This review article focuses on the surgical aspects of CC. As a variations of CC, anterior two-thirds, posterior one-third, and total callosotomy are described with intraoperative photographs. As less-invasive surgical variations, recent progress in endoscopic CC, and CC without craniotomy, is described. CC remains acceptable under the low prevalence of complications, and surgeons should make the maximum effort to minimize the complication rate.

Smaller Knife, Fewer Seizures? Recent Advances in Minimally Invasive Techniques in Pediatric Epilepsy Surgery

Children with drug-resistant epilepsy are at high risk for developmental delay, increased mortality, psychiatric comorbidities, and requiring assistance with activities of daily living. Despite the advent of new and effective pharmacologic therapies, about one in 5 children will develop drug-resistant epilepsy, and most of these children continue to have seizures despite trials of other medication. Epilepsy surgery is often a safe and effective option which may offer seizure freedom or at least a significant reduction in seizure burden in many children. However, despite published evidence of safety and efficacy, epilepsy surgery remains underutilized in the pediatric population. Patient and family fears about the risks of surgery may contribute to this gap. Less invasive surgical techniques may be more palatable to children with epilepsy and their caregivers. In this review, we present recent advances in minimally invasive techniques for the surgical treatment of epilepsy as well as intriguing possibilities for the future. We describe the indications for, benefits of, and limits to minimally-invasive techniques including Stereo-encephalography, laser interstitial thermal ablation, deep brain stimulation, focused ultrasound, stereo-encephalography-guided radiofrequency ablation, endoscopic disconnections, and responsive neurostimulation.

Postoperative Pneumocephalus on Computed Tomography Might Predict Post-Corpus Callosotomy Chemical Meningitis

BACKGROUND

A corpus callosotomy (CC) is a procedure in which the corpus callosum, the largest collection of commissural fibers in the brain, is disconnected to treat epileptic seizures. The occurrence of chemical meningitis has been reported in association with this procedure. We hypothesized that intraventricular pneumocephalus after CC surgery represents a risk factor for postoperative chemical meningitis. The purpose of this study was to analyze the potential risk factors for postoperative chemical meningitis in patients with medically intractable epilepsy who underwent a CC.

METHODS

Among the patients who underwent an anterior/total CC for medically intractable epilepsy between January 2009 and March 2021, participants were comprised of those who underwent a computed tomography scan on postoperative day 0. We statistically compared the groups with (c-Group) or without chemical meningitis (nc-Group) to determine the risk factors.

RESULTS

Of the 80 patients who underwent a CC, 65 patients (25 females and 40 males) met the inclusion criteria. Their age at the time of their CC procedure was 0-57 years. The c-Group (17%) was comprised of seven females and four males (age at the time of their CC procedure, 1-43 years), and the nc-Group (83%) was comprised of 18 females and 36 males (age at the time of their CC procedure, 0-57 years). Mann-Whitney U-tests (p = 0.002) and univariate logistic regression analysis (p = 0.001) showed a significant difference in pneumocephalus between the groups.

CONCLUSION

Postoperative pneumocephalus identified on a computed tomography scan is a risk factor for post-CC chemical meningitis.

Endoscopic Ipsilateral Interhemispheric Approach for Resection of Selected Deep Medial Brain Tumors

BACKGROUND

The interhemispheric fissure provides a natural surgical corridor to access tumors of the deep medial surface of the brain. Conventional microscopic approaches to these tumors are limited by the narrow width of the interhemispheric fissure and need for retraction of brain tissue or traversing overlying cortex. Over the last decade, the endoscope has been used to improve visualization of the operative field in neurosurgery, with benefits in terms of surgical ergonomics and extent of tumor resections. In the context of the interhemispheric fissure, an endoscopic approach may improve visualization of some tumors by providing a brighter, more divergent light source at depth and by enabling the operator to inspect around curved structures (e.g., corpus callosum).

CASE DESCRIPTION

In this report, we present a series of 5 cases with tumors at various locations along the anteroposterior extent of the interhemispheric fissure that were resected using an endoscopic ipsilateral interhemispheric approach.

CONCLUSIONS

The endoscopic ipsilateral interhemispheric approach is an effective and versatile approach to resection of selected deep medial brain tumors extending anteriorly from the genu of the corpus callosum to the splenium. It has notable advantages over the microscope and can be considered a useful adjunct in the surgeon's armamentarium.

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.

Recent advances in the neurosurgical treatment of pediatric epilepsy: JNSPG 75th Anniversary Invited Review Article

The field of epilepsy surgery has seen tremendous growth in recent years. Innovative new devices have driven much of this growth, but some has been driven by revisions of existing products. Devices have also helped to rejuvenate existing procedures, as in the case of robotic assistance for electrode placement for stereo-electroencephalography, and these devices have brought significant attention along with their introduction. Other devices, such as responsive neurostimulators or laser interstitial thermal therapy systems, have introduced novel treatment modalities and broadened the surgical indications. Collectively, these advances are rapidly changing much of the landscape in the world of pediatric neurosurgery for medically refractory epilepsy. The foundations for indications for neurosurgical intervention are well supported in strong research data, which has also been expanded in recent years. In this article, the authors review advances in the neurosurgical treatment of pediatric epilepsy, beginning with trials that have repeatedly demonstrated the value of neurosurgical procedures for medically refractory epilepsy and following with several recent advances that are largely focused on less-invasive intervention. ABBREVIATIONS AED = antiepileptic drug; ANT = anterior nucleus of the thalamus; BOLD = blood oxygen level dependent; CCEP = cortico-cortical evoked potential; DBS = deep brain stimulation; ECoG = electrocorticography; ERSET = Early Randomized Surgical Epilepsy Trial; FCD = focal cortical dysplasia; HH = hypothalamic hamartoma; LITT = laser interstitial thermal therapy; RCT = randomized controlled trial; r-fMRI = resting-state functional MRI; RNS = responsive neurostimulation; SEEG = stereo-electroencephalography; VNS = vagus nerve stimulation.

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.

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

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