Long-term outcomes of hemispheric disconnection in pediatric patients with intractable epilepsy

Insights on cognitive reorganization after hemispherectomy in Rasmussen's encephalitis. A narrative review

Rasmussen's encephalitis is a rare neurological pathology affecting one cerebral hemisphere, therefore, posing unique challenges. Patients may undergo hemispherectomy, a surgical procedure after which cognitive development occurs in the isolated contralateral hemisphere. This rare situation provides an excellent opportunity to evaluate brain plasticity and cognitive recovery at a hemispheric level. This literature review synthesizes the existing body of research on cognitive recovery following hemispherectomy in Rasmussen patients, considering cognitive domains and modulatory factors that influence cognitive outcomes. While language function has traditionally been the focus of postoperative assessments, there is a growing acknowledgment of the need to broaden the scope of language investigation in interaction with other cognitive domains and to consider cognitive scaffolding in development and recovery. By synthesizing findings reported in the literature, we delineate how language functions may find support from the right hemisphere after left hemispherectomy, but also how, beyond language, global cognitive functioning is affected. We highlight the critical influence of several factors on postoperative cognitive outcomes, including the timing of hemispherectomy and the baseline preoperative cognitive status, pointing to early surgical intervention as predictive of better cognitive outcomes. However, further specific studies are needed to confirm this correlation. This review aims to emphasize a better understanding of mechanisms underlying hemispheric specialization and plasticity in humans, which are particularly important for both clinical and research advancements. This narrative review underscores the need for an integrative approach based on cognitive scaffolding to provide a comprehensive understanding of mechanisms underlying the reorganization in Rasmussen patients after hemispherectomy.

Functional hemispheric disconnection procedures for chronic epilepsy: history, indications, techniques, complications and current practice in Europe. A consensus statement on behalf of the EANS functional neurosurgery section

Introduction

The surgical procedure for severe, drug-resistant, unilateral hemispheric epilepsy is challenging. Over the last decades the surgical landscape for hemispheric disconnection procedures changed from anatomical hemispherectomy to functional hemispherotomy with a reduction of complications and stable good seizure outcome. Here, a task force of European epilepsy surgeons prepared, on behalf of the EANS Section for Functional Neurosurgery, a consensus statement on different aspects of the hemispheric disconnection procedure.

Research question

To determine history, indication, timing, techniques, complications and current practice in Europe for hemispheric disconnection procedures in drug-resistant epilepsy.

Material and methods

Relevant literature on the topic was collected by a literature search based on the PRISMA 2020 guidelines.

Results

A comprehensive overview on the historical development of hemispheric disconnection procedures for epilepsy is presented, while discussing indications, timing, surgical techniques and complications. Current practice for this procedure in European epilepsy surgery centers is provided. At present, our knowledge of long-term seizure outcomes primarily stems from open surgical disconnection procedures. Although minimal invasive surgical techniques in epilepsy are rapidly developing and reported in case reports or small case series, long-term seizure outcome remain uncertain and needs to be reported.

Discussion and conclusion

This is the first paper presenting a European consensus statement regarding history, indications, techniques and complications of hemispheric disconnection procedures for different causes of chronic, drug-resistant epilepsy. Furthermore, it serves as the pioneering document to report a comprehensive overview of the current surgical practices regarding this type of surgery employed in renowned epilepsy surgery centers across Europe.

Intraventricular SEEG and laser ablation for the treatment of infantile spasm: Technical note

OBJECTIVES

Infantile spasm (IS) is an epileptic encephalopathy with ongoing neurological damage due to seizures and epileptiform abnormalities. Epilepsy surgery is considered for children refractory to drug therapy, especially when there is a focal brain lesion. In this study, we investigated the feasibility and efficacy of intraventricular stereotactic electroencephalography (SEEG) and laser ablation for the treatment of IS children with focal brain lesions.

METHODS

We performed the first reported study using ventriculoscopic laser ablation to treat IS. Seven IS children with drug-resistant epilepsy and definite encephalomalacia on brain magnetic resonance imaging scan were included in this study. Ablation was performed after confirmation of epileptiform discharges by SEEG under the surveillance of ventriculoscope.

RESULTS

The median follow-up time for the cohort was 3.1 years and 86% (6/7) of the children had an Engel class ≤III epilepsy at the final follow-up. Five (71%) children had a reduction in seizure medication usage, and the other two were on the same amount as preablation. None of the children experienced serious new neurological deficits. Laser ablation might result in seizure freedom by destroying the local brain network and blocking the spread of abnormal discharges.

CONCLUSIONS

Intraventricular SEEG and laser ablation was feasible and effective for the treatment of IS. Further studies are warranted.

Hemispherotomy Revised: A complication overview and a systematic review meta-analysis

Introduction

Hemispherectomy/hemispherotomy has been employed in the management of catastrophic epilepsy. However, initial reports on the associated mortality and morbidity raised several concerns regarding the technique's safety. Their actual, current incidence needs to be systematically examined to redefine hemispherotomy's exact role.

Research question

Our current study examined their incidence and evaluated the association of the various hemispherotomy surgical techniques with the reported complications.

Material & methods

A PRISMA-compliant systematic review and meta-analysis was performed. We searched PubMed, Scopus, and Web of Science until December 2022. Fixed- and random-effects models were employed. Egger's regression test was used for estimating the publication bias, while subgroup analysis was utilized for defining the role of the different hemispherotomy techniques.

Results

We retrieved a total of 37 studies. The overall procedure mortality was 5%, with a reported mortality of 7% for hemispherectomy and 3% for hemispherotomy. The reported mortality has decreased over the last 30 years from 32% to 2%. Among the observed post-operative complications aseptic meningitis and/or fever occurred in 33%. Hydrocephalus requiring a shunt insertion occurred in 16%. Hematoma evacuation was necessary in 8%, while subgaleal effusion in another 8%. Infections occurred in 11%. A novel post-operative cranial nerve deficit occurred in 11%, while blood transfusion was necessary in 28% of the cases.

Discussion and conclusion

Our current analysis demonstrated that the evolution from hemispherectomy to hemispherotomy along with neuroanesthesia advances, had a tremendous impact on the associated mortality and morbidity. Hemispherotomy constitutes a safe surgical procedure in the management of catastrophic epilepsies.

Tailored Hemispherotomy Using Tractography-Guided Laser Interstitial Thermal Therapy

BACKGROUND

Medically refractory hemispheric epilepsy is a devastating disease with significant lifetime costs and social burden. Functional hemispherotomy is a highly effective treatment for hemispheric epilepsy but is associated with significant complication rates. Percutaneous hemispherotomy through laser interstitial thermal therapy (LITT) based on morphological MRI has been recently described in a single patient but not replicated in the literature.

OBJECTIVE

To describe the first 2 cases of tractography-guided interstitial laser hemispherotomy and their short-term outcomes.

METHODS

Two 11-year-old male patients with medically refractory epilepsy secondary to perinatal large vessel infarcts were referred for hemispherotomy. Both patients underwent multitrajectory LITT to disconnect the remaining pathological hemisphere, using tractography to define targets and assess structural outcomes.

RESULTS

Both cases had minor complication of small intraventricular/subarachnoid hemorrhage not requiring additional intervention. Both patients remain seizure-free at all follow-up visits.

CONCLUSION

LITT hemispherotomy can produce seizure freedom with short hospitalization and recovery. Tractography allows surgical planning to be tailored according to individual patient anatomy, which often is distorted in perinatal stroke. Minimally invasive procedures offer the greatest potential for seizure freedom without the risks of an open hemispherotomy.

Surgery for pediatric drug resistant epilepsy: a narrative review of its history, surgical implications, and treatment strategies

BACKGROUND AND OBJECTIVE

Drug-resistant epilepsy (DRE), also known as medically refractory epilepsy, is a disorder of high prevalence and negatively impacts a patients quality of life, neurodevelopment, and life expectancy. Pediatric epilepsy surgery has been conducted since the late 1800s, and randomized controlled trials have demonstrated the marked effectiveness of surgery on seizure reduction and the potential for cure. Despite the strong evidence for pediatric epilepsy surgery, there is also strong evidence describing its underutilization. The objective of this narrative review is to describe the history, strength, and limitations in the evidence of surgery for pediatric drug resistant epilepsy.

METHODS

This narrative review was conducted utilizing standard search engines to include the relevant articles on the topic of surgery for drug resistant epilepsy in children, with main keywords including surgery in pediatric epilepsy and drug-refractory epilepsy.

KEY CONTENT AND FINDINGS

The first components describe the historical perspective of pediatric epilepsy surgery and the evidence that highlight the strengths and limitations of epilepsy surgery. We then highlight the importance of presurgical referral and evaluation, followed by a section detailing the surgical options for children with DRE. Lastly, we provide a perspective on the future of pediatric epilepsy surgery.

CONCLUSIONS

Evidence supports the role for surgery in pediatric medically refractory epilepsy in seizure frequency reduction, improved curative rates, and improvements in neurodevelopment and quality of life.

Surgical Strategy for Hemispherotomy

Hemispherotomy is a radical treatment for drug-resistant epilepsy that targets developmental, acquired, and progressive diseases with widespread epileptogenic regions in one cerebral hemisphere. Currently, two main approaches are utilized after repeated improvements: lateral and vertical approaches. With the lateral approach, the surgical field is wide, and the approach to the lateral ventricle is relatively easy. On the other hand, the vertical approach has the advantage of reducing intraoperative bleeding and operating time as the resection line of the radial fiber is short, and understanding the three-dimensional anatomy is relatively easy. The lateral approach is generally used for atrophic lesions, whereas the vertical approach is for hypertrophic lesions. Hemispherotomy is expected to not only suppress epileptic seizures but also improve psychomotor development by protecting the unaffected cerebral hemisphere. However, this method is one of the most invasive surgeries in epilepsy surgery, and it is important to fully consider its indications. Furthermore, understanding the neural fiber pathway is important for actual surgery.

Prognostic Value of Preoperative and Postoperative Electroencephalography Findings in Pediatric Patients Undergoing Hemispheric Epilepsy Surgery

OBJECTIVE

The seizure outcomes after hemispheric epilepsy surgery have been excellent, with 54%-90% of patients achieving long-term freedom from seizures. Similarly, the neuropsychological outcomes have been favorable. The prognostic value of pre- and postoperative electroencephalography (EEG) has not been well-studied. In the present study, we characterized the value of the pre- and postoperative EEG findings for predicting the seizure and neuropsychological outcomes for pediatric patients undergoing hemispherectomy.

METHODS

A total of 22 children who had undergone functional hemispherectomy at our institution from 2010 to 2020 were included. The ictal and interictal findings were categorized as ipsilateral to the operated hemisphere, independently arising from the contralateral hemisphere, and/or generalized. The seizure outcomes were classified using the Engel scale. All neuropsychological evaluations were performed in accordance with our institution's protocol. The relationship between the EEG findings and outcomes was analyzed.

RESULTS

Of the 22 patients, 19 (86%) were seizure free (Engel class IA) at the latest follow-up (mean, 4.2 years). On the preoperative EEGs, 9 had had seizures, all had had ipsilateral interictal discharges, and 9 had had contralateral interictal discharges. On the postoperative EEGs, obtained a median of 1 year after surgery, 3 had had seizures, 16 had had ipsilateral interictal discharges, and 5 had had contralateral interictal discharges. Of the 3 patients with seizures found on the postoperative EEG, all were clinically free of seizures. The patients who had not achieved Engel class IA were not significantly more likely to have abnormalities found on the EEG. The neuropsychological scores were stable from before to after surgery, with no evidence of EEG abnormalities having predictive value.

CONCLUSIONS

The seizure and neuropsychology outcomes after hemispherectomy were excellent in our study, with 86% of our cohort achieving freedom from seizures. The presence, lateralization, and evolution of pre- and postoperative EEG abnormalities were not predictive of the outcomes.

Seizure Outcomes and Reoperation in Surgical Rasmussen Encephalitis Patients

BACKGROUND

Rasmussen encephalitis (RE) is a rare inflammatory disease affecting one hemisphere, causing progressive neurological deficits and intractable seizures.

OBJECTIVE

To report long-term seizure outcomes, reoperations, and functional outcomes in patients with RE who underwent hemispherectomy at our institution.

METHODS

Retrospective review was performed for all patients with RE who had surgery between 1998 and 2020. We collected seizure history, postoperative outcomes, and functional data. Imaging was independently reviewed in a blinded fashion by 2 neurosurgeons and a neuroradiologist.

RESULTS

We analyzed 30 patients with RE who underwent 35 hemispherectomies (5 reoperations). Using Kaplan-Meier analysis, seizure-freedom rate was 81.5%, 63.6%, and 55.6% at 1, 5, and 10 years after surgery, respectively. Patients with shorter duration of hemiparesis preoperatively were less likely to be seizure-free at follow-up (P = .011) and more likely to undergo reoperation (P = .004). Shorter duration of epilepsy (P = .026) and preoperative bilateral MRI abnormalities (P = .011) were associated with increased risk of reoperation. Complete disconnection of diseased hemisphere on postoperative MRI after the first operation improved seizure-freedom (P = .021) and resulted in fewer reoperations (P = .034), and reoperation resulted in seizure freedom in every case.

CONCLUSION

Obtaining complete disconnection is critical for favorable seizure outcomes from hemispherectomy, and neurosurgeons should have a low threshold to reoperate in patients with RE with recurrent seizures. Rapid progression of motor deficits and bilateral MRI abnormalities may indicate a subpopulation of patients with RE with increased risk of needing reoperation. Overall, we believe that hemispherectomy is a curative surgery for the majority of patients with RE, with excellent long-term seizure outcome.

Endoscopic Anatomy of Transcallosal Hemispherotomy: Laboratory Study with Advanced Three-Dimensional Modeling

BACKGROUND

Epilepsy surgery has an important role in the treatment of patients with medically intractable seizures. Various authors have proposed an endoscopic technique to perform disconnective procedures. A detailed description of intracerebral anatomy seen through an endoscopic transcallosal corridor has not been reported. The aim of this study was to present a cadaveric step-by-step anatomical demonstration of endoscopic transcallosal hemispherotomy using a dedicated three-dimensional model.

METHODS

Anatomical dissections were performed on 6 cadaveric heads (12 hemispheres), and the disconnective procedure was performed using an endoscopic transcallosal approach. A dedicated three-dimensional model was used to better illustrate each step. A simulation of the disconnective procedure was performed by recreating the surgical steps on a subject from the Human Connectome Project dataset, and a calculation of the fiber tracts intersected was performed.

RESULTS

Analyzing data extracted from the three-dimensional model and tractography simulation, 100% of the fibers (streamlines) of corpus callosum, corticopontine tracts, corticospinal tract, and inferior fronto-occipital fascicle were transected. Moreover, a satisfactory number of fibers (>95%) of the thalamocortical tracts, corticostriatal tracts, corona radiata, fornix, and uncinate fascicle were disconnected.

CONCLUSIONS

This anatomical study described the relevant neurovascular structures to enable prediction of feasibility and control of the surgical procedure using the endoscopic transcallosal approach. The quantitative analysis permitted estimation of the theoretical efficacy of the procedure, confirming its relevant role in disconnective surgery.

Seizure outcomes of large volume temporo-parieto-occipital and frontal surgery in children with drug-resistant epilepsy

OBJECTIVE

In this study, we investigate the seizure outcomes of temporo-parieto-occipital (TPO) and frontal disconnections or resections in children with drug-resistant epilepsy (DRE) in order to determine factors which may predict surgical results.

METHODS

Children with DRE, who underwent either TPO or frontal disconnection or resection at Great Ormond Street Hospital for Children between 2000 and 2017, were identified from a prospectively collated operative database. Demographic data, age at surgery, type of surgery, scalp EEGs and operative histopathology were collected. Magnetic resonance imaging (MRI) was assessed to determine completeness of disconnection and presence of radiological lesion beyond the disconnection margins. Seizure outcome at 6, 12, and 24 months post-surgery was assessed using the Engel Scale (ES). Logistic regression was used to identify relationships between data variables and seizure outcome.

RESULTS

46 children (males = 28, females = 18; age range 0.5-16.6 years) who underwent TPO (n = 32, including a re-do disconnection) or frontal disconnection or resection (n = 15) were identified. Patients in the TPO treatment group had more favourable seizure outcomes than those in the frontal treatment group (ES I-II in 56 %vs 47 % at 6 months, 52 % vs 46 % at 12 months). Presence of the lesion beyond disconnection boundaries and older age at the time of surgery were associated with poorer seizure outcome. Gender, surgery type, completeness of disconnection, scalp EEG findings and underlying pathology were not related to seizure outcome, but subgroup numbers were small.

CONCLUSIONS

Both TPO and frontal disconnection are effective treatments for selected children with posterior multi-lobar or diffuse frontal lobe epilepsy. Confinement of the MRI lesion within the disconnection margins and a younger age at surgery are associated with favourable seizure outcomes. Further studies are required to elucidate these findings.

Pediatric hemispherectomy outcome: Adaptive functioning, intelligence, and memory

OBJECTIVE

Our purpose was to characterize neuropsychological evaluation (NP) outcome following functional hemispherectomy in a large, representative cohort of pediatric patients.

METHODS

We evaluated seizure and NP outcomes and medical variables for all post-hemispherectomy patients from Seattle Children's Hospital epilepsy surgery program between 1996 and 2020. Neuropsychological evaluation outcome tests used were not available on all patients due to the diversity of patient ages and competency that is typical of a representative pediatric cohort; all patients had at least an adaptive functioning or intelligence measure, and a subgroup had memory testing.

RESULTS

A total of 71 hemispherectomy patients (37 right; 34 females) yielded 66 with both preoperative (PREOP) plus postoperative (POSTOP) NPs and 5 with POSTOP only. Median surgery age was 5.7 (IQR 2-9.9) years. Engel classification indicated excellent seizure outcomes: 59 (84%) Class I, 6 (8%) Class II, 5 (7%) Class III, and 1 (1%) Class IV. Medical variables - including seizure etiology, surgery age, side, presurgical seizure duration, unilateral or bilateral structural abnormalities, secondarily generalized motor seizures - were not associated with either Engel class or POSTOP NP scores, though considerable heterogeneity was evident. Median PREOP and POSTOP adaptive functioning (PREOP n = 45, POSTOP n = 48) and intelligence (PREOP n = 29, POSTOP n = 36) summary scores were exceptionally low and did not reveal group decline from PREOP to POSTOP. Fifty-five of 66 (85%) cases showed stability or improvement. Specifically, 5 (8%) improved; 50 (76%) showed stability; and 11 (16%) declined. Improve and decline groups showed clinically interesting, but not statistical, differences in seizure control and age. Median memory summary scores were low and also showed considerable heterogeneity. Overall median PREOP to POSTOP memory scores (PREOP n = 16, POSTOP n = 24) did not reveal declines, and verbal memory scores improved. Twenty six percent of intelligence and 33% of memory tests had verbal versus visual-spatial discrepancies; all but one favored verbal, regardless of hemispherectomy side.

SIGNIFICANCE

This large, single institution study revealed excellent seizure outcome in 91% of all 71 patients plus stability and/or improvement of intelligence and adaptive functioning in 85% of 66 patients who had PREOP plus POSTOP NPs. Memory was similarly stable overall, and verbal memory improved. Medical variables did not predict group NP outcomes though heterogeneity argues for further research. This study is unique for cohort size, intelligence plus memory testing, and evidence of primacy of verbal over visual-spatial development, despite hemispherectomy side. This study reinforces the role of hemispherectomy in achieving good seizure outcome while preserving functioning.

Long-Term Patient-Reported Outcomes of Visual Field Defects and Compensatory Mechanisms in Patients After Cerebral Hemispherectomy

BACKGROUND

In cases of intractable epilepsy resistant to drug therapy, hemispherectomy is often the only treatment option to mitigate seizures; however, the true long-term subjective visual outcomes are relatively unexplored. In this study, we sought to determine and characterize patient-reported visual function years after hemispherectomy.

METHODS

This was an observational study conducted on a large cohort of children with seizure disorder treated with cerebral hemispherectomy. An online survey was sent to parents with questions to assess subjective visual function with a variety of questions from presence of visual field defects after hemispherectomy, to improvement over time, compensatory mechanisms used, and development of strabismus.

RESULTS

This survey was emailed to 248 parents of previously evaluated children who agreed to be re-surveyed, 48 (20%) of which responded. The average age at hemispherectomy was approximately 5 (±4) years, and the average time after hemispherectomy was 7 (±5) years. Thirty-nine patients (81%) were seizure-free after 1 surgery and 85% (n = 41) were seizure-free after ≥1 surgeries. Thirty-four (71%) experienced a visual field defect after surgery, but 25 (52%) experienced subjective improvement over time. Thirty-eight (79%) used compensatory mechanisms, such as head tilting, with 16 (33%) patients experiencing subjective improvement over time. Twenty-seven (56%) patients experienced a decrease in visual acuity after surgery with 12 (25%) experiencing subjective improvement over time.

CONCLUSION

In a large cohort examining patient-reported visual outcomes years after hemispherectomy, most patients experienced strabismus and/or visual field defects. However, more than half reported improvements and compensatory mechanisms (exotropic strabismus and ipsilateral esotropic strabismus) over time, presumably to enhance visual field function. By exploring subjective visual and cognitive function, this paper uniquely characterizes patient-reported improvements over time, and provides motivation for larger longitudinal studies using more quantitative measures of visual function and improvement after hemispherectomy.

Epilepsy surgery for Rasmussen encephalitis: the UCLA experience

OBJECTIVE

Rasmussen encephalitis (RE) is a rare inflammatory neurological disorder typically involving one hemisphere and resulting in drug-resistant epilepsy and progressive neurological decline. Here, the authors present seizure outcomes in children who underwent epilepsy surgery for RE at a single institution.

METHODS

The records of consecutive patients who had undergone epilepsy surgery for RE at the UCLA Mattel Children's Hospital between 1982 and 2018 were retrospectively reviewed. Basic demographic information, seizure history, procedural notes, and postoperative seizure and functional outcome data were analyzed.

RESULTS

The cohort included 44 patients, 41 of whom had sufficient data for analysis. Seizure freedom was achieved in 68%, 48%, and 22% of the patients at 1, 5, and 10 years, respectively. The median time to the first seizure for those who experienced seizure recurrence after surgery was 39 weeks (IQR 11-355 weeks). Anatomical hemispherectomy, as compared to functional hemispherectomy, was independently associated with a longer time to postoperative seizure recurrence (HR 0.078, p = 0.03). There was no statistically significant difference in postoperative seizure recurrence between patients with complete hemispherectomy and those who had less-than-hemispheric surgery. Following surgery, 68% of the patients could ambulate and 84% could speak regardless of operative intervention.

CONCLUSIONS

A large proportion of RE patients will have seizure relapse after surgery, though patients with anatomical hemispherectomies may have a longer time to postoperative seizure recurrence. Overall, the long-term data in this study suggest that hemispheric surgery can be seen as palliative treatment for seizures rather than a cure for RE.

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.

Treatment of infantile spasms: why do we know so little?

INTRODUCTION

Infantile spasm (IS) is an epileptic syndrome with typical onset within the first 2 years of life. This condition might be caused by several etiologies. IS is associated with pathological neuronal networks; however, definite hypotheses on neurobiological processes are awaited.

AREAS COVERED

Changes in NMDA and GABA_B receptors and increase of Ca²⁺ conductance are some of the possible pathophysiological mechanisms. Animal models can help, but most have only some features of IS. Outcome is strongly affected by etiology and the timing of treatment, which relies still on ACTH, oral steroids, and vigabatrin. No significant differences in terms of efficacy have been documented, though a combination of ACTH and vigabatrin seems to be associated with better long-term outcomes. Despite the increasing knowledge about the etiology and pathophysiology of IS, in the last years, no new treatment approaches have been recognized to be able to modify the neurobiological process underlying IS. Precision medicine has far to come in IS.

EXPERT OPINION

Recently, no new therapeutic options for IS have emerged, probably due to the lack of reliable animal models and to the extreme variability in etiologies. Consequently, the outlook for patients and families is poor and early recognition and intervention remain research priorities.

Need of Immediate Drug Reduction after Epilepsy Surgery - A Prospective Observational Study

Background

Patients undergoing epilepsy surgery are on polytherapy. Drug tapering is usually done after 1 year in adults and after 6 months in children. Sometimes, drugs have to be altered during the perioperative period, which is more commonly seen in hemispherotomy (HS) patients. The present study was done to compare perioperative drug alterations between HS and temporal (TL) lobectomy patients.

Materials and Methods

Prospective analysis of postoperative HS and TL patients was done. Primary outcomes were drug number, dosage changes, and seizure outcome. Secondary outcome studied was a change in intelligence quotient (IQ) in the two groups.

Results

At total of 71 patients were included. Perioperative drug stopping (clobazam - CLB) was needed in 3/38 patients in the HS group, due to sedation. Dosage was reduced in 23/38 (60.52%) in HS group, and in 2/33 (6%) in TL group P < 0.001. The most common drug was CLB, with reduction in 21/27 (77.77%) patients, with a mean reduction of 41.21 ± 4.01%. Two patients required drug substitution in the HS group. About 64/71 (90.1%) patients achieved Class I outcome at a 1-year postoperative time point (TL - 90.9%, HS - 89.47%). There was no change in IQ in any of the groups.

Conclusion

Perioperative drug alteration is often needed in the HS patients as compared to TL patients. Benzodiazepines have to be reduced to maintain alertness in the HS patients. The increased sedation postoperatively can be due to decreased cortical drive over the reticular activating system, gamma-aminobutyric acid (GABA) receptor denervation hypersensitivity, or increased activity of drugs over the remaining active hemisphere.

Etiology and Age Modifies Subjective Visual Function After Cerebral Hemispherectomy

BACKGROUND

Cerebral hemispherectomy is typically used to treat patients with pharmacoresistant epilepsy. Visual-related outcomes are relatively unstudied in this population, aside from the knowledge that patients develop a complete homonymous hemianopia contralateral to the side of the hemispherectomy. The purpose of this study was to determine and characterize parent-reported functional visual, oculomotor, and postural changes in a large population of patients following cerebral hemispherectomy.

METHODS

An online survey was sent to parents of children who had undergone hemispherectomy for seizure control. Families were recruited by the Brain Recovery Project: Childhood Epilepsy Surgery Foundation. Parent-reported subjective visual function was assessed by the presence of peripheral field defects, ocular misalignment and anomalous head posture.

RESULTS

A total of 196 (12.5%) participants responded. Postoperative follow-up was 92±78 months (range: 1-382). Ninety-three percent of parents reported the child had difficulties with peripheral vision. Torticollis was present postoperatively in 122 (62%) patients. Strabismus was noted in 93 (49%). Fifty-five (59%) of the strabismus patients demonstrated exotropia with the majority of exotropia patients demonstrating the exo-deviated eye in the direction contralateral to the hemispherectomy (74.5%). Both torticollis and strabismus were most frequently seen immediately after surgery. Sixty-six patients (34%) underwent strabismus treatment. Patients with younger age of seizure onset, younger age of surgery, and certain epilepsy etiologies (hemimegencephaly, Sturge-Weber syndrome) were more likely to develop strabismus and torticollis.

CONCLUSIONS

Torticollis and strabismus are common after hemispherectomy and appear to be influenced by etiology and age at surgery. Preoperative discussion with parents and patients regarding those compensatory mechanisms is recommended, and postoperative ophthalmologic assessments are also encouraged.

Volumetric Analysis of Cerebral Peduncles and Cerebellar Hemispheres for Predicting Hemiparesis After Hemispherectomy

BACKGROUND

In some cases of refractory epilepsy, hemispherectomy is the final invasive treatment option. However, predictors of postoperative hemiparesis in these patients have not been widely studied.

OBJECTIVE

To investigate how the volumetric analysis of cerebral peduncles and cerebellar hemispheres in patients who have undergone hemispherectomy may determine prognostic implications for postoperative hemiparesis.

METHODS

Twenty-two patients who underwent hemispherectomy at our institution were retrospectively included. Using iPlan/BrainLAB (BrainLAB, Feldkirchen, Germany) imaging software and a semiautomatic voxel-based segmentation method, we calculated the preoperative cerebral peduncle and cerebellar hemisphere volumes. Cerebral peduncle and cerebellar hemisphere ratios were compared between patients with worsened or unchanged/better hemiparesis postoperatively.

RESULTS

The ratios of ipsilateral/contralateral cerebral peduncles (0.570 vs 0.828; P = .02) and contralateral/ipsilateral cerebellar hemispheres (0.885 vs 1.031; P = .009) were significantly lower in patients who had unchanged/improved hemiparesis postoperatively compared with patients who had worsened hemiparesis. Relative risk of worsening hemiparesis was significantly higher in patients with a cerebral peduncle ratio < 0.7 (relative risk, 4.3; P = .03) or a cerebellar ratio < 1.0 (relative risk, 6.4; P = .006).

CONCLUSION

Although patients who undergo hemispherectomy are heterogeneous, we report a method of predicting postoperative hemiparesis using only standard volumetric magnetic resonance imaging. This information could be used in preoperative discussions with patients and families to help better understand that chance of retaining baseline motor function.

ABBREVIATIONS

CST, corticospinal tractfMRI, functional magnetic resonance imagingTMS, transcranial magnetic stimulation.

Visual Function 20 Years After Childhood Hemispherectomy for Intractable Epilepsy

PURPOSE

To investigate visual function in adults post hemispherectomy in childhood.

DESIGN

Noncomparative case series.

METHODS

All participants underwent visual acuity, binocular function, visual field, optical coherence tomography (OCT) of the retinal nerve fiber layer (RNFL), and monocular pattern reversal visually evoked potentials (prVEP).

PARTICIPANTS

Six adults who had a hemispherectomy in childhood (median 21.5 years postoperative).

MAIN OUTCOME MEASURES

Comparison was made of visual acuity, visual field height, global RNFL thickness, and prVEP amplitude evoked by full- and half-field stimulation. Comparison of the eye ipsilateral to the side of surgery to the contralateral eye was achieved employing paired t tests to the visual function measures.

RESULTS

All participants had homonymous hemianopia. The residual seeing visual field was constricted in all cases when compared with normative data despite crossing the midline into the blind hemifield in 11 of 12 eyes. This observation was supported by prVEP to stimuli presented in the blind half field. The height of the visual field was smaller in the eye contralateral to the side of surgery compared with the ipsilateral side (P = .047). Visual acuity and RNFL thickness also showed greater diminution in the contralateral eye (P = .040 and P = .0004). Divergent strabismus was found in 4 participants with greater field loss.

CONCLUSIONS

Adults post hemispherectomy in childhood may have better visual function in the eye ipsilateral to the side of the hemispherectomy compared with the contralateral eye. Possible mechanisms of the interocular difference are discussed. Though visual fields and prVEP responses demonstrate evidence of reorganization into the blind half field, they also reveal significant unexpected constriction of the functional field.

Complete prefrontal lobe isolation surgery for recurrent epilepsy: A case report

Epileptogenic focus resection is less effective for the treatment of frontal lobe epilepsy compared with temporal lobe epilepsy. However, there is currently a lack of effective therapeutic options for patients with frontal lobe epilepsy who are unsuitable for epileptogenic focus resection (such patients with epileptogenic foci in one frontal lobe in which the precise epileptic foci cannot be determined), or who experience recurrent epilepsy following epileptogenic focus resection. The present study reports a patient with frontal lobe epilepsy who underwent successful frontal lobe isolation surgery following a previous unsuccessful epileptogenic focus resection surgery. To ensure complete isolation of the prefrontal lobe, the surgery included division of the anterior commissure and the anterior part of the corpus callosum. The patient was followed-up for 16 months. Although the follow-up electroencephalogram presented a number of sharp waves on the affected side, the patient did not experience any seizures. The results suggest that prefrontal lobe isolation is an effective method of treating frontal lobe epilepsy, as division of the anterior commissure and the anterior part of the corpus callosum ensures disconnection of the prefrontal lobe from other regions of the brain.

Correction of Facial Deformity in Sturge-Weber Syndrome

Background:

Although previous studies have reported soft-tissue management in surgical treatment of Sturge–Weber syndrome (SWS), there are few reports describing facial bone surgery in this patient group. The purpose of this study is to examine the validity of our multidisciplinary algorithm for correcting facial deformities associated with SWS. To the best of our knowledge, this is the first study on orthognathic surgery for SWS patients.

Methods:

A retrospective chart review included 2 SWS patients who completed the surgical treatment algorithm. Radiographic and clinical data were recorded, and a treatment algorithm was derived.

Results:

According to the Roach classification, the first patient was classified as type I presenting with both facial and leptomeningeal vascular anomalies without glaucoma and the second patient as type II presenting only with a hemifacial capillary malformation. Considering positive findings in seizure history and intracranial vascular anomalies in the first case, the anesthetic management was modified to omit hypotensive anesthesia because of the potential risk of intracranial pressure elevation. Primarily, both patients underwent 2-jaw orthognathic surgery and facial bone contouring including genioplasty, zygomatic reduction, buccal fat pad removal, and masseter reduction without major complications. In the second step, the volume and distribution of facial soft tissues were altered by surgical resection and reposition. Both patients were satisfied with the surgical result.

Conclusions:

Our multidisciplinary algorithm can systematically detect potential risk factors. Correction of the asymmetric face by successive bone and soft-tissue surgery enables the patients to reduce their psychosocial burden and increase their quality of life.

Five-Year Long-Term Prognosis of Epileptic Children After Hemispheric Surgery: A Systematic Review and Meta-analysis

To estimate children's long-term seizure outcomes after hemispheric surgery and the associated predictors.A systematic review of 4 databases and a meta-analysis were performed from January 1, 1995 to August 31, 2015. The databases included PubMed, Embase, Science Direct, and Web of Science; patients were classified into the Engel Class I group and the Engel Class II to IV group, according to their seizure outcomes. Nine potential predictors were then stratified across the groups and estimated using the Wilcoxon rank-sum test for continuous variables and the Chi-squared test for categorical variables.The search yielded 15 retrospective studies, with a total sample size of 380. Five years after surgery, 268 (0.71, 95% confidence interval [CI]: 0.64-0.78) children were seizure free; the seizure onset age in the Engel Class I group was significantly higher than that of the Engel Class II to IV group (standardized mean difference [SMD] = 0.26, 95% CI: 0.03-0.49, P = 0.028); specifically, when predicting the positive long-term outcomes, the odds ratio for late onset age (≥3.6 months, median value of the Engel Class II-IV group) versus early onset age was 2.65 (95% CI: 1.454-4.836, z = 3.18, P = 0.001). The abnormal magnetic resonance imaging (MRI) findings were more predictive for positive seizure outcomes than the normal findings (odds ratio [OR] = 4.60, 95% CI: 1.27-16.62, P = 0.02).Following hemispheric surgery, the long-term prognosis of children with epilepsy was good. Late seizure onset (age ≥ 3.6 months) and abnormal MRI findings were positive predictors for long-term seizure control in children.

Rasmussen's encephalitis: advances in management and patient outcomes

PURPOSE

Rasmussen's encephalitis (RE) is a hemispheric inflammatory disorder resulting in progressive epilepsy, hemiparesis, and cognitive decline. Controversy surrounds the most effective timing of surgery with respect to language dominance, functional status, and seizure outcome. We describe our experience with RE to inform treatment decisions.

METHODS

A retrospective chart review was performed in children diagnosed with RE from 1983 to 2012.

RESULTS

Thirteen consecutive cases were identified: six males and seven females with a mean age of 10.6 years (range 5-18). Nine patients received immunotherapy, with transient benefit in three, treatment-associated complications in two, and no difference in their mean time to treatment (5.38 vs 6.37 years p = 0.74) or long-term outcome. Mean follow-up was 5.6 years (range 0.58-12.25). There was no difference in outcome based on pre-operative duration of seizures. At last follow-up, 63 % of surgically treated patients achieved seizure freedom, 100 % had improved seizure control, 90 % had improved cognitive function, 36 % stopped medication, and 63 % tapered medication. Language improved in 83 % of patients with dominant disease. These findings were not associated with age at treatment. All surgical patients were ambulatory at last follow-up.

CONCLUSIONS

Hemispherotomy achieves good seizure control with cognitive improvement and ambulatory status post-operatively. Time to surgery and dominant disease were not associated with outcome, suggesting that hemispherotomy can be offered early or late, with expectations of good seizure control and functional outcome, even with dominant disease.

Pediatric epilepsy surgery

Medically refractory epilepsy is a significant cause of morbidity and mortality in pediatric neurology. Surgical intervention has been well established as a viable treatment option in certain cases. This article reviews the process of selecting appropriate patients using the latest advances in neuroimaging and electrophysiologic techniques. It also discusses the various surgical techniques currently available, including recent advances in minimally invasive approaches.