Hemispheric epilepsy surgery for hemimegalencephaly: The UCLA experience.

OBJECTIVES: Hemimegalencephaly (HME) is a rare congenital brain malformation presenting predominantly with drug-resistant epilepsy. Hemispheric disconnective surgery is the mainstay of treatment; however, little is known about how postoperative outcomes compare across techniques. Thus we present the largest single-center cohort of patients with HME who underwent epilepsy surgery and characterize outcomes. METHODS: This observational study included patients with HME at University of California Los Angeles (UCLA) from 1984 to 2021. Patients were stratified by surgical intervention: anatomic hemispherectomy (AH), functional hemispherectomy (FH), or less-than-hemispheric resection (LTH). Seizure freedom, functional outcomes, and operative complications were compared across surgical approaches. Regression analysis identified clinical and intraoperative variables that predict seizure outcomes. RESULTS: Of 56 patients, 43 (77%) underwent FH, 8 (14%) underwent AH, 2 (4%) underwent LTH, 1 (2%) underwent unknown hemispherectomy type, and 2 (4%) were managed non-operatively. At median last follow-up of 55 months (interquartile range [IQR] 20-92 months), 24 patients (49%) were seizure-free, 17 (30%) required cerebrospinal fluid (CSF) shunting for hydrocephalus, 9 of 43 (21%) had severe developmental delay, 8 of 38 (21%) were non-verbal, and 15 of 38 (39%) were non-ambulatory. There was one (2%) intraoperative mortality due to exsanguination earlier in this cohort. Of 12 patients (29%) requiring revision surgery, 6 (50%) were seizure-free postoperatively. AH, compared to FH, was not associated with statistically significant improved seizure freedom (hazard ratio [HR] = .48, p = .328), although initial AH trended toward greater odds of seizure freedom (75% vs 46%, p = .272). Younger age at seizure onset (HR = .29, p = .029), lack of epilepsia partialis continua (EPC) (HR = .30, p = .022), and no contralateral seizures on electroencephalography (EEG) (HR = .33, p = .039) independently predicted longer duration of seizure freedom. SIGNIFICANCE: This study helps inform physicians and parents of children who are undergoing surgery for HME by demonstrating that earlier age at seizure onset, absence of EPC, and no contralateral EEG seizures were associated with longer postoperative seizure freedom. At our center, initial AH for HME may provide greater odds of seizure freedom with complications and functional outcomes comparable to those of FH.

Gait is not Affected by Hemispherotomy-Case Report from Two Children.

In children with therapy refractory epilepsy, the functional disconnection of one hemisphere (hemispherotomy) may be considered as a treatment option. The visual field defects and hand function effects associated with the procedure have been extensively studied. However, the effect of the hemispherotomy on gait pattern has thus far only been analyzed qualitatively, and there is limited quantitative data. At the Children's Hospital, we regularly perform standardized quantitative gait analysis studies and care for children with complex epilepsies. During the standard routine of care for two children with structural therapy refractory epilepsy, gait analysis was performed prior to and after hemispherotomy. Both patients had prenatal ischemic brain lesions, had developed severe epilepsy during the first 3 years of life, and were treated with the hemispherotomy at about 7 years of age. Interestingly, one patient did not show any changes in gait pattern, while for the other patient, differences could be observed by means of three-dimensional gait analysis. However, greater deviations to controls postoperatively may also be related to day-to-day variability.

Peri-Insular Hemispherotomy: A Systematic Review and Institutional Experience.

INTRODUCTION: Peri-insular hemispherotomy (PIH) is a hemispheric separation technique under the broader hemispherotomy group, a surgical treatment for patients with intractable epilepsy. Hemispherotomy techniques such as the PIH, vertical parasagittal hemispherotomy (VPH), and modified-lateral hemispherotomy are commonly assessed together, despite significant differences in anatomical approach and patient selection. We aim to describe patient selection, outcomes, and complications of PIH in its own right. METHODS: A systematic review of the literature, in accordance with the Preferred Reporting Items of Systematic Reviews and Meta-Analyses (PRISMA) guidelines, was conducted, with searches of the PubMed and Embase databases. A local series including patients receiving PIH and followed up at the Queensland Children's Hospital between 2014 and 2020 was included. RESULTS: Systematic review of the literature identified 393 patients from 13 eligible studies. Engel class 1 outcomes occurred in 82.4% of patients, while 8.6% developed post-operative hydrocephalus. Hydrocephalus was most common in the youngest patient cohorts. Developmental pathology was present in 114 (40.8%) patients, who had fewer Engel 1 outcomes compared to those with acquired pathology (69.1% vs. 83.7%, p = 0.0167). The local series included 13 patients, 11/13 (84.6%) had Engel class 1 seizure outcomes. Post-operative hydrocephalus occurred in 2 patients (15.4%), and 10/13 (76.9%) patients had worsened neurological deficit. CONCLUSION: PIH delivers Engel 1 outcomes for over 4 in 5 patients selected for this procedure, greater than described in combined hemispherectomy analyses. It is an effective technique in patients with developmental and acquired pathologies, despite general preference of VPH in this patient group. Finally, very young patients may have significant seizure and cognitive benefits from PIH; however, hydrocephalus is most common in this group warranting careful risk-benefit assessment. This review delivers a dedicated PIH outcomes analysis to inform clinical and patient decision-making.

Posterior quadrant disconnection for refractory epilepsy: how I do it.

BACKGROUND: Posterior quadrant disconnection (PQD) is intended to interrupt the propagation of intractable unilateral temporo-parieto-occipital epilepsy. METHOD: An enhanced operative video presents the illustrative case of a total PQD indicated for a 15-year-old boy with Sturge-Weber syndrome suffering from seizure recurrence after a partial PQD. We describe the surgical procedure with emphasis on relevant anatomy and multimodal intraoperative guidance in three steps: (i) parieto-occipital disconnection, (ii) posterior callosotomy, and (iii) temporal disconnection/resection. Pearls and pitfalls of surgical management are discussed. CONCLUSION: PQD is a less invasive surgical option to typical hemispherotomy and hemispherectomy for selected indications of posterior multilobar epilepsy.

[Hemispherotomy in pediatric epilepsy surgery-Surgical, epileptological and functional aspects]. / Hemisphärotomien in der pädiatrischen Epilepsiechirurgie ­ operative, epileptologische und funktionelle Aspekte.

Hemispherotomies represent a major part of surgical interventions for epilepsy in childhood (16-21%). The anatomical resection has been replaced by minimally invasive disconnection techniques with lower perioperative mortality and fewer postoperative complications. Today the procedure is not only carried out from the lateral aspect via the Sylvian fissure/insula but also via a vertical parasagittal approach. Depending on the publication, hemispherotomy leads to freedom from postoperative seizures in 60-90% of patients. Despite changes in the surgical technique, disturbances of the cerebrospinal fluid circulation continue to be the main complication in 5-15% of cases. Hemispheric epileptogenic lesions usually lead to early onset and difficult to treat epilepsy in childhood. These epilepsies are characterized by a high frequency of seizures and propagation of epileptic discharges to the healthy hemisphere. The aim of a hemispherotomy is, in addition to postoperative freedom from seizures, the complete disconnection of the affected hemisphere. When deciding on a hemispherotomy, the expected functional consequences play a major role in addition to epileptological aspects. In the case of deficits already present preoperatively (hemianopia, hemiparesis) or reorganization of functions in the contralesional hemisphere (language), no new deficits are to be expected from the operation. In terms of cognition, a hemispherotomy can improve function by releasing the neuroplastic potential of the healthy hemisphere. In order to keep the negative and often irreversible effects of epilepsy as low as possible and to be able to use as much potential for neuroplasticity of the healthy hemisphere as possible, surgery should be considered as early as possible.

Functional cognitive and language outcomes after cerebral hemispherectomy for hemimegalencephaly.

OBJECTIVE: Hemispheric surgeries are an effective treatment option to control seizures for children with hemimegalencephaly (HME); however, not enough is known about their cognitive outcomes. This study aimed to delineate the cognitive and language outcomes after hemispherectomy for HME and identify the clinical characteristics associated with cognition and language. METHODS: Data came from the Global Pediatric Epilepsy Surgery Registry, a patient-driven web-based registry for epilepsy surgery. We focused on children's functional status, assessed through parent-reports of cognitive and language skills. Parents also reported on their satisfaction with surgery, their child's quality of life, and various demographic, clinical, and surgery characteristics. RESULTS: Parents of 45 children (40% female) participated. Children were aged 2.6 (SD 6.5) months at seizure onset, 10.8 (SD 12.7) months at hemispherectomy, and 8.7 (SD 4.8) years at follow-up, at which point 68% were seizure-free. We found that at follow-up, 43% had average or mildly impaired cognition, 26% could speak age appropriately, and 21% had satisfactory reading skills. A total of 55%, 43%, and 17% of children first babbled, spoke their first words, and started speaking in sentences at an age-appropriate period, respectively. Children who had undergone a right hemisphere resection and those who were older at epilepsy onset were more likely to have better cognitive and language outcomes. SIGNIFICANCE: Children with HME have delayed language milestones and continue to require significant language and literacy support long-term after cerebral hemispherectomy.

Hemispherotomy for Epilepsy: The Procedure Evolution and Outcome.

Hemispherectomy is a unique epilepsy surgery procedure that has undergone significant modification and evolution since Dandy's early description. This procedure is mainly indicated to treat early childhood and infancy medically intractable epilepsy. Various epileptic syndromes have been treated with this procedure, including hemimegalencephaly (HME), Rasmussen's encephalitis, Sturge-Weber syndrome (SWS), perinatal stroke, and hemispheric cortical dysplasia. In terms of seizure reduction, hemispherectomy remains one of the most successful epilepsy surgery procedures. The modification of this procedure over many years has resulted in lower mortality and morbidity rates. HME might increase morbidity and lower the success rate. Future studies should identify the predictors of outcomes based on the pathology and the type of hemispherectomy. Here, based on a literature review, we discuss the evolution of hemispherectomy techniques and their outcomes and complications.

Hemispherotomy for pediatric epilepsy: a systematic review and critical analysis.

PURPOSE: Several variations of functional disconnection surgery have been described for the treatment of lateralized, hemispheric, drug-resistant epilepsy in children. The purpose of this study is to investigate the existing literature regarding patient selection, approach, and outcomes after hemispherotomy. METHODS: A systematic review of the English literature through February 2019 was performed in accordance with the PRISMA statement. The articles were classified by level of evidence and summarized in an evidentiary table. Seizure outcomes, functional outcomes, surgical techniques, complications, and patient selection were critically analyzed. RESULTS: A total of 173 papers were reviewed, of which 37 met criteria of inclusion and exclusion. Thirteen studies were classified as level III evidence, the remaining reached level IV. Vertical and lateral hemispherotomy achieve similar rates of seizure freedom and functional outcomes, though parasagittal and interhemispheric approaches may have shorter operative times and less blood loss. Etiology, bilateral MRI abnormalities, and nonlateralizing EEG did not predict worse seizure or functional outcomes. CONCLUSIONS: Both vertical and lateral hemispherotomy approaches result in durable, reproducible benefits to epilepsy severity and functional status in appropriately selected pediatric patients.

Vertical parasagittal hemispherotomy: a case report of postoperative mesio-temporal seizures via amygdalofugal pathway.

Vertical parasagittal hemispherotomy (VPH) is a well-established surgical treatment which is proposed for children with widespread unilateral onset of intractable epileptic seizures. VPH allows to disconnect from a vertical transventricular approach all white matter fibers of the hemisphere around a central core including the thalamus. We present the case of a girl who underwent VPH for hemimegalencephaly in early infancy. Postoperatively, she developed unexpected seizures of mesio-temporal origin. Stereo-EEG provided arguments for an amygdalar origin. High-resolution MRI with tractography confirmed the presence of the amygdalo-fugal pathway to be responsible of epileptic discharges propagation. She became seizure-free after temporal resection.

Memory outcomes following hemispherectomy in children.

OBJECTIVE: A vast proportion of children with epilepsy exhibit memory impairments. Although numerous studies have examined memory performance following pediatric resective epilepsy surgery, little is known about the memory outcomes following hemispherectomy. The few studies that report on memory performance typically include restricted measures, consist of case reports, or do not report on preoperative performance. Given the current limitations, the aim of this study was to delineate pre- and postoperative memory functioning in youth who underwent a hemispherectomy. METHOD: Participants included patients who had undergone a hemispherectomy at the Hospital for Sick Children, between 1999 and 2016. Standardized neuropsychological assessments of verbal (digit span, word list recall, word pair recall, stories) and visual (faces, dot locations) memory abilities prior to and after surgery were reviewed. A Wilcoxon signed rank test and effect sizes was completed to compare patients' memory performance to population norms and to assess pre- to postoperative difference scores. RESULTS: Thirteen participants were included in the study: five patients completed preoperative assessments only and eight patients completed pre- and postoperative assessments. Preoperatively, patients performed substantially worse relative to population norms as indicated by large effect sizes (r: 0.5-0.9). Postoperatively, effect sizes were large for the majority of the memory tests, demonstrating considerable differences in patients' memory scores over time. When clinically meaningful changes were examined, stable performance was evident on 63% of the memory tasks. CONCLUSION: Overall, the results highlight that youth who are eligible for hemispherectomy demonstrate profound memory deficits prior to surgery. In addition, undergoing hemispherectomy was not necessarily associated with declined memory performance, with the majority of patients showing stable scores.

Minimizing blood loss in hemispherectomy for hemimegalencephaly in low-weight infants: technical note.

INTRODUCTION: Drug-resistant seizures due to hemimegalencephaly in neonates and infants are a unique surgical and anesthesia challenge. While early surgery in these patients may predict a better seizure control, a lower body weight, limited blood volume, and surgical blood loss may make hemispherectomy prohibitive. METHODS: Two infants (weight, 8.7 kg and 3.7 kg) underwent interhemispheric vertical hemispherotomy with endoscope assistance. In the first case, during the lateral disconnection, excessive bleeding prompted the surgeon to coagulate the lenticulostriate arteries at the origin from the middle cerebral artery to reduce bleeding. In the second infant, the lenticulostriate arteries were coagulated before initiating the lateral disconnection. RESULTS: In both infants, the blood loss from lateral dissection was reduced by coagulation of lenticulostriate arteries. CONCLUSION: The authors suggest that early coagulation of the lenticulostriate arteries is a useful strategy to minimize blood loss in low-weight infants undergoing hemispherotomy.

Pediatric functional hemispherectomy: operative techniques and complication avoidance.

Functional hemispherectomy/hemispherotomy is a disconnection procedure for severe medically refractory epilepsy where the seizure foci diffusely localize to one hemisphere. It is an improvement on anatomical hemispherectomy and was first performed by Rasmussen in 1974. Less invasive surgical approaches and refinements have been made to improve seizure freedom and minimize surgical morbidity and complications. Key anatomical structures that are disconnected include the 1) internal capsule and corona radiata, 2) mesial temporal structures, 3) insula, 4) corpus callosum, 5) parietooccipital connection, and 6) frontobasal connection. A stepwise approach is indicated to ensure adequate disconnection and prevent seizure persistence or recurrence. In young pediatric patients, careful patient selection and modern surgical techniques have resulted in > 80% seizure freedom and very good functional outcome. In this report, the authors summarize the history of hemispherectomy and its development and present a graphical guide for this anatomically challenging procedure. The use of the osteoplastic flap to improve outcome and the management of hydrocephalus are discussed.

Multiple hippocampal transections: Post-operative Memory Outcomes and Seizure Control.

OBJECT: Temporal lobectomy with amygdalohippocampectomy is the standard surgical treatment for appropriate candidates with medically-intractable temporal lobe epilepsy. More recently, because of the risk of postoperative language/memory decline in a subset of patients with intact memory, a multiple hippocampal transection (MHT) approach has been proposed to preserve function. METHODS: Studies of MHT reporting both Engel and verbal memory outcome measures were included in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines for reporting of systematic reviews. Data were extracted on verbal memory function pre- and postoperatively, seizure outcome, and demographic factors. A random effects model was used to determine overall verbal memory function after MHT, and a meta-regression model was applied to identify factors associated with outcome. RESULTS: A total of 114 patients across five studies were included. Engel class I seizure outcome across all studies ranged from 64.7% to 94.7%, with 84 of the 114 patients achieving this outcome. Preoperative verbal memory score was most strongly associated with postoperative verbal memory preservation (p = 0.003). Of 59 patients with full verbal memory outcome scores, 86.8% (95% CI [confidence interval]: 77.6%-96%) had complete preservation of verbal memory relative to preoperative functional baseline. CONCLUSION: Multiple hippocampal transection is an evolving surgical technique. Although the present data are limited, the current systematic review suggests that this approach is effective at preserving verbal memory in patients with good baseline function. Although reasonable seizure outcomes have been reported with MHT, comparison to a well-established procedure such as temporal lobectomy and amydalohippocampectomy must be guided by further evidence.

A child with a stroke, drug-refractory epilepsy and congenital heart disease: can a hemispherectomy be safely performed between staged cardiac procedures?

BACKGROUND: The safety of hemispherectomy between staged cardiac procedures is unknown and not previously reported. METHOD: Retrospective review of a case with drug-resistant epilepsy due to stroke following bidirectional cavopulmonary connection (BDCPC). RESULTS: This report describes the first case of a successful pediatric peri-insular functional hemispherectomy in the setting of a BDCPC. A discussion of the complex preoperative planning from both a cardiac and neurological perspective is presented. Considerations regarding hemispherectomy and its effects on the cardiac physiology, and perioperative considerations are emphasized in clinical decision making. CONCLUSIONS: A multidisciplinary approach was critical in this child which led to a successful outcome.

Long term neurocognitive improvement after "late" right hemispherectomy: case report and review of the literature.

OBJECTIVE: To study the long-term neurocognitive changes of a right-handed girl with intractable epilepsy after late right hemispherectomy and compare them with data in the literature. METHOD: The girl was affected by an epileptic encephalopathy associated with right fronto-temporo-parietal polymicrogyria; she was submitted to right hemispherectomy at the age of 5 and examined with cognitive and neuropsychological tests at the age of 17 years. The girl took advantage of neurocognitive rehabilitation for several years; she is currently seizure-free and off therapy. RESULTS: At the end of the follow-up, the full-scale IQ is stable and within the normal range (p = 88). As the discrepancy between verbal IQ (pp = 120) and performance IQ (pp = 71) is significantly high, the girl was subjected to neurocognitive evaluation with the following results: verbal problem solving, verbal short- and long-term memory, and executive functions are within normal range. The most fragile functional areas are visual and spatial reasoning, verbal working memory, short-term visuospatial memory, visual attention, and processing speed, all > 2 SD. The spatial tests, such as coding, matrix reasoning, picture concepts, and arithmetic reasoning (which are favored by other functions such as associative memory and learning ability), are less severely impaired. CONCLUSIONS: These findings show that good conceptual skills and verbal reasoning can compensate for some deficits in visual-perceptual and visuospatial functions.

Extratemporal disconnective procedures for the treatment of epilepsy in children.

Surgical treatment of epilepsy in children often involves brain areas outside the temporal lobe and, therefore, techniques for extratemporal surgery must be included in the armamentarium of epilepsy surgery centers. Nowadays, disconnective procedures are preferable to traditional resective operations because they reduce the rate of complications related to extensive resections while achieving equivalent seizure outcomes. This article describes the practical anatomy and surgical techniques used for temporoparietooccipital (TPO), parietooccipital, and frontal disconnections, as well as the possibility of extending previous lobar disconnections to the whole hemisphere (hemispherotomy).

Surgical treatment for refractory epileptic spasms: The Detroit series.

OBJECTIVE: We reviewed our experience of surgery for epileptic spasms (ES) with or without history of infantile spasms. METHODS: Data were reviewed from 65 (33 male) patients with ES who underwent surgery between 1993 and 2014; palliative cases were excluded. RESULTS: Mean age at surgery was 5.1 (range 0.2-19) years, with mean postsurgical follow-up of 45.3 (6-120) months. Mean number of anticonvulsants used preoperatively was 4.2 (2-8), which decreased to 1.2 (0-4) postoperatively (p < 0.0001). Total hemispherectomy was the most commonly performed surgery (n = 20), followed by subtotal hemispherectomy (n = 17), multilobar resection (n = 13), lobectomy (n = 7), tuberectomy (n = 6), and lobectomy + tuberectomy (n = 2), with International League Against Epilepsy (ILAE) class I outcome in 20, 10, 7, 6, 3, and 0 patients, respectively (total 46/65 (71%); 22 off medication). Shorter duration of epilepsy (p = 0.022) and presence of magnetic resonance imaging (MRI) lesion (p = 0.026) were independently associated with class I outcome. Of 34 patients operated <3 years after seizure onset, 30 (88%) achieved class I outcome. Thirty-seven (79%) of 47 patients with lesional MRI had class-I outcome, whereas 9 (50%) of 18 with normal MRI had class I outcome. Positron emission tomography (PET) scan was abnormal in almost all patients [61 (97%) of 63 with lateralizing/localizing findings in 56 (92%) of 61 patients, thus helping in surgical decision making and guiding subdural grid placements, particularly in patients with nonlesional MRI. Fifteen patients had postoperative complications, mostly minor. SIGNIFICANCE: Curative epilepsy surgery in ES patients, with or without history of infantile spasms, is best accomplished at an early age and in those patients with lesional abnormalities on MRI with electroencephalography (EEG) concordance. Good outcomes can be achieved even when there is no MRI lesion but positive PET localization.

Thalamocortical connectivity is enhanced following functional hemispherotomy for intractable lateralized epilepsy.

Although developmental outcomes may improve following functional hemispherotomy for lateralized, catastrophic childhood epilepsy, the neuronal processes mediating these improvements are unknown. We report the case of a 14-year-old child with neurocognitive impairment who underwent functional hemispherotomy with longitudinal resting-state fMRI. Compared with preoperative fMRI, we report significantly more robust thalamo-default mode network connectivity on postoperative neuroimaging. Furthermore, we show decreased connectivity to nodes within the disconnected hemisphere, providing direct evidence that functional interactions are dependent upon structural connectivity. Since the vascular supply to these nodes remains intact, although they are disconnected from the remainder of the brain, these findings also confirm that blood-oxygen level dependent oscillations are driven primarily by neuronal activity. The current study highlights the importance of thalamocortical interactions in the understanding of neural oscillations and cognitive function, and their impairment in childhood epilepsy.