Seizure Outcome after Anterior versus Complete Corpus Callosotomy in Children: A Systematic Review with Meta-Analysis / Controle das crises epilépticas após calosotomia anterior versus completa em crianças: uma revisão sistemática com metanálise

Introduction Refractory epilepsy is a debilitating and challenging condition to manage. Corpus callosotomy (CC) seems to be an effective treatment option for patients with seizures not amenable to focal resection. The aim of the present study is to compare seizure outcome of pediatric patients following anterior CC, compared with complete CC. Method The authors performed a systematic review and meta-analysis of the English literature involving comparative studies. Results The present investigation includes four retrospective case-controlled studies and authors perform a pooled analysis of the surgical results. Seizure outcome presented favorable results in patients who underwent complete CC (Odds Ratio, M-H, Fixed, 95% CI: 3.02 [1.43, 6.387], p-value: 0.005). Clinical and neurological complications occurred independently when a complete or anterior CC was performed. Conclusion Complete CC seems to be the most effective treatment option to control intractable seizure in children not amenable to focal resection.

Introdução Epilepsia refratária é uma condição debilitante e desaadora para lidar. Calosotomia parece ser uma opção de tratamento ecaz para pacientes com convulsões não passíveis de ressecção focal. O objetivo do presente estudo é comparar o resultado de convulsões em pacientes pediátricos de acordo com calosotomia anterior e completa. Métodos Uma revisão sistemática e metanálise da literatura médica em inglês envolvendo estudos comparativos. Resultados Quatro casos retrospectivos foram incluídos na presente investigação e uma análise dos resultados cirúrgicos foi realizada. Convulsões decorrentes tiveram resultados favoráveis em pacientes submetidos a calosotomia complete (odds ratio, M-H, xo, 95% IC: 3,02 [1,43; 6,387], valor de p: 0,005). Complicações clínicas e neurológicas ocorreram independentemente de se calosotomia complete ou anterior. Conclusão Calosotomia completa parece ser a opção de tratamento mais ecaz para controlar convulsões não rastreáveis e não passíveis de ressecção focal em crianças.

Corpus Callosotomy in Lennox-Gastaut Syndrome / 대한간질학회지

PURPOSE: Lennox-Gastaut syndrome (LGS) is one of the most devastating pediatric epileptic syndromes characterized by various disabling seizures, generalized forms of abnormal epileptiform EEG features and progressive psychomotor retardation. Corpus callosotomy is one of treatment options in patients with intractable LGS without definitive focal cortical pathology. This study was designed to evaluate efficacy and safety of corpus callosotomy in patients with LGS. PATIENTS AND METHODS: Thirty patients (21 boys, 9 girls) with LGS who had corpus callosotomy at Severance Children's Hospital from October 2003 to January 2007, were enrolled with mean follow-up of 34.6+/-14.0 months. We retrospectively reviewed medical records, video-EEG monitoring, MRI, seizure outcome and postoperative complications. RESULTS: Mean age of corpus callosotomy was 100.7+/-56.4 months. Twenty-four patient (80.0%) underwent total corpus callosotomy and 6 (20.0%) underwent resection of the anterior 4/5 of corpus callosum. Seizure outcomes were as follows: 5 patients (16.7%) were Engel class I, 9 (30.0%) were class II, 6 (20.0%) were class III and 10 (33.3%) were class IV. Postoperative complications were seen in 4 patients (13.3%), such as hemorrhage (2 patients), involuntary movement (1 patient) and transient ataxia (1 patient), but all were recovered completely. Subsequent resective surgery was performed in 5 patients of Engel class III and IV, whose EEG features became lateralized without complete seizure control. Satisfactory surgical outcomes (class I and II) were achieved in 46.7% of total patients. CONCLUSIONS: Corpus callosotomy could be effective and safe treatment in medically intractable LGS without focal pathology.

Calosotomia em paciente com epilepsia generalizada primária e crises tônico-clônicas generalizadas refratárias: relato de caso / Callosotomy in patients with primary generalized epilepsy and generalized tonic-clonic seizures: case report

INTRODUÇÃO: Pacientes com epilepsia generalizada primária (idiopática) podem, raramente, não responder ao tratamento medicamentoso e assim apresentar crises tônico-clônicas generalizadas (CTCG) recorrentes, incapacitantes e que colocam o paciente em risco de complicações graves. OBJETIVO: Nesse artigo é relatado o caso de um paciente com epilepsia generalizada primária e CTCG semanais, refratárias a diversos esquemas medicamentosos, que foi submetido a uma calosotomia. RESULTADO: No curto espaço de 3 meses de seguimento pós-operatório, o paciente não mais apresentou CTCG. CONCLUSÃO: A calosotomia pode ser um procedimento útil na redução da freqüência de CTCG refratárias, mesmo em pacientes com epilepsia generalizada primária.

INTRODUCTION: Patients with idiophatic generalized epilepsy (IGE) may occasionally have frequent generalized tonic-clonic seizures (GTCS) which are not adequantely controlled by antiepileptic drugs. Frequent GTCS pose a significant risk of injury and other complications. In symptomatic generalized epilepsies, corpus callosotomy (CC) has been shown to be effective in reducing the number of generalized seizures. OBJECTIVE: We report a patient with refractory, weekly GTCS in the context of a primary generalized epilepsy syndrome who underwent subtotal CC. RESULT: In the 3 months since operation, no GTCS occurred. CONCLUSION: Corpus callosotomy can be helpful in reducing medically-refractory GTCS, even in patients with primary generalized epilepsies.

Epilepsy Surgery II

Epilepsy surgery is classified into two types: curative epilepsy surgery and palliative surgery. The most frequently performed curative epilepsy surgery is an anterior temporal lobectomy with amygdalohippocampectomy (ATL with AH). ATL with AH includes the resection of epileptic hippocampus/amygdala and anterior temporal lobe (3~4cm from temporal pole) and is performed for treating drug refractory mesial temporal lobe epilepsy. A literature reports that more resection of epileptic hippocampus had a better surgical outcome. However, a surgery should be planned to prevent or minimize a postsurgical memory decline especially in resection of a dominant temporal lobe. Cortisectomy is a resection of localized epileptic focus in patients with neocortical epilepsy such as frontal, parietal, occipital, and lateral temporal lobe epilepsies. Most of neocortical epilepsy patients need an intracranial electrode implantation for determination of resection margin and a brain stimulation on intracranial electrodes for functional mapping. For a successful cortisectomy, an epilepsy surgery team should have a good amount of knowledge and experiences in intracranial EEG monitoring for intractable epilepsy patients. It is very important to place the intracranial electrodes at a brain region where epileptic focus is located because a wrong placement of intracranial electrodes results in failure of surgery. The surgical principles of functional hemispherectomy (FH) aim at disconnecting the hemisphere while leaving as much of the ipsilateral brain as possible intracranially; it has been characterized as anatomically subtotal but physiologically complete hemispherectomy. The original technique consists of a large central tissue removal, complete callosotomy, frontal and parieto-occipital disconnection, temporal lobectomy and insular corticectomy. The candidates of FH are drug refractory partial epilepsy patients who have unilateral epileptic focus and severe brain damage in ipsilateral hemisphere with loss of finger movements of contralateral hand. Corpus callosotomy is a surgical technique severing the corpus callosum so that communication between the cerebral hemispheres is interrupted. In contrast with lobectomy, corpus callosotomy does not involve removing any brain tissue. Instead, it usually involves cutting the front two-thirds of this bundle (anterior callosotomy). Sometimes the other one-third is cut later (complete callosotomy). Corpus callosotomy is most effective for atonic seizures ("drop attacks"), less effective for tonic-clonic seizures and tonic seizures. Additionally, multiple subpial transection and neurostimulation techniques are described.

Epilepsy Surgery I

Epilepsy is a chronic neurological disorder manifesting recurrent unprovoked epileptic seizures. About 20~30% of epilepsy patients are resistant to antiepileptic medications. These patients suffer from high risk of physical injury, unemployment, marital problem, and psychological stress. Epilepsy surgery is the firstly recommended treatment modality for the patients with medically intractable epilepsy. Presurgical evaluation is the most important process for performing epilepsy surgery. The ultimate goal of the presurgical evaluation in patients with medically refractory partial seizures is the localization of the epileptogenic zone and the resection of which is also both necessary and sufficient to render the patient seizure-free. The localization of the epileptogenic zone derives from a hierarchical synthesis of localizing data independently obtained from clinical, electrographic, neuroimaging, and neuropsychological examination. In addition, closely related to the goal of localizing the epileptogenic zone is the significant need for anticipating the risks of functional deficits that could derive from the surgical resection. Mesial temporal lobe epilepsy (TLE) is the best candidate for epilepsy surgery. Anterior temporal lobectomy with amygdalohippocampectomy is a surgical treatment method for mesial TLE and its seizure-free rate (SFR) is 60~90%, whereas one-year SFR of antiepileptic drug treatment for mesial TLE is 10~20%. Cortisectomy is a surgical method for extratemporal epilepsy and its SFR is about 40~70%. Corpus callosotomy is a partial or complete division of corpus callosum for preventing seizure propagations between right and left hemispheres and is effective for controlling atonic seizures. The variation of postsurgical seizure outcomes is related to the qualities of epilepsy surgery program, presurgical evaluation and surgical techniques. For the good surgical outcome, the epilepsy surgery program should include neurologist, neurosurgeon, neuropsychologist, neuro-radiologist and neuro-nuclear medicine specialist for a comprehensive team approach.

Corpus Callosotomy for Intractable Epilepsy in Children: Seizure Outcome and Prognostic Factors / 대한간질학회지

PURPOSE: The therapeutic effectiveness of callosotomy in controlling medically intractable epilepsy has been discussed since first case reported. Nevertheless, patient selection, type of seizures and epileptic syndromes are now better determined. We reviewed the outcome of corpus callosotomy in 20 pediatric patients and tried to identify factors associated with good outcome. METHODS: The medical records of all pediatric patients who underwent corpus callosotomy at Asan medical center between 1996 and 2000 were retrospectively analyzed. RESULTS: At the time of last follow-up, four patients(20%) became seizure free, fifteen patients(75%) had significant improvement in seizure control, and two patients(10%) remained unchanged. No significant association was found between seizure outcome and age at operation, or duration of seizure, intracranial pathology, or extent of callosal section. Drop attacks are most likely to be benefited by callosotomy in view of the frequency of seizure. This was followed by generalized tonic-clonic and myoclonic seizures. Complex partial seizures had the worst response. CONCLUSIONS: Corpus callosotomy is valuable for controlling medically intractable generalized seizures in appropriate patients. Overall, drop attacks were one of the most frequent seizure pattern and they were also most likely to be benefited from corpus callosotomy. Though most patients do not become seizure-free after corpus callosotomy, worthwhile palliation of an otherwise intractable illness can be achieved. An analysis of prognostic factors should lead to better selection of patients for surgery.

The Effect of Corpus Callosotomy in the Lithium-Pilocarpine Induced Status Epileptic Rats

Section of the corpus callosum(SCC) is a useful surgical therapy in selected types of epilepsy, i.e., tonic, atonic, and intractable generalized convulsive seizures. The object of this study was to determine effect of SCC on behaviors, electroencephalography(EEG) and Fos expression in the lithium-pilocarpine model of status epilepticus in the rat. A total of 40 Sprague-Dawley rats were used. They were divided into two groups: control and lesioned group, 20 rats for each. The control group had no callosal section and was injected with lithium-pilocarpine. The lesioned group had callosal section before lithium-pilocarpine injection. In each group, ten rats were used for behavior and EEG monitoring and other 10 were used for Fos expression. The results were as follows: 1) In the SCC group, four(40%) rats never developed status epilepticus, among them two(20%) never exhibited any seizure, while all of the control group developed seizure and status epilepticus. None of the SCC animals died until 24 hours after lithium-pilocarpine injection but 70% of the control animals died within 24 hours of status epilepticus. This difference was statistically significant(p<0.05). 2) The mean latency to the first seizure, status epilepticus and periodic epileptiform discharges after lithium-pilocarpine injection were 34.7+/-2.6min, 32.3+/-1.8min and 180.4+/-9.8min, respectively, in the SCC group, while was 21.0+/-2.0min, 58.2+/-6.9min and 215.6+/-7.2min, respectively, in the control group. These latencies were significantly longer than in the control group(p<0.05). 3) There was a massive Fos expression on the cerebral cortex in the control group at 4 hours after lithiumpi-locarpine injection , while it was less in the SCC group. This difference was statistically significant(p<0.05). In conclusion, complete corpus callosotomy had contributed to the protective effect on the development of status epilepticus in the lithium-pilocarpine model which was similar to that observed in humans. And result of Fos expression suggest that Fos immunohistochemisty may be useful in the study of seizure pathways as a metabolic marker in the lithium-pilocarpine model.