Abstracts

Rationale: Corpus callosotomy (CC) is a palliative surgery performed to disrupt the bilateral synchrony of epileptiform discharges in epileptic subjects. This study aimed to determine seizure outcome of children with intractable epilepsy who underwent CC at Children's Hospital of Michigan (CHM) between 2000 and 2015. Specifically, we determined the efficacy of CC on several seizure types. Methods: A total of 22 children underwent CC at CHM. Clinical history, electroencephalography (EEG), neuroimaging and surgical outcome were assessed. Results: The mean age at surgery was 11.4 years (range 3 to 19 years) and the mean age of seizure onset was 4.3 years (range 2 weeks to 11 years). Fourteen were males. The etiology of epilepsy was unknown in 10; 8 had structural lesions and 4 had genetic etiologies. All had disabling drop attacks and all except one had multiple seizure types including atonic, tonic, myoclonic, atypical absence and generalized tonic clonic seizures (GTC). Two had non-lateralizing focal seizures that rapidly generalized. Seventeen patients satisfied the clinical and EEG criteria for the diagnosis of Lennox-Gastaut Syndrome (LGS). Nine had active vagus nerve stimulator (VNS) devices in place. Sixteen had complete CC, four had anterior 2/3 CC and two had anterior 2/3 followed later by total CC. Endoscopic CC was performed in 11 patients; 2 of these had a posterior approach. Seizure outcome was available in 20 patients with follow up period of 6 months to 10 years. All twenty had reduction in drop seizure frequency, including nine (45%) who became drop seizure-free (one of these has been successfully weaned of seizure medication). Drop seizure reduction of at least 90% in 2 and 75% in another 2 were noted and the remaining 7 had at least 50% reduction of drop seizures. Furthermore, 2 became GTC seizure-free and 1 had 90% reduction, one had 75% reduction and two had 50% reduction. Among the 19 patients with staring seizures (due to either atypical absence and/or complex partial seizures), only one had 90% reduction, three had at least 50% reduction and the rest showed no benefit from CC for these seizures. One child developed a new type of partial seizure. Complications were noted in 3 including transient reduction in speech, unilateral upper extremity weakness and unsteadiness. One patient with SCN1A mutation became non-ambulatory following CC. Conclusions: CC is an effective treatment for disabling drop seizures in children and may provide drop-seizure freedom in up to 45% of cases. CC can also reduce the frequency of GTC seizures, but is not as effective in atypical absence and complex partial seizures. Complications are transient in most cases. Funding: none