Abstracts

Rationale:
Intractable epilepsy can develop early in infancy and becomes an indication for surgical treatment, especially in those with hemimegalencephaly and large malformation of cortical development. The effectiveness of surgical treatment in children with drug-resistant focal epilepsy is well known, but most studies have been performed on subjects including school-age children and adolescents. Comprehensive reports on infantile epilepsy surgery are still limited. In this study, we report our experience of infantile epilepsy surgery.
Method:
This study included 75 consecutive patients with intractable epilepsy who underwent first resective surgery in our institution under 3 years of age between 2006 and 2019 and who were followed up for minimum one year post-operatively. The pre-operative clinical information, surgical complications, seizure and developmental outcomes were investigated retrospectively.
Results:
The median age and body weight at the time of surgery was 6 months (1 - 35) and 8.47 kg (4.08 - 15.8). The median age at the onset of epilepsy was 30 days (0 - 830). The etiology of epilepsy included 33 cases of malformation of cortical development, 22 of hemimegalencephaly, and 10 of tumors. The concordance rates of MRI, FDG-PET, interictal and ictal EEG findings to the surgically treated region were 89.3%, 78.7%, 70.7%, and 76.0%, respectively. Hemispherotomy and multi-lobar surgery were performed in 26 and 19 cases respectively. There was no operative mortality. 13 patients (17.3%) required CSF diversion surgery for hydrocephalus or post-operative cyst formation. Seizure free rate at one year after surgery and at the last follow-up were 82.7% and 70.7% (mean follow-up period: 55 months). The number of antiepileptic drugs used was significantly reduced after surgery. 19 patients (25%) were not taking antiepileptic medications at the last follow-up. The mean developmental quotient was 74.2 before surgery, 60.3 at one year after surgery, and 53.4 at the last follow-up.   Multiple logistic regression analysis revealed that body weight was a predictor of CSF diversion surgery (odds ratio = 0.719, p < 0.05) and concordant MRI finding was a predictor of post-operative seizure freedom (odds ratio = 14.1, p < 0.05).
Conclusion:
Epilepsy surgery in early infancy is an effective treatment with a high chance of seizure freedom. Reduction of antiepileptic medication is expected post-operatively. However, major complications requiring CSF diversion surgery are not rare. The influence of the complication on the later developmental outcome should be investigated.
Funding:
:Intramural Research Grant from Neurological and Psychiatric Disorders of National Center of Neurology and Psychiatry, Japan (28-4: Clinical Research for Diagnostic and Therapeutic Innovations in Developmental Disorders)