Abstracts

Rationale: Infantile spasms (IS) is a rare epileptic encephalopathy, characterized by epileptic spasms, hypsarrhythmia, and developmental regression. Early treatment with adrenocorticotrophic hormone, prednisolone, or vigabatrin is associated with improved neurodevelopmental outcomes. However outcomes remain poor, particularly in symptomatic cases.

This is a retrospective case series of children with IS who underwent epilepsy surgery at The Hospital for Sick Children (HSC) in Toronto, Canada. The primary outcomes of this study were seizure freedom and developmental outcomes. The secondary outcomes were timing of surgery, type of MRI lesion, and type of surgery.

Methods: The records of 223 patients were reviewed. Patients were included if they were < 18 years of age with a current/previous history of IS and a lesion detected on MRI who underwent epilepsy surgery. All patients underwent pre-surgical evaluation, including history and physical examination, EEG, MRI brain, neurodevelopmental assessment, and discussion in epilepsy surgery conference. Selected patients underwent PET or MEG scans.

Results: Nineteen patients met inclusion criteria. The etiology of IS was malformations of cortical development in 11 patients, encephalomalacia in six patients, atypical hypoglycaemic injury in one patient, and partial hemimegalencephaly in one patient. The age at the onset of IS ranged from four to eight months with a median of five months. Time between onset of spasms and initiation of medical treatment was less than one month in 18 patients and nine months in one patient. The number of anti-seizure medications (ASM) used prior to surgery ranged from one to five with a median of three.

All patients had focal ictal or interictal features that were ipsilateral or localizable to their MRI lesion on EEG. Five patients (26%) had focal activity that was both ipsilateral and contralateral to their MRI lesion.

Age at surgery ranged from two to 61 months with a median of 18 months. The duration of epilepsy prior to surgery ranged from two to 58 months with a median of 13 months. Nine patients underwent hemispherectomy and 10 patients underwent lobectomy/lesionectomy.

At the most recent follow-up visit, 15 patients (79%) were considered ILAE Seizure Outcome Class 1 (completely seizure free), three patients (16%) were considered Class 4, and one patient (5%) was considered Class 5. The number of ASM ranged from zero to five with a median of two. Developmental outcome was improved in 14 patients (74%) and stable in 5 patients (26%).

Conclusions: A generalized EEG pattern, such as hypsarrhythmia, should not be a contraindication for epilepsy surgery. A subset of patients with symptomatic IS are surgical candidates who can have good developmental outcomes and seizure freedom rates. Patients with encephalomalacia tend to have better seizure freedom and developmental outcomes than patients with cortical malformations, who are more likely to require repeat surgical resection. Patients should be referred for surgical assessment early. Early surgical intervention shortens the duration of active epilepsy, thus limiting the potentially irreversible effects of on-going seizures and ASM on brain development.

Funding: Please list any funding that was received in support of this abstract.: N/A.