Abstracts

Rationale: West syndrome is an epileptic encephalopathy syndrome characterized by infantile spasms (IS), developmental regression and hypsarrhythmia. In this series we review 4 patients who presented to a tertiary care academic center with IS, without hypsarrhythmia and with or without developmental impairment. Methods: A retrospective chart review of 4 children who presented with IS without hypsarrhythmia was performed. Information sought included age at onset of IS, EEG, neuro imaging, genetic and metabolic investigations. Treatments used included antiepileptic medications (AEDs), Adreno Cortico Trophic Hormone (ACTH) and vitamins (folic acid and folinic acid). Outcome measures were response of IS to treatment, developmental status and follow up EEGs. Results: 2 of 4 children were girls. Age at onset of spasms ranged from 1 to 21 months (median age was 3.7 months). 2 children had normal development and 2 were delayed at the time of diagnosis and the developmental profile was unchanged at follow-up. None had other types of seizures prior to onset of IS. None had hypsarrhythmia on EEG. 1 had normal interictal EEG and 3 had either focal spikes or multifocal spikes that did not meet criteria for hypsarrhythmia. Ictal EEG findings consisted of electrodecremental segments (ED) with or without superimposed fast activity in 3. No definitive ictal EEG change was observed in 1 patient. MRI brain was normal in 2 and abnormal in 2 (1 had abnormal signal in the left temporal white matter and the other had cerebellar and brain stem hypoplasia). Genetic and metabolic investigations were unrevealing of etiology. One child was treated with ACTH but IS recurred after ACTH taper and Topiramate (TPM) was added. All of them received TPM as first or second line treatment. 1 child received Vigabatrin as the second AED. 3 of 4 responded well with resolution of IS. Follow up interictal EEG was not significantly different and did not show hypsarrhythmia. Conclusions: 1. IS without hypsarrhytmia may be considered an atypical form of West syndrome, rather than a separate epileptic syndrome. 2. Delayed diagnosis and treatment of IS without hypsarrhythmia could result in poor prognosis for neuro-developmental outcome and epilepsy. 3. Although this series had limited subjects and duration of follow up, this atypical presentation of IS was not a precursor to development of hypsarrhythmia including the child whose IS persisted after treatment initiation. 4. Hypsarrhythmia has been considered a cause of neuro-developmental regression seen in West syndrome. In children with IS who do not have hypsarrhythmia it remains unclear if IS and developmental impairment are symptomatic of an underlying epileptogenic disease that is independent of hypsarrhythmia. A larger patient population and longer follow up would be helpful in improving our understanding of IS without hypsarrhythmia.