Genetic Association with Ictal Cardiorespiratory Phenomena: SCN8A Case Series

Abstract

Increased availability of genetic testing has led to identification of expanding SCN8A phenotypic spectrum ranging from early-infantile epileptic encephalopathy (EIEE) to developmental and cognitive disabilities, movement disorders, and a possible high incidence of sudden unexplained death in epilepsy patients (SUDEP). Children with SCN8A mutations may also have dysfunction of cardiac voltage gated sodium channels, resulting in ictal cardiac symptoms with associated respiratory distress. We report a case series of two patients with de novo SCN8A mutation. These patients presented with recurrent tonic seizures at 4 and 6 months of age, along with ictal bradycardia and asystole respectively. Interictally both patients had normal EEG and cardiac evaluation. The antiepileptic drug treatment choice was made prior to known genetic abnormality, with resultant decrease in seizure frequency and severity of cardiorespiratory symptoms in both patients. The association of SCN8A mutation–related rare epilepsy with ictal cardiac symptoms has not been well described in the literature. The association of ictal cardiac phenomena with this mutation is important in patient treatment, family education, and risk of complications such as SUDEP. The role of SCN8A in the mechanism of SUDEP requires future studies.

Keywords

sodium channel mutation - ictal bradycardia/asystole - SUDEP - SCN8A - epileptic encephalopathy

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