Startle epilepsy associated with infantile hemiplegia (SEIH): video-polygraphic features and long-term outcome

The aim of this study was to investigate the video-polygraphic features and the long-term outcome of epilepsy in two patients with startle epilepsy associated with infantile hemiplegia (SEIH).

Two patients (patient 1: a 14-year-old girl; patient 2: a 17 year-and-half-year-old girl), with hemiparesis and moderate mental retardation, underwent a full clinical and neurophysiological examination with video-polygraphic monitoring and recording of startle-evoked seizures. The follow-up was 9 years from epilepsy onset in patient 1, and 8 years from epilepsy onset in patient 2.

Firstly, video-polygraphic recordings of startle-evoked seizures, triggered by unexpected auditory stimuli, showed tonic asymmetrical postures with ictal EEG characterized by an abrupt and diffuse electrodecremental pattern or a seizure discharge predominant over the vertex and anterior regions controlateral to the posturing limbs. Electromyogram recording showed a prevalent involvement of proximal muscles with a concomitant tachycardia and apnoea. In particular, in patient 1 ictal heart rate was high, with persisting tachycardia for 60-120 s after the end of seizures. Secondly, a high seizure frequency persisted throughout the course of the disease, as seizures were medically refractory to all currently available anti-epileptic drugs.

The long-term outcome of epilepsy in SEIH, with constantly high seizure frequency, suggests an early surgical intervention, avoiding years with unsuccessful drug treatments and poor quality of life.