Proven startle-provoked epileptic seizures in childhood: semiologic and electrophysiologic variability

To delineate further the clinical and electrophysiologic features of proven startle-provoked epileptic seizures (SPESs) in children.

Clinical, neuroradiologic, and neurophysiologic data of 22 consecutive patients with SPESs were analyzed. Eighty-nine SPESs were documented by video-EEG and evaluated with respect to semiology and ictal and interictal EEG findings.

Mean age was 68 months (10-178 months). Most children had severe mental retardation (86%). Neuroimaging demonstrated diffuse cerebral abnormalities in 15 of 19. Somatosensory evoked potentials revealed cortical abnormalities in 10 of 13 children. The underlying causes were heterogeneous. Only two patients were normally developed. Seizure frequency was usually high (>10/day). Two children had less frequent SPESs (two per month; two per week). Seizures were easily precipitated by sudden sound (n=15), unexpected touch (n=3), or both (n=4). The most common semiologic findings (50%) were generalized tonic seizures or those characterized by a predominant tonic phase, followed in frequency by myoclonic seizures (36%), which were generalized in seven, and unilateral in one. Generalized clonic seizures were observed in one. A complex seizure spread was documented in two children. The most common ictal EEG finding (60%) was a diffuse electrodecremental pattern (DEP). Generalized spike/polyspike waves were found in five and focal discharges in four.

Our results imply that startle epilepsy is not a uniform epileptic entity. We were able to demonstrate a number of distinct patterns of SPESs, characterized by clinical, semiologic, and electrophysiologic features. Considering the high diversity of SPES patients, a common underlying pathophysiologic mechanism seems unlikely.