Reflex seizures are frequent in patients with Down syndrome and epilepsy

In a retrospective study of 30 Down syndrome (DS) patients with epilepsy, we found 6 cases (20%) with reflex seizures. One patient had benign myoclonic epilepsy of infancy with clinical photosensitivity. The other 5 cases had all startle-induced epileptic seizures and a form of symptomatic epilepsy. Three patients had a Lenox-Gastaut syndrome, one had generalized symptomatic epilepsy, and one had partial symptomatic epilepsy (PSE). Reflex epilepsy was also used as a classification category in the PSE case, as most or all seizures were stimulus-related in this patient. Seizures precipitated by stimuli were stereotyped in 4 patients, but 2 patients responded to stimuli with different types of seizures. The actual occurrence of reflex seizures in DS patients with epilepsy is probably underestimated. These cases seem to confirm previous reports showing deficiencies in cortical inhibition in the brain of DS patients.