Stimulus-induced reflex epileptic spasms in 5p- syndrome

Here we describe two patients with 5p- syndrome who suffered from epilepsy characterised by stimulus-induced epileptic spasms manifesting as head nodding. In patient 1, a series of spasms were exclusively triggered by eating, and were associated with diffuse high-voltage slow waves on ictal EEG, particularly presenting as a positive slow potential at the left mid-temporal area. Clusters of sharp waves with negative polarity emerged in the same area during the inter-spasm periods during eating. In patient 2, spasms were provoked by either eating or micturition. Ictal EEG of clustered spasms after micturition showed positive slow or triphasic waves, which correlated with each spasm, over the bifrontal and vertex areas. These findings suggest that the focal cortical areas act as trigger regions in reflex epilepsies, and that a spasm-generator responsible for the execution of reflex spasms exists either in other cortical areas or in the subcortical structures. Although epilepsy is an unusual complication of 5p- syndrome, this syndrome may have a propensity to develop reflex epilepsy, particularly epileptic spasms. However, identification of responsible genes and their roles in this phenotype requires further investigations.