Prevalence of a photoparoxysmal response in the electroencephalograms of epileptics in the three main ethnic groups of Namibia.

This descriptive study consists of 1493 EEGs from patients with epilepsy referred to the State Hospital in Windhoek, over the years 1983-1988. Excluded were patients with febrile convulsions, acute symptomatic epilepsy and a history of alcoholism. A standardized procedure of intermittent photic stimulation (IPS) was performed. The three main population groups blacks, coloureds (people of mixed race) and whites, were adequately represented in the sample. Classical photoparoxysmal responses (PPR) occurred in 0.4, 4.2 and 5.2%, respectively. Climatic factors are not considered relevant in the elicitation of a PPR. It is postulated that different mutations occurred in the genes that were involved in the expression of the PPR in epileptic patients of different ethnic groups.