The evoked epilepsies.

Epileptic activity may be strongly influenced by events occurring outside the central nervous system. At least 6% of recurrent seizures are evoked by specific afferent stimuli, and these are reviewed. The commonest environmental stimulus is light; photosensitive epilepsy occurs not only in humans but also in the baboon (Papio papio). Recognition and hence avoidance of factors which evoke seizures is an important part of the management of the epilepsies.