Chapter 96 - How reflex mechanisms cause epilepsy

Summary

Reflex seizures were known long before the advent of the electroencephalogram (EEG), particularly with visual stimuli. Most clinical attention was devoted to epileptic sensitivity to unpatterned intermittent white light flash stimulation delivered by a stroboscope in the EEG laboratory and to the closely related problem of seizures triggered by environmental visual stimulation. Several reflex stimuli which are subserved by localized cortical areas or by functional networks can cause clinically bilateral or generalized EEG paroxysmal activity, often in patients with underlying idiopathic generalized epileptic syndromes. Praxis induction and seizures induced by thinking appear almost exclusively in idiopathic generalized epilepsies and particularly in juvenile myoclonic epilepsy (JME), although seizures induced by thinking can occur with no motor component in the stimulus or the response. Functional magnetic resonance imaging (MRI) has shown the distribution of cortical networks activated by many mental activities in normal controls and also in patients with reflex seizures.