Monosynaptic reflexes during generalized spike and wave activity, provoked by intermittent photic stimulation

Achilles tendon (T) and Hoffmann (H) reflexes were evoked during spike and wave activity (SWA) in 6 patients with generalized epilepsy, selected on the basis of their photosensitivity. SWA was provoked by intermittent photic stimulation (IPS). It was demonstrated that monosynaptic reflex amplitudes were larger during SWA than at rest. Although IPS caused by itself a slight increase in amplitudes, there was an obvious difference from the larger increase during SWA. T reflexes showed a more explicit increment than H reflexes. The activity changes in the spinal motor circuits were nearly always present in the absence of any clinical manifestation of motor activity. The possible mechanisms are discussed.