Photostimulation

Under photostimulation is understood in neurology, especially in Epileptology a provocation method. During EEG recording, the subject is " irritated " with a flickering light in rising and falling again frequency 4-20 Hz. In susceptible individuals can be observed in brain power curve that the surface electrical activity of the brain increasingly synchronized ( so-called " photoparoxysmal reaction "). This is reflected in ever increasing waves of amplitude always shorter wavelength, so-called " steep waves," called by other authors also "hyper synchronous activity " or " epileptiform potentials ".

Methodology

The EEG recording is done, if not already digital only raw data are stored in bipolar longitudinal rows in a darkened EEG room. For 30 seconds, the flashing frequency is increased from 4 to 20 Hz, and again reduced to 4 Hz for the next 30 seconds. Subsequently, each 30 seconds long stimulated with 5, 10, 12, 15 and 20 Hz. Finally, with irregular flashes ( average frequency > 10 Hz) over 80 s is provoked. In a photoparoxysmalen reaction occurs, the provocation should be discontinued immediately, because otherwise, by such photostimulation even a seizure can be triggered.

• The diagnostic method in neurology