Intermittent photic stimulation

Intermittent photic stimulation (IPS) is a procedure performed in the EEG laboratory to detect abnormal sensitivity to light stimuli (i.e., photosensitivity), thus providing information on seizure susceptibility of the individual exposed to intermittent lights. More specific purposes would include quantifying the degree of photosensitivity and relating this phenomenon to definite epileptic syndromes.

The effectiveness of IPS is indicated by the capability of inducing an abnormal EEG response in the highest number of patients in whom visual stimulation can potentially precipitate a seizure, reducing to a minimum the chance of obtaining such responses in normal subjects. Methodologic aspects are crucial when assessing photosensitivity in laboratory conditions.

Unfortunately, no agreement on IPS procedure exists; therefore, considerably different protocols and photic stimulators are used, rendering difficult the evaluation and comparison of IPS effects across laboratories[1]. In recent years, efforts have been made to standardize the methods and interpretation of the results of IPS[2][3][4].


1. a Rubboli G, Salvi F. Neurophysiological investigations in photosensitive epilepsies: methodological considerations and critical reappraisal. In: Andermann F, Beaumanoir A, Mira A, eds. Occipital seizures and epilepsies in children. London : John Libbey, 1993: 145–50.
2. a Trenité DG, Binnie CD, Harding GF, Wilkins A, Covanis T, Eeg-Olofsson O, Goosens L, Henriksen O, Krämer G, Leyten F, Da Silva FH, Da Silva AM, Naquet R, Pedersen B, Ricci S, Rubboli G, Spekreijse H, Waltz S. Medical technology assessment photic stimulation--standardization of screening methods. Neurophysiol Clin. 1999 Sep;29(4):318-24. doi: 10.1016/s0987-7053(99)90045-x.
[PMID: 10546250] [DOI: 10.1016/s0987-7053(99)90045-x]
3. a Kasteleijn-Nolst Trenité DG, Binnie CD, Harding GF, Wilkins A. Photic stimulation: standardization of screening methods. Epilepsia. 1999;40 Suppl 4:75-9. doi: 10.1111/j.1528-1157.1999.tb00911.x.
[PMID: 10487178] [DOI: 10.1111/j.1528-1157.1999.tb00911.x]
4. a Kasteleijn-Nolst Trenité DG, Guerrini R, Binnie CD, Genton P. Visual sensitivity and epilepsy: a proposed terminology and classification for clinical and EEG phenomenology. Epilepsia. 2001 May;42(5):692-701. doi: 10.1046/j.1528-1157.2001.30600.x.
[PMID: 11380581] [DOI: 10.1046/j.1528-1157.2001.30600.x]
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