Photosensitive epilepsy
-Jeavons Syndrome (JS) – rare genetic occipital epilepsy found PPR up to 90% - seizures that are often triggered by
eye closure, characterized by eyelid myoclonia, upward jerking of the eyelids, and may present with absence
behavior.
Response/Artifact Source EEG Appearance Localization Clinical Relevance
Photic Driving Cortical:
physiologic
Temporal relationship w
stimulus frequency:
Harmonic – 2x of flash strobe/
, Subharmonic- ½ of fs
-Stop when flash stop
Occipital -Most drive at alpha 8-13 Hz
- No photic driving can be normal esp. in
older > 50, drowsy
- Asymmetrical responses are likely
abnormal but need to consider
asymmetrical light exposure.
-Absent on one side is abnormal
(Banquad)
Photoparoxysmal
(PPR)
Cortical
: Epileptic
-Spikes, polyspikes, spike-wave
-no temporal relation to
flashing
-May persist after flash stop
Occipital,
parietal, frontal,
generalized
(waltz I, II, III, IV)
Photosensitive epilepsy (mostly genetic) *
Barbiturate/Alcohol withdrawal
most in 10 s of 15-25 Hz flashing strobe
Stop flashing if a clinical seizure
Photomyogenic
(PMR)/Photomyoclonic
and
Electroretinogram
(ERG)
Frontalis muscle
Retinal
High-frequency spikes
Low-amplitude waves
Frontal Involuntary frontal muscle response
Normal retinal response
Photoelectric Artifact Electrodes that
have poor
impedance
Rhythmic signal at IPS
frequency
Single channel Test by covering the suspected
electrode/fixing the electrode
