A stereoelectroencephalographic (SEEG) study of light-induced mesiotemporal epileptic seizures.
OBJECTIVE
This study explored the mechanism of light-induced complex partial seizures by using ictal intracerebral recordings in a patient with refractory epilepsy of the right temporal lobe.


METHODS
Presurgical evaluation of this patient was realized by means of video-EEG recordings, WADA test, magnetic resonance imaging (MRI), F18-deoxyglucose and C11-flumazenil positron emission tomography (PET) interictal neuroimaging data, and stereoelectroencephalographic (SEEG) ictal recordings.


RESULTS
SEEG investigations demonstrated the right mesiotemporal origin of all the patient's seizures. This result was confirmed by a successful right temporal lobectomy. Moreover, SEEG recordings revealed a frequent interictal spiking activity in the right occipital visual cortex that was undetectable on scalp recordings. However, the occipital cortex was not involved at the onset of mesiotemporal ictal discharges and was not hyperresponsive to focal electrical stimulation.


CONCLUSIONS
This study shows that, in spite of interictal occipital spiking, the photosensitivity of mesiotemporal seizures can be observed in both the absence of occipital cortex involvement during ictal discharges and demonstrable hyperexcitability of the occipital cortex to light or direct electrical stimulation.
Isnard
J
J
Functional Neurology and Epileptology Department, Neurological Hospital, Lyon, France.
Guénot
M
M
Fischer
C
C
Mertens
P
P
Sindou
M
M
Mauguière
F
F
D000328:Adult; D001921:Brain / Q000503:physiopathology*; D004558:Electric Stimulation; D004567:Electrodes, Implanted; D004569:Electroencephalography / Q000379:methods*; D017029:Epilepsy, Complex Partial / Q000175:diagnosis* / Q000209:etiology* / Q000503:physiopathology; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008027:Light / Q000009:adverse effects*; D009778:Occipital Lobe / Q000503:physiopathology; D010775:Photic Stimulation / Q000009:adverse effects; D013238:Stereotaxic Techniques; D013702:Temporal Lobe / Q000503:physiopathology / Q000601:surgery; D014743:Videotape Recording; D014793:Visual Cortex / Q000503:physiopathology