Reading epilepsy from the dominant temporo-occipital region.
BACKGROUND
Reading epilepsy is a rare form of epilepsy, classified among idiopathic, age- and localisation-related (partial) epilepsies as a reflex epilepsy syndrome. Seizures usually consist of myoclonic jerks restricted to the jaw. However, distinct ictal features including visual symptoms and paroxysmal a- or dyslexia are described in some patients. The anatomical substrate of ictogenesis in reading epilepsy remains poorly understood.


METHODS
The authors report here the case of a primary reading epilepsy for which ictal semiology was characterised by visual symptoms and dyslexia, investigated by MRI, interictal high-resolution EEG and PET, ictal video-EEG and SPECT. Brain MRI was normal. Interictal high-resolution EEG was performed with 64 scalp channels, a realistic head model and different algorithms to solve the inverse problem.


RESULTS
Interictal source localisations highlighted the left occipito-temporal junction. Interictal PET demonstrated bilateral occipito-temporal hypometabolism with left-sided predominance. Ictal EEG showed a rhythmic discharge in left temporo-parieto-occipital junction channels, with left occipito-temporal predominance. MRI fusion of the coregistered subtraction between ictal and interictal SPECT individualised relative hyperperfusion affecting (a) the left occipito-parietal junction area, (b) the left lateral middle and inferior temporal gyri and (c) the left inferior frontal area.


CONCLUSIONS
Besides reading-induced myoclonic jerks of the jaw, a second variant of reading epilepsy exists with clearly partial seizures manifested by visual symptoms and a- or dyslexia. These seizures originate from the occipito-temporal region of the dominant hemisphere, corresponding to the posterior part of the neural network that underlies the function of reading.
Gavaret
Martine
M
Assistance Publique Hôpitauxde Marseille, Hôpital de la Timone, 264 rue Saint Pierre, Marseille 13005, France. martine.gavaret@ap-hm.fr
Guedj
Eric
E
Koessler
Laurent
L
Trébuchon-Da Fonseca
Agnès
A
Aubert
Sandrine
S
Mundler
Olivier
O
Chauvel
Patrick
P
Bartolomei
Fabrice
F
D000328:Adult; D003545:Cysteine / Q000031:analogs & derivatives; D004410:Dyslexia / Q000209:etiology / Q000523:psychology; D004569:Electroencephalography; D020195:Epilepsy, Reflex / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D009778:Occipital Lobe / Q000503:physiopathology*; D015609:Organotechnetium Compounds; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D013702:Temporal Lobe / Q000503:physiopathology*; D015899:Tomography, Emission-Computed, Single-Photon; D014786:Vision Disorders / Q000209:etiology / Q000523:psychology
D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C059659:technetium Tc 99m bicisate; D003545:Cysteine