THE VARIANTS OF READING EPILEPSY - A CLINICAL AND VIDEO-EEG STUDY OF 17 PATIENTS WITH READING-INDUCED SEIZURES

We present the clinical and electrographic data of 17 patients with re ading-induced seizures documented with ictal video-EEG studies during provocation with language related tasks. The median age at onset was 1 5 years (range 11-22 years) and the male:female ratio was 2.4. Fourtee n patients had no spontaneous seizures of any type while the remaining three had infrequent generalized tonic-clonic seizures during nocturn al sleep. Two distinct electroclinical ictal patterns were confirmed o n video-EEG analysis, (i) Fifteen patients had reading-induced jerks w hich invariably involved the region of the jaw but also included the u pper limbs in five of them, Ictal EEG discharges were noted in 12 pati ents; these were brief but varied in terms of morphology and spatial d istribution, with a clear tendency for left-sided predominance. All bu t one of these patients had similar myoclonic seizures induced by ling uistic activities other than reading, the phenomenon probably justifyi ng the term 'language-induced epilepsy'. Some patients had evidence of transient cognitive impairment associated with the reading-induced ja w or limb jerks, Three patients had a sibling with reading epilepsy bu t there was no other family history of epileptic seizures. (ii) Two pa tients had reading-provoked paroxysmal alexia without motor symptoms, associated with prolonged focal ictal EEG abnormalities. Reading provo ked a subclinical, continuous and reproducible EEG activation over the left posterior temporal area, We propose that ictogenesis in reading or language-induced epilepsy is based on the reflex activation of hype rexcitable network that subserves the function of speech and extends o ver multiple cerebral areas on both hemispheres. The parts of this net work responding to the stimulus may, secondarily, drive the relative m otor areas producing the typical regional myoclonus, This network hype rexcitability can be genetically determined and its clinical expressio n is age-related.