Brain, Vol 121, Issue 10 1937-1949, Copyright © 1998 by Oxford University Press
WT Blume
This report documents clinical and EEG features of 13 patients whose most
frequent EEG abnormality was unilateral interictal spike-waves that
occurred consistently over the same hemisphere on multiple recordings.
These 13 patients were selected from a 25000-patient database encompassing
25 years. The hemisphere involved was the left in 8 (62%) of the 13
patients. Bisynchronous spike-waves also appeared on a majority of
recordings in 10 (77%) patients. Focal spikes occurred in a majority of
recordings in 7 (54%) patients; these usually predominated in the frontal
or frontal temporal regions and were always ipsilateral to hemispheric
spike-waves. Their field distribution often merged with regional or
hemispheric spike-waves. EEG evidence of ictal origin ipsilateral to
hemispheric spike-waves appeared in 7 of 8 patients whose seizures were
recorded; ictal potentials never predominated contralaterally. All patients
had seizure disorders beginning in childhood or adolescence. Eleven (85%)
had more than one type of seizure. Principal ictal types contained no focal
phenomena in 10 (77%) patients. Bilateral motor seizures were tonic-clonic
(12 patients), myoclonic (3), tonic (3) and atonic (1). Absence-like
attacks occurred in 10 patients: only staring, automatisms and loss of
awareness occurred in 6, with aurae in 3, and with motor phenomena in 3.
Features of some seizures in 9 patients (69%) suggested a focal or
unilateral origin or involvement, but these consistently occurred
contralaterally to principal spike-waves in only 4 patients. At a median
follow-up of 19 years, 11 patients (85 %) continued to have seizures; the 2
seizure-free patients required two anti-epileptic drugs each. History,
neurological examination and neuro-imaging failed to disclose an aetiology
or structural lesion in any patient. Eleven patients (85%) had normal
intelligence. This newly documented syndrome of hemispheric epilepsy
therefore comprises four components: (i) diffuse unilateral spike-waves on
EEG which consistently appear over the same hemisphere in a given patient;
(ii) a persistent, usually intractable seizure disorder with generalized
ictal features in all patients and focal in most; (iii) onset of seizures
in childhood or adolescence; and (iv) no apparent aetiology or related
structural abnormality of the CNS.
ARTICLES
Hemispheric epilepsy
London Health Sciences Centre-University Campus, The University of Western Ontario, Canada.
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