Electrophysiological evidence of persisting unilateral auditory cortex dysfunction in the late outcome of Landau and Kleffner syndrome.
OBJECTIVE
In the late outcome of Landau and Kleffner syndrome (LKS), a childhood-acquired epileptic aphasia, most patients show after complete recovery of epilepsy a permanent one-ear extinction on dichotic listening tests contralateral to the temporal cortex previously affected by the epileptic focus. The pathophysiological significance of this dichotic extinction is not yet understood. It may be a consequence of a permanent dysfunction in the auditory system due to epileptic activity during the maturing period of the auditory system. Evoked potentials were used to check this hypothesis and to localize the level of the dysfunction along the auditory pathways.


METHODS
Early, middle latency and late auditory evoked potentials were recorded in 5 right-handed children having recovered from LKS. They were compared with those of 5 control children paired for age and gender.


RESULTS
In all 5 LKS patients, early and middle latency auditory evoked potentials were normal. But the amplitude of N1c (arising from associative auditory areas) was strongly reduced at temporal electrodes contralateral to the extinguished ear, whereas latency and amplitude of N1b (related to primary auditory areas) were in the normal range.


CONCLUSIONS
Unilateral voltage reduction of late auditory evoked potentials over the temporal areas previously involved by epileptic discharges suggests a permanent dysfunction in the associative auditory cortex, the behavioral expression of which is the unilateral dichotic extinction.
Wioland
N
N
Service d'Explorations Fonctionnelles du Système Nerveux, Clinique Neurologique, Hôpitaux Universitaires de Strasbourg, 67091 cedex, Strasbourg, France. norma.wioland@chru-strasbourg.fr
Rudolf
G
G
Metz-Lutz
M N
MN
D000293:Adolescent; D000328:Adult; D001303:Auditory Cortex / Q000503:physiopathology*; D002648:Child; D004594:Electrophysiology; D005072:Evoked Potentials, Auditory; D005260:Female; D006801:Humans; D018887:Landau-Kleffner Syndrome / Q000503:physiopathology*; D008297:Male; D011930:Reaction Time; D012016:Reference Values