Abstracts

Isolated thalamic lesions have been recently described in symptomatic continuous spike and waves during sleep syndrome (CSWS). Disturbances of thalamo-cortical networks could be involved in this epilepsy. CSWS is characterized by severe cognitive deterioration related to a major diffusion and synchronisation of focal spike and waves. In order to investigate the thalamic involvement in this syndrome, we performed a morphological and metabolic exploration of this region, during interictal state in symptomatic or cryptogenic CSWS.
A spectroscopic MRI was performed in 10 children affected by symptomatic (4/10) or cryptogenic (6/10) CSWS. The epilepsy was still active, but 8/10 patients were seizure-free since more than 6 months. Their median age was 8.3 year.
Spectroscopy showed an abnormal lactate presence in the thalamic region, in 7/10 children during interictal state. Morphological thalamic abnormalities were found in 5/10 children (3/4 symptomatic and 2/6 cryptogenic cases). A further volumetric analysis will be performed in order to evaluate more subtle anatomical changes of the thalamus .
Focal thalamic lactate presence, during a seizure-free period, confirms the existence of a permanent active metabolic abnormality during [quot]interictal[quot] state in CSWS. This metabolic dysfunction is probably related to EEG abnormalities and cognitive symptoms. The presence of morphological thalamic malformations, often isolated and unnoticed on previous MRI, argue about its implication in CSWS, besides the focal cortical dysfunction previously demonstrated.