EEG observations in a case with thalamic syndrome.

A case of thalamic syndrome of the Déjerine-Roussy type is presented. EEG studies reveal that although bilaterally symmetrical rhythmic activity may be present when the patient is awake, during drowsiness and deeper sleep a marked asymmetry often appears with early disappearance of alpha activity and reduction or abolition of spindles on the side involved. Thalamic integration in the sleep mechanism is briefly discussed.