SQUARE-WAVE JERKS AND SQUARE-WAVE OSCILLATIONS - TREATMENT WITH VALPROIC ACID

Experimental studies in monkeys have demonstrated that injection of ga mma-aminobutyric acid (GABA) agonists into the superior colliculus res tricts saccadic eye movements, while injection of GABA antagonists lea ds to square-wave jerks (SWJ). To investigate the role of GABA in sacc adic interruptions of fixation, we treated five patients who had SWJ a nd square-wave oscillations (SWO) with valproic acid (VPA) (2000 mg/d) , which has been shown to increase brain GABA levels. VPA effectively reduced the SWJ/SWO in three patients, abolished them in one patient, but was ineffective in the fifth, who had a localized lesion in the ce rebellar vermis. VPA effects may have been due to the restoration of t he GABAergic tonic inhibitory action from the substantia nigra pars re ticulata to the superior colliculus.