Dystonia: pallidal or thalamic target?

Abstract

Objective: Determine the e½cacy of bilateral chronic anterior thalamic stimulation in dystonic patients not signi®cantly improved after bilateral Gpi-DBS. Material and Method: 2 patients treated with bilateral Gpi-DBS and showing only modest response underwent bilateral anterior thalamic implantation of stimulating electrodes in the nucleus ventrooralis anterior (VOA: 2 mm anterior to MC, 5 mm superior to AC-PC, 10 mm lateral). Results: Improvement after VOA-DBS was not immediate but followed a silent period of a few weeks in one patient and 5 months in the other. In one patient, wheel-chair bound, the improvement was spectacular with recovery of an harmonious gait and writing, while less dramatic in the other and still ongoing, with loss of dystonic postures of the feet and reduced athetotic movements. Conclusion: Chronic bilateral stimulation of e¨erent pallidal pathways going through the thalamus, speci®cally the VOA, is e¨ective in improving motor function in dystonic patients where Gpi-DBS does not produce signi®cant improvement