Unilateral lesions of the globus pallidus: report of four patients presenting with focal or segmental dystonia.

OBJECTIVES To interpret clinical features after unilateral lesions of the globus pallidus on the basis of physiology of the basal ganglia. METHODS Four patients with unilateral lesions in the globus pallidus (GP) were clinically examined and the literature on patients with pallidal lesions was reviewed. RESULTS Three patients presented with contralateral dystonia largely confined to one arm in one case and one leg in two cases. One patient had predominant contralateral hemiparkinsonism manifested mainly as micrographia and mild dystonia in one arm. The cause of the lesions was unknown in two patients. In the other two symptoms had developed after head trauma and after anoxia. All lesions involved the internal segment of the GP. Two patients, including the patient with hemiparkinsonism, had additional involvement of the external segment of the GP. In the literature reports on 26 patients with bilateral lesions restricted to the GP only two with unilateral lesions were found. The patients with bilateral pallidal lesions manifested with dystonia, parkinsonism, or abulia. One of the patients with unilateral GP lesions had contralateral hemidystonia, the other contralateral arm tremor. CONCLUSION These cases emphasise the importance of the GP, particularly its internal segment, in the pathophysiology of dystonia.