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 g lobus pallidus on the basis of physiology of the basal ganglia. Methods-Four patients with unilateral lesions in the globus pallidus (GP) w ere clinically examined and the Literature on patients with pallidal lesion s was reviewed. Results-Three patients presented with contralateral dystonia largely confin ed to one arm in one case and one leg in two cases. One patient had predomi nant contralateral hemiparkinsonism manifested mainly as micrographia and m ild dystonia in one arm. The cause of the lesions was unknown in two patien ts. In the other two symptoms had developed after head trauma and after ano xia. All lesions involved the internal segment of the GP. Two patients, inc luding the patient with hemi-parkinsonism, had additional involvement of th e external segment of the GP. In the literature reports on 26 patients with bilateral lesions restricted to the GP only two with unilateral lesions we re found. The patients with bilateral pallidal lesions manifested with dyst onia, parkinsonism, or abulia. One of the patients with unilateral GP lesio ns 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.