Pallidal lesions. Structural and functional magnetic resonance imaging
S. F. Bucher, K. C. Seelos, R. C. Dodel, W. Paulus, M. Reiser and W. H. Oertel
Department of Neurology, Klinikum Grosshadern, Ludwig-Maximilians-University, Munich, Germany.
OBJECTIVE: To study noninvasively the functional anatomy and
pathophysiologic characteristics of the globus pallidus external (GPe) and
internal (GPi) divisions. DESIGN: Structural and functional neuroimaging
using high-resolution magnetic resonance imaging. SETTING: University
medical center research facility. SUBJECTS. Seven patients with pallidal
lesions, 4 with an akinetic-rigid syndrome and 3 with a dystonic syndrome,
and 15 age-matched volunteers. MAIN OUTCOME MEASURES: T2-weighted
anatomical magnetic resonance imaging and number of activated voxels in the
GP during rapid supination and pronation of the hand. RESULTS: T2-weighted
images showed hyperintense bilateral lesions in the GP of all patients.
Patients with dystonic syndromes had isolated lesions in the GPi. Patients
with signs of akinetic-rigid syndromes showed abnormalities in the GPe or
in central portions of the GP (GPc). Patients with lesions in both parts of
the GP had akinetic-rigid or dystonic syndromes. All patients showed
activation in the areas of the lesions. The number of activated voxels in
the GP was significantly smaller (P < .005, Wilcoxon signed rank test)
in patients than in control subjects. Activation of the GP was
predominantly contralateral to the moving hand. CONCLUSIONS: Lesions in the
GPi result in a loss of inhibitory pallidal projections to the thalamus,
which may explain the hyperkinetic signs. Lesions in the GPe lead to an
increased inhibition of the thalamus, which may explain the hypokinetic
signs. Neuronal activation in lesion sites suggests the presence of
remaining functionally vital tissue.
