Evidence of functional somatotopy in GPi from results of pallidotomy.

Full Abstract

The objective of this study was to explore the functional anatomy of the globus pallidus internus (GPi) by studying the effects of unilateral pallidotomy on parkinsonian 'off' signs and levodopa-induced dyskinesias (LID). We found significant positive correlations between the preoperative levodopa responsiveness of motor signs and the levodopa responsiveness of scores in timed tests (Core Assessment Program for Intracerebral Transplantations) in the contralateral limbs and the improvement in these scores after surgery, whereas there was no correlation with the improvement in LID. We also found a highly significant correlation (P: < 0.0001, r = 0.8) between the volume of the ventral lesion in the GPi and the improvement in LID in the contralateral limbs, whereas there was no correlation between the ventral volume and the improvement in parkinsonian 'off' signs. The volumes of the total lesion cylinder and the dorsal lesion did not correlate with the outcome of either dyskinesias or parkinsonian 'off' signs. The differential predictive value of levodopa responsiveness for the outcome of parkinsonian 'off' signs and LID and the different correlations of ventral lesion volume with dyskinesias and parkinsonian 'off' signs indicate that different anatomical or pathophysiological substrates may be responsible for the generation of parkinsonian 'off' signs and dyskinesias. Whereas cells in a wider area of the GPi may be implicated in parkinsonism, the ventral GPi seems to be crucial for the manifestation of LID. We suggest that our observations are additional proof of the functional somatotopy of the systems within the GPi that mediate parkinsonism and dyskinesias, especially along the dorsoventral trajectory used in pallidotomy. The outcome of pallidotomy in which the lesion involves the ventral and dorsal GPi could be the net effect of alteration in the activity of pathways which mediate different symptoms, and hence could be variable.

Author information

Author/s: Kishore, A (A); Panikar, D (D); Balakrishnan, S (S); Joseph, S (S); Sarma, S (S);

Affiliation: Departments of Neurology, Neurosurgery, Radiology and Statistics, Comprehensive Care Centre for Movement Disorders, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Kerala, India. asha(-atsign-)sctimst.ker.nic.in

Journal and publication information

Publication Type: Clinical Trial; Journal Article

Journal: Brain : a journal of neurology (Brain), published in ENGLAND. (Language: eng)

Reference: 2000-Dec; vol 123 Pt 12 (issue ) : pp 2491-500

Dates: Created 2000/12/20; Completed 2001/01/04; Revised 2004/11/17;

PMID: 11099450, status: MEDLINE (last retrieval date: 2/18/2009, IMS Date: )

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