Opposite motor effects of pallidal stimulation in Parkinson’s disease

P. Krack, P. Pollak, P. Limousin, D. Hoffmann, A. Benazzouz, J. F. Le Bas, A. Koudsie, A. L. Benabid
Ann Neurol.. 1998-02-01; 43(2): 180-192
DOI: 10.1002/ana.410430208

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1. Ann Neurol. 1998 Feb;43(2):180-92. doi: 10.1002/ana.410430208.

Opposite motor effects of pallidal stimulation in Parkinson’s disease.

Krack P(1), Pollak P, Limousin P, Hoffmann D, Benazzouz A, Le Bas JF, Koudsie A,
Benabid AL.

Author information:
(1)Department of Clinical and Biological Neurosciences, and INSERM U318, Joseph
Fourier University of Grenoble, France.

We studied the effects–on parkinsonian signs, on levodopa-induced dyskinesias,
and on levodopa response–of acute experimental high-frequency stimulation of
the internal pallidum (GPi) during off-drug and on-drug phases. Thirteen
quadripolar electrodes were evaluated in 8 patients with Parkinson’s disease
(PD). Stimulation of the most ventral contacts, lying at the ventral margin of
or just below the GPi, led to pronounced improvement in rigidity and a complete
arrest of levodopa-induced dyskinesias. The antiakinetic effect of levodopa was
also blocked and the patients became severely akinetic. Stimulation of the most
dorsal contacts, lying at the dorsal border of the GPi or inside the external
pallidum, usually led to moderate improvement of off-drug akinesia and could
also induce dyskinesias in some patients. When using an intermediate contact for
chronic stimulation, a good compromise between these opposite effects was
usually obtained, mimicking the effect of pallidotomy. We conclude that there
are at least two different functional zones within the globus pallidus, at the
basis of a different pathophysiology of the cardinal symptoms of PD. The
opposite effects may explain the variable results of pallidal surgery reported
in the literature and may also largely explain the paradox of PD surgery. A
possible anatomical basis for these differential functional effects could be a
functional somatotopy within the GPi, with the segregation of the pallidofugal
fibers from the outer portion of the GPi, on one hand, forming the ventral ansa
lenticularis and from the inner portion of the GPi, on the other hand, forming
the dorsal lenticular fasciculus.

DOI: 10.1002/ana.410430208
PMID: 9485059 [Indexed for MEDLINE]

Auteurs Bordeaux Neurocampus