L-Dopa in Parkinsonism and the Influence of Previous Thalamotomy

Abstract

SummaryA double-blind cross-over trial over 24 weeks (10 weeks on the active remedy, 4 weeks off treatment, and 10 weeks on placebo) of the effect of L-dopa on idiopathic Parkinsonism (paralysis agitans) has shown no difference in the response obtained in patients who had undergone previous stereotaxic ventrolateral thalamotomy and in those who had not. Of the 34 patients (18 men and 16 women) in the trial 18 had been operated on (nine unilateral, nine bilateral operations) and 16 had not. All patients entering the trial were taking anticholinergic drugs in stable dosage and these were continued throughout. The only factor which seemed to limit the response to treatment was pre-existing hypertension. Of 31 patients who completed the 10-week treatment period, 12 showed marked improvement, 15 moderate improvement, and 4 a mild or negligible change. It seems that previous ventrolateral thalamotomy affords some protection against the development of L-dopa-induced involuntary limb movements on the side contralateral to the operation. As found by others, maximum benefit was seen in bradykinesia and rigidity and related features but a significant reduction in tremor was also noted during treatment. Side effects (nausea, hypotension, and involuntary movements) were common but rarely limited the therapeutic response.

The neural mechanisms and progressive nature of symptoms of Parkinson's disease—based on clinical, neurophysiological and morphological studies

“…The latter is assumed to depend more on the projection from the caudate nucleus to the SNr, which cannot be relieved by surgery but can be modified well by levodopa. Since levodopa exerts its effect of compensating for DA deficiency diffusely on both the putamen and caudate nucleus, its effect is diffuse on rigidity and secondary akinesia, as well as on primary akinesia (Hughes et al, 1974). The difference in the spectrum of symptoms in the therapeutic effect between surgical and medical treatment can thus be explained.…”

The use of thalamotomy in the treatment of levodopa-induced dyskinesia

“…1971). However several authors note that patients with a previous thalamotomy have not gone on to develop levodopa induced dyskinesia (Hughes 1971, Tasker 1983, Matsumoto 1976, Narabayashi 1984, Miyamoto 1985. The complication of thalamotomy most commonly described is post-operative dysphasia, especially a difficulty in word finding, which does appear to improve a little with time.…”

Thalamic Stimulation for Parkinson’s Disease: Clinical Studies on DBS

“…Vim-DBS actually improved the majority of PD disabling tremors and the quality of life in tremor-dominant cases (Limousin-Dowsey 2002 ); however, its effect on other motor symptoms has been equivocal. Ventrolateral thalamotomy attenuated levodopa-induced dyskinesia (Hughes et al 1971 ;Narabayashi et al 1984 ;Jankovic et al 1995 ); Vim-DBS alleviated only 18 % of dyskinesia (Benabid et al 1993 ) and only peak-dose but not diphasic dyskinesia (Caparros-Lefebvre et al 1993 ). Contralateral limb akinesia/rigidity was mildly alleviated but ipsilateral akinesia/rigidity and axial symptoms, such as dysarthria, postural instability and gait disturbance were not changed by unilateral or bilateral surgery (Limousin et al 1999 ).…”