Evidence Table SURG 1What is the effectiveness and safety of any deep brain stimulation procedure vs. standard medical therapy in the treatment of motor fluctuations and complications in patients with Parkinson’s disease?

Bibliographic referenceBenabid AL, Pollak P, Seigneuret E, Hoffmann D, Gay E, Perret J. Chronic VIM thalamic stimulation in Parkinson’s disease, essential tremor and extra-pyramidal dyskinesias. Acta Neurochir Suppl (Wien) 1993;58:39–44.
Study typeBefore and after study
Evidence level3
Study objectiveTo report on the author’s experience over 5 years and the differential effects of Vim thalamic stimulation on various types of tremor.
Number of patientsN=87 patients suffering from disabling and drug-resistant tremor
 N= 61 Parkinson’s disease (PD) patients
 N=13 essential tremor (ET) patients
 N=13 action tremor (mainly related to mesencephalic lesions)

Location: Grenoble, France
sites: single
Patient characteristics87 patients suffering from disabling and drug-resistant tremor, 61 Parkinson’s disease (PD) patients, 13 essential tremor (ET) patients, and 13 action tremor (mainly related to mesencephalic lesions- including 4 with multiple sclerosis). Eleven patients had previously undergone contralateral thalamotomy and 39 (45%) had bilateral Vim stimulation at the same time, making a total of 50/87 (57%) with bilateral thalamic surgery.
No details on demographics, diagnosis, inclusion/exclusion criteria or disease severity.
InterventionChronic ventral intermediate (Vim) thalamic stimulation- see paper for details
ComparisonPre-operative assessments
Length of follow-upNot stated (5 year experience but no detail on time period from surgery to results listed below)
Outcome measuresTremor suppression, morbidity/mortality and side effects
Effect size➢ The effect on tremor was scored independently by the neurologist on a 5-point scale
➢ (4= complete disappearance of tremor in all circumstances, 3= reappearance of slight tremor on rare occasions, for instance under stress, 2= moderate benefit, 1= slight benefit without real improvement in daily life, 0= no benefit at all or worsening of tremor)
Tremor suppression
➢ Immediately after surgery a thalamotomy-like effect was responsible for a transitory tremor suppression for a few days
➢ During the test period- various combinations of stimulation parameters were evaluated
➢ The best effect/side effects ratio was observed for pulse width of about 60 μsec
➢ The threshold intensity versus frequency necessary to suppress totally the tremor was assessed: the minimum was a plateau from about 100 to 2000 Hz
➢ The stimulators are therefore set at 130 to 185 Hz
➢ Voltage value was actually set according to patient choice based on his compromise between benefit and side effects
➢ Voltage increased during first 6 weeks
➢ The average voltage at the last follow-up for each patient was 2.7 volts (range 0.4 to 5.5V)
➢ A good result (scores of 3 or 4) was obtained in 71% of the operated sides
Major benefit was obtained in 88% of cases with PD
➢ (68% of cases with ET and 18% of cases related to other causes)
➢ Rest tremor was better controlled than action tremor
Distal limb tremor better controlled than proximal or axial tremor
➢ Upper better controlled than lower limb tremor
➢ In all cases the effect was strictly simulataneous with stimulation without significant delay of onset or post-effect at arrest
Tremor was the only parkinsonian sign influenced by Vim stimulatuion
In 1/3 PD patients - L-dopa doses could be reduced by more than 30%

Morbidity and mortality
➢ No mortality in this series of patients
➢ Two patients had secondary skin ulceration of the scalp in front of the electrode-to-extension connection
➢ Two patients had asymptomatic intracranial micro-haematomas
Side effects
➢ Were mild and immediately disappeared when stimulation was decreased or turned off
➢ Included: contralateral paresthesias (9%), limb dystonia (9%), disequilibrium (7.6%), and dysarthria (15% on the whole: 6% with bilateral stimulation, 7.5% with previous unilateral thalamotomy and contralateral stimulation, and 1.5% with unilateral stimulation)
Dysarthria was therefore observed in 14% of the bilaterally stimulated patients and in 50% of the patients previously thalatomised
➢ No spontaneous psychological disturbance was reported
➢ Suddenly switching on the stimulator could induce transient (a few seconds) and not disabling contralateral parathesiae
➢ Switching off the stimulator induced a transient rebound tremor in about half of the patients which made them use the stimulator at night
➢ Continuous stimulation (mainly those with action tremor) a kind of ‘tolerance’ with decreasing efficacy of stimulation
Source of fundingPrivate and university funding
Additional comments➢ Unblinded
➢ Uncontrolled
➢ No details of patient recruitment
➢ Lack of patient characteristic details
➢ Combination of results from patients of various diseases
NCC CC ID (Ref Man)19728

From: Evidence Tables

Cover of Parkinson's Disease
Parkinson's Disease: National Clinical Guideline for Diagnosis and Management in Primary and Secondary Care.
NICE Clinical Guidelines, No. 35.
National Collaborating Centre for Chronic Conditions (UK).
Copyright © 2006, Royal College of Physicians of London.

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