OBJECTIVE: To study the efficacy ofbilateral pallidal stimulation in parkinsonians with untreatable motor fluctuations. BACKGROUND: Bilateral pallidal stimulation is one of the surgical alternatives in parkinsonians with severe untreatable fluctuations. The major advantages of this procedure over pallidotomy reside in its reversibility and in the possibility to modulate the electrical parameters of the stimulation in order to balance benefits with side effects.
DESIGN/METHODS: 7 non-demented dopa-responsive parkinsonians with untreatable motor fluctuations underwent bilateral contemporaneous pallidal stimulation and were followed-up over a mean of 6 months (3-9) with the CAPIT protocol of assessment without PET scan. There were 4 women and 3 men, with a mean age of 58 y (43-57), a mean duration of disease of 19.6 y (16-24y), a mean Hoehn and Yahr (HY) on/off stage of 3/4.3 (3/5), and a mean daily dopa dose of 837.5 mg (600-1000) divided in 8 doses (6-10). Their mean on/offUPDRS motor score (UMS) was 37.3/76.1 (26-60/48-91), the mean UPDRS ADL on/off score was 25.3/32.3 (11-28/23-42), the mean complication of treatment score (CTTS) was 15 (5-21), the mean dyskinesia score (DS) was 3.5 (2-4) and the mean off time/day (MOT) was 43.4% (20-50%). RESULTS: After the operation, only two patients still presented fluctuations, one with mild gait ignition failure during a few minutes/day, and one with relapse in on-off periods after 9 months, probably due to technical problems with electrodes, which are planned to be relocated. Five of them are entirely free of any fluctuation (MOT=O%). All patients had a minimum follow-up of 3 months (3-10). At 3 months, the DS went dramatically down to 1.1, the UMS on score was only mildly improved (23.3; 23-31), but the UMS off score was divided by 2 (35;28-41) and the mean MOT by 4, off score being only observed when performing the L-dopa-test, which do not reflect the status of otherwise non-fluctuating patients. The mean daily dopa dose was not significantly modified (840; 600-1000 mg divided in 7 doses (6-8)) but CTTS was divided by 4 and HY off state lost 1 point. One of the patients could be delivered from a 3-year continuous s.c apomorphine administration by pump, and was kept with an unchanged dose of 800 mg in 7 doses. Two patients showed mild improvements in dysexecutive fonctions, whereas no change in cognitive fonctions was observed in all others. Side effects (orolingual dyskinesia in one patient, confusion in another) or efficacy could be improved by modifying stimulation parameters.
CONCLUSIONS: Bilateral pallidal stimulation is a safe, reversible, efficient method to treat dopa-sensitive parkinsonians with untreatable motor fluctuations. Fine tuning of the electrical parameters of stimulation allows to control side effects and efficacy, but the evaluation of the duration ofbenefits needs further long-term follow-up.