Outcome of bilateral subthalamic nucleus stimulation in the treatment of Parkinson's disease: correlation with intra-operative multi-unit recordings but not with the type of anaesthesia.

BACKGROUND: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) gained general acceptance in the treatment of Parkinson's disease (PD).
OBJECTIVE: To study the clinical outcome and the predicting factors of efficacy of chronic STN stimulation, while DBS electrodes were implanted under local or general anaesthesia with intra-operative electrophysiological guidance based on multi-unit recordings.
METHODS: We included a large single-centre cohort of 54 patients with advanced PD (mean age: 59 years; disease duration: 14 years). Clinical evaluation was performed by the Unified Parkinson's Disease Rating Scale (UPDRS) before and 1 year after surgical placement of DBS electrodes.
RESULTS: In the on-stimulation and off-medication condition, the UPDRS part III score was reduced by 56% compared to the off-stimulation condition or pre-operative off-drug score. In the on-stimulation and on-medication condition, this score was reduced by 73%. The severity of motor fluctuations and dyskinesia (UPDRS part IV) and the activities of daily living (UPDRS part II) were reduced by 65 and 80%, respectively, in the on-stimulation/on-medication condition compared to the pre-operative baseline. The daily dose of antiparkinsonian treatment was diminished by 72%. Among the various pre- and intra-operative data, the most important predictive factor for clinical efficacy of STN stimulation was the length of hyperactivity along the best track observed in intra-operative multi-unit recordings. Other predictive factors included age, disease duration and pre-operative levodopa responsiveness or baseline off-drug values of the Hoehn and Yahr and UPDRS part III scores. In contrast, the type of anaesthesia (local vs. general) did not significantly influence the clinical outcome.
CONCLUSION: The present results are in the average of previously published results, but they have been obtained from a large single-centre cohort of patients with important reductions in the daily dose of antiparkinsonian drugs. This study confirmed the efficacy of the STN-DBS technique and emphasized the value of an original intra-operative electrophysiological approach based on multi-unit and not single-unit quantified recordings. This method allows DBS electrode implantation to be safely performed under general anaesthesia without lessening the rate of efficacy of the procedure. Copyright 2008 S. Karger AG, Basel.