Deep-Brain Stimulation in Parkinson's Disease

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Abstract
The Deep-Brain Stimulation for Parkinson's Disease Study Group (Sept. 27 issue)1 reported the results of a prospective, double-blind, crossover study in patients with advanced Parkinson's disease, in whom electrodes were implanted in the subthalamic nucleus or pars interna of the globus pallidus and who then underwent bilateral high-frequency deep-brain stimulation. In the Discussion section, the authors wrote: “Although initiation of stimulation was associated with transient symptoms in some patients, we do not believe that this influenced the blinded assessment, since neither the patients nor the investigators were certain of whether stimulation was being given at the time.” In 1998, some of the same authors reported, with respect to a double-blind evaluation of deep-brain stimulation of the subthalamic nucleus in eight of the same patients, that “all patients were able to guess which assessments were performed with the stimulators on.”2 Everyone with some experience of deep-brain stimulation of the subthalamic nucleus knows that neither the patient nor the evaluator can be blinded to the status of a patient with advanced Parkinson's disease who has resumed stimulation of the subthalamic nucleus after having been without stimulation and medication for 12 hours. Since the authors themselves have admitted this fact in a previous publication,2 one cannot help but wonder about the validity of this double-blind evaluation.