Outcome of unilateral and bilateral pallidotomy for Parkinson's disease: patient assessment

Pallidotomy has recently regained acceptance as a safe and effective treatment for Parkinson's disease symptoms. The goal of this study was to obtain the patients' perspective on their results after undergoing this procedure. Special attention was focused on the potential complications and the respective advantages and risks of unilateral versus bilateral pallidotomy.

Fifty-six patients were studied during a 2-year period; 44 completed the evaluation, with a median follow-up of 7 months. Of these patients, 22 underwent unilateral pallidotomy, and 17 had bilateral simultaneous pallidotomy. Five patients who underwent staged bilateral pallidotomy were excluded from the statistical analysis, because the number of patients was considered too small for analysis. The procedures were performed with magnetic resonance imaging determination of the target, combined with physiological confirmation, including microelectrode recording.

According to Visual Analog Scale scores, unilateral pallidotomy significantly improved dyskinesias (P < 0.05) but no other symptoms. Simultaneous bilateral pallidotomy improved slowness, rigidity, tremor, and dyskinesias (P < 0.05) but worsened speech function (P < 0.05). According to the patients' most frequently chosen answers to multiple-choice questions, unilateral pallidotomy improved night sleep, muscle pain, freezing, overall "on," overall "off," and the duration of "off periods," but it worsened the volume of the voice and articulation, increased drooling, and reduced concentration. Bilateral pallidotomy improved night sleep, muscle pain, freezing, overall "on," overall "off," duration of "off periods," and the amount of medication taken, but it increased drooling and worsened the volume of the voice, articulation, and writing. Subjective visual disturbance was noted in 36 and 41% of patients who underwent unilateral and simultaneous bilateral pallidotomy, respectively. Globally, the result of the procedure was rated "good" or "excellent" by 64% of the patients who underwent unilateral pallidotomy and by 76% of the patients who underwent bilateral pallidotomy. An age less than 70 years was a positive prognostic factor for the global outcome (P < 0.05), as were severe preoperative dyskinesias (P < 0.05).

This study confirms that, from a patient standpoint, unilateral and simultaneous bilateral pallidotomy can reduce all the key symptoms of Parkinson's disease (i.e., akinesia, tremor, and rigidity) and the side effects of L-dopa treatment (i.e., dyskinesias). Preoperative severe dyskinesias and younger age are positive prognostic factors for a successful outcome. Simultaneous bilateral pallidotomy was more effective than unilateral pallidotomy regarding tremor, rigidity, and dyskinesias, but it conferred a higher risk of postoperative speech deterioration.