Background: Deep brain stimulation is being widely used in advanced Parkinson's disease (PD). Outcome determinants are not known.
Objective: Some relevant data about outcome may be obtained from the study of patients with unsatisfactory results.
Patients and methods: We have retrospectively analyzed the number and causes of unsatisfactory results (insufficient improvement 6 months after the intervention) in 211 patients.
Results: Forty patients (18.9%) experienced an unsatisfactory result. Inadequate clinical selection by advanced age, abnormal MRI and levodopa unresponsive symptoms was the main cause in 28 cases. In 11 patients a misplacement of the electrode was reported. In 2 cases no cause was identified. Thirty-four out of the 40 patients corresponded to the early experience of the teams involved in the study.
Conclusion: We conclude that the main factors responsible for a negative outcome are related to the inadequate clinical selection of the patients and the incorrect placement of the electrode. The experience of the team may also be a key factor.