Objective: The objective of this work is to assess the discrepancy in distance between the target chosen by magnetic resonance imaging (MRI) and the final electrode placement after intraoperative microrecording in patients submitted to deep brain stimulation (DBS) for alleviating the Parkinson's disease (PD).
Methods: Thirty patients with PD and motor complications were operated with stereotactic surgery by MRI and microrecording. In 19 patients, the target chosen was the subthalamic nucleus (STN) and in 11 others the target was globus pallidus internus (GPi). In this work it is considered that the electrode has a current field below usual parameters of 1.5 mm radius. Consequently, when the distance error between the final physiological target and the MRI target, is between 1.5 and 3 mm was considered as partial discrepancy and distances of 3 mm or more were considered as total discrepancy.
Results: Partial discrepancy for STN and GPi were in 25 and 33% of the cases respectively and total discrepancy was 57 and 42% for each nucleus. The average distance error between both targets, final and image, for X stereotactic coordinate (mediolateral distance) was 1.54 mm for STN and 0.8 mm for GPi. The average distance for Y coordinate (anteroposterior distance) was 2.3 mm for STN and 2.2 mm for GPi.
Conclusion: There is a significant discrepancy between the final physiological target after microrecording and the target chosen by MRI during surgery for alleviating PD that may induce variations or absence of clinical efficacy in parkinsonian patients submitted to the DBS surgery. Authors suggest the necessity of the microelectrode recording in order to reach the surgical target with the best clinical condition.