The microlesion effect on cognition after Deep Brain Stimulation in Parkinson’s Disease

Background an rationale:
Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an effective treatment for advanced Parkinson’s disease (PD). In the first days to weeks after surgery, alleviation of PD symptoms without active stimulation is often observed, referred to as the microlesion effect (MLE). The presence of MLE on cognition after DBS surgery has not been studied well, while this non-motor aspect of PD might be of great importance to the patient.

Objective:
To determine the presence and predictive value of MLE on cognition after DBS in PD.

Study design:
Prospective observational study.

Study population:
Adult PD-patients undergoing DBS of the STN.

Main study parameters/endpoints:
The primary endpoints of the study are the SDMT, Stroop and WAIS part IV Digit Span scores to assess the MLE on cognitive functioning.

Nature and extent of the burden and risks associated with participation, benefit and group relatedness:
There are no risks associated with the proposed study.
Assessing cognitive functioning 12 months after DBS surgery leads to better attention for possible cognitive deficits, which could initiate early postoperative cognitive deterioration detection and cognitive training to prevent further cognitive deterioration.

The hypothesis is that the microlesion effect affects cognitive functioning in Parkinson's disease patients undergoing STN-DBS.

Various clinical tests will be administered on several time points:
1 day before the surgery: the MoCA
The morning before the surgery: SDMT, Stroop, WAIS IV Digit Span
During the surgery, after electrode insertion: SDMT, Stroop, WAIS IV Digit Span
2 days after the surgery: SDMT, Stroop, WAIS IV Digit Span
12 months after the surgery: the MoCA