Objective: To determine how intraoperative microelectrode recordings (MER) and intraoperative lead placement influence symptoms and also whether target location (subthalamic nucleus (STN) or globus pallidus interna (GPi)) was important.
Background: Following MER and/or test stimulation there may be a resultant “collision/implantation or microlesion” effect, thought to result from disruption of cells and/or fibers within the penetrated region.
Methods: Forty-seven consecutive Parkinson disease patients undergoing unilateral DBS for PD (either STN or GPi DBS) were evaluated. Motor function was measured at six time points with a modified UPDRS: 1) preoperative (before penetration on the day of surgery), 2) immediately post- MER, 3) immediately post lead implantation/collision, 4) four months following surgery- off medications, on DBS (12 hour medication washout), 5) six months postoperative- off medication and off DBS (12 hour washout), and 6) six months- on medication and off DBS (12 hour washout).
Results: Significant improvements in motor scores (p<.05) (tremor, rigidity, bradykinesia) were observed as a result of MER and lead placement. The improvements were similar in magnitude to what was observed at four and six months post-DBS following programming and medication optimization. When washed out (medications and DBS) for twelve hours, UPDRS motor scores were still improved compared to preoperative testing. There was a larger improvement in STN when compared to GPi following MER (p<.05), and a trend for significance following lead placement (p<.08), however long-term outcome was similar.
Conclusion: This study demonstrated significant intraoperative penetration effects resulting from MER and lead placement/collion in PD.