Objective: To evaluate whether using multiple versus single MER-guidance peroperatively influence improvement of motor symptoms by STN-DBS in advanced PD.

Background: It is well established that STN-DBS improves motor symptoms in advanced PD. However, the debate is ongoing whether the use of intraoperative MER affects the efficacy or safety of STN-DBS. The mixed clinical outcome found in a non-randomized study (Temel Y et al, 2007) warranted a randomized trial, to increase knowledge of this issue.

Methods: Eligible patients were included at a single center, Oslo University Hospital, April 2009 – December 2013. On the day of surgery computer generated block randomization was performed; one group that should get 1 MER (sMER) and one group that should get 5 MER (mMER) to guide the location of the permanent electrode in the STN. In the sMER group additional MERs were allowed if the first MER yielded unsatisfactory recordings. In the mMER group the number of MER could be reduced if anatomical limitations compromised safety. Primary endpoint was the change in MDS-UPDRS motor score in the off medication state (UPDRSIII-off) from baseline to12 months (UPDRSIII-off-diff).

Results: We included 60 patients; 45 men: 15 women, with mean(SD) age 60.5(6.9) and disease duration 11.6 years(4.3). At baseline, in sMER group and mMER group respectively, mean (SD) levodopa equivalent daily dose was 1332(332) and 1269(532), UPDRSIII-off medication was 45(9) and 52(15). Three patients were explanted due to infection and 2 patients missed the 12 months evaluation. Thus, the primary endpoint analysis included 29 patients in the sMER group and 26 patients in the mMER group. At 12 months of STN-DBS, the mean MDS-UPDRS III off difference was 26(10) in the sMER group and 35(12) in the mMER group (P= 0.01). Mean MDS-UPDRS III off was reduced to 19(-58%) in sMER group and 20(-64%) in mMER group. Median MDS-UPDRS IV was reduced from 11 in sMER group and 10 in mMER group to 1 in both groups. Frequency of serious adverse events was similar in the two groups, and no intracerebral hemorrhage was encountered.

Conclusions: The use of multiple MER is safe, and the mMER group had a larger reduction in UPDRSIII-off-score than the sMER group. Further analyses will be presented that explore which factors that may influence this result.

Preliminary data presented at German Scandinavian Movement Disorder meeting October 2015.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/single-versus-multiple-microelectrode-recordings-mer-in-stn-dbs-surgery-for-pd-a-randomized-double-blind-controlled-trial/