Objective: To determine the change in MDS-UPDRS III severity level after Subthalamic Nucleus Deep Brain Stimulation (STN-DBS) in patients with Parkinson’s disease (PD) and evaluate its subsequent correlation with MDS-UPDRS II and IV.

Background: Despite the availability of MDS-UPDRS severity levels correlating with PD scales rated by clinicians (Clinical Impression of Severity Index, Global Impression of Severity) and patients (Patient Global Impression of Severity),[1] their modification after STN-DBS or correlation with other outcome measures has not been explored, with percentual change in MDS-UPDRS III Off being the most reported DBS outcome.[2,3]

Method: PD patients who underwent STN-DBS and had prospective follow-up between 12-24 months were analyzed. MDS-UPDRS Severity Levels were defined according to cut-off scores as mild/moderate/severe as follows: II (≤12/13-29/≥30), III (≤32/33-58/≥59), and IV (≤4/5-12/≥13).[3]  STN-DBS response was considered optimal if MDS-UPDRS III Off severity level reduced one or more levels. Subjects with baseline mild severity underwent separate analysis since reduction of category was not possible. Baseline and follow-up MDS-UPDRS II and MDS-UPDRS IV change (total and severity levels) were compared between and within groups.

Results: 51 subjects (F16/M35) were included, mean age at surgery 59.7±9.9 years, disease duration 12.1±3.9 years. 22 patients with mild MDS-UPDRS severity level at either subsection were analyzed separately. All subjects experienced significant improvement from their baseline MDS-UPDRS III Off (45%,p<0.01), IV (64%,p<0.01), and II (48%,p<0.01), and 24(83%) had optimal response with a mean MDS-UPDRS III Off decrease of 48%. Compared to those unchanged, those with MDS-UPDRS III severity level change had a greater response in MDS-UPDRS IV, both in total score (2.0±1.2 vs 6.8±2.5, p<0.01) and severity level (96% vs 0%, p<0.01); and greater response in MDS-UPDRS II (8.2±4.6 vs 13.8±4.8, p=0.03) but without changing the severity level (83% vs 80%, p=0.86). All patients with mild MDS-UPDRS severity at baseline improved significantly from in III Off (40%, p<0.01), IV (32%, p<0.01), and II (34% p<0.01), but had lower responses in IV (32% vs 64%, p=0.06), III Off (40% vs 45%, p=0.24), and II (34% vs 48% p=0.15).

Conclusion: Improvement in MDS-UPDRS III Off severity level seems to be associated with a change in severity score of MDS-UPDRS III and IV, and a reduction in MDS-UPDRS II score.

References: [1] Lin Z, Zhang C, Li D, Sun B. Preoperative Levodopa Response and Deep Brain Stimulation Effects on Motor Outcomes in Parkinson’s Disease: A Systematic Review. Mov Disord Clin Pract 2022;9(2):140-155.
[2] Lachenmayer ML, Murset M, Antih N, et al. Subthalamic and pallidal deep brain stimulation for Parkinson’s disease-meta-analysis of outcomes. NPJ Parkinsons Dis 2021;7(1):77.
[3] Martinez-Martin P, Rodriguez-Blazquez C, Mario A, et al. Parkinson’s disease severity levels and MDS-Unified Parkinson’s Disease Rating Scale. Parkinsonism Relat Disord 2015;21(1):50-54.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/mds-updrs-iii-off-severity-level-changes-as-a-marker-of-dbs-response/