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  • MER-determined STN Width as a Predictor of Post-Operative UPDRS Improvement

    Final Number:

    James Dylan Whisenhunt BS; Mahesh B. Shenai MD; Bonita Agee; Harrison Walker MD; Stephanie Guthrie RN; Barton L. Guthrie MD

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    Subject Category:

    Meeting: Congress of Neurological Surgeons 2013 Annual Meeting

    Introduction: DBS of the STN is an effective treatment for medically refractory Parkinson’s Disease. Intraoperative measurement of STN width through microelectrode recording (MER) is a common proxy for optimal electrode location.

    Methods: Records were reviewed for 126 patients who underwent their first single-sided STN DBS placement for PD between 2005 and 2010 at UAB Medical Center. Patients lacking pre-operative, intra-operative, or post-operative records were excluded. Reviews of pre-operative and 3-month post-operative UPDRS Part III, intra-operative MER records, and post-operative MRI scans were conducted. Global UPDRS scores were split into ipsilateral, contralateral, and midline scores. The final cohort consisted of 73 patients (mean age = 60 yrs (± 11), length of disease = 13 yrs (± 5.6), baseline UPDRS global = 37 (± 11), contralateral = 15 (± 5.6), ipsilateral = 9.0 (± 4.2), midline = 4.2 ((± 4.0)). STN widths were defined as depths associated with increased background activity and motor-driven, spiking action potentials on MER. Additionally, widths were normalized to AC-PC length (mean = 25.69 mm (± 1.65)). Relationships between STN width and UPDRS improvement were investigated using correlation and multivariate linear regression.

    Results: Mean global and contralateral UPDRS improvements were 38% (± 24) and 58% (± 24). Mean STN width was 5.1 mm (± 1.6, min = 0.0, max = 8.7). There were no statistically significant relationships between STN width and UPDRS improvement, with and without AC-PC normalization (R2<.05). Stratification of STN widths failed to produce a statistically significant relationship. Baseline scores were the only predictors of UPDRS improvement.

    Conclusions: This retrospective analysis raises questions about seeking maximal electrophysiological width of STN as a proxy for optimal outcome in DBS for PD. We suggest that this strategy for DBS placement in PD be subject to more robust prospective investigation.

    Patient Care: This research highlights the need for critical evaluation of a current strategy for DBS placement that carries significant risk of morbidity and mortality. Refinement and improvement of the strategy would potentially decrease the incidence of adverse outcomes during DBS placement.

    Learning Objectives: By the conclusion of this session, participants should be able to: 1) Understand the general technique for microelectrode recording in STN for Parkinson's disease, 2) Understand the relationship between electrophysiological STN recordings and anatomic dimensions, 3) Further understand the relationship between STN recordings and UPDRS outcomes for DBS treatment of Parkinson's disease.


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