Background: Falls and postural instability (PI) are major sources of morbidity in Parkinson disease (PD). Deep brain stimulation (DBS) is a major therapy for PD. The effects of DBS on PI and falls remain controversial.
Objective: To study if DBS worsens PI, validated measures of PI (Timed Up and Go, Berg Balance Scale, Unified Parkinson's Disease Rating Scale 3.12 [Pull Test], and the Biodex Sway Index with eyes closed on a firm and soft surface) and reported falls were used to prospectively evaluate the effect of DBS on PI at 3 and 12 mo postoperatively compared to baseline measurements. The primary outcomes were a positive result on 4 out of the 5 PI tests and falls.
Methods: Patients presenting for DBS were prospectively enrolled and evaluated at presentation and, 3 and 12 mo postoperatively. All tests were performed at each visit.
Results: At 3 mo 4 of 5 positive showed noninferiority to baseline, with a rate of 28% vs 41% (relative risk [RR] 0.8 [0.5-1.3]). At 12 mo, 4 of 5 positive had a rate of 35% vs 30% (RR 1.2 [0.8-1.8]) and falls had a rate of 54% vs 46% (RR 1.2 [0.6-2.3]). These did not meet criteria to prove noninferiority. Sensitivity analysis at 12 mo showed noninferiority for 4 of 5 (RR 0.9 [0.6-1.5]) but not falls (RR 1.1 [0.5-2.3]).
Conclusion: This evidence is consistent with the hypothesis that DBS does not worsen PI when measured at 3 and 12 mo postoperatively.