Short-term efficacy analysis of STN-DBS for Parkinson′s disease in patients with low improvement rate in levodopa challenge test

Abstract

Objective To investigate the short-term efficacy of STN-DBS (subthalamic nucleus-deep brain stimulation) in patients with Parkinson′s disease and an improvement rate of <30% in levodopa challenge test (LCT). Methods A retrospective analysis was conducted on the clinical data of 35 patients with Parkinson′s disease and an improvement rate of <30% in LCT who underwent STN-DBS from March 2015 to December 2017 at Department of Neurosurgery, Changhai Hospital Affiliated to Navy Medical University. All those patients were divided into tremor dominant (TD) type (n=12), postural instability/gait disturbance (PIGD) type (n=17) and indeterminate type (n=6) according to the motor symptoms of Parkinson′s disease. The preoperative LCT improvement rate and the improvement rate of motor symptoms in an on-stimulation off-medication state (referred to as the postoperative improvement rate of motor movement symptoms) were compared in 3 groups of patients. Comparison and analysis were conducted on the improvement rate of LCT before surgery and the improvement rate of motor symptoms at 1 month post STN-DBS. Results The improvement rates in LCT of TD, PIGD and indeterminate types of patients prior to operation were (19.38±6.85)%, (23.76±5.02)% and (16.48±10.00)% respectively. There was no statistical difference among the 3 groups (F=2.31, P=0.12). The postoperative improvement rates of motor symptoms in those 3 types were (51.75±8.65)%, (41.52±13.11)% and (38.90±14.15)% respectively. There was significant difference among the groups (F=3.39, P=0.04). The postoperative improvement rate of motor symptoms was significantly higher than the improvement rate in preoperative LCT in 35 patients (t=9.46, P<0.01) and in subgroup aualysis(P<0.01 respectively). The elevation from preoperative improvement rate in LCT to post-DBS improvement rate of motor symptoms in 3 groups of patients was statistically significant (F=4.12, P=0.03), and the difference between TD and PIGD types was statistically significant (P=0.02). Conclusion STN-DBS seems effective for improving the motor symptoms of Parkinson′s disease patients with LCT<30%, particularly in TD types in terms of short-term outcome. Key words: Parkinson disease; Tremor; Deep brain stimulation; Levodopa challenge test; Treatment outcome