Affiliations: Univ Lille Nord de France, Lille, France | EA 1046, Lille, France | Department of Clinical Neurophysiology, Lille University Medical Center, Lille, France | Department of Neurology, Lille University Medical Center, Lille, France | Department of Biostatistics, UDSL, EA 2694, Lille University Medical Center, Lille, France | Department of Clinical Pharmacology, Lille University Medical Center, Lille, France | Department of Neurosurgery, Lille University Medical Center, Lille, France | UMR 837 INSERM, JParc, IRCL, Lille, France
Note:  Correspondence to: Professor Luc Defebvre, Department of Neurology, Roger Salengro Hospital, F-59037 Lille cedex France. Tel.: +33 320 446 752; Fax: +33 320 446 680; E-mail: [email protected]
Abstract: Background: After several years duration of Parkinson's disease, with or without deep brain stimulation, axial signs (such as postural instability, freezing of gait) may worsen. High-voltage, low-frequency stimulation has been shown to improve severe gait disorders in some patients. Objective: To identify predictive factors for the efficacy of low-frequency stimulation. Methods: We assessed the respective effects of low- and high-frequency stimulation using an acute stand-walk- sit test, and on motor performance in 22 patients with longstanding, bilateral sub-thalamic nucleus stimulation. We calculated the difference in the number of steps (delta steps) between high and low -frequency stimulation during the stand-walk-sit test. Our aim was to establish a profile for low-frequency responders, which was defined by a positive value for delta steps. Results: Low frequency responders presented higher age, a severe axial phenotype five years after surgery and a lower L-dopa responsiveness of (i) the Unified Parkinson's Disease Rating Scale part III score and its akinesia subscore before surgery and (ii) the axial subscore one year after surgery. Conclusion: Here we defined a specific and severe axial profile of minority of patients who could benefit from low frequency stimulation parameters. Our findings challenge the conventional treatment approach (i.e. high-frequency stimulation) in patients who develop gait disorders after several years of stimulation.
Keywords: Parkinson's disease, gait disorders, deep brain stimulation, therapeutics