11. Excessive inhibitory visuomotor connections in Parkinson's disease with freezing of gait. Issue 12 (December 2017)

• Record Type: Journal Article
• Authors: Pizzamiglio, C.; Strigaro, G.; Barbero, P.; Tondo, G.; Magistrelli, L.; Rovellotti, C.; Comi, C.; Cantello, R.
• Is Part Of: Clinical neurophysiology. Volume 128:Issue 12(2017:Dec.)
• Page Start: e417
• Page End: e418
• Publication Date: 2017-12
• Subjects: Neurophysiology -- Periodicals; Electroencephalography -- Periodicals; Electromyography -- Periodicals; Neurology -- Periodicals; 612.8
• DOI: 10.1016/j.clinph.2017.09.018
• Languages: English
• ISSNs: 1388-2457

Abstract

Abstract : Freezing of gait (FoG) is an invalidating symptom in patients with Parkinson's disease (PD); it is a brief, episodic absence/marked reduction of forward progression of the feet despite the intention to walk. The pathophysiology remains obscure. Visual information is crucial for the initiation and control of movement, therefore an impairment of the visuomotor connections may underlie FoG. We used transcranial magnetic stimulation (TMS) to assess bilateral physiological connections (VMc) between primary visual (V1) and motor (M1) areas in PD with (PD+FoG) and without FoG (PD−FoG). Twelve PD+FoG were compared with 12 PD−FoG and 12 healthy subjects (HS) of similar age/sex. VMc was assessed bilaterally by delivering a conditioning stimulus (CS) over V1 phosphene hotspot followed at two random interstimulus intervals (ISI = 18–40 ms) by a test stimulus (TS) over left and right M1 to elicit a motor evoked potential (MEP) of ∼1 mV from controlateral FDI. In HS and PD−FoG, VMc was reproducible with MEP suppression at ISI = 18–40 ms. PD+FoG behaved differently, since the inhibitory VMc was significantly enhanced in the right, non-dominant hemisphere. PD+FoG had an excessive inhibitory response of the right M1 to inputs travelling from V1. This may represent one core factor for the pathophysiology of FoG.