Modulation of cortical and spinal inhibition with functional recovery of upper extremity motor function among patients with chronic stroke

Article type: Research Article

Authors: Fujiwara, Toshiyuki^{a; *} | Honaga, Kaoru^b | Kawakami, Michiyuki^b | Nishimoto, Atsuko^b | Abe, Kaoru^c | Mizuno, Katsuhiro^b | Kodama, Mitsuhiko^a | Masakado, Yoshihisa^a | Tsuji, Tetsuya^b | Liu, Meigen^b

Affiliations: [a] Department of Rehabilitation Medicine, Tokai University School of Medicine, 143 Shimokasuya, Isehara, Kanagawa, Japan | [b] Department of Rehabilitation Medicine, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo, Japan | [c] Department of Rehabilitation Medicine, Keio University Hospital, 35 Shinanomachi, Shinjuku, Tokyo, Japan

Correspondence: [*] Corresponding author: Toshiyuki Fujiwara, Department of Rehabilitation Medicine, Tokai University School of Medicine, 143 Shimokasuya, Isehara, Kanagawa 259-1193, Japan. Tel.: +81 463 93 1121; Fax: +81 463 95 8248; E-mail: tofuji@xc5.so-net.ne.jp

Abstract: Purpose:We hypothesized that recovery of upper extremity motor function is associated with reduction of intracortical inhibition and improved reciprocal inhibition. This study examines the relationships of functional recovery in chronic stroke with the intracortical inhibition and spinal reciprocal inhibition. Methods:Participants were 61 patients with chronic hemiparetic stroke. The participants were applied hybrid assistive neuromuscular dynamic stimulation (HANDS) therapy for 3 weeks. The Fugl-Meyer test upper extremity motor score (FM) and modified Ashworth scale (MAS) were assessed before (T0), immediately after (T1) and 3 months after (T2) the end of HANDS therapy. A paired pulse TMS paradigm was applied to assess short intracortical inhibition (SICI). Reciprocal inhibition (RI) was assessed with H reflex conditioning-test paradigm. Results:FM and MAS were improved until T2. The change of FM from T0 to T2 was positively correlated with the change in affected SICI from T0 toT1. The change of wrist MAS from T0 to T1 was positively correlated with the change of RI. Conclusions:In chronic stroke patients with moderate or severe hemiparesis, well-recovered patients showed disinhibition of ipsilesional hemisphere and increased resiprocal inhibition of forearm.

Keywords: Stroke, rehabilitation, upper extremity function, motor cortex, spinal cord, transcranial magnetic stimulation, electrical stimulation, reciprocal inhibition, intracortical inhibition, motor function

DOI: 10.3233/RNN-150547

Journal: Restorative Neurology and Neuroscience, vol. 33, no. 6, pp. 883-894, 2015