Article

OBJECTIVE: To investigate the effects of anodal transcranial direct current
stimulation (a-tDCS) intensity on corticospinal excitability and affected muscle
activation in individuals with chronic spinal cord injury (SCI). DESIGN:
Single-blind, randomized, sham-controlled, crossover study. SETTING: Medical
research institute and rehabilitation hospital. PARTICIPANTS: Volunteers (N = 9)
with chronic SCI and motor dysfunction in wrist extensor muscles. INTERVENTIONS:
Three single session exposures to 20 minutes of a-tDCS (anode over the extensor
carpi radialis [ECR] muscle representation on the left primary motor cortex,
cathode over the right supraorbital area) using 1 mA, 2 mA, or sham stimulation,
delivered at rest, with at least 1 week between sessions. MAIN OUTCOME MEASURES:
Corticospinal excitability was assessed with motor-evoked potentials (MEPs) from
the ECR muscle using surface electromyography after transcranial magnetic
stimulation. Changes in spinal excitability, sensory threshold, and muscle
strength were also investigated. RESULTS: Mean MEP amplitude significantly
increased by approximately 40% immediately after 2mA a-tDCS (pre: 0.36 +/- 0.1
mV; post: 0.47 +/- 0.11 mV; P = .001), but not with 1 mA or sham. Maximal
voluntary contraction measures remained unaltered across all conditions. Sensory
threshold significantly decreased over time after 1mA (P = .002) and 2mA (P =
.039) a-tDCS and did not change with sham. F-wave persistence showed a
nonsignificant trend for increase (pre: 32% +/- 12%; post: 41% +/- 10%;
follow-up: 46% +/- 12%) after 2 mA stimulation. No adverse effects were reported
with any of the experimental conditions. CONCLUSIONS: The a-tDCS can transiently
raise corticospinal excitability to affected muscles in patients with chronic SCI
after 2 mA stimulation. Sensory perception can improve with both 1 and 2 mA
stimulation. This study gives support to the safe and effective use of a-tDCS
using small electrodes in patients with SCI and highlights the importance of
stimulation intensity.
CI - Copyright (c) 2015 American Congress of Rehabilitation Medicine. Published by
Elsevier Inc. All rights reserved.

Langue : ANGLAIS