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Clin Neurophysiol. 2013 Feb;124(2):371-8. doi: 10.1016/j.clinph.2012.07.026. Epub 2012 Sep 19.

Functional repetitive transcranial magnetic stimulation increases motor cortex excitability in survivors of stroke.

Author information

1
Physical Therapy and Rehabilitation Science Department, University of Maryland School of Medicine, Baltimore, MD 21201, USA. cmassie@som.umaryland.edu

Abstract

OBJECTIVE:

To determine if repetitive transcranial magnetic stimulation (rTMS) applied to the motor cortex with simultaneous voluntary muscle activation, termed functional-rTMS, will promote greater neuronal excitability changes and neural plasticity than passive-rTMS in survivors of stroke.

METHODS:

Eighteen stroke survivors were randomized into functional-rTMS (EMG-triggered rTMS) or passive-rTMS (rTMS only; control) conditions. Measures of short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF), force steadiness (coefficient of variation, CV) at 10% of maximum voluntary contraction, and pinch task muscle activity were assessed before and after rTMS. Functional-rTMS required subjects to exceed a muscle activation threshold to trigger each rTMS train; the passive-rTMS group received rTMS while relaxed.

RESULTS:

Significant interactions (time × condition) were observed in abductor pollicis brevis (APB) SICI, APB ICF, CV of force, and APB muscle activity. Functional-rTMS decreased APB SICI (p < 0.05) and increased ICF (p < 0.05) after stimulation, whereas passive-rTMS decreased APB muscle activity (p < 0.01) and decreased CV of force (p < 0.05). No changes were observed in FDI measures (EMG, ICF, SICI).

CONCLUSION(S):

Functional-rTMS increased motor cortex excitability, i.e., less SICI and more ICF for the APB muscle. Passive stimulation significantly reduced APB muscle activity and improved steadiness.

SIGNIFICANCE:

Functional-rTMS promoted greater excitability changes and selectively modulated agonist muscle activity.

PMID:
22999319
DOI:
10.1016/j.clinph.2012.07.026
[Indexed for MEDLINE]

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