http://nnr.sagepub.com/content/30/4/328?etoc
- Michelle L. Harris-Love, PhD1,2⇑
- Evan Chan, MS2
- Alexander W. Dromerick, MD1,2,3
- Leonardo G. Cohen, MD4
- 1Georgetown University Medical Center, Washington, DC, USA
- 2MedStar National Rehabilitation Hospital, Washington, DC, USA
- 3District of Columbia VA Medical Center, Washington, DC, USA
- 4Human Cortical Physiology and Neurorehabilitation Section, NINDS, NIH, Bethesda, MD, USA
- Michelle L. Harris-Love, PhD, 102 Irving Street NW, Room 1058, Washington, DC 20010, USA. Email: Mh672@georgetown.edu
Abstract
In well-recovered stroke patients with
preserved hand movement, motor dysfunction relates to interhemispheric
and intracortical
inhibition in affected hand muscles. In less fully
recovered patients unable to move their hand, the neural substrates of
recovered arm movements, crucial for performance of
daily living tasks, are not well understood. Here, we evaluated
interhemispheric
and intracortical inhibition in paretic arm muscles
of patients with no recovery of hand movement (n = 16, upper extremity
Fugl-Meyer Assessment = 27.0 ± 8.6). We recorded
silent periods (contralateral and ipsilateral) induced by transcranial
magnetic
stimulation during voluntary isometric contraction
of the paretic biceps and triceps brachii muscles (correlates of
intracortical
and interhemispheric inhibition, respectively) and
investigated links between the silent periods and motor recovery, an
issue
that has not been previously explored. We report
that interhemispheric inhibition, stronger in the paretic triceps than
biceps
brachii muscles, significantly correlated with the
magnitude of residual impairment (lower Fugl-Meyer scores). In contrast,
intracortical inhibition in the paretic biceps
brachii, but not in the triceps, correlated positively with motor
recovery
(Fugl-Meyer scores) and negatively with spasticity
(lower Modified Ashworth scores). Our results suggest that
interhemispheric
inhibition and intracortical inhibition of paretic
upper arm muscles relate to motor recovery in different ways. While
interhemispheric
inhibition may contribute to poorer recovery,
muscle-specific intracortical inhibition may relate to successful motor
recovery
and lesser spasticity.
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