Article

Mirror therapy provides a visual illusion of a normal moving limb by
using the mirror reflection of the unaffected arm instead of viewing the paretic
limb and is used in rehabilitation to improve hand function.
Little is known
about the mechanism underlying its effect in children with hemiparesis.
OBJECTIVE: To investigate the effect of the mirror illusion (MI)
on the
excitability of the primary motor cortex (M1) in children and adolescents.
METHODS: Twelve patients with hemiparesis (10-20 years) and 8 typically
developing subjects (8-17 years) participated. Corticospinal reorganization was
classified as contralateral (projection from contralateral hemisphere to affected
hand) or ipsilateral (projection from ipsilateral hemisphere to affected hand).
M1 excitability of the hemisphere projecting to the affected (nondominant in
typically developing subjects) hand was obtained during 2 different conditions
using single-pulse transcranial magnetic stimulation (TMS). Each condition
(without/with mirror) consisted of a unimanual and a bimanual task. Motor-evoked
potentials (MEPs) were recorded from the abductor pollicis brevis and flexor
digitorum superficialis muscles. RESULTS: MEP amplitudes were significantly
increased during the mirror condition ( P = .005) in typically developing
subjects and in patients with contralateral reorganization. No significant effect
of MI was found in subjects with ipsilateral reorganization. MI increased M1
excitability during active movements only. This increase was not correlated to
hand function. CONCLUSION: MI increases the excitability of M1 in hemiparetic
patients with contralateral corticospinal organization and in typically
developing subjects. This finding provides neurophysiological evidence supporting
the application of mirror therapy in selected children and adolescents with
hemiparesis.

Langue : ANGLAIS