P. Cicinelli et al., POSTSTROKE REORGANIZATION OF BRAIN MOTOR OUTPUT TO THE HAND - A 2-4 MONTH FOLLOW-UP WITH FOCAL MAGNETIC TRANSCRANIAL STIMULATION, ELECTROMYOGRAPHY AND MOTOR CONTROL-ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY, 105(6), 1997, pp. 438-450
Focal transcranial magnetic stimulation (TCS) was employed for the rep
resentation of the motor cortex in a population of 18 patients to inve
stigate the functional properties of hand motor areas 2-4 months after
a monohemispheric stroke. Eleven sites were stimulated to elicit moto
r evoked potentials (MEPs) in abductor digiti minimi muscle after TCS
of affected (AH) and unaffected (UH) hemispheres; recording sessions w
ere performed al the beginning (T1) and after 8-10 weeks (T2) of neuro
rehabilitation. Barthel index and Canadian neurological scale scores w
ere evaluated. A group of 20 healthy control subjects was enrolled. In
stroke patients the AH was less excitable than normal, combined with
a decrease in motor cortical output area (P < 0.05) in T1. In T2, ther
e was an enlargement of the: hand motor area on the AH combined with a
n improvement of clinical scores (P < 0.001). In T1 and T2, the amplit
ude of MEPs in the AH was reduced (P < 0.001) with a prolongation of c
entral conduction time (P < 0.001) and with a tendency towards improve
ment in T2; the amplitude of contracted MEPs was larger than normal in
the UH in T1. Both in T1 and T2, anomalous 'hot spot' (most excitable
) scalp sites, never seen in normals, were often encountered (T2 > T1)
on the AH and UH. Interhemispheric differences for topography and lat
ency of MEPs were remarkably affected, Our data are consistent with a
rearrangement of the brain motor cortical output between 2 and 4 month
s following stroke. The amelioration of the neurophysiological paramet
ers was correlated with clinical improvement in disability and neurolo
gical scores. This study confirms the existence in adults of brain 'pl
asticity' still operating between 2 and 4 months from an acute vascula
r monohemispheric insult. (C) 1997 Elsevier Science Ireland Ltd.