Post-stroke reorganization of hand motor area: a 1-year prospective follow-up with focal transcranial magnetic stimulation.
OBJECTIVE
Focal transcranial magnetic stimulation was used to test prospectively corticospinal excitability changes and reorganization of first dorsal interosseous (FDI) motor cortical representation in 31 patients who experienced a first ischemic stroke in the middle cerebral artery territory. All had severe hand palsy at onset.


METHODS
Patients were assessed clinically with the Medical Research Council, Rankin, the National Institutes of Health stroke scales and Barthel Index at days 1, 8, 30, 90, 180 and 360 after stroke. The following parameters of FDI motor evoked potential (MEPS) to focal transcranial magnetic stimulation were measured at the same delays: motor threshold, MEP amplitude, excitable cortical area, hot spot and center of gravity of FDI motor maps on affected and unaffected hemispheres. Correlations were sought between clinical and electrophysiological parameters.


RESULTS
In patients whose affected motor cortex remained excitable at day 1, motor thresholds were not significantly different between sides and were similar to those of controls. Persistence of MEP on the affected side at day 1 was a strong predictor of good recovery. If present at day 1, MEPs recorded in affected FDI were significantly smaller than of the opposite side or in normals and progressively recovered up to day 360. In these patients, area of excitable cortex remained stable throughout the entire study. At day 1, amplitudes of MEPs obtained in unaffected FDI were significantly larger than later. Between days 1 and 360, we observed a significant displacement of center of gravity of motor maps towards more frontal regions on the affected side while no change was noted on the unaffected side.


CONCLUSIONS
Our data confirm the early prognosis value of transcranial magnetic stimulation in stroke. They indicate that the brain insult induces a transient hyperexcitability of the unaffected motor cortex. The evolution of FDI motor maps along the course of recovery mostly reflect corticospinal excitability changes but might also reveal some degree of brain plasticity. Most modifications observed occurred within 3 months of stroke onset.
Delvaux
Valérie
V
University Department of Neurology, Hôpital de la Citadelle, Boulevard du XIIème de Ligne, 1, B-4000 Liège, Belgium.
Alagona
Giovanna
G
Gérard
Pascale
P
De Pasqua
Victor
V
Pennisi
G
G
de Noordhout
Alain Maertens
AM
D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D001931:Brain Mapping; D016022:Case-Control Studies; D004558:Electric Stimulation / Q000379:methods*; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D005500:Follow-Up Studies; D006225:Hand / Q000502:physiology*; D018737:Hand Strength / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology; D011446:Prospective Studies; D020127:Recovery of Function / Q000502:physiology*; D020521:Stroke / Q000503:physiopathology* / Q000628:therapy*; D013997:Time Factors; D050781:Transcranial Magnetic Stimulation