ABSTRACT
The aim of this study was to evaluate and compare the reorganization of corticospinal pathways innervating upper extremity muscles in patients with spastic hemiplegic cerebral palsy (CP). Thirty-2 patients (17 male, 15 female) with spastic hemiplegic CP were enrolled. The average age (mean ± standard deviation) was 7.5 ± 4.6 (range: 2–17) years. Transcranial magnetic stimulation (TMS) was applied to the unaffected and affected motor cortices in turn, and bilateral electromyographic recordings were made from the first dorsal interossei (FDI), the biceps brachii (BB), and the deltoid muscles during rest. The onset latency, central motor conduction time, and peak-to-peak amplitude of motor evoked potentials (MEPs) were measured for each muscle bilaterally. Whilst TMS of both affected and unaffected hemispheres elicited contralateral MEPs in all muscles, the number of MEPs evoked from the affected hemisphere was less than from the unaffected hemisphere for FDI and BB. TMS responses to stimulation of the affected side showed prolonged latency and reduced amplitude. The amplitudes of MEPs increased with age whereas the latencies were relatively constant. These results suggest that the corticospinal pathways to the proximal and distal muscles of the upper extremity undergo sequential maturation and reorganization patterns.