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Updated: Sep 13, 2026

Utility of Dissociated Intrinsic Hand Muscle Atrophy in the Diagnosis of Amyotrophic Lateral Sclerosis
Published on: March 4, 2014
Cortical muscle representation in amyotrophic lateral sclerosis patients: changes with disease evolution
M de Carvalho1, P C Miranda, M L Luís
1Department of Neurology, EMG Laboratory, Centro de Estudos Egas Moniz, Hospital de Santa Maria, Av. Prof. Egas Moniz, 1600 Lisbon, Portugal. mamedemg@mail.telepac.pt
Abstract:
Transcranial magnetic stimulation (TMS) mapping was performed regularly on 11 patients with amyotrophic lateral sclerosis (ALS). Map area decreased by 25% (P = 0.03) and normalized volume decreased by 47% (P = 0.01) in those patients who were mapped four times over a period of 11.6 months. The center of gravity (CoG) position moved randomly along the interaural line by distances larger than could be explained by experimental error (P = 0.002). Central conduction time, threshold, and motor evoked potential:compound muscle action potential (MEP:CMAP) amplitude ratio did not change significantly with time (P > 0.05). There were significant linear correlations between strength and CMAP amplitude and between map area and volume. No correlation was found between strength or CMAP amplitude and area or volume. The changes in map parameters were attributed primarily to loss of cortical cells. These results indicate that map parameters may be more sensitive to cortical neuronal loss than other TMS parameters.
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