Corticomotor organisation and motor function in multiple sclerosis.
Our objective was to determine whether there are changes in the corticomotor map for the hand in multiple sclerosis, and whether these changes correlate with indices of motor function and measures of corticomotor conduction or excitability. Transcranial magnetic stimulation (TMS) maps, motor evoked potential (MEP) latency and amplitude, motor threshold and EDSS and Purdue-pegboard measurements were made in 26 subjects with relapsing-remitting multiple sclerosis. Correlations were sought between these measurements using the Pearson product-moment correlation with a level of significance of p = 0.05 (two-tailed). Map displacement was positively correlated with MEP latency (p = 3 x 10(-4)) and EDSS (p = 0.007), and negatively correlated with Purdue score (p = 4 x 10(-4)). Purdue scores correlated with all MEP parameters (latency, p = 4 x 10(-10); threshold, p = 4 x 10(-6); amplitude, p = 0.003). We conclude that motor reorganisation is associated with impaired corticomotor conduction and may reflect a process of neural plasticity associated with axonal demyelination in MS. An understanding of motor function in MS should incorporate models of both axonal demyelination and conduction deficits as well as neural plasticity.
Thickbroom
Gary W
GW
Centre for Neuromuscular and Neurological Disorders M518, University of Western Australia, Queen Elizabeth II Medical Centre, Nedlands, WA 6009, Australia. gthickbr@cyllene.uwa.edu.au
Byrnes
Michelle L
ML
Archer
Sarah A
SA
Kermode
Allan G
AG
Mastaglia
Frank L
FL
D000328:Adult; D000368:Aged; D001931:Brain Mapping; D004056:Differential Threshold / Q000528:radiation effects; D004185:Disability Evaluation; D004558:Electric Stimulation / Q000379:methods; D019054:Evoked Potentials, Motor / Q000502:physiology* / Q000528:radiation effects; D005260:Female; D006801:Humans; D008280:Magnetics; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000473:pathology / Q000503:physiopathology* / Q000528:radiation effects; D009103:Multiple Sclerosis / Q000473:pathology / Q000503:physiopathology* / Q000628:therapy; D009460:Neurologic Examination / Q000379:methods; D011930:Reaction Time / Q000502:physiology / Q000528:radiation effects; D013223:Statistics as Topic / Q000379:methods