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A novel central motor conduction abnormality in D90A‐homozygous patients with amyotrophic lateral sclerosis
Author(s) -
OseiLah Abena D.,
Turner Martin R.,
Andersen Peter M.,
Leigh P. Nigel,
Mills Kerry R.
Publication year - 2004
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.20032
Subject(s) - amyotrophic lateral sclerosis , motor cortex , corticospinal tract , medicine , transcranial magnetic stimulation , abnormality , pyramidal tracts , neuroscience , sod1 , stimulation , anatomy , magnetic resonance imaging , psychology , disease , psychiatry , diffusion mri , radiology
Patients with amyotrophic lateral sclerosis (ALS) who are homozygous for the D90A SOD1 mutation have been noted to have central motor abnormalities distinct from those of patients with idiopathic ALS. We stimulated the motor cortex of ten patients homozygous for the D90A SOD1 mutation, using transcranial magnetic stimulation (TMS), and recorded the response evoked in the right first dorsal interosseous muscle when the muscle was at rest and when voluntarily active. A subgroup of patients had two distinct evoked responses when the cortex was stimulated at high intensity with the muscle at rest. When the muscle was modestly contracted, the first of these responses disappeared, whereas the second response was facilitated. Both fast and slow components of the corticospinal tract were usually intact and excited by TMS in these patients. We propose that there is an abnormality of intracortical or intraspinal inhibition in a subgroup of D90A SOD1 ALS patients, which suppresses fast‐conducted activity when the muscle is active. Apart from further defining the phenotype of familial ALS, these findings may have importance in understanding the pathogenesis of central motor abnormalities in these patients. Muscle Nerve 29: 790–794, 2004