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The natural history of central motor abnormalities in amyotrophic lateral sclerosis.
Brain. 2003 Nov; 126(Pt 11):2558-66.B

Abstract

Degeneration of spinal motoneurons has been well documented in amyotrophic lateral sclerosis (ALS), but the evolution of central motor abnormalities is largely unknown. It has been suggested that glutamate-mediated neuroexcitotoxicity may be involved in the pathogenesis of ALS and that this may be manifest as an increase in corticomotor excitability early in the disease. Serial measurements of corticomotor threshold, central motor conduction time (CMCT), silent period duration and the amplitude of compound muscle action potentials (CMAPs) from ulnar nerve stimulation in the right and left first dorsal interosseous muscles were made in 76 patients with idiopathic ALS, 49 of whom were followed from presentation to death. Threshold to transcranial magnetic stimulation was determined by standard methods and CMCT was measured using the F-wave method. Silent period was estimated during a small background contraction of the muscle. Patients were classified according to the region of onset and the physical signs in the hands. The region of onset was bulbar in 17 patients, lower limb in 31 patients and upper limb in 28 patients. At presentation, 23 patients had no abnormal physical signs in the hands, 25 had lower motoneuron signs only, 14 had upper motoneuron signs only and the remainder (14) had mixed upper and lower motoneuron signs in the hands. Evolution of the central conduction parameters was determined in relation to time from onset of symptoms and also as a function of normalized total disease duration in the patients who had died. Corticomotor threshold and CMCT showed no change as the disease evolved except for patients with mixed signs, who had a terminal increase in threshold and prolongation of CMCT. Silent period duration was shorter than normal early in the disease and showed progressive lengthening throughout the illness, but nevertheless remained within the normal range regardless of the region of onset. CMAP amplitude showed a linear decline over the course of the disease. There was therefore no evidence of a phase of increased corticomotor hyperexcitability at any stage of disease progression. The early shortening of silent period, however, probably represents a shift in the balance of excitatory and inhibitory inputs to the cortical output cells responsible for voluntary action, and could be a reflection of degeneration of cortical interneurons. None of the measures of central motor function in ALS are likely to be useful for monitoring patients in a clinical trial setting.

Authors+Show Affiliations

Academic Unit of Clinical Neurophysiology, Guy's, King's and St Thomas' School of Medicine, King's College Hospital, London UK. K.Mills@iop.kcl.ac.uk

Pub Type(s)

Journal Article

Language

eng

PubMed ID

12937082

Citation

Mills, K R.. "The Natural History of Central Motor Abnormalities in Amyotrophic Lateral Sclerosis." Brain : a Journal of Neurology, vol. 126, no. Pt 11, 2003, pp. 2558-66.
Mills KR. The natural history of central motor abnormalities in amyotrophic lateral sclerosis. Brain. 2003;126(Pt 11):2558-66.
Mills, K. R. (2003). The natural history of central motor abnormalities in amyotrophic lateral sclerosis. Brain : a Journal of Neurology, 126(Pt 11), 2558-66.
Mills KR. The Natural History of Central Motor Abnormalities in Amyotrophic Lateral Sclerosis. Brain. 2003;126(Pt 11):2558-66. PubMed PMID: 12937082.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The natural history of central motor abnormalities in amyotrophic lateral sclerosis. A1 - Mills,K R, Y1 - 2003/08/22/ PY - 2003/8/26/pubmed PY - 2003/12/4/medline PY - 2003/8/26/entrez SP - 2558 EP - 66 JF - Brain : a journal of neurology JO - Brain VL - 126 IS - Pt 11 N2 - Degeneration of spinal motoneurons has been well documented in amyotrophic lateral sclerosis (ALS), but the evolution of central motor abnormalities is largely unknown. It has been suggested that glutamate-mediated neuroexcitotoxicity may be involved in the pathogenesis of ALS and that this may be manifest as an increase in corticomotor excitability early in the disease. Serial measurements of corticomotor threshold, central motor conduction time (CMCT), silent period duration and the amplitude of compound muscle action potentials (CMAPs) from ulnar nerve stimulation in the right and left first dorsal interosseous muscles were made in 76 patients with idiopathic ALS, 49 of whom were followed from presentation to death. Threshold to transcranial magnetic stimulation was determined by standard methods and CMCT was measured using the F-wave method. Silent period was estimated during a small background contraction of the muscle. Patients were classified according to the region of onset and the physical signs in the hands. The region of onset was bulbar in 17 patients, lower limb in 31 patients and upper limb in 28 patients. At presentation, 23 patients had no abnormal physical signs in the hands, 25 had lower motoneuron signs only, 14 had upper motoneuron signs only and the remainder (14) had mixed upper and lower motoneuron signs in the hands. Evolution of the central conduction parameters was determined in relation to time from onset of symptoms and also as a function of normalized total disease duration in the patients who had died. Corticomotor threshold and CMCT showed no change as the disease evolved except for patients with mixed signs, who had a terminal increase in threshold and prolongation of CMCT. Silent period duration was shorter than normal early in the disease and showed progressive lengthening throughout the illness, but nevertheless remained within the normal range regardless of the region of onset. CMAP amplitude showed a linear decline over the course of the disease. There was therefore no evidence of a phase of increased corticomotor hyperexcitability at any stage of disease progression. The early shortening of silent period, however, probably represents a shift in the balance of excitatory and inhibitory inputs to the cortical output cells responsible for voluntary action, and could be a reflection of degeneration of cortical interneurons. None of the measures of central motor function in ALS are likely to be useful for monitoring patients in a clinical trial setting. SN - 0006-8950 UR - https://www.unboundmedicine.com/medline/citation/12937082/The_natural_history_of_central_motor_abnormalities_in_amyotrophic_lateral_sclerosis_ L2 - https://academic.oup.com/brain/article-lookup/doi/10.1093/brain/awg260 DB - PRIME DP - Unbound Medicine ER -