title: The CMAP scan as a tool to monitor disease progression in ALS and PMA.
abstract: Amyotrophic lateral sclerosis (ALS) and progressive muscular atrophy (PMA) are characterized by a loss of motor units (MUs), reinnervation and, eventually, muscle fibre loss. These three aspects are all reflected in the compound muscle action potential scan (CMAP scan, a high-detail stimulus response curve), which visualizes large MU potentials as 'steps'. We explored changes in the CMAP scan over time, combined the information on steps and CMAP amplitude into a CMAP scan-based progression score (CSPS), and correlated this score with motor unit number estimates (MUNE). Ten patients (three PMA, seven ALS; age 37-77 years) were included. CMAP scan and MUNE measurements were performed five times during a three-month period. Nine patients had additional measurements. The follow-up period was 3-24 months. Results demonstrated that abnormalities in steps preceded a decline in maximum CMAP amplitude during follow-up. Usually, both steps and maximum CMAP amplitude changed between recordings. The correlation between the CSPS and MUNE was -0.80 (p < 0.01). In conclusion, the CMAP scan can be used to visualize and quantify disease progression in a muscle affected by MND. The CSPS is a measure of MU loss that is quick and easy to obtain and that, in contrast to MUNE, has no sample bias.
authors.affiliation: Department of Clinical Neurophysiology, Erasmus MC, University Medical Centre Rotterdam, The Netherlands.
authors.forename: Ellen M
authors.initials: EM
authors.lastname: Maathuis
authors.forename: Judith
authors.initials: J
authors.lastname: Drenthen
authors.forename: Pieter A
authors.initials: PA
authors.lastname: van Doorn
authors.forename: Gerhard H
authors.initials: GH
authors.lastname: Visser
authors.forename: Joleen H
authors.initials: JH
authors.lastname: Blok
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000328:Adult; D000368:Aged; D000690:Amyotrophic Lateral Sclerosis / Q000175:diagnosis / Q000503:physiopathology*; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009134:Muscular Atrophy, Spinal / Q000175:diagnosis / Q000503:physiopathology*