title: Weakness and fatigue in diverse neuromuscular diseases.
abstract: Weakness and fatigue are captured by the 6-minute walk test, but the relationship between these symptoms is uncertain. Comparison across neuromuscular diseases has not been examined. A cohort study of 114 patients with spinal muscular atrophy, Duchenne/Becker muscular dystrophy, myasthenia gravis, and energy failure syndromes were included. Percent-predicted distance on the 6-minute walk test was computed from normative values to determine weakness. Fatigue was determined by the decrement in distance from the first to sixth minute. Weakness was seen across all groups (61.9%) but significant fatigue was seen only in spinal muscular atrophy (21.0%). Other groups showed little fatigue. Correlation between weakness and fatigue was significant only in spinal muscular atrophy (R = -0.71; P < .001). Longitudinally, distance walked declined only in Duchenne/Becker muscular dystrophy. In spinal muscular atrophy, weakness did not change, but fatigue increased significantly. These findings suggest independent mechanisms underlying weakness and fatigue in diverse neuromuscular conditions.
authors.affiliation: 1Department of Neurology, Columbia University Medical Center, New York, NY, USA.
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Montes
authors.forename: Michelle
authors.initials: M
authors.lastname: Blumenschine
authors.forename: Sally
authors.initials: S
authors.lastname: Dunaway
authors.forename: Aliza S
authors.initials: AS
authors.lastname: Alter
authors.forename: Kristin
authors.initials: K
authors.lastname: Engelstad
authors.forename: Ashwini K
authors.initials: AK
authors.lastname: Rao
authors.forename: Claudia A
authors.initials: CA
authors.lastname: Chiriboga
authors.forename: Douglas M
authors.initials: DM
authors.lastname: Sproule
authors.forename: Darryl C
authors.initials: DC
authors.lastname: De Vivo
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D005080:Exercise Test; D005221:Fatigue / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018908:Muscle Weakness / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology; D009468:Neuromuscular Diseases / Q000150:complications* / Q000503:physiopathology
keywords: 6-minute walk test; fatigue; neuromuscular disease; spinal muscular atrophy; weakness