Compound muscle action potential and motor function in children with spinal muscular atrophy.
Reliable outcome measures that reflect the underlying disease process and correlate with motor function in children with SMA are needed for clinical trials. Maximum ulnar compound muscle action potential (CMAP) data were collected at two visits over a 4-6-week period in children with SMA types II and III, 2-17 years of age, at four academic centers. Primary functional outcome measures included the Modified Hammersmith Functional Motor Scale (MHFMS) and MHFMS-Extend. CMAP negative peak amplitude and area showed excellent discrimination between the ambulatory and non-ambulatory SMA cohorts (ROC = 0.88). CMAP had excellent test-retest reliability (ICC = 0.96-0.97, n = 64) and moderate to strong correlation with the MHFMS and MHFMS-Extend (r = 0.61-0.73, n = 68, P < 0.001). Maximum ulnar CMAP amplitude and area is a feasible, valid, and reliable outcome measure for use in pediatric multicenter clinical trials in SMA. CMAP correlates well with motor function and has potential value as a relevant surrogate for disease status.
Lewelt
Aga
A
Division of Physical Medicine and Rehabilitation, University of Utah School of Medicine, Salt Lake City, Utah 84132, USA. aga@genetics.utah.edu
Krosschell
Kristin J
KJ
Scott
Charles
C
Sakonju
Ai
A
Kissel
John T
JT
Crawford
Thomas O
TO
Acsadi
Gyula
G
D'anjou
Guy
G
Elsheikh
Bakri
B
Reyna
Sandra P
SP
Schroth
Mary K
MK
Maczulski
Jo Anne
JA
Stoddard
Gregory J
GJ
Elovic
Elie
E
Swoboda
Kathryn J
KJ
D000200:Action Potentials / Q000502:physiology*; D000293:Adolescent; D002331:Carnitine / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D004576:Electromyography; D005260:Female; D018682:GABA Agents / Q000627:therapeutic use; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology; D018482:Muscle, Skeletal / Q000503:physiopathology*; D012372:ROC Curve; D015203:Reproducibility of Results; D014897:Spinal Muscular Atrophies of Childhood / Q000188:drug therapy / Q000503:physiopathology*; D016896:Treatment Outcome; D014459:Ulnar Nerve / Q000503:physiopathology; D014635:Valproic Acid / Q000627:therapeutic use
D018682:GABA Agents; D014635:Valproic Acid; D002331:Carnitine