An 8-year longitudinal study of muscle strength, muscle fiber size, and dynamic electromyogram in individuals with late polio.
Twenty-one subjects with polio 24 to 51 years prior to the first examination were studied on three occasions, each 4 years apart with measurements of muscle strength and endurance for knee extension, macro EMG, and muscle biopsy from vastus lateralis. On average the muscle strength decreased during the 8-year follow-up by 9-15%. Endurance decreased during the observation period. The muscle fiber area was markedly increased in most subjects. There was a decrease in the capillarization during the follow-up. Macro EMG was increased in all subjects (range 3-42 times control) and increased in 20 legs during the 8-year follow-up, but showed a decrease in 8 of 9 legs with an approximative breakpoint when macro MUPs were around 20 times the normal size. Thus, evidence of on-going denervation/reinnervation as well as of failing capacity to maintain large motor units was demonstrated. SFEMG showed a moderate degree of disturbed neuromuscular transmission.
Grimby
G
G
Department of Rehabilitation Medicine, Sahlgrenska University Hospital, Göteborg University, Sweden.
Stålberg
E
E
Sandberg
A
A
Sunnerhagen
K S
KS
D000328:Adult; D000368:Aged; D001706:Biopsy; D002950:Citrate (si)-Synthase / Q000032:analysis; D004576:Electromyography; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009046:Motor Neurons / Q000502:physiology / Q000821:virology*; D009119:Muscle Contraction / Q000502:physiology; D018485:Muscle Fibers, Skeletal / Q000201:enzymology* / Q000473:pathology; D018908:Muscle Weakness / Q000503:physiopathology; D018482:Muscle, Skeletal / Q000294:innervation / Q000473:pathology / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology; D011051:Poliomyelitis / Q000503:physiopathology*; D019415:Torque
D002950:Citrate (si)-Synthase