Skeletal muscle atrophy and increased intramuscular fat after incomplete spinal cord injury

Abstract

Study design: Cross-sectional and longitudinal design. Objectives: (1) To quantify skeletal muscle cross-sectional area (CSA) after correcting for intramuscular fat (IMF) in thigh muscle groups 6 weeks after incomplete spinal cord injury (SCI), (2) to monitor the changes in muscle CSA and IMF after 3 months from the initial measurement. Setting: Academic institution Athens, GA, USA. Methods: Six incomplete SCI patients (28±4 years, 178±5 cm and 78±6 kg, mean±SE, C7 to L3, American Spinal Injury Association B or C) were tested at 5±1 weeks and 3 months after the initial measurement. T1-weighted magnetic resonance images were taken of both thighs. Six able-bodied (AB) controls were matched in age, sex, height and weight (29±4 years, four male and two female subjets, 179±5 cm and 77±6 kg). Results: At 6 weeks post-injury, muscle CSA was 82±4 cm² in incomplete SCI and 123±21 cm² in AB controls (P=0.04). IMF CSA was 5.2±1.3 and 2.3±0.6 cm² in incomplete SCI and AB controls, respectively (P=0.03). Relative IMF was three-fold higher (P=0.03) in the SCI group versus AB controls (5.8±1.4 versus 2.0±0.6%). After 3 months, IMF increased 26% in the SCI group compared to the initial measurement (P=0.02). Conclusions: Skeletal muscle atrophy is associated with greater IMF accumulation in SCI group 6 weeks post-injury compared to AB controls. Moreover, IMF continues to increase over time in incomplete SCI.