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Hemiparetic muscle atrophy and increased intramuscular fat in stroke patients
Alice S Ryan1, C Lynne Dobrovolny, Gerald V Smith
1Department of Medicine, Division of Gerontology, University of Maryland School of Medicine, Baltimore, MD, USA. aryan@grecc.umaryland.edu
Objective:
To determine if skeletal muscle atrophy and greater fat deposition within the muscle are present in the hemiparetic limb of chronic (>6 mo) hemiparetic stroke patients.
Design:
Cross-sectional study.
Setting:
Hospital-based research center.
Participants:
Sixty patients (47 men, 13 women; mean age +/- standard deviation, 65+/-9 y).
Interventions:
Not applicable.
Main Outcome Measures:
Patients underwent a total body scan by dual-energy x-ray absorptiometry to determine percentage of body fat, total lean mass, fat mass, and lean mass of the paretic and nonaffected legs, thighs, and arms. Thirty patients received computed tomography (CT) scans of their midthigh to determine muscle area, subcutaneous fat, and low-density lean tissue, as a measure of fat within the muscle area, of the paretic and nonaffected midthigh.
Results:
Patients were deconditioned (VO(2)peak: 1.2+/-0.3 L/min) with a percentage of body fat of 31.4%+/-9.8% and total lean mass of 51.4+/-9.1 kg. Lean mass of the paretic leg and thigh were 4% and 3% lower than the nonaffected leg (P<.001), but leg fat was not different. Arm lean mass of the paretic side was 7% lower than the nonaffected side, whereas arm fat was not different. CT studies showed that midthigh muscle area was 20% lower in the paretic limb than in the nonaffected leg (P<.001), midthigh subcutaneous fat was similar, and midthigh low-density lean tissue showed a trend to be 3% higher in the paretic leg (P=.06). The ratio of midthigh low-density lean tissue to muscle area was higher in the paretic leg (P<.001), which indicates a greater intramuscular fat relative to muscle area in the affected limb.
Conclusions:
Our results show hemiparetic skeletal muscle atrophy and more fat within the muscle, factors that may contribute to functional disability and increased cardiovascular disease risk in chronic hemiparetic stroke patients.