Complications associated with immobility after acquired brain injury

Immobilization of the human body has long been known to affect physiology in ways detrimental to normal function since Hippocrates. For persons with acquired brain injury, immobilization may be worsened by disorders stemming from the brain injury itself such as posturing, spasticity, dysautonomia, endocrine abnormalities, and other body system injuries. Significant changes occur in the musculoskeletal system in the first 4-6 weeks of immobilization, including up to 40% loss of muscle strength, decrements in bone density, and shortening of collagen-containing tissues. Immobilization, specifically, is associated with a moderate decrease in bone resorption but an even larger decrease in mineralization of bone matrix. There is some evidence that some of the muscle atrophy and loss of oxidative capacity can be prevented by isometric exercise during the period of immobilization. There are reduced cortical responses after immobilization of a joint that are proportional to the length of time of immobilization.