Muscular, Skeletal, and Neural Adaptations Following Spinal Cord Injury

Abstract

Spinal cord injury is associated with adaptations to the muscular, skeletal, and spinal systems. Experimental data are lacking regarding the extent to which rehabilitative methods may influence these adaptations. An understanding of the plasticity of the muscular, skeletal, and spinal systems after paralysis may be important as new rehabilitative technologies emerge in the 21st century. Moreover, individuals injured today may become poor candidates for future scientific advancements (cure) if their neuromusculoskeletal systems are irreversibly impaired. The primary purpose of this paper is to explore the physiological properties of skeletal muscle as a result of spinal cord injury; secondarily, to consider associated changes at the skeletal and spinal levels.Muscular adaptations include a transformation to faster myosin, increased contractile speeds, shift to the right on the torque-frequency curve, increased fatigue, and enhanced doublet potentiation. These muscular adaptations may be prevented in individuals with acute paralysis and partially reversed in individuals with chronic paralysis. Moreover, the muscular changes may be coordinated with motor unit and spinal circuitry adaptations. Concurrently, skeletal adaptations, as measured by bone mineral density, show extensive loss within the first six months after paralysis. The underlying science governing neuromusculoskeletal adaptations after paralysis will help guide professionals as new rehabilitation strategies evolve in the future. J Orthop Sports Phys Ther 2002;32:65-74.

Bone Mineral Density After Spinal Cord Injury: A Reliable Method for Knee Measurement

“…For the hip, distal femur, and proximal tibia, BMD was lower in people with SCI, a finding that generally agrees with different measurement methods from previous reports. 3,11,12,24 No difference existed between the BMD of the 2 groups at the lumbar spine. One explanation for this dissociation between the lumbar spine and the hip is that during wheelchair use after SCI, the lower extremities receive very little loading.…”

“…Bone mineral density (BMD) of the paralyzed extremities declines precipitously in the first 2 years after SCI, eventually reaching a level below fracture threshold. [1][2][3][4] Between 1% and 6% of people with SCI will sustain fractures in their paralyzed extremities. [5][6][7] Fractures are often caused by trivial insults to the limbs 5,7,8 that people with SCI frequently encounter during everyday mobility.…”

Assessment of upper limb in tetraplegia: Considerations in evaluation and outcomes research

“…Previous investigators reported on electrophysiological changes that occur to peripheral and central structures following primary spinal insult [73][74][75][76][77][78][79][80][81]. While electrophysiological testing has been performed in SCI for predicting injury [74][75][82][83][84][85], examining the nature of neurological injury [71][72][86][87][88][89][90][91][92], monitoring the integrity of spinal conduction [77,[93][94], and assessing for concomitant or secondary neurological conditions [95][96][97][98][99], its role as a method of evaluating the impact of various interventions [65][66][81][82][100][101][102][103][104][105][106] is the concern of this article.…”

Resistance training and locomotor recovery after incomplete spinal cord injury: a case series

“…2,3 Improvements in functional ability, however, vary greatly and the incidence of disability remains high. 4,5 Previous data suggest that persons after incomplete SCI produce less voluntary torque about the knee and ankle than non injured controls. Perhaps more importantly, impairments in the ability to produce torque in a timely manner as well as a reduced walking velocity are also common to these persons.…”