Shawn Marshall MD MSc FRCPC, Shannon Janzen MSc, Jo-Anne Aubut BA, Scott Janssen MSc, Robert Teasell MD FRCPC
The primary cause of motor impairment and movement dysfunction post acquired brain injury (ABI) is upper motor neuron syndrome (UMNS). The former results in both positive symptoms of enhanced stretch reflexes (spasticity), released flexor reflexes in the lower limbs, such as the Babinski sign and mass synergy patterns, as well as negative symptoms including loss of dexterity and weakness (Mayer 1997).These symptoms of UMNS have physiologic implications for muscles that may subsequently develop stiffness and contracture, thereby negatively affecting effective movement even further (Mayer 1997).
For UMNS following brain injury, both the extent and timing of the individual’s symptoms should be considered when deciding on a course of action. Focal or diffuse spasticity may appear following an ABI and frequently follow common patterns in the upper and lower limbs (Mayer 1997). Time post injury is another important consideration. Spontaneous neurological recovery may continue for up to 9 to 15 months post injury; however, the potential for functional motor recovery beyond that point is possible with intervention, such as correction of deformity or medication interventions that allow for improved motor control (Mayer et al. 1996). Motor impairment can also result from the independent effects of prolonged immobilization and bed rest in the acute period. Prolonged immobility effects multiple body systems, although it is the direct effects on the musculoskeletal system and the cardiovascular system that impact motor function the most (Bushbacher & Porter 2000).
Following diffuse central nervous system injury, there are potential impairments involving the cognitive, behavioral and physical domains. It is the physical domain that is emphasized early on within the rehabilitation process. Most acute in-patient rehabilitation programs focus on activities of daily living which are commonly assessed by outcome measures such as the Functional Independence Measure or the Barthel Index (Linacre et al. 1994; McDowell 2006). The emphasis on physical impairments during rehabilitation is common as both the patient and family members are more likely to recognize and acknowledge physical impairments, in contrast to cognitive and behavioral impairments.