The importance of early detection of spared corticospinal connections to improve functional abilities post-spinal cord injury: A case study

In Australia, 300-400 people sustain a spinal cord injury (SCI) annually. A detailed description of the impact of SCI on sensorimotor control is difficult to achieve with the current clinical assessment, the International Standard for Neurological Classification of Spinal Cord Injury (ISNCSCI). The ISNCSCI is a crude measure and is unable to identify all the spared corticospinal (CS) connections, which can be promoted through appropriate rehabilitation. In tetraplegics, evenmodest improvements in upper limb function can have a substantial impact on their lives. Although electrophysiological methods can complement the clinical evaluation by providing quantitative, objective data about conduction across the SCI site, these techniques are not used routinely in clinical practice. We recently assessed a patient with SCI (5 months post injury) using transcranial magnetic stimulation (TMS) in a rehabilitation centre, to explore the existence of spared CS projections to upper limb muscles, and thus the potential for regaining further functional abilities. His ISNCSCI assessment, categorized his injury as Complete A with neurological level of C4. Since the strength of his Triceps muscles on both sides was recorded as 0/5 during repeated assessments by his therapists, no therapeutic intervention was directed to these muscles during his rehabilitation. Motor evoked potentials were recorded easily from Triceps on both sides, which confirmed the existence of spared CS projections to control the activity of these muscles in this patient. He received EMG-triggered neuromuscular stimulation (10 minutes, x 3 per day) for three weeks. The strength of his Triceps gradually improved to 2/5 on both sides. The stable level of cortical excitability from preto post-training suggests that the improvement in muscle function occurred at the level of the muscle. Electrophysiological assessment can be useful in identifying residual function below the level of injury, which can, in turn, be enhanced through appropriate rehabilitation strategies.