PREVALENCE OF DISCOMPLETE SENSORIMOTOR SPINAL CORD INJURY AS EVIDENCED BY NEUROPHYSIOLOGICAL METHODS: A CROSS-SECTIONAL STUDY

OBJECTIVES: To assess the prevalence of residual trans-lesion connectivity in persons with chronic clinically complete spinal cord injury (discompleteness) by neurophysiological methods. PARTICIPANTS: A total of 23 adults with chronic sensorimotor complete spinal cord injury, identified through regional registries the regional spinal cord registry of Östergötland, Sweden. METHODS: Diagnosis of clinically complete spinal cord injury was verified by standardized neurological examination. Then, a neurophysiological examination was performed, comprising electroneurography, electromyography, sympathetic skin response and evoked potentials (sensory, laser and motor). Based on this assessment, a composite outcome measure, indicating either strong, possible or no evidence of discomplete spinal cord injury, was formed. RESULTS: Strong neurophysiological evidence of discomplete spinal cord injury was found in 17% (4/23) of participants. If also accepting “possible evidence”, the discomplete group comprised 39% (9/23). The remaining 61% showed no neurophysiological evidence of discompleteness. However, if also counting reports of subjective sensation elicited during neurophysiological testing in the absence of objective findings, 52% (12/23) showed indication of discomplete spinal cord injury. CONCLUSION: Evidence of discomplete spinal cord injury can be demonstrated using standard neurophysiological techniques in a substantial subset of individuals with clinically complete spinal cord injury. This study adds to the evidence base indicating the potential of various modes of cross-lesional sensorimotor functional restoration in some cases of chronic clinically complete spinal cord injury. LAY ABSTRACT Spinal cord injuries are usually classed as complete or incomplete. A complete injury implies that no residual function exists below the neurological level of injury. This status is determined by standardized neurological examination and is thought to correlate with spinal cord function in each individual with spinal cord injuries. However, studies have indicated that, in some people with complete spinal cord injury, there may be residual function that is not detected by such testing. The aim of the current study was to examine whether residual function, which is not detected by such testing, exists, and, if so, how common it is among people with complete spinal cord injuries (based on clinical testing) in a chronic stage (>2 years since injury). A battery of neurophysiological tests was used. Signs of “subclinical” residual function were found in 17–39% of 23 participants. This finding may lead to improvements in rehabilitative outcomes for people with complete spinal cord injury.