Using Sympathetic Skin Responses in Individuals With Spinal Cord Injury as a Quantitative Evaluation of Motor Imagery Abilities

Motor imagery (MI) ability should be evaluated in selected individuals with spinal cord injury (SCI) who can benefit from MI training in their rehabilitation program. Electrodermal activity seems to be a reliable indicator for assessing MI ability. However, individuals with SCI have a variety of autonomic dysfunctions. This study aimed to investigate electrodermal responses (EDRs) elicited by MI. A cost-utility analysis of EDR above and below the lesion level in individuals with complete or incomplete SCI (n = 30) versus a control group of individuals who were healthy (n = 10) was used. The EDR was recorded above and below the lesion level during MI of a drinking action. Duration, latency, and amplitude of EDR were the outcome measures. Hand and foot EDR in the control group occurred with the same pattern and similar latencies, suggesting a common efferent sympathetic pathway to sweat glands of the hand and foot mediating a sympathetic skin response. Individuals with SCI elicited responses above the lesion level. The EDR amplitude was correlated to the lesion level and autonomic dysreflexia history. No foot response was recorded in individuals with complete cervical and thoracic motor lesions. Foot response with a lower amplitude and higher latency occurred in participants with incomplete motor lesion, suggesting a link between the descending motor pathway and sympathetic function. The small sample of individuals with incomplete SCI limits the generalization of the results obtained at the foot site. Electrodermal response above the lesion level may be a reliable index for assessing MI ability in individuals with SCI. It is a noninvasive, user-friendly method for clinicians to consider before enrolling individuals in MI training.