Examining segmental sensory function and recovery in individuals with spinal cord injury using dermatomal somatosensory evoked potentials

More than 30,000 Canadians live with spinal cord injury (SCI). SCI often leads to devastating neurological deficits that markedly reduce quality of life and life expectancy. During the first year of SCI, individuals typically recover some sensory function. Sensory testing, an important component of early diagnosis and prognosis, is currently done with light touch and pin prick sensation tests. Though this method is valuable for quickly assessing sensory function, it has limitations: it is difficult to obtain reliable results from uncooperative or unconscious individuals, it does not provide a quantifiable measure of sensation, and does not identify minor changes in sensory function. In undamaged sensory pathways, electrical impulses are rapidly conducted along mixed nerves to the spinal cord, where they ascend in sensory pathways to the brain. Following SCI, the spinal cord is typically compressed and damaged but not completely severed, meaning an electrical signal can still be recorded from the brain. However, this signal is expected to be delayed and to undergo distinct changes in the path it follows to the brain. John Kramer is examining spinal cord conductivity during recovery, applying methods currently used in clinical neurology, but new to SCI practice. He is assessing conductivity at each level of the spine by stimulating specific areas of the skin’s surface with electrical current, and recording the activity with scalp electrodes. To describe the contribution of sensory function at each level to sensory recovery, he will conduct these tests multiple times over the first year of SCI. Kramer’s investigation will provide important information concerning sensory recovery following SCI. The results from this study will have implications for delivery of care for individuals with SCI, and will prove beneficial for determining the efficacy for future SCI interventional therapies