Use of Point-of-care Neuro-sacral Electrophysiology Following Spinal Cord Injury

Overview

Assessing the sacral nerves is an integral aspect of the evaluation after a spinal cord injury. Being located at the lower end of the spinal cord, the sacral nerves reflect how signals travel through the injured spinal cord. Sacral assessment is therefore essential to determine the level and severity of the spinal cord injury, which helps selecting the proper treatment and predicting recovery (worse when abnormal sacral function. The current assessment relies solely on a manual evaluation, which depends heavily on the physician's experience and does not provide any quantitative value of the dysfunction. The lack of a quantitative method adapted to the clinical setting is a major barrier limiting our knowledge on the impact of sacral function on recovery. We have recently developed an electrophysiological method providing quantitative sacral assessment at bedside after spinal cord injuries. Using this method, we will quantify sacral function in 250 patients with acute spinal cord injuries, and determine its association with recovery 6 months post-injury. We hypothesize that sacral function assessed early within the first 6 weeks after the injury with our method is associated with a better 6-month recovery of motor, sensory, bowel and bladder function. Our objectives are to assess the changes is sacral function during the first 6 months after the injury, and the relationship between early sacral function and 6-month recovery. Sacral function and recovery will be assessed up to 6 months post-injury by the attending physician, in order to measure the electromyographic magnitude of voluntary anal contraction, electromyographic magnitude of anal contraction elicited through sacral reflex testing, and minimal electrical stimulation for which anal sensation is present. The analysis will determine if and how sacral function evolves in time, and if there are specific quantitative criteria of sacral function that physicians can use to determine if patient will have a favorable recovery.

BACKGROUND: Following spinal cord and cauda equina injuries, clinicians perform a neuro-sacral assessment to establish the injury severity, select proper treatment and rehabilitation needs (neuro-sacral dysfunction is an indication for surgery and requires rehabilitation in a specialized facility), and predict recovery. Current assessments rely on a qualitative digital rectal evaluation, which lacks sensitivity and depends heavily on the clinician's experience. Our previous findings suggest that assessing acute neuro-sacral function within the first days post-injury provides important insights on motor, sensory and bowel/bladder recovery. However, the lack of an accessible quantitative evaluation method adapted to the clinical setting is a major barrier limiting our knowledge on neuro-sacral function, hampering the improvement in care management. We have recently validated an quantitative electrophysiological method to assess neuro-sacral function at bedside that preserves the key assessments of the manual evaluation (anal contraction/sensation and sacral reflexes) and eliminates the need to insert the finger into the rectum while being more sensitive to detect changes in neuro-sacral function. GOALS: We believe that using a quantitative evaluation method is an essential step for optimizing the neurological assessment by clinicians, and for underpinning the impact of early neuro-sacral function on long-term recovery. We therefore hypothesize that acute neuro-sacral function is associated with motor, sensory and bowel/bladder recovery 6 months post-injury. The specific aims are: 1. Assess longitudinal neuro-sacral function for 6 months post-injury. 2. Assess the relationship between neuro-sacral function and neurofunctional recovery, in order to identify clinical phenotypes of neuro-sacral function and quantitative thresholds associated with improved recovery. METHODS: For this 4-year longitudinal study, neuro-sacral function and recovery will be assessed in 450 individuals 1, 2, 6 weeks and 6 months after an acute spinal cord and cauda equina injuries. Neuro-sacral assessments will be performed by the attending physiatrist to measure the 1) electromyographic signal amplitude of voluntary anal contraction, 2) electromyographic signal amplitude of anal contraction elicited through anal reflex testing, and 3) perianal electrical perceptual threshold. Study endpoints 6 months post-injury include the improvement in neurological status (primary endpoint: 10-point improvement in motor score) and bowel/bladder function. Longitudinal changes in neuro-sacral function will be characterized from ANOVA. Classification and regression tree analysis will be used to identify clinical phenotypes and objective quantitative thresholds. EXPECTED OUTCOMES: By implementing an accessible point-of-care quantitative method to assess neuro-sacral function in the clinical setting, we have a real potential to transform the care standards for spinal cord and cauda equina injuries, and improve the efficiency and accuracy for identifying of neuro-sacral dysfunction. We will improve our understanding of the early changes in neuro-sacral dysfunction, therefore bringing new knowledge on the predictors of recovery. We will identify clinical phenotypes of neuro-sacral function and propose objective threshold values to help clinicians identifying proper care trajectory and optimize resources use, using an accessible and validated method that is well tolerated by patients.