Epicritic Sensation in Cervical Spinal Cord Injury: Diagnostic Gains Beyond Testing Light Touch

Abstract

Abstract Applied as a bedside test of gross dorsal column function, the testing of light touch (LT) sensation is of high clinical value in the diagnosis of human spinal cord injury (SCI). However, the assessment of overall dorsal column deficit by testing only LT may be limited, because the dorsal column pathway conveys several large diameter afferent modalities (e.g., sensation of touch, two-point discrimination, and proprioception). Therefore, the objective of this study was to compare the epicritic sensation assessed by LT, Semmes-Weinstein monofilament (SWM), and electrical perception threshold (EPT) across cervical dermatomes (C3-C8) in individuals with cervical SCI. A multicenter cross-sectional study was performed at 6 months after cervical SCI, applying combined measures of LT, SWM, and EPT, bilaterally over predefined key sensory points (C3-C8). A total of 300 left- and right-sided dermatomes were tested for each outcome measure in 25 participants. The percentage agreement between classifications according to LT and SWM/EPT testing for all dermatomes between C3 and C8 ranged from 95.5% to 36.2%. The degree of agreement showed considerably variable κ coefficients (-0.1≥kw≤0.7) for each dermatome between C3 and C8. The additional measurements of epicritic sensation by SWM and EPT increased sensitivity by detecting and quantifying differences in sensory thresholds above, at, and below the LT level of injury. This is relevant for early clinical trials (phase 1/2), in which disclosing any biological activity of an intervention may be revealed by subtle sensory changes that might gain a clinical relevance.