Time-Dependent Discrepancies between Assessments of Sensory Function after Incomplete Cervical Spinal Cord Injury

Abstract

We recently demonstrated that the electrical perceptual threshold (EPT) examination reveals spared sensory function at lower spinal segments compared with the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) examination in humans with chronic incomplete cervical spinal cord injury (SCI). Here, we investigated whether discrepancies in sensory function detected by both sensory examinations change over time after SCI. Forty-five participants with acute (<1 year), chronic (≥1-10 years), and extended-chronic (>10 years) incomplete cervical SCI and 30 control subjects were tested on dermatomes C2-T4 bilaterally. EPT values were higher in subjects with acute (2.5 ± 0.8 mA), chronic (2.2 ± 0.7 mA), or extended-chronic (2.8 ± 1.1 mA) SCI compared with controls (1.0 ± 0.1 mA). The EPT examination detected sensory impairments in spinal segments above (2.3 ± 0.9) and below (4.2 ± 2.6) the level detected by the ISNCSCI sensory examination in participants with acute and chronic SCI, respectively. Notably, both examinations detected similar levels of spared sensory function in the extended-chronic phase of SCI (0.8 ± 0.5). A negative correlation was found between differences in EPT and ISNCSCI sensory levels and time post-injury. These observations indicate that discrepancies between EPT and ISNCSCI sensory scores are time-dependent, with the EPT revealing impaired sensory function above, below, or at the same spinal segment as the ISNCSCI examination. We propose that the EPT is a sensitive tool to assess changes in sensory function over time after incomplete cervical SCI.

Cerebellar contribution to sensorimotor adaptation deficits in humans with spinal cord injury

“…Specifically, participants with injuries for more years showed larger cerebellar atrophy than individuals with injures for fewer years. This agrees with recent results showing that differences exist in proprioceptive function in humans who had SCI for more and less than 10 years 54 . It is also possible that aging contributed to our results.…”

“…In control subjects, we tested the dominant arm and in participants with SCI, we tested the “more affected arm”. SCI largely damages both sides of the spinal cord resulting in asymmetrical deficits in sensory and motor function 54 , 74 . Thus, the handedness of SCI participants is affected by the injury 76 .…”

Brain Gray Matter Atrophy after Spinal Cord Injury: A Voxel-Based Morphometry Study

“…The duration of the disease was from 1 month to 33 years, with a mean of 5.2 ± 8.7 years. The SCI group was divided into complete SCI (CSCI) group (10 cases) and incomplete SCI (ISCI) group (11 cases) based on the injury severity, and into sub-acute (duration 1–12 months; 8 cases) and chronic (duration >12 months; 13 cases) group based on the injury duration (Macklin et al, 2016 ). All patients had various degrees of bilateral sensorimotor dysfunction, with the exception of two patients who exhibited only unilateral dysfunction (one on the left and the other on the right side).…”

Targeted-Plasticity in the Corticospinal Tract After Human Spinal Cord Injury

“…This is in contrast with the rather large fraction of discomplete patients who theoretically could develop meaningful motor behaviors. Several factors could contribute to these findings, including the lack of sensitivity of current clinical assessments to examine changes in sensorimotor outcomes over time [48] and the intensity used in training regimes, which does not allow people with clinically complete SCI to have any recovery in muscles below the level of the injury [30]. Overall, it is evident that residual connections are present in a large number of humans after SCI and we discuss how increasing transmission in those connections might open avenues for motor recovery.…”