New evidence for preserved somatosensory pathways in complete spinal cord injury: A fMRI study.

Trauma to the spinal cord rarely results in complete division of the cord with surviving nerves sometimes remaining silent or failing to function normally. The term motor or sensory discomplete has been used to describe this important but unclassified subgroup of complete SCI. Importantly, silent motor or sensory pathways may contribute to aversive symptoms (spasticity, pain) or improved treatment success. To demonstrate more objectively the presence of subclinical preserved somatosensory pathways in clinically complete SCI, a cross-sectional study using functional MRI (fMRI) was undertaken. The presence of brain activation following innocuous brushing of an insensate region below-injury (great toe) was analyzed in 23 people (19 males (83%), mean ± SD age 43 ± 13 years) with clinically complete (AIS A) SCI with (n = 13) and without (n = 10) below-level neuropathic pain and 21 people without SCI or pain (15 males (71%); mean ± SD age 41 ± 14 years). Location appropriate, significant fMRI brain activation was detected in 48% (n = 11/23) of subjects with clinically complete SCI from below-injury stimulation. No association was found between the presence of subclinical sensory pathways transmitting innocuous mechanical stimuli (dorsal column medical lemniscal) and below-level neuropathic pain (χ  = 0.034, P = 0.9). The high prevalence of sensory discomplete injuries (∼50% complete SCI) strengthens the case to explore inclusion of this category into the international SCI taxonomy (ISNCSCI). This would ensure more widespread inclusion of discomplete SCI in ongoing pain and motor recovery research. Neurophysiological tests such as fMRI may play a role in this process. Hum Brain Mapp 39:588-598, 2018. © 2017 Wiley Periodicals, Inc.