Many people who have suffered severe spinal injuries have more surviving nerves than they realize. These nerves could open the path to restoring some of their functions, even allowing wheelchair users to walk again in the most optimistic scenario.
Currently, spinal cord injuries (SCIs) are categorized as either complete or incomplete impairment. This is done using examination techniques that often miss partially preserved nerve pathways, leading to incorrect assessments of complete severing, something that has been revealed in postmortem studies to occur more than half the time. When this happens, prospects for recovery can be missed. Pain can also be neglected as a consequence of misdiagnosis.
Since waiting for a postmortem would be leaving it too late for the patient, Dr Sylvia Gustin of the University of New South Wales and Neuroscience Research Australia decided to try another approach. Twenty-three people with SCIs were given fMRI scans to detect whether appropriate regions of their brains activated when their big toes were brushed. Although none of these individuals were conscious of the brushing, 11 showed responses in the part of the brain that would respond to stimulation of a healthy person's toe.
Reporting the findings in Human Brain Mapping, Gustin argues a new category of “sensory discomplete injuries” should be recognized for cases such as these.
Gustin told IFLScience that we don't yet know how to translate a sensory discomplete diagnosis into a recovery program, but there are a number of possible options she would like to use in trials. “It is possible we could use electrical activation of the brain, or maybe Transcranial Magnetic Stimulation, to change maladaptive rhythms,” she said. “Spinal stimulation below the injury site is also a possibility. This could enhance the surviving pathways. We definitely need properly controlled randomized trials." Meanwhile, she added, the findings “give hope [to injury survivors], which is what we need in life.”
The discovery could also assist SCI survivors who suffer pain in areas they can otherwise no longer feel or control. Gustin has previously published research on this topic and said this suffering is at least partly a result of malfunctioning in the brain's thalamus region, but the spinal cord may also be contributing. Only 13 of those in the study were suffering in this way, which Gustin told IFLScience is too small a sample to identify much about the influence of surviving spinal nerves, but further research may change this.
In the light of the postmortem studies, and research showing blunt forces seldom fully sever animal spines, the findings did not surprise Gustin. Nevertheless, this represents the first objective evidence of discomplete SCIs' frequency.
Gustin hopes that, besides diagnosis, fMRI scans, or a not-yet-tested alternative called quantitative sensory testing, could be used to track the progress of healing, be it natural or in response to therapies.