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Distinct spatiotemporal dynamics of tissue-specific neurodegeneration were found above and below spinal cord injuries (SCIs), according to study findings published in the Journal of Neurology, Neurosurgery and Psychiatry.
SCI leads to neurodegeneration across the neuraxis, however, little is known about the trajectories of spinal cord grey and white matter above and below the injury. Although there is no cure for SCI, a better understanding of these processes can be beneficial for long-term recovery and treatment for patients with SCI.
In the current study, patients with traumatic (n=13) or nontraumatic (n=3) SCIs and healthy control participants (n=10) were enrolled from the Balgrist University Hospital in Switzerland between 2016 and 2019. During the course of 1.5 years, participants underwent magnetic resonance imaging (MRI) at 3 timepoints for the identification of tissue-specific neurodegeneration.
Patients and the healthy control participants had a mean age of 50.3±16.0 years and 45.3±19.2 years, respectively. A total of 3 participants in each cohort were women. Among patients with an injury, 8 had tetraplegia and 8 had paraplegia, classified according to the American Spinal Injury Association Impairment Scale A (n=2), B (n=1), C (n=2), and D (n=11).
During the study, upper and lower extremity motor scores improved by 1.5 points per log month (95% CI, 0.6-2.3 points per log month; P =.002) and 2.4 points per log month (95% CI, -0.8 to 5.6 points per log month; P =.131), respectively. Significant improvements in Spinal Cord Independence Measure (SCIM) were reported (mean, 10.5 points per log month; P =.005), but not in light touch scores (P =.101) and pinprick scores (P =.718).
In patients with assessable lesions, mean midsagittal lesions had an average width of 4.9±2.2 mm, length of 19.9±17.0 mm, and area of 70.2±70.9 mm2 at 2 months post-injury. The width of lesions tended to decrease significantly (P =.016) with time, but no changes in lesion length or area were reported.
At 2 months after surgery, SCIs were associated with decreased spinal cord area (mean difference, -7.9%; P =.008) and white matter area (mean difference, -9.7%; P =.004) at C2/C3.
Above the injury at C2/C3, patients with an SCI had decreases in spinal cord area at a rate of 0.42% per month (P =.002), gray matter area at a rate of 0.70% per month (P =.004), and white matter area at a rate of 0.34% per month (P =.020). At the lumbar enlargement, below the injury, decreases in spinal cord area and white matter area both progressed at 0.35% per month (P <.001 and P =.007, respectively).
Fractional anisotropy values in the dorsal column at C2/C3 at baseline were correlated with follow-up SCIM scores (z-score, 4.18; P =.037) and baseline radial diffusivity negatively correlated with follow-up SCIM scores (z-score, 4.01; P =.035).
Study limitations included that fact that these findings may not be generalizable to all patients with SCIs, as most participants had heterogeneous injury types and severities.
The study authors concluded that temporospatial dynamic trajectories of patients with an SCI differed above and below the injury. “The clinical eloquence of these findings is reflected by the clinicopathological association between early degenerative changes and functional and neurological recovery. These MRI measures could be used to track the efficacy of therapeutic interventions, including rehabilitation.”
Disclosure: Multiple authors declared affiliations with industry. Please refer to the original article for a full list of disclosures.
Reference
David G, Pfyffer D, Vallotton K, et al. Longitudinal changes of spinal cord grey and white matter following spinal cord injury. J Neurol Neurosurg Psychiatry. Published online August 2, 2021. doi:10.1136/jnnp-2021-326337
