Lateral Corticospinal Tract Damage Correlates With Motor Output in Incomplete Spinal Cord Injury.
Andrew C Smith, Kenneth A Weber, Denise R O'Dell and 3 others
PMID 29107041WHAT IT FOUND
Greater lateral corticospinal tract damage was associated with weaker same-side ankle and knee torque and shorter 6-minute walking in 14 people with chronic cervical incomplete spinal cord injury.
Gracile fasciculus damage did not show the same side-specific motor pattern.
Key findings
01Total spinal cord damage was significantly correlated with averaged plantarflexion torque (r = −0.54, p < 0.05), averaged knee extension torque (r = −0.59, p < 0.05), and distance walked in 6 minutes (r = −0.61, p < 0.05).
02Right-sided LCST damage was significantly correlated with right plantarflexion torque (r = −0.67, p < 0.01) and right knee extension torque (r = −0.54, p < 0.05), but not with left-sided motor output; left-sided LCST damage was significantly correlated with left plantarflexion torque (r = −0.56, p < 0.05) and left knee extension torque (r = −0.68, p < 0.01), but not with right-sided motor output.
03Right GF damage was not significantly correlated with right plantarflexion or knee extension torque, and left GF damage was not significantly correlated with left plantarflexion or knee extension torque; right and left GF damage showed only a non-significant trend with 6-minute walk distance (r = −0.51, p = 0.06 for both sides).
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The design was cross-sectional, so it cannot show that spinal cord damage caused the motor deficits. Only 14 participants were studied, and the sample included one female and one male participant injured 31 years earlier, so it was small and not homogeneous. The study was exploratory and assumed the spinal cord damage measure was valid; MRI artefact could have affected accuracy, and participants classified as AIS D had cord damage ranging from 0.54 to 0.91. The Spinal Cord Toolbox and white matter atlas were created and validated using healthy control imaging data, so their use in spinal cord injury still needs confirmation. Spasticity was not quantitatively assessed, although it may have influenced motor output and ambulation.
Declared interests
The work was supported by NIH extramural research. Elliott and Parrish reported relevant financial activities outside the submitted work: board membership, consultancy, other (Pain ID LLC), and payment for lectures.
The easy way to misread this
Do not read these correlations as evidence that MRI tract damage causes motor deficits or can predict a patient's recovery. The study was a small cross-sectional pilot, and the dorsal column measure was not significant.