Longitudinal estimation of intramuscular Tibialis Anterior coherence during subacute spinal cord injury: relationship with neurophysiological, functional and clinical outcome measures.
Elisabeth Bravo-Esteban, Julian Taylor, Manuel Aleixandre and 6 others
PMID 28619087WHAT IT FOUND
A high-frequency muscle signal pattern increased in 20 people with incomplete spinal cord injury during subacute recovery, while brain-to-muscle pathway measures did not change.
This is an experimental marker, not a clinical test.
Key findings
01During the last testing session, SCI subjects showed a significant increase in 40-60 Hz TA intramuscular coherence during maximal voluntary dorsiflexion (p = 0.03).
02TA MEP amplitude and latency did not change over subacute SCI in subjects with or without spasticity.
03At the final session, subjects with SCI spasticity had higher intramuscular TA coherence during isokinetic dorsiflexion at 120°/s for 40-60 Hz (p < 0.01), 24-40 Hz (p < 0.01), 15-30 Hz (p = 0.02), and 10-16 Hz (p = 0.04).
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The SCI group was small: 22 subjects were recruited, but 20 completed the four sessions after dropouts. Follow-up was short, with four sessions about 2 weeks apart during the first 8 months after injury. The design was descriptive and longitudinal; it observed changes over time instead of testing a treatment. The authors note that the small cohort and short follow-up require caution before concluding that the high-frequency coherence increase is not due to a corresponding increase in TA MEP amplitude. The small and short-duration TA muscle activation produced by patients with SCI may have affected MEP size, and MEP standardisation may be needed. Healthy controls were tested once and had a median age of 26 years, compared with a median age of 39 years in the SCI group. The paper does not state a pre-registered primary outcome. Some correlations were weak or borderline, such as 40-60 Hz coherence with TA muscle score (rho = 0.22, p = 0.05).
Declared interests
The supplied text does not report funding or conflicts of interest.
The easy way to misread this
Do not read the coherence increase as a clinical predictor of recovery or as proof that subcortical pathways caused improvement. The study had 20 SCI subjects, only about 2-week intervals between four sessions, and no treatment was tested. The authors say further studies are needed to assess the clinical impact of this technique at the individual level.