Vagus Nerve Stimulation Paired With Rehabilitative Training Enhances Motor Recovery After Bilateral Spinal Cord Injury to Cervical Forelimb Motor Pools.
Michael J Darrow, Miranda Torres, Maria J Sosa and 5 others
PMID 31969052WHAT IT FOUND
In rats with cervical spinal cord injury, pairing vagus nerve stimulation with rehabilitative training improved forelimb strength and spontaneous use more than training alone.
These gains persisted after stimulation stopped and extended to untrained tasks. This is animal data, not human evidence.
Key findings
01VNS paired with rehabilitative training significantly improved volitional forelimb strength and hit rate compared to rehabilitative training alone.
02The benefits of VNS paired with training generalized to untrained tasks, showing greater spontaneous forelimb use and improved grip strength in the trained limb.
03VNS did not change the intensity of rehabilitative training or the extent of the spinal lesion, indicating the recovery was not due to increased effort or neuroprotection.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study was conducted entirely in rats, so the findings do not directly translate to human patients. The sample size was small, with only 18 animals included in the final analysis after 40 were excluded for various reasons. The follow-up period for assessing the persistence of benefits was only one week after the cessation of stimulation. The authors note that improvements in grip strength could potentially reflect spasticity rather than purely voluntary motor control.
Declared interests
One author has a financial interest in MicroTransponder, Inc., which develops VNS devices. Another author is a co-owner of Vulintus, Inc., which makes the behavioral testing systems used in the study, and owns Teliatry, which is developing a novel VNS device.
The easy way to misread this
Do not interpret this as evidence that vagus nerve stimulation is currently a viable treatment option for human patients with spinal cord injury. The study was conducted in rats, and the authors explicitly state that the clinical manifestation of human cervical SCI often involves damage to motor neuron pools that this animal model attempts to simulate, but animal models fail to capture the full variability and complexity of human injury.