Effects of motor stimulation of the tibial nerve on corticospinal excitability of abductor hallucis and pelvic floor muscles.
Gevorg Eginyan, Xueqing Zhou, Alison M M Williams and 1 others
PMID 36726808WHAT IT FOUND
Tibial nerve stimulation increased brain-to-muscle signals in the foot muscle it directly innervates, but not in the pelvic floor.
Neither continuous nor intermittent patterns differed in effect. This suggests no immediate cortical boost to pelvic floor muscles via this specific nerve stimulation.
Key findings
01Stimulation of the tibial nerve increased corticospinal excitability for the abductor hallucis muscle (a target muscle) but not for the pelvic floor muscles (a non-target muscle sharing segmental innervation).
02There was no difference in the effect on corticospinal excitability between intermittent and continuous patterns of stimulation.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study used healthy participants, not those with pelvic floor dysfunction or lower urinary tract symptoms, so findings may not apply to clinical populations. Corticospinal excitability is just one measure of neural function; the study could not rule out effects on spinal reflex pathways, which are often the target of such therapies. The pelvic floor muscles have fewer direct corticospinal projections than limb muscles, making them inherently harder to modulate and measure via TMS. Stimulation intensity was at motor threshold (causing muscle contraction), whereas clinical TibNS is typically delivered at sensory threshold (no visible contraction), potentially limiting direct comparability to clinical practice.
Declared interests
Funded by the Canadian Institutes of Health Research. No other conflicts declared.
The easy way to misread this
Do not conclude that tibial nerve stimulation is ineffective for pelvic floor dysfunction. This study only examined acute changes in brain-to-muscle signaling (corticospinal excitability) in healthy individuals. It did not measure clinical outcomes like continence or spinal reflex changes, which may still occur.