Effects of Pulsed Ultrasound Therapy on Sensory Nerve Conduction Parameters and the Pain Threshold Perceptions in Humans.

BACKGROUND: Therapeutic ultrasound is an often-used clinical modality in the nonsurgical treatment of entrapment neuropathies. To date, the possible mechanism of action of pulsed ultrasound therapy on the peripheral nerve in the treatment of entrapment neuropathies is unclear.

OBJECTIVE: To examine the effects of pulsed ultrasound therapy on peripheral nerve conduction parameters.

DESIGN: A prospective, randomized, single blind, crossover study.

SETTING: Outpatient clinic of a university department of physical medicine and rehabilitation.

PARTICIPANTS: Twelve healthy volunteers between 22 and 38 years of age (8 male, 4 female).

METHODS: Each patient (blinded) received ultrasound therapy (1W/cm2 , pulsed: 1:5; over the course of the superficial branch of the radial nerve of the nondominant arm) and placebo (intensity: zero). The interval between the individual interventions was 1 week.

MAIN OUTCOME MEASUREMENT: The sensory nerve conduction velocity, sensory nerve action potential, supramaximal stimulation intensity of the sensory fibers of the radial nerve, and the pressure pain threshold in the sensory area of the radial nerve before and after an ultrasound-therapy and placebo intervention. To compare the results of the intervention with placebo, a paired-samples t test was applied.

RESULTS: Compared with placebo, a significant increase after pulsed ultrasound therapy was found for the supramaximal stimulation intensity (P = .02). For the other primary outcome parameters, a significant difference was not found.

CONCLUSIONS: The immediate effect of pulsed ultrasound therapy on a sensory nerve is minimal. Therefore, the previously reported benefit of pulsed ultrasound therapy in entrapment neuropathies might be not due to its effect on the sensory nerve.

LEVEL OF EVIDENCE: I.