The use of splints, local corticosteroid injections and surgical decompression has limited effectiveness in the treatment of carpal tunnel syndrome. Ultrasound therapy applied to the wrist may induce an anti-inflammatory effect that could provide relief of symptoms of carpal tunnel syndrome. Ebenbichler and colleagues conducted a controlled clinical trial to evaluate the use of ultrasound therapy in patients with mild to moderate bilateral carpal tunnel syndrome.

Patients in the study had been referred to an outpatient clinic for symptoms of carpal tunnel syndrome. The diagnosis was confirmed by clinical and electrophysiologic criteria, and other potential causes for the symptoms were excluded. Patients were randomly assigned to receive either active ultrasonic therapy or “sham” treatment under identical conditions. A total of 34 patients completed the study.

Ultrasound therapy was administered daily for 10 days, followed by twice-weekly treatments for five weeks. Corticosteroids and nonsteroidal anti-inflammatory drugs were prohibited, but analgesics were permitted for pain relief during the course of treatment. Discomfort was assessed with visual analog scales, and electroneurographic measurements were used to assess the effectiveness of therapy.

At the end of treatment, satisfactory improvement or complete remission of symptoms was noted in 23 of 34 wrists (68 percent) treated with ultrasound and in 13 of 34 wrists (38 percent) receiving sham treatment. Thirty of the 34 patients completed the six-month follow-up assessment. At that time, satisfactory improvement or complete relief of symptoms was noted in 74 percent of the actively treated wrists (22 of 30 wrists). This degree of improvement was noted in 20 percent of the wrists receiving sham treatment (six of 30 wrists).

Motor distal latency and velocity of sensory nerve conduction were both significantly improved in the active treatment group but remained unchanged in the sham group. Hand grip, finger-pinch strength and the patients' overall impressions were significantly better in the active treatment group, both immediately following therapy and at the six-month assessment. No side effects were reported, and use of analgesics was low.

The authors conclude that ultrasound therapy provides good short-term relief of symptoms in patients with moderate carpal tunnel syndrome and that the beneficial effects persist for at least six months. The authors state that further research is needed to determine optimal treatment schedules and to discover whether ultrasound treatment is superior to other forms of nonsurgical treatment, either alone or in combination with one of the nonsurgical treatments, or whether early decompression provides better long-term results.