By Megan Rauscher

NEW YORK, Sep 27(Reuters) Local injections of botulinum toxin type A (Botox) may provide long-lasting relief of pain associated with carpal tunnel syndrome (CTS), Taiwanese researchers report.

CTS is a disabling disorder of the wrist and hand caused by compression of the median nerve, which runs through a narrow passageway in the wrist -- the carpal tunnel. Symptoms include pain, numbness, and weakness in the hand, fingers and wrist.

Repetitive motions, such as those performed using computer keyboards or operating factory machinery, are chiefly responsible for CTS, which is estimated to affect 8 per cent of the population.

Botox, used by dermatologists to banish wrinkles, has been increasingly used in various types of neuromuscular disorders including dystonia, tics, tremors and spasticity. It's also recently been reported to be effective in the relief of migraine and facial pain.

In a pilot study, Dr Ching-Piao Tsai and colleagues from The Neurological Institute, Taipei Veterans General Hospital and National Yang-Ming University treated five middle-aged women with a 1- to 2-year history of CTS, with 60 units of Botox injected into the carpal tunnel.

The agent was well tolerated and safe, with no exacerbation of hand weakness observed in any patient. At 3 months, the pain was ameliorated in three patients, stationary in one, and aggravated in one patient, the team reports.

Pain scores showed a trend toward improvement during 3 months of follow up, although this did not reached statistical significance.

''This is the first positive study ... to describe the efficacy of Botulinum toxin type A for the relief of CTS,'' team leader Tsai told Reuters Health.

Tsai and colleagues say a double-blind, placebo-controlled trial is now warranted, noting that the current study ''may have been confounded by the placebo effect of intracarpal injection.'' Reuters DKB RS0918