Spinal 'Botox' jab could relieve pain

A new study has found that Botulinum neurotoxin type A (BoNT/A)-better known as Botox-reduces responses to an inflammation-related pain stimulus when injected into the spinal canal in mice.

"BoNT/A, with its long-lasting antinociceptive effect, may be a useful analgesic in inflammatory pain," Newswise quoted Won-Ho Lee, of Seoul National University, who led the research, as saying.

The researchers used a standard experimental model of pain in mice to examine the effects of spinal (intrathecal) BoNT/A injection. In this model, a chemical called formalin is injected into the paw, producing a predictable two-phase inflammatory pain response. Pain behaviors were monitored for up to four weeks in mice that did and did not receive spinal Botulinum neurotoxin.

Even a single spinal injection of Botulinum neurotoxin produced a pain-reducing effect: mice receiving the injection exhibited significantly fewer pain behaviors, particularly during the second phase of the pain response.

These effects were not accompanied by any movement abnormalities, suggesting that Botulinum neurotoxininjection did not adversely affect spinal cord function.

The pain-reducing effect of a single injection of Botulinum neurotoxin peaked at 10 days, then decreased up to 14 days. Mice treated with Botulinum neurotoxin also had significant reductions in certain neurotransmitters involved in various types of pain conditions.

The study has been published in the January issue of Anesthesia and Analgesia, official journal of the International Anesthesia Research Society (IARS).