NEW YORK (Reuters Health) – Treatment with botulinum toxin type A (BoNT/A) appears to substantially reduce neuropathic pain and improve sleep quality in some patients with diabetes, according to results of a pilot study conducted in Taiwan.

Previous trials of BoNT/A “have succeeded in extending the field of traditional pain therapy, particularly for the unsatisfactory treatment of neuropathic pain,” Dr. Chaur-Jong Hu, at Taipei Medical University, and co-authors note in the April 28 issue of Neurology.

Their randomized, double-blind, crossover trial included 18 patients with type 2 diabetes and neuropathic pain in both feet. Patients were randomly assigned to receive BoNT/A or saline injections, then 12 weeks later crossed over to receive the opposite treatment. The intradermal injections were administered at 12 sites across the dorsum of the foot, using in total 50 U of BoNT/A in 1.2 mL of saline or saline alone.

At baseline, the visual analog scale (VAS) pain score averaged 6.36.

Significant differences between the BoNT/A and placebo injections were noted for reductions in VAS scores: 2.22 vs -0.11 at 4 weeks (p = 0.014); 2.33 vs 0.42 at 8 weeks (p = 0.039), and 2.53 vs 0.53 at 12 weeks (p = 0.024).

Moreover, 44% of patients achieved a good response to BoNT/A, defined as a VAS score reduction of at least 3 within 12 weeks. There also appeared to be a transient significant improvement in sleep quality with active treatment at week 4.

“This trial indicates that intradermal BoNT/A injections are an effective and safe method of relieving diabetic neuropathic pain in the feet,” Dr. Hu’s team concludes. However, “the detailed underlying mechanisms, optimal dosage, and precise course of therapy require further evaluation.”

In a related editorial, Dr. Stuart C. Apfel at Parallax Clinical Research in West Hempstead, New York, points out that another recent trail showed that BoNT/A is effective for treating focal neuropathies such as postherpetic neuralgia or posttraumatic neuropathy.

Although both trials were small, he says, “Remarkable similarities between the two studies, despite targeting different types of neuropathic pain,… provide cause to feel optimistic about the validity of their conclusions.”

Nevertheless, the editorialist maintains, large, multicenter clinical trials of longer duration and with multiple dosing are needed to confirm the potential of BoNT/A injections “as a novel approach to the treatment of both focal and diffuse types of painful neuropathy.”

Reference:
Neurology 2009;72:1473-1478.