OnabotulinumtoxinA improves tactile and mechanical pain perception in painful diabetic polyneuropathy.

Objectives: Diabetic neuropathic pain may be relieved by onabotulinumtoxinA (BoNT/A). However, whether BoNT/A changes sensory perception in neuropathic patients remains unknown. This study used a double-blind crossover design to explore the possible effect of BoNT/A on sensory perception.

Methods: Eighteen patients with painful diabetic polyneuropathy underwent 2 consecutive 12-week periods of treatment either in the sequence of saline (control) and then BoNT/A (SB cohort, n=9) or BoNT/A followed by saline (BS cohort, n=9). Sensory perception was assessed according to the tactile threshold [TT, logarithmized force (g) of von Frey filaments] and mechanical pain threshold [PT, logarithmized weight (g) of weighted syringes], both being averages from 4 individual measurements of bilateral medial and lateral feet obtained at baseline (before injections) and at weeks 1, 4, 8, and 12 after treatment.

Results: In either the SB or the BS cohort, there was a decrease in the TT and the PT after treatment with BoNT/A but not with saline. In the analysis merging both cohorts (n=18), BoNT/A resulted in a significant decrease in TT and PT at weeks 1, 4, 8, and 12 (all Ps<0.05 vs. saline). The longitudinal effect of BoNT/A on TT and PT remained significant when baseline values, treatment sequences, and periods were controlled using generalized estimating equations.

Discussion: BoNT/A may improve tactile and mechanical pain perception in painful diabetic polyneuropathy. The beneficial effects of BoNT/A deserves further study to elucidate the exact mechanism and potential for preventing insensate injuries.