[Pain-relieving effect of cantharidin blister on lumbar spinal stenosis].

OBJECTIVE Lumbar spinal stenosis (LSS) is a common cause of chronic lumbar pain and disability. Conventional therapy approaches include analgesics and spinal surgery. Topical cantharidin applications are used for the treatment of severe chronic lumbar pain in traditional European medicine (TEM). We tested the pain-relieving effect of lumbar cantharidin blisters in a non-randomised controlled pilot study. PATIENTS AND METHODS 28 consecutive patients with manifest LSS were included. The first 20 patients received a cantharidin blister, 8 patients served as controls (waiting list). Pain was assessed by means of a numeric visual analogue scale (VAS; 0 indicating no pain, 10 indicating strongest pain). Treatment started after a 3-day run-in phase, the blister was applied once for 12 h. RESULTS Patients were comparable with respect to baseline pain. In the blister group, the pain score continuously improved from 7.2 +/- 2.1 at baseline to 2.9 +/- 2.3 (VAS) at day 7, whereas the score remained unchanged in control patients. Adjusted for baseline, the difference between the blister and the control group was estimated at 4.1 (95% CI: 2.4-5.9, p < 0.0001). The use of analgesics was slightly higher in the control group. No serious adverse events were observed. CONCLUSION In this first study on the efficacy of cantharidin blisters, a clinically relevant pain-relieving short-term effect on LSS was observed. As the trial was non-randomised and only included a limited number of patients, the results should be interpreted with caution.