title: A randomized, double-blind, placebo-controlled trial of injected capsaicin for pain in Morton's neuroma.
abstract: Intermetatarsal neuroma or Morton's neuroma is a painful condition of the foot resulting from an entrapment of the common digital nerve typically in the third intermetatarsal space. The pain can be severe and especially problematic with walking. Treatment options are limited and surgery may lead to permanent numbness in the toes. Capsaicin, the pungent ingredient of hot peppers, produces analgesia by inducing retraction of nociceptive afferents from the area of innervation and is effective in treating certain neuropathic pain disorders. A randomized double-blind placebo-controlled study was conducted to test the efficacy, tolerability, and safety of a single 0.1 mg dose of capsaicin vs placebo injected into the region of the neuroma. A total of 58 subjects diagnosed with Morton's neuroma with foot pain ≥4 (0-10 numerical pain rating scale) were injected with 2 mL of lidocaine into the intermetatarsal space proximal to the neuroma to provide local anesthesia. After 5 minutes, 0.1 mg capsaicin or placebo was injected into the intermetatarsal space containing the painful neuroma. Average foot pain was rated for 2 weeks before through 4 weeks after injection. At weeks 1 and 4, the decrease in pain was significantly greater in the subjects treated with capsaicin (P = 0.021 and P = 0.019, respectively). A trend toward significance was noted at weeks 2 and 3. Improvements in functional interference scores and reductions in oral analgesic use were also seen in the capsaicin-treated group. These findings suggest that injection of capsaicin is an efficacious treatment option for patients with painful intermetatarsal neuroma.
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA Chesapeake Podiatry Group, Owings Mills, MD, USA Centrexion, Baltimore, MD, USA Clene Nanomedicine, Brighton, MI, USA Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Claudia M
authors.initials: CM
authors.lastname: Campbell
authors.forename: Eric
authors.initials: E
authors.lastname: Diamond
authors.forename: William K
authors.initials: WK
authors.lastname: Schmidt
authors.forename: Margaret
authors.initials: M
authors.lastname: Kelly
authors.forename: Robert
authors.initials: R
authors.lastname: Allen
authors.forename: William
authors.initials: W
authors.lastname: Houghton
authors.forename: Kerrie L
authors.initials: KL
authors.lastname: Brady
authors.forename: James N
authors.initials: JN
authors.lastname: Campbell
mesh_terms: D000328:Adult; D000368:Aged; D002211:Capsaicin / Q000627:therapeutic use*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D000070607:Morton Neuroma / Q000150:complications*; D009437:Neuralgia / Q000188:drug therapy* / Q000209:etiology; D016896:Treatment Outcome
chemical_list: D002211:Capsaicin