Peripheral nerve crushing to relieve chronic pain in diabetic and ischaemic foot ulcers.

OBJECTIVE: We retrospectively assessed the effectiveness of peripheral nerve crushing (Smithwick operation) in relieving intractable chronic pain associated with foot ulcers caused by diabetes mellitus (DM) or atherosclerosis.

METHOD: From April 2009 to April 2012, patients underwent peripheral nerve crushing in the leg affected by foot ulceration. The cause of ulceration was either DM alone, atherosclerosis alone, or both DM and atherosclerosis. Because sensation in the foot is associated with five nerves: the tibial, deep peroneal, superficial peroneal, sural, and saphenous, one or more of these nerves were crushed over a length of 1.5cm by using a 'pean' in the distal third of leg the where there are no major motor nerves.

RESULTS: There were 36 patients recruited with ulcers grade 3-5 according to the Wagner ulcer classification system that affected the toes, dorsum pedis, or any part of the plantar surface or the heel. The mean duration of foot ulcerations before the nerve crushing was 22.3±9.7 weeks. In all 36 patients, the nerve crushing was performed successfully without any perioperative surgical complication. Of the 36 patients, 34 (94.4%) had substantial pain relief immediately after nerve crushing. While the mean pain level before the procedure was 86.6±0.51mm on visual analogue scale (VAS), pain level dropped significantly after the operation to 18.6 ± 5.4mm at one week, 14.8±4.8mm at one month, 13.7±4.1mm at two months, 9.8±4.1mm at three months, 11.8±5.7mm at four months, 10.1±4.7mm at five months and 8.8±3.3mm at six months. The time to regeneration of the sensory nerves was 121±6.5 days (range: 80-181 days). The surgical complications were wound infection (6 patients) and temporary toe paralysis (three patients). The foot ulcers in 20 of the 36 patients (55.6%) were resolved by debridement or minor amputation. In seven patients (19.4%), a major amputation (five below and two above the knee) was required because of ischemia or infection. No patient died within 30 days of the operation, while nine patients died during the observation period because of comorbid conditions.

CONCLUSION: Peripheral nerve crushing could be the alternative procedure for achieving analgesia in patients with intractable chronic pain from foot ulcers caused by DM or atherosclerosis.