ELECTRICAL SPINAL-CORD STIMULATION FOR PAINFUL DIABETIC PERIPHERAL NEUROPATHY

Background Conventional treatment for painful peripheral diabetic neur opathy is largely symptomatic and often ineffective, with unacceptable side-effects. We tested electrical spinal-cord stimulation for the ma nagement of chronic neuropathic pain, Methods Ten diabetic patients wh o did not respond to conventional treatment (mean age 51 [SD 9.3] year s, six with type II diabetes, mean duration of diabetes 12 [6.3] years , mean duration of neuropathy 5 [2.1] years) were studied. The electro de was implanted in the thoracic/lumbar epidural space. Immediate neur opathic pain relief was assessed by visual analogue scale (VAS) after connecting the electrode, in a random order, to a percutaneous electri cal stimulator or to a placebo stimulator, Exercise tolerance was asse ssed on a treadmill. Findings Eight subjects had statistically signifi cant pain relief with the electrical stimulator (p<0.02) and were ther efore converted to a permanent system, Statisically significant relief of both background and peak neuropathic pain was achieved at 3 months (n=7, p=0.016), at 6 months (n=7, p=0.03), and at the end of the stud y (14 months, n=7, background pain p=0.06, peak pain p=0.03). One pati ent died 2 months after the start of the study of unrelated cause whil e continuing to benefit from treatment and another patient ceased to b enefit at 4 months. McGill pain questionnaire scores with the stimulat or turned off did not change significantly from baseline scores, indic ating that the severity of the underlying pain was unaltered. However, with the stimulator turned on, there was a statistically significant (p<0.05) improvement in all four components of the score, by the end o f the study. At the end of the study, six patients continued to gain s ignificant pain relief and used the stimulator as the sole treatment f or their neuropathic pain. For example, median background and peak pai n scores at the end of study, were, respectively, 77 and 81 with the s timulator off and 23 and 20 with the stimulator on. Exercise tolerance significantly improved at 3 months (n=7, median % increase 85 [IQR, 6 2-360], p=0.015) and at 6 months (n=6, 163 [61-425], p=0.0007). Electr ophysiological tests, vibration perception-threshold, and glycaemic co ntrol were unchanged. Interpretation Electrical spinal-cord stimulatio n offers a new and effective way of relieving chronic diabetic neuropa thic pain and improves exercise tolerance. The technique should be con sidered in patients with neuropathic pain who do not respond to conven tional treatment.