Henning Harke

Neuropathic pain (NP) is often refractory to pharmacologic and noninterventional treatment. On behalf of the International Association for the Study of Pain Neuropathic Pain Special Interest Group, the authors evaluated systematic reviews, clinical trials, and existing guidelines for the interventional management of NP. Evidence is summarized and presented for neural blockade, spinal cord stimulation (SCS), intrathecal medication, and neurosurgical interventions in patients with the following peripheral and central NP conditions: herpes zoster and postherpetic neuralgia (PHN); painful diabetic and other peripheral neuropathies; spinal cord injury NP; central poststroke pain; radiculopathy and failed back surgery syndrome (FBSS); complex regional pain syndrome (CRPS); and trigeminal neuralgia and neuropathy. Due to the paucity of high-quality clinical trials, no strong recommendations can be made. Four weak recommendations based on the amount and consistency of evidence, including degree of efficacy and safety, are: 1) epidural injections for herpes zoster; 2) steroid injections for radiculopathy; 3) SCS for FBSS; and 4) SCS for CRPS type 1. Based on the available data, we recommend not to use sympathetic blocks for PHN nor radiofrequency lesions for radiculopathy. No other conclusive recommendations can be made due to the poor quality of available data. Whenever possible, these interventions should either be part of randomized clinical trials or documented in pain registries. Priorities for future research include randomized clinical trials, long-term studies, and head-to-head comparisons among different interventional and noninterventional treatments.

UNLABELLED: We studied the effects of spinal cord stimulation (SCS) on postherpetic neuralgia (PHN). Data of 28 patients were prospectively investigated over a median period of 29 (quartiles 9--39) mo. In addition, four patients with acute herpes zoster (HZ) pain were studied simultaneously. After intractable pain for more than 2 yr, long-term pain relief was achieved in 23 (82%) PHN patients (median, 70 yr) during SCS treatment confirmed by a median decrease from 9 to 1 on the visual analog scale (P < 0.001). In five cases with serious comorbidity, the initial pain alleviation could not be stabilized. Spontaneous improvement was always confirmed or excluded by SCS inactivation tests at quarterly intervals. Eight patients discontinued SCS permanently because of complete pain relief after stimulation periods of 3--66 mo, whereas 2 reestablished SCS because of recrudescence after 2 and 6 mo. Considerable impairments in everyday life, objectified by the pain disability index, were also significantly improved (P < 0.001). In 4 patients with acute HZ pain, SCS was promptly effective and after periods of 2.5 (quartiles 2--3) months the pain had subsided. SCS seems to offer a therapeutic option for pharmacological nonresponders. IMPLICATIONS: In many patients with postherpetic neuralgia and acute herpes zoster pain is not satisfactorily alleviated with pharmacological approaches. We report on 23 of 28 patients with postherpetic neuralgia and 4 of 4 with acute herpes zoster whose chronic pain was improved by electrical spinal cord stimulation.

BACKGROUND AND PURPOSE: In this prospective trial we assessed the long-term effect of spinal cord stimulation (SCS) on the improvement of functional status in complex regional pain syndrome type I (CRPS I). METHODS: A prerequisite for eligibility to SCS treatment was the responsiveness of patients to sympathetic nerve block. In 29 patients with chronic sympathetically maintained CRPS I, the efficacy of SCS on deep pain, allodynia and functional disability was determined. Pain intensity was estimated during SCS free intervals of 45 min (inactivation test) every 3 months and compared with that under SCS treatment. RESULTS: On SCS treatment, both deep pain and allodynia could be permanently reduced from 10 to 0-2 on a 10 cm visual analogue scale (VAS) (p<0.01). During the inactivation tests, reoccurrence of pain up to 8 VAS (quartiles 6-8) was measured. Considerable impairments in daily living activities, objectified by the pain disability index, were also restored (p<0.01). After a follow-up period of 35.6+/-21 months, 12 of 16 patients with affected upper limb showed significant increase of the fist grip strength from 0 to 0.35 (quartiles 0.1-0.5) kg compared with 0.9 (quartiles 0.7-1.1) kg on the unaffected side (p<0.01). Eight of ten patients with lower limb disability resumed walking without crutches. Previous pain medication could be significantly reduced (p<0.01). CONCLUSIONS: As a result of permanent pain relief under long-term SCS combined with physiotherapy, the functional status and the quality of life could be significantly improved in sympathetically maintained CRPS I.

Forty-three patients with peripheral neuropathic pain, exclusively pain reduced by spinal cord stimulation (SCS), were switched into a painful state after SCS inactivation. This mode was used to assess the pain-relieving effect of carbamazepine (CMZ) and opioids in a double-blinded, placebo-controlled trial. In Phase 1, the patients were randomly allocated to receive either CMZ (600 mg/d) or placebo during an SCS-free period of 8 days. In Phase 2, after a CMZ elimination interval of 7 days, 38 patients received either sustained-release morphine (90 mg/d) or placebo for 8 days. In cases of intolerable pain, the patients were authorized to reactivate their SCS. The pain intensity was rated on a numeric analog scale. In 38 patients who completed Phase 1, significant delay in pain increase was observed in the CMZ group as compared with placebo (P = 0.038). In Phase 2, the trend observed with morphine was insignificant (P = 0.41). Two CMZ patients and one morphine patient showed complete pain relief and preferred to continue the medication. Thirty-five patients returned to SCS. We conclude that CMZ is effective in peripheral neuropathic pain. Morphine obviously requires larger individually titrated dosages than those used in this study for results to be adequately interpreted. Implications This study included patients with neuropathic pain suppressed by spinal cord stimulation (SCS). After deactivation of SCS, different drug effects were evaluated. In contrast to morphine, carbamazepine showed significant pain relief compared with placebo.

Forty-three patients with peripheral neuropathic pain, exclusively pain reduced by spinal cord stimulation (SCS), were switched into a painful state after SCS inactivation. This mode was used to assess the pain-relieving effect of carbamazepine (CMZ) and opioids in a double-blinded, placebo-controlled trial. In Phase 1, the patients were randomly allocated to receive either CMZ (600 mg/d) or placebo during an SCS-free period of 8 days. In Phase 2, after a CMZ elimination interval of 7 days, 38 patients received either sustained-release morphine (90 mg/d) or placebo for 8 days. In cases of intolerable pain, the patients were authorized to reactivate their SCS. The pain intensity was rated on a numeric analog scale. In 38 patients who completed Phase 1, significant delay in pain increase was observed in the CMZ group as compared with placebo (P = 0.038). In Phase 2, the trend observed with morphine was insignificant (P = 0.41). Two CMZ patients and one morphine patient showed complete pain relief and preferred to continue the medication. Thirty-five patients returned to SCS. We conclude that CMZ is effective in peripheral neuropathic pain. Morphine obviously requires larger individually titrated dosages than those used in this study for results to be adequately interpreted. Implications This study included patients with neuropathic pain suppressed by spinal cord stimulation (SCS). After deactivation of SCS, different drug effects were evaluated. In contrast to morphine, carbamazepine showed significant pain relief compared with placebo.