The use of neurolytic blockade is a staple in the management of cancer pain. However, the data on neurolysis for chronic pain are plagued by inconsistencies in patient selection, diagnostic criteria, technical standards, and outcome measures. No one neurolytic agent or technique has been proven superior to another. Current evidence suggests that patients with pain of malignant origin may benefit from a variety of neurolytic techniques, as the benefit of documented short-term pain relief may outweigh risk at the end of life. In the absence of compelling data suggesting low-risk long-term efficacy, neurolysis for chronic benign pain should be cautiously considered, in most cases, only after failure of aggressive multidisciplinary management.
Objectives-The proportion of chronic pain patients with suspected neuropathic pain who will have clinically meaningful pain relief with intravenous (IV) lidocaine and the clinical characteristics that identify these patients have not been described previously.Methods-We conducted a cohort study of 99 patients who underwent IV lidocaine infusions for suspected neuropathic pain. An 11-point Numerical Rating Score (NRS) of pain intensity was recorded at the beginning and end of each infusion. A predefined literature-based criteria for "clinically meaningful" reductions in pain score was used to classify patients as responders or nonresponders. Multivariate logistic regression was used to determine clinical variables that predicted an increased likelihood of being a lidocaine responder.Results-The mean reduction in NRS during lidocaine infusions was 2.34 (95% confidence interval 2.83-1.85, P<0.001). Forty-two percent of patients (95% confidence interval 32.5%-52.8%) had NRS reductions of 30% or greater and met the predefined criteria as lidocaine responders. Univariate and multivariate analyses indicated that advancing age and pain severity significantly increased the odds of being a lidocaine responder. Controlled for all other factors, each decade of advancing age increased the odds of being a lidocaine responder by 36%. Each 1-point increase, on an 11-point scale of baseline pain severity, increased the odds of being a lidocaine responder by 29%.Discussion-IV lidocaine effectively reduces pain in a minority of patients suspected of having neuropathic pain. Pain severity and patient age can be used to target therapy to those most likely to respond. Lidocaine can be safely and effectively administered intravenously (IV) to treat neuropathic pain. 4,5 Lidocaine's efficacy has recently been confirmed and reviewed in a meta-analysis by et al. 6 Nonetheless, little has been published to clarify the degree of relief which can be expected, and the proportion of patients who will achieve relief. Furthermore, little has been done to identify the patients most likely to benefit from systemic lidocaine. One cohort study of IV lidocaine treatment in peripheral neuropathic pain patients reported that response to lidocaine is predicted by the severity of mechanical allodynia, and the degree of sensory impairment. 7 Other variables such as age of patients, pain duration, and pain severity did not significantly impact the degree of relief in response to systemic lidocaine. 7
KeywordsThe same group reported on another cohort of patients with central neuropathic pain treated with IV lidocaine. 8 They reported that lidocaine significantly reduced ongoing spontaneous pain in patients with central neuropathic pain. This study did not evaluate factors possibly associated with analgesia such as age, sex, pain duration, severity, or the degree to which patients had been refractory to previous treatments. 8 The power of these studies to identify factors predicting analgesic response was limited by the small number of patients st...
Ziconotide showed analgesic activity, as shown by decreased PCA morphine equivalent consumption and lower VASPI scores. Because of a favorable trend of decreased morphine consumption with an acceptable side-effect profile in the low-dose ziconotide group, 0.7 microg/h may be closer to the ideal dose than 7 microg/h. Large-scale studies are required to clarify this issue.
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