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Abstracts & Commentary
Synopsis: A consensus panel updates recent understanding about the causes and treatment in common neuropathic pain problems.
Source: Dworkin RH, et al. Arch Neurol. 2003;289:295-305.
Neuropathic pain results from lesions of the peripheral or central nervous system most often seen as a consequence of long-standing diabetes mellitus, but it is also observed in many other conditions. The presence of both negative (eg, numbness) and positive (eg, paresthesias) sensory neurologic symptoms are common presenting complaints. Nerve conduction velocity and electromyography may be normal despite profound abnormalities in small myelinated and unmyelinated nerves. Inflammatory and myofascial pain mechanisms may combine with neuropathic processes making differential diagnosis difficult. Advances in understanding the underlying pathophysiology demonstrate that a variety of peripheral and central processes may be present in any one patient.
Randomized, controlled trials have shown efficacy in neuropathic pain with gabapentin, lidocaine patch 5%, opioids, tramadol, and tricyclic antidepressants. The underlying pathophysiology suggests that treatment approaches involving one drug or a combination of drugs is justified in any pain syndrome involving nerve injury even without clinical trial results.
Comment by Bill McCarberg, MD, FABPM
Neuropathy is common and difficult to treat. Diagnosis is often the result of a characteristic history confirmed by physical examination and laboratory findings. Neuropathic pain mechanisms may significantly contribute to the discomfort felt in many common chronic pain problems including chronic low back and neck pain. Treatment is often difficult and requires several drugs with different mechanisms of action. Although 5 drugs or drug categories have demonstrated efficacy in randomized trials, only gabapentin, lidocaine patch 5%, and carbamazepine have FDA approval for treatment in specific neuropathic problems. Head-to-head trials are lacking to guide therapy of one drug class compared to another or a combination of drug categories. Polypharmacy is the rule in difficult cases. Special consideration should be given to tricyclic antidepressants and opioids due to increased risk of use—especially in selected populations.
Dr. McCarberg is Director of the Chronic Pain Management Program; Coordinator of Pain Services, Kaiser Permanente, San Diego, Calif.