Review of current guidelines on the care of postherpetic neuralgia.

An unfortunate minority of patients with acute herpes zoster (AHZ) experience pain beyond the typical 4-week duration, and roughly 10% develop the distressing complication of postherpetic neuralgia (PHN), often defined as pain persisting for > 4 months after the onset of the rash. Elderly patients are at increased risk of PHN. The pathophysiology of PHN is complex, likely involving both peripheral and central processes. This complexity may create opportunities for pharmacologic interventions with multiple differing mechanisms of action. Consequently, complementary combinations of pharmacologic agents are frequently more effective than any monotherapy. Current US and international guidelines on the care of patients with PHN are reviewed and interpreted here to facilitate their effective incorporation into the practice of primary care physicians, acknowledging the contrasts that often exist between the clinical trial populations analyzed to craft so-called evidence-based medicine and the individual patients seen in daily practice, many of whom may not have been candidates for those clinical trials. First-line treatments for PHN include tricyclic antidepressants, gabapentin and pregabalin, and the topical lidocaine 5% patch. Opioids, tramadol, capsaicin cream, and the capsaicin 8% patch are recommended as either second- or third-line therapies in different guidelines. Therapies that have demonstrated effectiveness for other types of neuropathic pain are discussed, such as serotonin-norepinephrine reuptake inhibitors, the anticonvulsants carbamazepine and valproic acid, and botulinum toxin. Invasive procedures such as sympathetic blockade, intrathecal steroids, and implantable spinal cord stimulators have been studied for relief of PHN, mainly in patients refractory to noninvasive pharmacologic interventions. The main guidelines considered here are those issued by the American Academy of Neurology for the treatment of postherpetic neuralgia (2004) and general guidelines for the treatment of neuropathic pain issued by the Special Interest Group on Neuropathic Pain of the International Association for the Study of Pain (2007) and the European Federation of Neurological Societies (2010).