LAS VEGAS—Postherpetic neuralgia (PHN) is often unrecognized and undertreated, and most patients have persistent pain despite treatment, said Charles E. Argoff, MD, CPE.
For these reasons, care should be individualized and the clinician should persevere with different therapeutic modalities, using one or a combination of the many options currently available, said Dr. Argoff, Professor of Neurology and Director, Comprehensive Pain Center, Albany Medical Center, New York.
Reactivation of the varicella zoster virus, which usually occurs in immunocompromised individuals, results in herpes zoster. He defined PHN as ongoing pain after the herpes zoster rash virus has healed, generally lasting longer than 3 months. Patients describe the pain as burning, sensitive, numb, constant, or episodic; a painful itch may also exist. Risk factors include age, severity and extent of rash, and intensity of initial pain as well as painful prodrome, female gender, slower healing, and more sensory changes.
Dr. Argoff outlined gaps that exist in evidence-based guidance for the management of PHN in primary care that he and colleagues recently addressed in an article in Postgraduate Medicine in July 2013. These include that “clinical studies typically enroll patient populations that are highly selected, thus not reflecting true clinical practice.” Other areas that remain unaddressed are formulation differences, tolerability in subpopulations, and doses that can truly be achieved in clinical practice. Head-to-head and multidrug studies are also lacking.
Treatment should include medical, psychological, and complementary and alternative medicine options as well as rehabilitation. In selecting treatment, he noted that very little comparative literature exists, and no one treatment works for most patients. In addition, some medications are not appropriate for some patients and some patients only want procedures. Others want only medications and still others, alternative approaches. And, because some pain is focal, and some, part of the systemic process, the bottom line is, “care must be individualized.”
The best evidence for medications, for example, are the tricyclic antidepressants, gabapentin and pregabalin, carbamazepine (for trigeminal neuralgia), opioids, tramadol, topical lidocaine patch, and duloxetine or venlafaxine. Relatively newer treatments for PHN include a high concentration (8%) topical capsaicin patch, gastroretentive gabapentin, gabapentin enacarbil, and pregabalin in combination with lidocaine plaster, oxycodone, or transcutaneous electrical nerve stimulation (TENS).
Making practical treatment decisions for PHN include tolerability, dosing and onset of analgesia, and managing PHN in specific populations, such as the older patient, those with renal and/or hepatic impairment or with anxiety and/or depression, and in the substance abuser. Finally, preventing PHN through vaccination against herpes zoster should be emphasized, he concluded.