Managing post-herpetic neuralgia
A woman aged 55 years has herpes zoster that affects the trigeminal nerve on the right side of her face. The post-herpetic pain is continuous and unbearable. Multiple drugs, including gabapentin (Neurontin) and topiramate (Topamax), have been unsuccessful. She cannot tolerate any anticonvulsants. She is currently taking morphine under the care of a pain specialist. This is the only thing that relieves her pain. She does not want to live the rest of her life on heavy-duty pain medications, but cannot function otherwise. What nonpharmacologic or referral options are available? — Bodil Morris, ARNP, Altamonte Springs, Fla.
Postherpetic neuralgia (PHN) occurs in approximately 10%-15% of herpes zoster patients and is defined as pain lasting at least three months after resolution of the rash ( J Fam Pract 2009;58:384d-384f). Systemic agents used to treat PHN include opioid analgesics (e.g., morphine, oxycodone), tricyclic antidepressants (e.g., amitriptyline [Elavil, Endep, Vanatrip], desipramine [Norpramin]) and anticonvulsants (e.g., gabapentin [Fanatrex, Gabarone, Neurontin], pregabalin [Lyrica], lamotrigine [Lamictal]).
Topical agents most frequently used include lidocaine 5% patch or gel and capsaicin cream (ranging from 0.025% to 0.075%) (J Am Osteopath Assoc. 2009;109:S7-S12); recently, an 8% capsaicin patch has been developed and has been shown to be effective (J Pain Palliat Care Pharmacother. 2011;25:32-41). Less common topical therapies include acetylsalicylic acid (in either acetone, alcohol, chloroform, or ether) and geranium oil. Such nonpharmacologic treatments as acupuncture, behavioral therapies (relaxation techniques), and transcutaneous electrical nerve stimulation have also been used (Int J Clin Pract. 2009;63:1386-1391). — Philip R. Cohen, MD (155-3)