Shingles is a disease caused by reactivation of the varicella-zoster virus---the same virus that causes chickenpox---within the roots of the sensory nerves. Shingles causes acute symptoms similar to chickenpox; however, the main problem with shingles, according to the Centers for Disease Control and Prevention, is that up to 70 percent of patients develop a chronic pain syndrome called neuralgia. In a 2005 report in "Neurology," Mayo Clinic neurologists Kenneth Hentschel, David J. Capobianco and David W. Dodick describe the diagnosis and treatment of the "explosive" and "electric shock-like" pain that patients with facial neuralgia pain from shingles experience.
Corticosteroids
Oral corticosteroids, such as prednisone, have long been known to quell facial and other neuralgias due to herpes zoster, by reducing inflammation of the affected nerves and surrounding tissues, explains dermatologist Steven K. Tyring in the December 2007 edition of the "Journal of the American Academy of Dermatology." The main problem, says Tyring, is that corticosteroids often cause unacceptable side effects, especially in the older individuals who constitute the major group of patients affected by shingles. In patients who can tolerate corticosteroids, Tyring recommends starting at conservative doses and tapering the drugs over the course of three weeks or longer.
Anticonvulsants
According to the Mayo Clinic website, anticonvulsants such as gabapentin and pregabalin work for patients with facial and other kinds of neuralgia due to shingles much as they do for patients with seizure disorders, by stabilizing abnormal electrical activity within affected nerves. According to Tyring, starting the drugs early---during the active episode of shingles---may help prevent facial neuralgia from ever appearing in the first place. Patients who take gabapentin and pregabalin, continues Tyring, often experience significant reductions in pain. However, the drugs often cause side effects such as dizziness and sleepiness.
Topical Agents
Patches implanted with the local anesthetic lidocaine provide safe and effective relief for neuralgia that affects the body but often prove unwieldy for use on the face. According to a 2009 report in the "Journal of the German Society of Dermatology," twice-daily application of a cream containing marijuana-derived n-palmitoylethanolamine controls 90 percent of facial neuralgia pain in up to two-thirds of treated patients. Facial neuralgia pain, explain the authors, comes from nerve fibers that have few opioid receptors, but many cannabinoid receptors, explaining the limited efficacy of narcotics. Topical use avoids side effects that would normally follow oral or inhalational use of marijuana derivatives.
Time
According to Hentschel and colleagues, 50 percent of patients experience spontaneous remission of facial neuralgia within six months. Thus, it can be difficult to tell whether a specific treatment is effective or whether the symptoms have simply resolved. As a result, Hentschel and colleagues recommend administering any treatment for at least eight weeks, followed by a slow taper over a similar time frame. Patients whose symptoms worsen on lower doses can easily be switched back to the full dose, while patients who no longer require a full dose avoid overmedication.
References
- "Neurologist"; Facial Pain; K. Hentschel et al.; 2005
- "Journal of the German Society of Dermatology"; Adjuvant Topical Therapy With a Cannabinoid Receptor Agonist in Facial Postherpetic Neuralgia; N.G. Phan et al.; 2009
- "Journal of the American Academy of Dermatology"; Management of Herpes Zoster and Post Herpetic Neuralgia; S.K. Tyring; December 2007
- Mayo Clinic: Postherpetic Neuralgia: Treatments and Drugs
- Centers for Disease Control and Prevention: Herpes Zoster Disease: Q & A's for Providers
