Postherpetic Neuralgia, PHN

Herpes zoster is a blistering skin eruption in a dermatomal distributions often presented in chest wall. After primary infection with chicken pox the virus persists in the ganglia of sensory cranial nerves and spinal dorsal root ganglia.

Shingles cannot be passed from one person to another. However, the virus that causes shingles, the varicella zoster virus, can be spread from a person with active shingles to another person who has never had chickenpox. In such cases, the person exposed to the virus might develop chickenpox, but they would not develop shingles.

The virus is spread through direct contact with fluid from the rash blisters caused by shingles.

A person with active shingles can spread the virus when the rash is in the blister-phase. A person is not infectious before the blisters appear. Once the rash has developed crusts, the person is no longer contagious.

Shingles is less contagious than chickenpox and the risk of a person with shingles spreading the virus is low if the rash is covered.

Acute pain associated with infection with Varicella-Zoster virus which continues even after treatment of infections and results in chronic pain problem. The pain often is debilitating and sever in nature and is described as burning or sharp, constant or intermittent with severity as high as 8 of 10. An estimated 20% of people with shingles will go on to develop post-herpetic neuralgia. People with poor immune system, individuals with diabetes and older people are particularly at risk.

The rate of PHN has been reported at 5% in those younger than 60 years up to 10% in those aged 60 to 69 years and to 20% in those aged 80 years or older.

• herpes simplex virus
• impetigo
• candidiasis
• contact dermatitis
• insect bites
• autoimmune blistering disease
• dermatitis herpetiformis
• drug eruptions

Herpes zoster is usually diagnosed clinically by:

• Pain
• Vesicular rash
• Dermatomal distribution over chest wall

• shell vial viral culture
• detection of viral DNA by polymerase chain reaction
• direct fluorescent antibody staining
• immunoperoxidase staining
• Tzanck smear

Medications with strong evidence support:

• Tricyclic Antidepressants (TCA):
  • Amitriptyline
  • Nortriptyline
  • Desipraamine
  • Maprotiline
• GABA agonists:
  • Gabapentin
  • Pregabalin
• Opioids
  • Tylenol 3
  • Tramadol
  • Morphine
• Anesthetics:
  • Topical lidocaine patches

• Yawn BP, Saddier P, Wollan P, St Sauver JL, Kurland MJ, Sy LS. A population-based study of the incidence and complication rates of herpes zoster before zoster vaccine introduction [published correction appears in Mayo Clin Proc. 2008;83(2):255] Mayo Clin Proc. 2007November;82(11):1341-1349.
• Gilden DH, Kleinschmidt-DeMasters BK, LaGuardia JJ, Mahalingam R, Cohrs RJ. Neurologic complications of the reactivation of varicella-zoster virus [published correction appears in N Engl J Med. 2000;342(14):1063] N Engl J Med. 2000;342(9):635-645.
• Yawn BP, Saddier P, Wollan P, St Sauver JL, Kurland MJ, Sy LS. A population-based study of the incidence and complication rates of herpes zoster before zoster vaccine introduction [published correction appears in Mayo Clin Proc. 2008;83(2):255] Mayo Clin Proc. 2007November;82(11):1341-1349.
• Harpaz R,, Ortega-Sanchez IR, Seward JF. Prevention of herpes zoster: recommendations of the Advisory Committee on Immunization Practices (ACIP) [published correction appears in MMWR Recomm Rep.2008;57(28): 779] MMWR Recomm Rep. 2008;57(RR-5):1-30.