Post Herpetic Neuralgia (PHN)
Herpes Zoster is caused by the reactivation of the same virus which causes chickenpox. If you have had chickenpox before, the virus lies inactive in the nervous system till the time it gets an opportunity (such as in old age or when body’s immunity is reduced) to spread along the nerve. This produces the typical rash of Herpes Zoster accompanied by pain, numbness, itching, skin pigmentation and sometimes scarring. One out of five patients goes on to develop PHN where the pain persists for more than 120 days after the onset of rash. PHN is rare in age group below 50 years and incidence increases after the age of 60 years. Risk factors for PHN or persisting pain include older age and widespread rash with severe pain at onset. Presentation Pain character in PHN is generally burning, shooting, throbbing or electric shock like and this may occur spontaneously or in response to stimuli. It is most commonly observed in chest wall region (thoracic dermatomes) and in the distribution of ophtha...