Acute Herpes Zoster

The classic rash of shingles is a group of small red vesicles following a dermatomal distribution.

Shingles, also known as acute herpes zoster, is a painful condition in a circumscribed area of the body, commonly associated with a characteristic vesicular rash. Acute zoster occurs in people who have previously been exposed to the varicella zoster virus, the causative agent for chickenpox. After recovery from the chickenpox, the varicella virus lies dormant in the nervous system and can be reactivated at any time. The exact cause of the reactivation is unknown, but stress, fatigue and immune suppression are known to be risk factors. The disease has a peak incidence in middle and old age, but can occur in any decade.

 

Acute zoster usually presents as a burning, lancinating or electrical pain in the distribution of a single spinal root or a single division of a cranial nerve, followed 4-5 days later by the characteristic rash. On occasion shingles can present in a small number of adjacent dermatomes and is very infrequently bilateral. Rarely the characteristic rash may be so mild as to be overlooked or completely absent (zoster sine herpete) making the diagnosis very difficult to establish. The vesicles usually begin to crust over about 2-3 weeks after they appear, often accompanied by a decrease or a disappearance of the pain. Complete healing of the lesions may take up to 5-6 weeks and it is not uncommon for a faint erythematous or hyperpigmented area of skin to remain.

 

A rare complication of acute shingles is post-herpetic neuralgia, where the skin lesions heal but the pain persists. Risk factors for the occurrence of post herpetic neuralgia are the length and severity of the prodromal phase, the length, severity and the extent of the acute phase and the persistence of pain after healing of the rash has begun. Post-herpetic neuralgia has an extremely poor prognosis, so a major focus of therapy is its prevention.

 

Modern therapy for acute shingles usually focuses on antiviral medications and oral steroids, but injection therapy is highly effective in severe and resistant cases. It has been know since the early part of the 20th century that selective nerve root blocks or cranial nerve blocks speed the rate of healing tremendously and significantly reduce the risk of post-herpetic neuralgia.

 

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