Dermatology - Herpes Zoster

Dermatology - Herpes Zoster 
Herpes Zoster 

Acute dermatomal recurrence of varicella-zoster virus (VZV), commonly referred to as shingles or herpes zoster, is typified by intense unilateral pain and a vesiculobullous reaction. Phrenic neuralgia (PHN) is a significant morbidity.


Three separate clinical stages are present in herpes zoster: prodrome, active infection, and postherpetic neuralgia. Angina or an acute abdomen can be mimicked by the pain and tenderness in the affected dermatome during the prodrome. There can be zoster without rash.
There may be flu-like symptoms, such as lymphadenopathy. Lesions appear in waves during the active infection, lasting roughly a week each, and then subside in two to four weeks. There may be temperature, pain, and touch sensory nerve abnormalities as well as (mild) motor paralysis (Bell Palsy). Complications include uveitis, keratitis, conjunctivitis, retinitis, optic neuritis, glaucoma, proptosis, cicatricial lid retraction, and extraocular muscular palsies can arise from ocular involvement. After ocular involvement, delayed contralateral hemiparesis may also develop, presenting with hemiplegia and headache.
Constant, intense, stabbing, or scorching pain that lasts for months or years is known as postherpetic neuralgia.
Damage
On an edematous base, the lesions are erythematous. Clear, clustered vesicles are superimposed; these can occasionally bleed and degrade to produce crusted lesions. The dermatome innervated by the sensory ganglion where the infection was reactivated is the only area where lesions can occur.
The thoracic (>50%), trigeminal (10–20%), lumbosacral, and cervical (10–20%) dermatomes are the most common locations for them. Depending on the dermatome involved, vesicles and erosions may appear in the mouth, vagina, and bladder.

The Tzanck test, DFA, or viral culture can be used to confirm the clinical diagnosis and rule out HSV infection. The prodrome can mimic vertigo, acute abdominal, cardiac or pleural illness, or migraine. Phytoallergy (poison ivy) and herpes simplex virus (HSV) infection are two differential diagnoses for the lesions.

If antiviral therapy is initiated early in the course of the illness, it is successful. Give oral valacyclovir 1 g every 8 hours, acyclovir 800 mg five times a day for seven days, or famciclovir 500 mg every eight hours. For individuals who are not significantly immunocompromised, extend treatment to 10 days and provide intravenous acylclovir or foscarnet. Gabapentin, pregabalin, tricyclic antidepressants, capaicin cream, and nerve block are useful for treating postherpetic neuralgia.