EMmedonline

• Primary infection with varicella zoster (VZV) results in chickenpox, characterized by viremia with a diffuse rash and seeding of multiple sensory ganglia, where the viruses establishes lifelong latency.

• Herpes zoster is caused by reactivation of latent VZV in cranial nerve or dorsal root ganglia, with spread of the virus along the sensory nerve to the dermatome.

Clinical Feature

• The rash of herpes zoster is dermatomal and doesn't cross the midline, a feature that is consistent with reactivation from a single dorsal-root or cranial nerve ganglion.

• Thoracic, trigeminal and cervical dermatomes are the most frequent sites of rash, although any area of the skin can be involved. Few scattered lesion outside the affected dermatome are unexpected.

• The rash is often preceded by tingling,itching or pain for 2-3 days.

• The rash begins as macules and papules which evolves into vesicles and pustules.

• New lesions appear over a period of 3-5 days. They usually crust in 7 -10 days.

• Patients may have parasthesia, dysteshesia(altered painful sensitivity to touch), allodynia (Pain associated with non painful stimuli).

Diagnosis

• Clinical

• In atypical rashes the diagnosis is confirmed by PCR or direct immunoflurescence assay for VZV

Complication

• Bell's Palsy

• Ramsay Hunt Syndrome

• Transverse Myelitis

• TIA/Stroke

• Opthalmologic complications like keratitis, scleritis, uveitis and acute retinal necrosis.

• Immunocompromised patients can develop acute or chronic progressive retinal necrosis.

Management

• Antiviral Therapy

• Indication

  • Age >50 years

  • Moderate or severe pain

  • Severe rash

  • Involvement of face or eye

  • Other complication of herpes zoster

  • Immunocompromised

     

• Acyclovir, Valcyclovir and famciclovir is approved by FDA.

• In immunocmpromised patients IV acyclovir 10mg/kg q 8^th hourly for 7 -10 days alternatively foscarnet 40mg/kg IV q 8^th hourly until lesions are healed.

• Glucocorticoids

• Use of glucocortiocids in uncomplicated cases remains controversial .

• Randomised controlled trials have shown benefit of tapering course of prednisolone or prednisone.

Analgesics

• NSAID's

• Opioids are more effective in severe pain.

Postherpetic Neuralgia

• Postherpetic neurlagia is treated with topical lidocaine, gabapentin, pregabalin,opiods, TCA.

• Combination therapy like opiod and gabapentin or gabapentin & nortriptyline is more effective.

Updated on 1/2/2015

Reference

• Herpes Zoster . . Cren G. Solomon. Clinical Practice NEJM 2013