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Dr. Ajith Kumar J MD
Dept. of Emergency Medicne
Travancore Medicity, Kollam
India
editor
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.
Drug | Dose | Effects | Side Effects |
Acyclovir | 800mg five times a daily for 7 -10 days | Reduced time to last new lesion formation, loss of vesicles, full crusting, cessation of viral shedding, reduced severity of acute pain | Malaise |
Famciclovir | 500 mg tid for 7 days | Reduced time to last new lesion formation, loss of vesicles, full crusting, cessation of viral shedding, reduced severity of acute pain | Headache, nausea |
Valcyclovir | 1 gm tid for 7 days | Reduced time to last new lesion formation, loss of vesicles, full crusting, reduced severity of acute pain | Headache, nausea |
In immunocmpromised patients IV acyclovir 10mg/kg q 8th hourly for 7 -10 days alternatively foscarnet 40mg/kg IV q 8th 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
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emmedonline
Dr. Ajith Kumar J MD
Dept. of Emergency Medicne
Travancore Medicity, Kollam
India
editor