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BASICS

Description

  • Reactivation of latent VZV (human herpesvirus type 3).
  • Presents as unilateral, dermatomal, painful vesicular rash.
  • PHN: persistent pain ≥1 month after rash heals.
  • HZO: VZV involving ophthalmic branch of trigeminal nerve.
  • Systems affected: nervous, integumentary, exocrine.

Epidemiology

  • Incidence increases with age; 2/3 cases ≥50 years.
  • Lifetime risk ~30% in U.S.
  • ~1 million new cases yearly in U.S.
  • PHN occurs in 18% adults; 33% in those ≥79 years.
  • Pregnancy: possible occurrence.
  • Pediatric: rare, reported in utero infection.
  • Geriatric: increased incidence of zoster and PHN.

Etiology & Pathophysiology

  • VZV reactivates from dorsal root or cranial nerve ganglia.
  • Viral replication causes inflammation and vesicle formation in dermatome.

Risk Factors

  • Increasing age.
  • Immunosuppression (malignancy, chemotherapy).
  • Physical trauma.
  • Female sex.
  • HIV infection.
  • Spinal surgery.

General Prevention

  • Recombinant zoster vaccine (Shingrix) preferred.
  • Recommended for adults previously vaccinated with Zostavax.
  • Patients with active zoster can transmit varicella virus by direct contact.

DIAGNOSIS

History

  • Prodrome: sensory changes (tingling, itching, pain) in dermatome.
  • Acute phase: constitutional symptoms, dermatomal vesicular rash.

Physical Exam

  • Rash progresses from erythematous maculopapules to grouped vesicles.
  • Common sites: thoracic and lumbar dermatomes.
  • Vesicles pustulate/hemorrhage by days 3-4.
  • Rash crusts within 14-21 days.
  • HZO: Hutchinson sign (vesicles on nose tip) indicates nasociliary nerve involvement and higher risk of ocular complications.
  • Motor nerve involvement (1-5%), Ramsay Hunt syndrome, radiculopathies possible.

Differential Diagnosis

  • Herpes simplex virus.
  • Coxsackievirus.
  • Contact dermatitis.
  • Superficial pyoderma.

Diagnostic Tests

  • Usually clinical diagnosis.
  • Viral culture, PCR, Tzanck smear (limited sensitivity/specificity).
  • Immunofluorescence, VZV IgM for confirmation.

TREATMENT

General Measures

  • Symptom control and complication prevention.
  • Antivirals reduce viral replication, inflammation, nerve damage, severity/duration of pain.
  • Calamine lotion, colloidal oatmeal for itching/burning relief.

Medications

First Line

  • Antiviral therapy within 72 hours of rash onset:
  • Valacyclovir 1,000 mg PO TID × 7 days.
  • Famciclovir 500 mg PO TID × 7 days.
  • Acyclovir 800 mg PO 5 times daily × 7 days.
  • Analgesics: acetaminophen, NSAIDs.
  • Corticosteroids may speed acute neuritis resolution but do not prevent PHN.
  • Neuropathic pain treatments:
  • TCAs (amitriptyline 10–25 mg bedtime, titrate as tolerated).
  • Lidocaine patch 5%.
  • Gabapentin 300–600 mg TID.
  • Pregabalin 150–300 mg divided doses.
  • Capsaicin cream and opioids (sparingly) may be adjuncts.

Prevention of PHN

  • No definitive prevention.
  • Early antivirals may shorten pain duration.
  • Low-dose amitriptyline within 72 hours may reduce PHN incidence/duration.
  • Paravertebral or epidural nerve blocks during acute phase may reduce PHN.

Precautions

  • Assess renal function prior to antivirals and neuropathic agents.
  • Valacyclovir, famciclovir, acyclovir are pregnancy Category B.

ADDITIONAL MANAGEMENT

Complementary & Alternative Medicine

  • Cupping therapy has potential but lacks definitive evidence.

Admission Criteria

  • Usually outpatient unless disseminated, immunocompromised, or severe disease.
  • Ophthalmology consult for HZO.

ONGOING CARE

Follow-Up Recommendations

  • Monitor symptom duration, especially PHN.
  • Hospitalize if immunocompromised, multiple dermatomes involved, severe symptoms, or complications.

Patient Education

  • Rash lasts 2-3 weeks.
  • Maintain hygiene and skin care.
  • Warn about dissemination risk and PHN.
  • Advise on transmission risk to susceptible persons.
  • Seek medical attention for eye symptoms.

PROGNOSIS

  • Immunocompetent recover in weeks.
  • Rash resolves in 14-21 days.
  • PHN may persist despite treatment.
  • HZO occurs in 10-20% cases.

COMPLICATIONS

  • Postherpetic neuralgia (PHN).
  • Herpes zoster ophthalmicus (HZO).
  • Secondary bacterial skin infection.
  • Meningoencephalitis.
  • Disseminated zoster.
  • Hepatitis, pneumonitis, myelitis.
  • Cranial and peripheral nerve palsies.
  • Acute retinal necrosis.

REFERENCES

  1. Patil A, Goldust M, Wollina U. Herpes zoster: a review of clinical manifestations and management. Viruses. 2022;14(2):192.

  2. Tsatsos M, Athanasiadis I, Myrou A, et al. Herpes zoster ophthalmicus: a devastating disease coming back with vengeance or finding its nemesis? J Ophthalmic Vis Res. 2022;17(1):123-129.

  3. Harbecke R, Cohen JI, Oxman MN. Herpes zoster vaccines. J Infect Dis. 2021;224(12 Suppl 2):S429-S442.

CLINICAL PEARLS

  • Initiate antiviral therapy within 72 hours of rash onset for maximal effect.
  • Active herpes zoster patients can transmit varicella (chickenpox) to susceptible individuals.
  • Shingrix vaccine is recommended for adults ≥50 years, including those previously vaccinated with Zostavax.
  • Hutchinson sign predicts increased risk of HZO, a potentially debilitating complication.