Herpes Zoster (Shingles) Assessment

Herpes Zoster (Shingles) Assessment and Diagnosis

• Cause: Varicella-zoster virus (VZV), which becomes latent in sensory ganglia after chickenpox, reactivates later as shingles.
• Risk Factors: Patients over 60 and immunocompromised individuals are highly susceptible, with higher complications (complications) risk.
• Initial Infection: VZV enters through mucous membranes (e.g., upper respiratory tract, conjunctiva), spreads via bloodstream.
• Latency: VZV remains dormant in sensory ganglia, often the ophthalmic division of the trigeminal nerve and spinal ganglia (T3-L2).
• Reactivation: Reactivation leads to replication, ganglion nerve cell destruction, and migration to innervated dermatomes, producing skin lesions.
• Symptoms (Subjective):
  • Pain, often preceding skin lesions, can be constant or intermittent, worse at night and with temperature fluctuations. Pain typically occurs in a single ganglion (unilateral dermatome).
  • Lingering pain for more than a week suggests postherpetic neuralgia (PHN), seen in 25-50% of cases.
  • Symptoms include unexplained constant/intermittent pain, tingling, stabbing, and pain along the affected dermatome.
  • Herpes Zoster Ophthalmicus (HZO) in the trigeminal V1 distribution can cause blindness, requiring immediate ophthalmologist referral.
  • Symptoms may include eye pain, redness, inflammation (conjunctiva, cornea, uvea), photophobia, mucoid discharge, forehead rash, eyelid swelling, preceding fever and skin tingling; cornea may seem clear or cloudy.
• Symptoms (Objective):
  • Unilateral vesicular rash along a dermatome (commonly thoracic/lumbar).
  • Rash: starts as erythema, progresses to papules, vesicles, ruptures, scabs. Sometimes vesicles combine to form blisters (bullae).
  • Disease duration: 10-15 days, though lesions can persist for longer (up to 30 days).
• Diagnosis:
  • Comprehensive history and physical examination. Characteristic rash distribution and preceding pain help diagnosis.
  • PCR to detect viral DNA, or antibody titers, if needed.
  • If CNS involvement, cerebrospinal fluid (CSF) analysis may be required.
• Differential Diagnosis (DDx):
  • Rule out other causes of rashes, including impetigo, herpes simplex virus, coxsackie virus, cellulitis, insect bites, candidiasis, and drug eruptions.
  • Gram stain to check for Gram-positive cocci (in impetigo).
• Management:
  • Antiviral Agents: Acyclovir, Famciclovir, or Valacyclovir within 72 hours of rash onset are crucial to reduce neuritis and speed healing. Early treatment is key.
  • Corticosteroids: Systemic corticosteroids (prednisone) may help reduce pain and potential PHN risk when used with antivirals.
  • Pain Relief: Non-narcotic to narcotic analgesics, gabapentin, topical lidocaine patches, and capsaicin cream provide relief.
  • Chronic PHN: Regional block with or without corticosteroids at a pain center.
  • Other measures: Calamine lotion or Burow's solution dressings to soothe/prevent scratching.
• Patient Education:
  • Outpatient treatment is typical.
  • Shingles vaccine (Zostavax) is first-line prevention, and it's recommended for immunocompetent adults aged 50 and older.
  • Vaccine contraindicated in immunocompromised.
  • Antivirals are tolerated better with food.
  • Rash fluid is infectious before crusting; isolation from vulnerable individuals is crucial.
  • Avoid scratching.