Shingles

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management

Definition

Shingles (Herpes Zoster) is a viral infection caused by the reactivation of the varicella zoster virus (VZV), which remains dormant in the dorsal root ganglia after a primary chickenpox infection. It presents as a painful, vesicular rash in a dermatomal distribution.

Aetiology

Shingles occurs due to reactivation of VZV, often triggered by immunosuppression or ageing.

Common Triggers:

  • Age related immune decline (most common in adults over 50).
  • Immunosuppression (e.g., HIV, chemotherapy, organ transplantation).
  • Psychological stress or physical trauma.
  • Recent illness or infection.

Pathophysiology

  • After primary chickenpox infection, VZV remains latent in sensory ganglia.
  • Reactivation leads to viral replication and inflammation along the affected nerve.
  • The virus spreads along the dermatome, causing vesicular eruptions and neuropathic pain.

Risk factors

  • Age >50 years.
  • Immunosuppression (HIV, cancer, steroid use).
  • Chronic conditions (diabetes, autoimmune diseases).
  • Psychological stress.
  • History of varicella (chickenpox) infection.

Signs and symptoms

Shingles typically presents with a unilateral, painful rash following a dermatomal pattern.

Prodromal Phase (1–5 days before rash):

  • Localised burning or tingling pain along a dermatome.
  • Fever, malaise, and headache.

Acute Phase (Rash Stage):

  • Vesicular rash: erythematous papules evolve into grouped vesicles, then crust over.
  • Dermatomal distribution: rash does not cross the midline.
  • Severe pain: often described as burning or stabbing.

Complications:

  • Post-herpetic neuralgia (PHN): persistent pain lasting >3 months after rash resolution.
  • Ophthalmic zoster (Zoster Ophthalmicus): involvement of the ophthalmic branch of the trigeminal nerve, leading to vision loss.
  • Ramsay Hunt syndrome: facial nerve involvement, causing facial palsy and ear pain.
  • Bacterial superinfection: secondary bacterial infection of the lesions.

Investigations

  • Clinical diagnosis: based on characteristic rash and pain.
  • Tzanck smear: shows multinucleated giant cells (rarely used).
  • Viral PCR: confirms VZV in uncertain cases.
  • HIV testing: consider in younger patients with shingles.

Management

1. Antiviral Therapy (Start Within 72 Hours of Rash Onset):

  • First-line: aciclovir 800 mg five times daily for 7 days.
  • Alternative: valaciclovir 1 g three times daily for 7 days (better compliance).

2. Pain Management:

  • First-line: paracetamol or NSAIDs.
  • Neuropathic pain: amitriptyline, gabapentin, or pregabalin if severe.

3. Supportive Care:

  • Cool compresses and calamine lotion for rash discomfort.
  • Maintain hygiene to prevent secondary infection.

4. Post-Herpetic Neuralgia Management:

  • Amitriptyline or pregabalin for persistent pain.
  • Lidocaine patches or capsaicin cream for localised pain relief.

5. Prevention:

  • Shingles vaccine: Recommended for adults >50 years (Shingrix vaccine preferred).
NeurologymypanotesShingles