EMed

Shingles (Herpes Zoster)

Background

  • Herpes zoster infection / reactivation
  • Contageous (< 1° varicella) - contact or resp. route
  • No seasonal variation
  • Beware HZ ophthalmicus
    (causes keratitis, uveitis, nerve palsies)
  • Sight risk not associated with severity of rash
  • F ≥M
  • Zoster Associated Pain (ZAP) is real

Risk factors

  • Age (↓ cell mediated immunity)
  • Immunosuppression (incl. immunotherapy)
  • Cancer (particularly haematological)
  • IBD

Location

  • Thoracic > Cervical >Trigeminal dermatomes
  • Bilateral = ? immunocompromise

Clinical

  • Prodromal sensory changes then
  • Erythema then
  • Regialional adenopathy then
  • Clumped vesicles (clear) then
  • Pain (often neuropathic type)
  • ± local tenderness/hyperaesthesia
  • Crusting
  • Possible 2° infection
  • Delayed resolution of erythema
HZ Ophthalmicus

Management

  • Most benign & resolve (esp. children)
  • Beware immunocompromised/ophthalmicus (? refer ophth. / admit)
  • If <72hrs of rash onset prescribe Valacyclovir
  • Consider PO steroids (help symptoms but not post herpetic neuralgia)
  • If pain - post herpetic neuralgia developing (Mx difficult) & consider:
    • TCADS
    • Anticonvulsant agents (e.g. pregabalin)
    • Try avoid opiates

Notes

  • If hypo-immune considerations are involved discuss with ID team
  • Normal dose of Valaciclovir 1g q8h po
  • Patients with severe disease or high risk of severe disease: Aciclovir 10mg/kg q8h iv. Use IBW to calculate iv Aciclovir dose. ↓ dose in renal impairment. More details on dosing/weight at NCHD.ie
  • Early (< 48 hrs after onset of rash) antivirals ↓ duration of herpes related pain
  • Suggested analgesia Paracetamol/Codeine (500/30mg) plus
  • Amitriptyline 10 mg nocte (↑ing to 20 mg if required) or Pregabalin
  • Be frank with patients about the risk of Zoster Associated Pain (ZAP) from the outset

ZAP

Risks

  • Older age
  • Female
  • Presence of a prodrome
  • Greater rash severity
  • Greater acute pain severity

Content by Dr Íomhar O' Sullivan. Last review 25/11/21.