Epidemiology

Age > 50 (most significant risk factor due to immunosenescence).
Immunocompromised (IC) states (HIV, malignancy, transplant, immunosuppressive meds, radiation therapy).
Physical trauma or severe psychological stress.

Etiology

Prodrome:
- Burning, tingling, itching, or lancinating pain in a dermatomal distribution.
- Allodynia: a sensation of pain triggered by a stimulus that is not ordinarily considered painful. c
- Precedes the rash by 48-72 hours.
- Fever, malaise, headache may occur.
Eruptive phase:
- Unilateral, dermatomal erythematous macules/papules.
- Progresses to grouped vesicles on an erythematous base (“dewdrops on a rose petal” appearance).
- Does not cross the midline.
- Most common in thoracic and trigeminal dermatomes.
- Vesicles pustulate, ulcerate, and crust over within 7-10 days (no longer infectious once fully crusted).

Definition: reactivation of VZV in the ophthalmic division of the trigeminal nerve
Clinical features
- Fever and skin symptoms as in shingles
- Herpes zoster conjunctivitis
- Herpes zoster keratitis
- Involvement of the ophthalmic nerve: reduced corneal sensitivity with severe pain in the innervated regions (forehead, bridge and tip of the nose)
- Involvement of the nasociliary nerve:
  - Possible severe intraocular infection (uveitis, iritis, conjunctivitis, keratitis, and optic neuritis)
  - Positive Hutchinson sign of the nose: a vesicular rash on the nasal alae

Definition: reactivation of VZV in the geniculate ganglion, affecting the seventh (facial) and eighth (vestibulocochlear) cranial nerves (also known as Ramsay Hunt syndrome)
Clinical features
- Classic Triad:
  1. Severe otalgia (deep, burning, paroxysmal ear pain).
  2. Vesicular rash: Erythematous vesicles/crusts on the pinna, external auditory canal (EAC), tympanic membrane (TM), or anterior 2/3 of the tongue / soft palate. c
  3. Peripheral facial nerve (CN VII) palsy: Ipsilateral upper AND lower facial weakness (inability to furrow forehead, close eye, or smile; loss of nasolabial fold). c
- CN VIII Involvement (frequent due to proximity in the internal auditory canal):
  - Sensorineural hearing loss (SNHL).
  - Tinnitus.
  - Vertigo, nystagmus, nausea, and vomiting.
- Other Associated Features:
  - Altered taste (anterior 2/3 of tongue via chorda tympani).
  - Decreased lacrimation (dry eye) or salivation.
  - Hyperacusis (stapedius muscle paralysis).

Positive Hutchinson sign of the nose: a vesicular rash on the nasal alae

Definition: chronic neuropathic pain persisting for at least three months in the area previously affected by the rash
- Postherpetic neuralgia only happens in VZV, not other herpesviruses
Epidemiology
- Most common complication (occurs in 10–20% of overall herpes zoster cases)
- Strong association with age
Risk factors
- Age > 50 years
- Severe infection (severe pain or rash)
Clinical features
- Pain (including allodynia, paresthesias, dysesthesias) in the same dermatome as the rash
- Duration of symptoms > 3 months but can persist for years
Treatment
- One of the following tricyclic antidepressants:
  - Reduces serotonin and norepinephrine at the same time
  - Amitriptyline
  - Nortriptyline
  - Relative contraindications: patients with heart disease, epilepsy, or glaucoma
  - Should be used with caution in elderly patients
- One of the following anticonvulsants:
  - Pregabalin
  - Gabapentin
- Topical treatments
  - Capsaicin patch or cream

tags	t1
aliases	Varicella-zoster virus, VZV, Ramsay Hunt syndrome