Understanding Shingles: Symptoms, and Treatment

Posted on Feb 21, 2025 in Biomedical Sciences

Zoster (Herpes Zoster, Shingles)

Definition, Epidemiology, Pathogenesis, Clinical Features, Complications, Differential Diagnosis, Treatment

Definition

Segmental (dermatomal) painful skin disease caused by reactivation of Varicella-Zoster Virus (VZV).

Epidemiology

Approximately 10–20% of seropositive adults develop clinically apparent zoster. The peak incidence is between 50–70 years of age. In younger patients, consider HIV and iatrogenic immunosuppression.

Pathogenesis

Following the initial varicella (chickenpox) infection, VZV persists life-long in the sensory ganglia of the spinal cord and cranial nerves. When reactivated, it follows the associated nerves into the skin, thus involving both the peripheral nerve and the skin of its dermatome.

Note: When patients know that the disease starts in a nerve, they seem to accept the dysesthesias and pain better.

Clinical Features

  • Prodromal phase: Dysesthesias or pain in the distribution of the affected nerve without visible skin changes; may last up to 7 days. Typically burning or lancinating pain.
  • Eruption: Grouped vesicles and then pustules on an erythematous base appear, occasionally becoming hemorrhagic or necrotic; this phase also lasts about 7 days. The rash always respects the midline, and only a few lesions are outside the involved dermatome and its two immediate neighbors. More widespread disease suggests immunosuppression.
  • Healing: Characterized by drying, crusting, and usually some scarring; also lasting about 7 days. Note: The clinical picture is more synchronous and uniform than in varicella.
  • Uncommon variants: Zoster pneumonitis, encephalitis, nephritis, cystitis, and cholecystitis.
  • Postherpetic neuralgia: Pain in the involved dermatome that lasts more than 6 weeks; the most dreaded complication of zoster.
  • Zoster in pregnancy: Generally, no serious problems are associated with zoster during pregnancy.

Complications

  • Ocular involvement: When the first branch of the trigeminal nerve (ophthalmic nerve) is involved, 50% have ocular involvement, including keratitis, corneal erosions, conjunctivitis, iridocyclitis, secondary glaucoma, optic neuritis, impairment of muscles (double vision), and facial paralysis. Vesicles on the tip of the nose (Hutchinson sign) indicate nasociliary nerve involvement and a greater likelihood of eye involvement.
    Caution: Always consult an ophthalmologist.
  • Otic involvement: Involvement of the inner ear when the 8th cranial nerve is affected, leading to reduced hearing, vertigo, and zoster lesions of the tympanic membrane and outer ear canal.
  • Ramsay Hunt syndrome: Involvement of both the 7th and 8th cranial nerves, leading to facial paralysis, hearing loss, vertigo, and zoster lesions of the tympanic membrane and outer ear canal.
  • Affected sacral ganglia can lead to retention of urine or stool.
  • Generalized zoster: Usually in immunosuppressed patients, resembles varicella but starts in a dermatome before disseminating.

Diagnostic Approach

Diagnosis is usually based on clinical features. A Tzanck smear can be used, and if questions exist, immunofluorescent staining of the smear with monoclonal antibodies can confirm the diagnosis. With trigeminal nerve involvement or any signs and symptoms of eye involvement, always obtain an ophthalmologic consultation.

Differential Diagnosis

The primary differential diagnosis is Herpes Simplex Virus (HSV) infection. In such cases, immunofluorescent examination of a smear can readily differentiate VZV from HSV.

Therapy

Acute Zoster
  • Drying measures (zinc oxide lotion, calamine lotion).
  • In the case of severe infections or in immunosuppressed patients, antiviral therapy is recommended. Ideally, treatment should be started within 48 hours of the presence of vesicles; however, most patients come to a physician’s attention much later.
  • Acyclovir iv or p.o. (800mg five times daily for 5-7 days)
  • Brivudin 125mg once daily
  • Famciclovir 250mg three times daily
  • Valaciclovir 1000mg four times daily
Postherpetic Neuralgia

Pain therapy is associated with a wide variety of side effects. Inexperienced physicians should work closely with a specialized pain clinic or physician.