INSTRUCTION

Look at this patient.

SALIENT FEATURES

History

• Pain, particularly in the ophthalmic branch of the trigeminal nerve and in the lower thoracic dermatomes (postherpetic neuralgia occurs in about 50% ofpatients with zoster over the age of 60 years).

• Past history of chickenpox.

• Presence of an underlying immunocompromised state (e.g. recurrent zosterindicates a poorer prognosis in patients with established AIDS). Zoster occurs at leastseven times more frequently in homosexual men with HIV infection than in HIV-negativecontrols.

Examination

• Vesicular rash along a dermatome (usually affects thoracic and lumbardermatomes).

• Enlargement of a draining lymph node.

Proceed as follows:

Remember that the virus affects both the posterior horn of the spinal cord and the skinsupplied by sensory fibres that pass through the diseased root ganglion.

DIAGNOSIS

This patient has a vesicular rash along the 6th thoracic dermatome (lesion) due toherpes zoster (aetiology), and has severe local pain (functional status).

ADVANCED-LEVEL QUESTIONS

In which layer of the skin are the vesicles formed?

They are formed in the prickle-cell layer of the epidermis as a result of the "balloondegeneration' of cells and serous exudation from the corium.

How does this condition present?

Pain in the distribution of the dermatome, malaise: fever, followed a few days later by arash in the same distribution as the pain. The rash starts as macules, then formsvesicles and then pustules.

Which nerve is affected when the lesions are present on the tip of the nose?

The ophthalmic division of the trigeminal nerve.

How would you confirm the diagnosis?

The diagnosis is usually clinical. It is confirmed by rising viral titres and isolation of thevirus from the blister. The Tzanck smear demonstrates a multinucleated giant cell andviral inclusions when material scraped from the floor of a vesicle is stained with Wright'sstain. The Tzanck test can be positive in infections with herpes simplex, herpes zosterand varicella.

How would you manage such a patient?

• Topical idoxuridine 5% solution if caught in the first 36 hours of the eruption.

• Painrelief, including amitriptyline in severe cases.

• Intravenous aciclovir in the immunocompromised individual (N Engl J Med 1994;330: 896).

• Interferon appears to be effective in limiting zoster in patients with cancer.

Is varicella-zoster immune globulin (VZIG) useful in preventing zoster eruptions?

There are no known means of effectively preventing zoster eruptions; however, resultson the effectiveness of the recently developed live attenuated varicella vaccine areawaited. Although there is considerable controversy, with arguments for and againstuniversal vaccination, the American Academcy of Pediatrics has recently adopted aposition in support of universal vaccination of healthy nonimmune children and adults.

What are the complications of herpes zoster?

• Corneal ulcerations.

• Gangrene of the affected area.

• Phrenic nerve palsy.

• Meningoencephalitis.

• Ramsay Hunt syndrome.

• Postherpetic neuralgia - intrathecal methyl prednisolone is an effective treatmentfor postherpetic neuralgia (N Engl J Med 2000; 343:1514-19)

• Disseminated zoster including pneumonia.

What are the features of herpes zoster in patients with HIV infection?

It is usuallyunidermatomai and uneventful. However, it may be multidermatomal, disseminatedrecurrent, or chronically persistent as a hyperkeratotic nodular lesion.

How does the varicella zoster virus affect the central nervous system in patients withAIDS?

In acquired immune deficiency syndrome the virus may cause the following:

• Multitocal encephalitis.

• Ventriculitis.

• Acute haemorrhagic meningomyeloradiculitis.

• Focal necrotizing myelitis.

• Vasculitis of the leptomeningeal arteries.J. Ramsay Hunt US neuroiogist.