Varicella Zoster Vasculopathy

Varicella zoster vasculopathy is a productive infection of cerebral arteries by varicella zoster virus after reactivation, causing ischaemic stroke, transient ischaemic attack, aneurysm, haemorrhage or arterial dissection. It follows zoster rash (ophthalmic division) in about two thirds, weeks to months earlier, and also occurs without rash. Children after chickenpox and immunosuppressed adults are at risk.

Pathophysiology. The virus spreads along the trigeminal nerve to the cerebral arteries, causing inflammation, medial damage, thickening of the intima and stenosis or ectasia.

Stroke or transient ischaemic attack (large and small vessel), headache, confusion, seizures, and visual loss. Large and small vessel involvement with multifocal infarcts at the grey white junction is typical. Arterial aneurysm or haemorrhage occurs in a minority.

Red flags.

• Stroke weeks to months after zoster, especially ophthalmic.
• Stroke in a child within a year of chickenpox.
• Immunosuppression with stroke.

CSF shows mild lymphocytic pleocytosis and raised protein in most. Anti-varicella zoster virus IgG in CSF with a raised antibody index is the most sensitive test, and DNA by PCR is positive in about one third. MRI shows infarcts, and vessel imaging (CT or MR angiography, or catheter angiography) shows focal or multifocal stenosis, beading or occlusion. Vessel wall MRI shows enhancement. Check HIV and vasculitis screen.

Differential diagnosis.

• Primary angiitis of the central nervous system, atherosclerosis and dissection.
• Reversible cerebral vasoconstriction syndrome, moyamoya disease and infective endocarditis.
• Giant cell arteritis and syphilis.

Antiviral. Aciclovir 10 to 15 mg/kg IV every 8 hours for 14 days (adjust to renal function, ensure hydration).

Corticosteroids. Prednisolone 1 mg/kg daily (maximum 60 mg) for 5 days, with a taper over a few weeks, considered for added benefit by reducing arterial inflammation.

Stroke care. Antiplatelet therapy (aspirin 75 to 300 mg daily) once haemorrhage is excluded, and thrombolysis if eligible. Treat vascular risk factors.

Immunosuppressed patients. Longer courses of aciclovir, followed by oral valaciclovir.

Prevention. Recombinant zoster vaccine in older adults and immunosuppressed patients, and childhood varicella vaccination.

Monitoring. Repeat vessel imaging and CSF at follow up, with recurrence in some patients.

Referral and escalation. Refer urgently to neurology and stroke services.

Special groups. In children, treat with the same drug, adjusted to weight (aciclovir 10 mg/kg every 8 hours).