Vasculopathies caused by varicella zoster virus
Vasculopathies caused by varicella zoster virus (VZV) represent a group of illnesses involving both small and large CNS arteries caused by a inflammatory process involving the media and the vascular endothelium. Usually it occurs in immunocompromised individuals due the viral reactivation and spread through the vessel wall. As a consequence, it may cause ischemic infarction, aneurysm, cerebral and subarachnoid hemorrhage, and arterial ectasia .
For a complementary discussion on CNS involvement, please refer on varicella zoster virus encephalitis.
In children, varicella zoster virus vasculopathy is responsible for ~ 30% of all arterial ischemic strokes and often occurs weeks to months after zoster or varicella. In adults, there is no accurate estimative, but it is definitely more common in immunocompromised individuals .
A variety of neurological symptoms could be present related to a stroke or transient ischemic attacks.
Varicella zoster virus vasculopathy should be strongly suspected when after a recent history of varicella or zoster a patient presents a transient ischemic attack or stroke corroborated by MRI abnormalities .
CSF analysis demonstrates modest pleocytosis, predominantly mononuclear. Concentrations of protein are commonly increased and concentrations of glucose are normal . The presence of anti-VZV IgG antibody or VZV DNA usually confirm the diagnosis.
Varicella zoster is an alpha herpesvirus found exclusively in humans . Primary VZV infection, which usually occurs in children, results in chickenpox (varicella) and, after the acute illness resolves, the virus remains latent in ganglionic neurons. In immunocompromised or elderly patients, or rarely in younger healthy patients too, the virus may reactivate.
Different theories seek to explain how the virus involves the intracranial vessels, such as haematogenous seeding or spreading via the sympathetic nervous system. The infection causes a inflammatory reaction and a functional damage to the vascular endothelium may resulting in thrombosis and promoting subendothelial proliferation of smooth muscle cells, fibroblasts, and collagen, leading to areas of stenosis and occlusion .
CT and MRI
Scans can show cortical and deep abnormalities involving both the grey and white matter, and grey-white matter junctions in special, mainly related to ischemic lesions . Varicella zoster virus vasculopathy rarely can also affect the spinal-cord causing putative infarction.
Subarachnoid and intracerebral hemorrhage can also occur.
Contrast enhancement could be present in some lesions indicating breakdown of the blood–brain barrier.
About 70% of patients show vascular abnormalities on angiographic studies (CTA/MRA/DSA) . The main feature is the presence of segmental arterial constrictions often followed by post stenotic dilatation, also creating a beading pattern. Occlusions could also be shown.
It is important to note that a negative angiogram does not exclude the diagnosis, as the disease in small arteries is not detected as readily as in large arteries .
Treatment and prognosis
Patients are usually treated with antiviral medications, such as intravenous acyclovir.