Stroke risk after varicella-zoster virus infection: a systematic review and meta-analysis

Varicella-zoster virus (VZV) infection may cause vascular inflammatory changes leading to an increased risk of stroke. Previous studies have focused on the risk of stroke and less on changes in stroke risk and prognosis. We aimed to explore the changing patterns of stroke risk and stroke prognosis after VZV infection. This study is a systematic review and meta-analysis. We searched PubMed, Embase, and the Cochrane Library for studies on stroke after VZV infection between January 1, 2000, and October 5, 2022. Relative risks were combined for the same study subgroups using a fixed-effects model and pooled across studies using a random-effects model. 27 studies met the requirements, including 17 herpes zoster (HZ) studies and ten chickenpox studies. There was an increased risk of stroke after HZ, and this risk decreased over time: relative risk 1.80 (95% CI 1.42-2.29) within 14 days, 1.61 (95% CI 1.43-1.81) within 30 days, 1.45 (95% CI 1.33-1.58) within 90 days, 1.32 (95% CI 1.25-1.39) within 180 days, 1.27 (95% CI 1.15-1.40) at one year and 1.19 (95% CI 0.90-1.59) after one year, with the same trend in the stroke subtype. The risk of stroke after herpes zoster ophthalmicus was higher, with a maximum relative risk of 2.26 (95% CI 1.35-3.78). The risk of stroke after HZ was higher in patients aged around 40 years: relative risk 2.53 (95% CI 1.59-4.02), and similar in men and women. Also, after pooling studies of post-chickenpox stroke, we found that the middle cerebral artery and its branches were most frequently involved (78.2%), with a better prognosis in most patients (83.1%) and less frequent vascular persistence progression (8.9%). In conclusion, the risk of stroke increases after VZV infection, decreasing over time. Post-infection vascular inflammatory changes often occur in the middle cerebral artery and its branches, with a better prognosis in most patients and less frequent persistent progression.