Patterns and characteristics of cranial nerve neuropathy in West Nile virus infection: a systematic review of cases reported globally.

objectiveThis study aims to review case reports/series on West Nile virus (WNV) infection-associated cranial nerve (CN) neuropathy to explore the associated patterns and characteristics.

designA systematic review was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria. DATA SOURCES: We reviewed the literature in PubMed/Medline, Google Scholar and ScienceDirect databases to retrieve relevant case reports. ELIGIBILITY CRITERIA: Case reports published in the past 25 years on CN neuropathy in WNV-infected patients, with no language or geographic restrictions. DATA EXTRACTION AND SYNTHESIS: Retrieved data included patient demographics, disease presentation and treatment outcomes. Descriptive statistical analyses were performed to describe frequency and characteristics of CN neuropathies. Cross tabulation was performed to calculate statistical significance of association between patient characteristics, disease factors and treatment outcomes. Risk of bias was assessed using the JBI Critical Appraisal Tool for case reports.

resultsA total of 30 case reports satisfied inclusion criteria. These studies described 42 cases that developed CN neuropathies as an outcome of WNV infection. Patients were in the main males (54.8%) and had a mean age of 52.5±15.5 years. The most frequently affected CNs were, in descending order, optic (n=21, 50.0%), facial (n=14, 33.3%) and abducent nerves (n=8, 19.0%). Age was significantly associated with optic nerve neuropathy (≥51 years) and facial palsy (<51 years) (p=0.005 and p=0.008, respectively). Regression analysis of patient and disease variables did not reveal any significant predictor for delay of CN neuropathy following the onset of illness. As for treatment outcomes, complete recovery was significantly associated with absence of comorbidities and administration of systemic antivirals (p=0.029 and p=0.041, respectively).

conclusionsCN neuropathy represents an important subset of neuroinvasive disease caused by WNV. There is a slight male preponderance among the patient population who are mostly middle aged. Optic and facial nerves are mostly affected. Most patients show complete recovery, particularly in the absence of chronic diseases. The role of systemic antivirals in improving disease outcomes should be further investigated. Early detection of CN neuropathies is recommended by routine CN screening and use of specific tools such as MRI and neurophysiological tests.