Bilateral facial nerve palsy in a patient with West Nile neuroinvasive disease.

Introduction: Bilateral facial nerve palsy (FNP) is a rare condition that is idiopathic in only 20%. FNP is the most common cranial neuropathy in West Nile neuroinvasive disease (WNND) but is usually unilateral and only a few cases of bilateral FNP have been reported.

Case: We present a case of a 65-year-old woman with confirmed WNND and simultaneous bilateral FNP.

Results: In August 2022, the patient presented with ataxia, gait instability, tremor, fever, and vomiting. Following admission, due to her cerebrospinal fluid analyses she was diagnosed with WNV encephalitis. Her initial symptoms subsided, but on the 17th day of the disease, right FNP was observed. Three days later bilateral FNP developed, predominantly on the right side, with bilateral otalgia. Further diagnostic was performed but no other aetiology that could contribute to FNP was found. The patient was treated with a 3-day metilprednisolone course, followed by 60 mg of prednisone with dose tapering for 12 days. One month later she was discharged with significant regression of the left and slight regression of the right FNP. Subsequent physical therapy was conducted. The patient's neurological status gradually improved and 4 months after the first symptoms onset, her neurological examination was normal.

Conclusions: WNND should be included in the differential diagnosis of acquired bilateral FNP. It can result in full recovery, but unfavorable course is also possible.