Case Presentation: A 71 year old male, with no significant past medical history, presented with generalized weakness, malaise and body aches for the past 3 weeks, followed by right upper and lower facial weakness for the past 2 days. Denied stroke-like symptoms. He had been working in the wooded areas, but denied tick bite or rash. Physical examination revealed right upper and lower facial paresis, House- Brackmann grade IV-V, but rest of the cranial and neurological examination was unremarkable. ECG showed normal sinus rhythm. Chest x-ray was normal, with no bilateral hilar lymphadenopathy. Laboratory values revealed leukocytosis of 13,000 x 10^9/L. Erythrocyte sedimentation rate was 56. Antinuclear antibodies and rheumatoid factor were negative. CT Head without contrast was unremarkable. Lyme’s titer and Human Immunodeficiency virus testing were negative. Eventually, fluoroscopy-guided lumbar puncture was performed for diagnostic purpose. Cerebrospinal fluid analysis was positive for West Nile IgM antibody. The patient was symptomatically managed. Facial palsy started to improve after 6 weeks.

Discussion: West Nile Virus (WNV) is a neurotropic virus that targets motor neurons in the anterior horn of the spinal cord and causes asymmetric flaccid paralysis that is usually associated with fever, meningitis, and encephalitis. WNL does not commonly target brainstem nuclei or cause isolated facial palsy. Our case presents an unusual presentation of WNV-induced facial palsy with an initial viral prodromal symptoms before the development of paresis.

Conclusions: Facial palsy is defined as the decrease in motor function of facial nerve, the primary motor nerve of facial muscles. The causes can be central or peripheral; the main cause of peripheral facial palsy is mostly idiopathic, followed by viral-mediated, the most common being herpes-simplex virus. WNV can be a rare cause of isolated facial palsy.