Case Presentation: A 46-year-old female with a past medical history of hypertension, diabetes mellitus, and asthma who initially presented 2 weeks prior to the emergency department for right-sided facial paralysis and was diagnosed with idiopathic facial paralysis (Bell’s palsy). Despite being started on prednisone and valaciclovir, 2 weeks later she had suddenly developed left-sided facial paralysis. Examination showed bilateral complete lower motor neuron type facial palsy. Laboratory tests for CBC, CMP, ACE levels, Lyme and HIV serologies were all unremarkable. MRI brain with and without contrast was normal. Lumbar puncture was unremarkable. A diagnosis of bilateral idiopathic facial paralysis (bilateral Bell’s palsy) was made. Prednisone was restarted and her symptoms had completely resolved 1 month later.
Discussion: Bilateral facial nerve palsy has an incidence of only 1 per 5 million people per year. Common causes include Lyme disease, Guillain-Barré syndrome, sarcoidosis, infectious mononucleosis and trauma. Bilateral facial nerve palsy may be a presenting feature of a potentially life-threatening illness, therefore care must be taken to exclude potential metabolic, infectious, vasculitic, traumatic, immunological and neoplastic causes before diagnosing bilateral idiopathic facial palsy. Only 20% of bilateral facial nerve palsy cases are idiopathic where no evidence of systemic or local disease can be found. Prognosis for bilateral facial palsy is dependent on the underlying etiology. The prognosis may be worse with age over 60 years, diabetes mellitus, hypertension, pain and decreased tearing.
Conclusions: Bilateral facial nerve palsy may be a presenting feature of a potentially life-threatening illness. Only 20% of cases are idiopathic where no evidence of systemic or local disease can be found.