Teaching Neuro Images : Facial palsy due to arteriovenous malformation of the cheek

A 44-year-old man presented with acute left facial weakness. Left Bell palsy with involvement of all motor divisions was diagnosed through neurologic examination and neurophysiologic studies. However, the clinical course was atypical for Bell palsy, as it worsened despite medical treatment for 2 months, prompting detailed neuroimaging studies. CT angiography revealed facial arteriovenous malformation (AVM) (figure, A), and gadolinium-enhanced T1-weighted axial MRI showed that the AVM compressed the facial nerve distal to the stylomastoid foramen (figure, B). The patient underwent digital subtraction angiography and coil embolization 2 months after neuroimaging studies (figure, C), and his symptoms improved immediately after intervention. Parotid tumor and hemangioma have previously been reported as rare causes of facial palsy.1,2 Our case shows that AVM can also cause facial palsy.