Peripheral Facial Nerve Palsy due to Spontaneous Internal Carotid Artery Dissection

A man in his 50s experienced novel, continuous, and progressive headache and neck pain prior to the onset of left-sided peripheral facial nerve palsy. Sequential palsies of left lower Cranial Nerves IX and XII followed. Imaging showed spontaneous cervical artery dissection (sCeAD) of the ipsilateral internal carotid artery. Lower cranial nerve palsies in sCeAD are a frequent result of a local mass effect exerted by the formation of a mural hematoma. The only close topographical relationship between the facial nerve and the internal carotid artery is within the petrous part of the temporal bone but still separated in two different bony canals (facial canal and carotid canal). Thus, a mural hematoma of an internal carotid artery dissection could not cause compression of the facial nerve. In the rare case of facial nerve palsy due to sCeAD, hypoperfusion of the vasa nervorum is the most likely cause. As sCeAD is one of the main reasons for stroke in the youth, it is critical to know and identify potential red flags in patients with peripheral facial nerve palsy, which should lead to additional vascular imaging.