Internal carotid artery dissection and pseudoaneurysm formation with resultant ipsilateral hypoglossal nerve palsy.

Craniocervical artery dissection is a potentially disabling condition caused by an intimal tear allowing blood to enter and dissect the media in the cranial direction which can occur spontaneously or as a result of trauma. When the dissection extends toward the adventitia, it can form a protrusion from the weakened vessel wall called a pseudoaneurysm, which may become a nidus for distal thromboembolism or cause mass effect on adjacent structures. Accurate and prompt diagnosis is critical as timely treatment can significantly reduce the risk of complications such as stroke. Here, we present a case of cervical ICA dissection and pseudoaneurysm formation causing mass effect with resultant compressive ipsilateral hypoglossal nerve palsy.