Objective: We report a case of spontaneous dissection of the cervical internal carotid artery.Case Presentations: A 42-year-old man presented with dysarthria, dysphagia, lingual deviation to the left, left lingual atrophy and paralyzed left soft palate. He had no history of trauma. Although brain MRI showed no abnormal findings, brain MRA, cervical MRA and angiography revealed a dissection of the cervical internal carotid artery and a dissecting aneurysm. From these findings, we diagnosed the patient with peripheral lower cranial nerve palsy caused by a spontaneous dissection of the left cervical internal carotid artery. After 1 week of conservative management, angiography demonstrated enlargement of the dissecting aneurysm. The dissection of the dissecting aneurysm was then treated with carotid artery stenting to prevent the onset of stroke. After stenting, the patient’s symptoms improved gradually.Conclusion: Spontaneous cervical internal carotid artery dissection should be considered as a differential diagnosis of lower cranial nerve palsy and was successfully treated with endovascular therapy in our case.