Bilateral medial medullary infarction(MMI)was a rare subtype of stroke.The clinical manifestations of bilateral MMI were complicated,which leaded to misdiagnosis.Patients with bilateral MMI could progress rapidly,and were easy to progress to respiratory failure and even death.Patients with this type of cerebral infarction did not respond well to medication.One case data of a patient with bilateral MMI was reviewed and analyzed.The weakness on the right side of the body was presented,accompanied by slurred speech,and was finally diagnosed with atherosclerosis of the large arteries through cranial MR examination.The patient had occlusion of the left posterior inferior cerebellar artery distal to the left vertebral artery V4 segment on the left side.The patient was treated with stent thrombectomy and balloon angioplasty,and the follow-up phone call at 3 months after discharge was showed good prognosis.Through a review of the literature,combined with the clinical and imaging features of this case,a preliminary analysis suggested that atherosclerosis of the large arteries may be the most common cause of bilateral MMI.Cranial MR imaging is an important method for diagnosing this condition.For patients with bilateral MMI accompanied by occlusion of the vertebral artery V4 segment,endovascular intervention may be attempted.