[Conjugate deviation in ischemia of medial medullary oblongata--report of three cases]

Abstract

Medial medullary infarct (MMI) is a rare type of brain stem infarction. Its clinical picture was characterized by contralateral hemiparesis, deep sensory disturbance, and ipsilateral hypoglossal paresis, but conjugate deviation or nystagmus is uncommon as initial symptom. Case 1: A 73-year-old man developed vomiting and vertigo. Examination revealed right conjugate deviation and horizontal nystagmus beating toward the left side, and numbness on his right upper limb,but no hypoglossal nerve palsy. Cranial MRI demonstrated an infarction in the left paramedian region of the upper medulla and thrombus of the left vertebral artery. Case 2: A 74-year-old man suffered from dizziness and nausea. He showed left conjugate deviation and right-beating horizontal nystagmus without Horner syndrome or hypoglossal nerve palsy. MRI disclosed an infarction in the right upper medial medulla. MRA revealed the right dissecting vertebral artery. Case 3: A 71-year-old man developed vertigo when watching at TV. He showed transient left conjugate deviation and transient motor paresis on the left upper limb. MRI showed the thickened wall of the right vertebral artery but no abnormal ischemic lesion. Digital subtraction angiograms revealed the dissecting right vertebral artery. All ischemic events limited to the upper third of the medulla were caused by the vertebral artery lesions, and prognosis was good. The unilateral MMI lesion in the nucleus prepositus hypoglossi and/or the medullary reticular formation caused contralesional shift of the eyes and ipsilesional nystagmus. The upper MMI will be characterized by a triad of contralateral hemiparesis, deep sensory disturbance and abnormal ocular motor findings.