title: Pure midbrain infarction: clinical, radiologic, and pathophysiologic findings.
abstract: OBJECTIVE
  To describe the clinical features, MRI findings, and the pathogenesis of the pure midbrain infarction.
  
  
  METHODS
  Forty patients with infarcts limited to the midbrain were studied. MRI and angiography (mostly MR angiography) were performed in all patients.
  
  
  RESULTS
  Clinical manifestations included gait ataxia in 27 (68%) patients, dysarthria in 22 (55%), limb ataxia in 20 (50%), sensory symptoms in 17 (43%), third nerve palsy in 14 (35%), definitive limb weakness (< or =IV/V) in nine (23%), and internuclear ophthalmoplegia in five (13%). According to MRI findings, the lesions were categorized into four groups. The anteromedial group (n = 18) was characterized by oculomotor disturbances (89%), ataxia (89%, bilateral in 17%), and sensory changes (39%) usually restricted to the perioral and hand areas. Lesions restricted to the subcortical area (n = 10) were usually related to small vessel disease (SVD) (78%), whereas those involving the medial surface (n = 8) were caused by large vessel disease (LVD) (78%). The anterolateral group (n = 11) was characterized by ataxia (70%) and definitive hemiparesis (30%) usually caused by LVD (82%). The combined group (n = 6) had frequent oculomotor disturbances (83%), definitive hemiparesis (67%), and ataxia (50%) and was usually associated with LVD (67%). The lateral group (n = 2) was characterized by prominent sensory symptoms. The prognosis was generally good except for one patient with a bilateral lesion.
  
  
  CONCLUSIONS
  Clinical-radiologic correlation study yields four distinct subgroups: anteromedial, anterolateral, combined, and lateral. Large vessel disease and small vessel disease are usual pathogenic mechanisms, whereas cardiogenic embolism is rare.
authors.affiliation: Department of Neurology, University of Ulsan, Asan Medical Center, Seoul, Korea. jongskim@amc.seoul.kr
authors.forename: Jong S
authors.initials: JS
authors.lastname: Kim
authors.forename: Jeeyeon
authors.initials: J
authors.lastname: Kim
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001259:Ataxia / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D001488:Basilar Artery / Q000473:pathology / Q000503:physiopathology; D020526:Brain Stem Infarctions / Q000175:diagnosis* / Q000503:physiopathology*; D002318:Cardiovascular Diseases / Q000150:complications; D018450:Disease Progression; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography; D008279:Magnetic Resonance Imaging; D008297:Male; D008636:Mesencephalon / Q000098:blood supply / Q000473:pathology* / Q000503:physiopathology*; D008875:Middle Aged; D015840:Oculomotor Nerve Diseases / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D010291:Paresis / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D020769:Posterior Cerebral Artery / Q000473:pathology / Q000503:physiopathology; D011237:Predictive Value of Tests; D011379:Prognosis; D012307:Risk Factors; D012678:Sensation Disorders / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D014715:Vertebrobasilar Insufficiency / Q000175:diagnosis* / Q000503:physiopathology*