title: Nystagmus in SCA territory cerebellar infarction: pattern and a possible mechanism.
abstract: OBJECTIVE
  To investigate the frequency and pattern of nystagmus associated with isolated cerebellar infarction in the territory of the superior cerebellar artery (SCA) and to discuss its possible mechanism.
  
  
  METHODS
  We identified 41 consecutive patients with isolated SCA territory cerebellar infarction diagnosed by MRI. Each patient completed a standardised dizziness questionnaire and underwent neurotological evaluations. Eye movements were recorded using 3-dimensional video-oculography during the acute period.
  
  
  RESULTS
  Approximately half (19/41) of the patients experienced true vertigo early in the course of the SCA distribution infarct. 11 (27%) of the 41 patients showed spontaneous nystagmus (SN) or direction changed bidirectional gaze-evoked nystagmus (GEN). SN was observed in 10 patients (24%) and the horizontal component of SN was predominant in most case (80%, 8/10) and always beat towards the lesion side. Direction changed bidirectional GEN was observed in five patients and was mostly (4/5) accompanied by SN. Lesion subtraction analyses revealed that damage to the rostral anterior cerebellum including the ala of the central lobule and part of the quadrangular lobule was more frequent in patients with nystagmus compared to patients without nystagmus (9/11, 82% vs 11/30, 37%) (p=0.015). In most (82%, 9/11) patients with SN or GEN, the nystagmus subsided within 1 week after hospitalisation.
  
  
  CONCLUSIONS
  Vertigo and nystagmus in SCA territory cerebellar infarction are more common than previously thought. Ipsilesional SN may result from damage to the anterior lobe of the cerebellum, which transmits the vestibular output to the fastigial nucleus.
authors.affiliation: Department of Neurology, Brain Research Institute, Keimyung University School of Medicine, 194 Dongsan dong, Daegu 700-712, South Korea.
authors.forename: Hyung
authors.initials: H
authors.lastname: Lee
authors.forename: Hyun-Ah
authors.initials: HA
authors.lastname: Kim
mesh_terms: D000368:Aged; D020520:Brain Infarction / Q000150:complications* / Q000473:pathology; D002526:Cerebellar Diseases / Q000150:complications* / Q000473:pathology; D038524:Diffusion Magnetic Resonance Imaging; D004244:Dizziness / Q000209:etiology; D005133:Eye Movements / Q000502:physiology; D005260:Female; D005403:Fixation, Ocular / Q000502:physiology; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D020766:Intracranial Embolism / Q000150:complications / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009759:Nystagmus, Pathologic / Q000209:etiology* / Q000473:pathology; D011795:Surveys and Questionnaires; D014717:Vertigo / Q000209:etiology