title: Spontaneous, headshaking, and positional nystagmus in post-lateral medullary infarction dizziness.
abstract: OBJECTIVE
  Lateral medullary infarction (LMI) sometimes causes long-lasting dizziness. However, the characteristics of nystagmus in patients with post-LMI dizziness are unknown. We undertook a prospective, comparative study of nystagmus in patients with and without post-LMI dizziness to determine the characteristic pattern of nystagmus of chronic post-LMI dizziness.
  
  
  METHODS
  We evaluated and compared nystagmus under spontaneous, head-shaking, and positional testing conditions in 12 patients with post-LMI dizziness and in 6 patients without post-LMI dizziness.
  
  
  RESULTS
  In the dizziness group, contralateral spontaneous nystagmus, ipsilateral head-shaking nystagmus, and horizontal direction-changing geotropic positional nystagmus were observed in patients in whom the LMI had occurred <60days previously (subacute period). In patients with dizziness in whom the LMI had occurred >90days previously (chronic period), the nystagmus was ipsilateral under all conditions. In the non-dizziness group, ipsilateral nystagmus was observed in 1 of the 2 subacute patients only after head-shaking and in 1 of the 4 chronic patients only during positional testing.
  
  
  CONCLUSIONS
  Ipsilateral nystagmus observed under all spontaneous, head-shaking, and positional testing conditions characterizes chronic post-LMI dizziness.
authors.affiliation: Department of Neuroendovascular Therapy, Yokohama Brain and Spine Center, Yokohama, Japan.
authors.forename: Kazumitsu
authors.initials: K
authors.lastname: Amari
authors.affiliation: Department of Neurology, Yokohama Brain and Spine Center, Yokohama, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Kudo
authors.affiliation: Department of Neurology, Yokohama Brain and Spine Center, Yokohama, Japan.
authors.forename: Kosuke
authors.initials: K
authors.lastname: Watanabe
authors.affiliation: Department of Neurology, Yokohama Brain and Spine Center, Yokohama, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yamamoto
authors.affiliation: Department of Clinical Laboratory, Yokohama Brain and Spine Center, Yokohama, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Takahashi
authors.affiliation: Department of Clinical Laboratory, Yokohama Brain and Spine Center, Yokohama, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Tanaka
authors.affiliation: Department of Neurology, Yokohama Brain and Spine Center, Yokohama, Japan. Electronic address: ke00-johkura@city.yokohama.jp.
authors.forename: Ken
authors.initials: K
authors.lastname: Johkura
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D038524:Diffusion Magnetic Resonance Imaging; D004244:Dizziness / Q000209:etiology*; D005260:Female; D019416:Head Movements / Q000502:physiology*; D006801:Humans; D007238:Infarction / Q000150:complications; D008297:Male; D008526:Medulla Oblongata / Q000473:pathology*; D008875:Middle Aged; D009760:Nystagmus, Physiologic / Q000502:physiology*; D011187:Posture / Q000502:physiology*
keywords: Dizziness; Head-shaking nystagmus; Lateral medullary infarction; Positional nystagmus; Spontaneous nystagmus