title: Ipsilateral hemiparesis in lateral medullary infarction: Clinical investigation of the lesion location on magnetic resonance imaging.
abstract: BACKGROUND
  In 1946, Opalski reported two cases of Wallenberg syndrome with ipsilateral hemiparesis (IH). His hypothesis seems to be based on the view that IH is caused by post-decussating pyramidal tract damage. Afterwards, other researchers proposed a different hypothesis that ipsilateral sensory symptoms of limbs (ISSL) or ipsilateral limb ataxia (ILA) caused by lateral medullary infarction (LMI) might lead to ipsilateral motor weakness. The present study is aimed to clarify whether IH in LMI patients is attributable mainly to ISSL/ILA or disruption of ipsilateral post-decussating pyramidal tract.
  
  
  METHODS
  Thirty-two patients with acute LMI admitted during the last 13years were divided to IH Group (n=7) and Non-IH Group (n=25). Lesion location/distribution on MRI and neurological findings were compared between the two groups.
  
  
  RESULTS
  LMI involved the lower medulla in all seven IH patients and 12 of 25 Non-IH patients. The lower medullary lesion extended to the cervico-medullary junction (CMJ) in four of seven IH patients and one of 12 Non-IH patients. Definitive extension to upper cervical cord (UCC) was confirmed in none of the patients. ISSL was found in two IH and three Non-IH patients all showing only superficial sensory impairments. ILA or hypotonia was observed in 57% of IH and 60% of Non-IH patients.
  
  
  CONCLUSIONS
  IH in LMI appears to be due mainly to post-decussating pyramidal tract damage at the lower medulla instead of ILA or ISSL participation.
authors.affiliation: Department of Neurology, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Uemura
authors.affiliation: Department of Neurology, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Naritomi
authors.affiliation: Department of Neurology, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan.
authors.forename: Hisakazu
authors.initials: H
authors.lastname: Uno
authors.affiliation: Department of Neurology, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan.
authors.forename: Arisa
authors.initials: A
authors.lastname: Umesaki
authors.affiliation: Department of Neurology, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan. Electronic address: kmiyasit@hsp.ncvc.go.jp.
authors.forename: Kotaro
authors.initials: K
authors.lastname: Miyashita
authors.affiliation: Department of Cerebrovascular Medicine, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Toyoda
authors.affiliation: Department of Cerebrovascular Medicine, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Minematsu
authors.affiliation: Department of Neurology, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan.
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Nagatsuka
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D020520:Brain Infarction / Q000150:complications* / Q000000981:diagnostic imaging*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008526:Medulla Oblongata / Q000000981:diagnostic imaging*; D008875:Middle Aged; D010291:Paresis / Q000000981:diagnostic imaging* / Q000209:etiology*; D012189:Retrospective Studies
keywords: Cerebral infarction; Ipsilateral hemiparesis; Lateral medullary infarction; Magnetic resonance imaging; Opalski's syndrome; Pyramidal tract