title: Postoperative Paralysis From Thoracic Ossification of Posterior Longitudinal Ligament Surgery Risk Factor of Neurologic Injury: Nationwide Multiinstitution Survey.
abstract: METHODS
  Retrospective case-control study.
  
  
  OBJECTIVE
  The purpose of this study was to examine the factors of postoperative paralysis in patients who have undergone thoracic ossification of posterior longitudinal ligament (OPLL) surgery.
  
  
  BACKGROUND
  A higher percentage of thoracic OPLL patients experience postoperative aggravation of paralysis than cervical OPLL patients, including patients that presented great difficulties in treatment. However, there were a few reports to prevent paralysis thoracic OPLL.
  
  
  METHODS
  The 156 patients who had received thoracic OPLL surgery were selected as the subjects of this study. The items for review were the duration of disease; the preoperative muscle strength (Muscle Manual Testing); OPLL levels (T1/2-4/5: high, T5/6-8/9: middle, and T9/10-11/12: low); the spinal canal occupancy ratio; the ratio of yellow ligament ossification as a complication; the ratio of transcranial-motor evoked potential (Tc-MEP) derivation; the preoperative/postoperative kyphotic angles in the thoracic vertebrae; the correction angle of kyphosis; the duration of surgery; and the amount of bleeding. The subjects were divided into two groups based on the absence or presence of postoperative paralysis to determine the factors of postoperative paralysis.
  
  
  RESULTS
  Twenty-three patients (14.7%) exhibited postoperative paralysis. Multivariate analysis identified factors associated with postoperative paralysis: the duration of disease (odds ratio, OR = 3.3); the correction angle of kyphosis (OR = 2.4); and the ratio of Tc-MEP derivation (OR = 2.2).
  
  
  CONCLUSIONS
  The risk factors of postoperative paralysis are a short duration of disease and a small correction angle of kyphosis. In addition, ratios of Tc-MEP derivation below 50% may anticipate paralysis.
  
  
  METHODS
  4.
authors.affiliation: Japanese Society for Spine Surgery and Related Research, Nagoya University School of Medicine, Naogya, Aichi, Japan.
authors.forename: Zenya
authors.initials: Z
authors.lastname: Ito
authors.forename: Yukihiro
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authors.lastname: Matsuyama
authors.forename: Muneharu
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authors.lastname: Ando
authors.forename: Shigenori
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authors.lastname: Kawabata
authors.forename: Tsukasa
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authors.lastname: Kanchiku
authors.forename: Kazunobu
authors.initials: K
authors.lastname: Kida
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Fujiwara
authors.forename: Kei
authors.initials: K
authors.lastname: Yamada
authors.forename: Naoya
authors.initials: N
authors.lastname: Yamamoto
authors.forename: Sho
authors.initials: S
authors.lastname: Kobayashi
authors.forename: Takanori
authors.initials: T
authors.lastname: Saito
authors.forename: Kanichiro
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authors.lastname: Wada
authors.forename: Nobuaki
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authors.lastname: Tadokoro
authors.forename: Masato
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authors.lastname: Takahashi
authors.forename: Kazuhiko
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authors.lastname: Satomi
authors.forename: Kenichi
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authors.lastname: Shinomiya
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Tani