title: Hydrocephalus Caused by Fat Embolism: A Rare Complication of Atlanto-Axial Fixation for Odontoid Fractures.
abstract: BACKGROUND
  Odontoid fracture is not uncommon and surgical treatment that uses posterior screw/rod fixation is an acceptable option. This is the first report of delayed hydrocephalus due to subarachnoid fat migration as a complication of posterior atlanto-axial (AA) fixation.
  
  
  METHODS
  A 27-year-old man underwent posterior C1 lateral mass and C2 pedicle screw fixation for a recent Anderson-D'Alonzo type 2 odontoid fracture. Autologous bone graft was wired for onlay fusion. The surgery was smooth, except that there was an incidental durotomy intraoperatively. The patient had significant relief of his neck pain, although computed tomography (CT) demonstrated a medial breach of the left C1 screw postoperation; however, he gradually developed headache and dizziness after discharge. Five weeks after operation, magnetic resonance imaging demonstrated a large pseudo-meningocele at the surgical site, which was managed conservatively. Nine weeks after the AA fixation, the patient was sent to the emergency department for altered consciousness. A brain CT demonstrated hydrocephalus and multiple fat emboli in the subarachnoid and intraventricular space. A ventriculoperitoneal shunt was inserted to manage the hydrocephalus and pseudo-meningocele. The patient recovered well and was followed up to 13 months after operation. To date, this was the first report of delayed hydrocephalus caused by fat embolism after AA fixation surgery.
  
  
  CONCLUSIONS
  Incidental durotomy in posterior AA fixation may predispose the patient to a serious complication of fat-cerebrospinal fluid embolism and subsequent hydrocephalus. There should be a heightened awareness for such a complication. Both CT and magnetic resonance imaging are useful for the diagnosis of subarachnoid fat droplets.
authors.affiliation: Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan; School of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Chun-Hao
authors.initials: CH
authors.lastname: Wang
authors.affiliation: Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan; School of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Peng-Yuan
authors.initials: PY
authors.lastname: Chang
authors.affiliation: Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan; School of Medicine, National Yang-Ming University, Taipei, Taiwan. Electronic address: jauching@gmail.com.
authors.forename: Jau-Ching
authors.initials: JC
authors.lastname: Wu
authors.affiliation: Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan; School of Medicine, National Yang-Ming University, Taipei, Taiwan; Molecular Medicine Program, Taiwan International Graduate Program (TIGP), Academia Sinica, Taipei, Taiwan.
authors.forename: Tsung-Hsi
authors.initials: TH
authors.lastname: Tu
authors.affiliation: Department of Radiology, Taipei Veterans General Hospital, Taipei, Taiwan; School of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Ching-Lan
authors.initials: CL
authors.lastname: Wu
authors.affiliation: Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan; School of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Wen-Cheng
authors.initials: WC
authors.lastname: Huang
authors.affiliation: Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan; School of Medicine, National Yang-Ming University, Taipei, Taiwan; Institute of Pharmacology, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Henrich
authors.initials: H
authors.lastname: Cheng
mesh_terms: D000328:Adult; D001268:Atlanto-Axial Joint / Q000293:injuries / Q000601:surgery; D004620:Embolism, Fat / Q000000981:diagnostic imaging / Q000209:etiology* / Q000601:surgery; D005593:Fracture Fixation, Internal / Q000009:adverse effects*; D006801:Humans; D006849:Hydrocephalus / Q000000981:diagnostic imaging / Q000209:etiology* / Q000601:surgery; D008297:Male; D009809:Odontoid Process / Q000293:injuries* / Q000601:surgery*; D019919:Prosthesis Implantation; D016103:Spinal Fractures / Q000150:complications / Q000601:surgery*; D016896:Treatment Outcome; D017287:Ventriculoperitoneal Shunt
keywords: Atlanto-axial (AA) fixation; Fat embolism; Pseudo-meningocele; Ventriculoperitoneal shunt