title: Migration of Bone Wax into the Sigmoid Sinus after Posterior Fossa Surgery.
abstract: OBJECTIVE
  Bone wax is a hemostatic agent that has been reported in some instances to migrate into the sigmoid sinus following posterior fossa surgery. The purpose of this study was to characterize the CT and MR imaging findings of this entity.
  
  
  METHODS
  The study included 212 consecutive patients who underwent posterior fossa surgery and postoperative CT and contrast-enhanced MR imaging. The presence of sigmoid sinus bone wax migration was determined with the following criteria: sigmoid sinus filling defect showing low signal on all MR imaging pulse sequences; sigmoid sinus filling defect showing low CT attenuation, similar to fat attenuation; and clinical confirmation that bone wax was used intraoperatively. CT and MR imaging of an in vitro bone wax sample was also performed.
  
  
  RESULTS
  We identified 6 cases of sigmoid sinus bone wax migration. In each case, a low-signal-intensity, low-attenuation filling defect was noted in the sigmoid sinus. The morphology was linear (n= 3) or globular (n= 3). In patients with serial imaging, the appearance of migrated bone wax remained stable over time. No adverse outcomes related to sigmoid sinus bone wax migration were encountered. In vitro imaging of bone wax confirmed low CT attenuation and low MR imaging signal intensity on T1WI and T2WI.
  
  
  CONCLUSIONS
  Bone wax migration into the sigmoid sinus is a recognizable imaging finding after posterior fossa surgery that appears to have a benign clinical course. The finding should be distinguished from more serious complications, such as venous sinus thrombosis.
authors.affiliation: From the Department of Neuroradiology (K.B., A.K.), NYU Langone Medical Center, New York, New York kory.byrns@gmail.com.
authors.forename: K
authors.identifier: http://orcid.org/0000-0002-3489-0393
authors.initials: K
authors.lastname: Byrns
authors.affiliation: From the Department of Neuroradiology (K.B., A.K.), NYU Langone Medical Center, New York, New York.
authors.forename: A
authors.identifier: http://orcid.org/0000-0002-7037-0416
authors.initials: A
authors.lastname: Khasgiwala
authors.affiliation: Division of Neuroradiology (S.P.), University of Virginia Health System, Charlottesville, Virginia.
authors.forename: S
authors.identifier: http://orcid.org/0000-0002-9739-4362
authors.initials: S
authors.lastname: Patel