title: Posttraumatic orbital emphysema: incidence, topographic classification and possible pathophysiologic mechanisms. A retrospective study of 137 patients.
abstract: OBJECTIVE
  The aim of this study was to retrospectively evaluate the incidence of posttraumatic orbital emphysema (OE) and to propose a radiologic topographic classification as well as a possible pathophysiologic model.
  
  
  METHODS
  Orbital fine-cut (1 mm) computerized tomographic scan slices from 137 patients were used to assess the fracture's type, the presence and position of OE, and periorbital tissue herniation. The OE was categorized into the following 5 compartments: subcutaneous periorbital, peribulbar, retrobulbar extra- and intraconal, and pterygopalatine fossa.
  
  
  RESULTS
  The incidence of OE was 61%. OE was more frequently associated with isolated medial wall (78%; P < .001) and combined medial wall/orbital floor (82%; P < .01) fractures. Palpable isolated subcutaneous eyelid emphysema was not related to fracture's type (P = .85).
  
  
  CONCLUSIONS
  OE suggested medial wall fractures alone or combined with orbital floor fractures. Pathophysiologically, according to the Poiseuille law, the difference in length between the ethmoid and sinusal infundibulii could explain the increased incidence of OE when the medial wall is involved.
authors: Clinical Fellow in Ophthalmology, Department of Ophthalmology, Ipswich Hospital, Ipswich, Suffolk, United Kingdom.
authors: Christopher
authors: C
authors: van Issum
authors: Delphine S
authors: DS
authors: Courvoisier
authors: Paolo
authors: P
authors: Scolozzi
mesh_terms: D000328:Adult; D004646:Emphysema / Q000000981:diagnostic imaging / Q000209:etiology*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009915:Orbit / Q000000981:diagnostic imaging* / Q000503:physiopathology; D009917:Orbital Fractures / Q000145:classification / Q000150:complications* / Q000000981:diagnostic imaging; D010256:Paranasal Sinuses / Q000503:physiopathology*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed