Fractures of the posterolateral maxillary sinus: a masticator space blowout injury?
OBJECTIVE
Segmental, depressed fractures of the posterolateral maxillary sinus may occur as a result of trauma to the masticator space, previously described in association with mandibular fractures. The authors hypothesize that the fracture is due to a transient increase in pressure in the masticator space (blow out) and therefore should be seen in association with other regional fractures.


METHODS
Injuries of the masticator space were retrospectively identified by searching the imaging database from January 2014 to November 2014 for keywords that would identify regional trauma. The images were reviewed for segmental depressed fractures in the posterolateral aspect of the maxillary sinus accompanied by herniation of a variable amount of masticator space fat and/or muscle into the adjacent sinus. Three neuroradiologists reviewed the images and agreed by consensus on the presence or absence of a masticator space blowout fracture.


RESULTS
Forty-three zygomaticomaxillary complex (ZMC) fractures, 89 mandibular fractures, and 49 isolated zygomatic arch fractures were identified. While all of the ZMC fractures had a maxillary component, 3 of 43 (7.0 %) additional fractures met our fracture definition. Five of 89 (5.6 %) of the mandibular fractures and 6 of 49 (12.2 %) zygomatic arch fractures had an associated posterolateral maxillary fracture.


CONCLUSIONS
Segmental depressed fracture of the posterolateral maxillary sinus is relatively common, occurring in conjunction with other regional injuries. The authors hypothesize that it is due to a transient increase in pressure in the masticator space and is a separate entity from other fractures of the region that may occur concurrently.
University of Arizona, 1501 N. Campbell Avenue, PO Box 245067, Tucson, AZ, 85724, USA. erly@radiology.arizona.edu.
William K
WK
Erly
University of Arizona, 1501 N. Campbell Avenue, PO Box 245067, Tucson, AZ, 85724, USA.
Jennifer L
JL
Becker
St. Paul Radiology, 166 4th St E, St. Paul, MD, 55101, USA.
Radha
R
Inampudi
University of Arizona, 1501 N. Campbell Avenue, PO Box 245067, Tucson, AZ, 85724, USA.
Seung John
SJ
Hur
Mt. Sinai Hospital, 1468 Madison Avenue, New York, NY, USA.
Kambiz
K
Nael
University of Arizona, 1501 N. Campbell Avenue, PO Box 245067, Tucson, AZ, 85724, USA.
Wayne S
WS
Kubal
D006801:Humans; D008337:Mandibular Fractures / Q000000981:diagnostic imaging; D008440:Maxillary Fractures / Q000000981:diagnostic imaging*; D008443:Maxillary Sinus / Q000293:injuries*; D009104:Multiple Trauma / Q000000981:diagnostic imaging; D009917:Orbital Fractures / Q000000981:diagnostic imaging*; D012189:Retrospective Studies; D015050:Zygoma / Q000293:injuries
CT; Fracture; Isolated; Lateral; Masticator; Maxillary sinus; Posterior