So you’re working a Saturday overnight B side shift at Elmhurst. Its 3am and you have a patient in the hallway who looks questionably intoxicated and has been assaulted. Grossly he has no facial or head injuries (no lacs or abrasions) but you walk over to the patient and he is grabbing his jaw. You talk to the patient and with your excellent decision making skills determine that he does not need a CTH however you’re suspicious that this patient could possibly have a mandible fracture. So you order a CT scan of the facial bones and call it a day. But wait, is that really necessary?…..
A quick bedside test to assess for mandibular fractures involves a very accessible and user friendly tool…the tongue depressor! The tongue blade test has been shown in two different literature reviews to be 95-97% sensitivity. This test has also been shown to have a negative likelihood ratio of 0.07 (so great test for RULING OUT).
The test is easy and can be done in 15 seconds or less. Insert a tongue blade into the patient’s right side of the jaw, have them bite down, then apply a torsional force until the blade breaks (see pic above). Do the same on the left side. If the blade breaks GREAT, chances are you do NOT need a CT scan to r/o fracture. If the patient is unable to break the blade you should consider obtaining a CT scan!
Core EM has a quick video on how this is done: https://coreem.net/procedures/tongue-blade-test/
References:
1. Alonso L L, Purcell T B. Accuracy of the tongue blade test in patients with suspected mandibular fracture. J Emerg Med. 1995;13(3):297–304.
