The “tongue blade test” is one of the fun, functional tests in Emergency Medicine. If you’ve got facial trauma and you’re concerned about a mandible fracture, simply align a wooden tongue blade over the molars in a patient’s mouth and have them bite down firmly. Then, twist the blade medially. If the patient is not limited by pain, they’ll be able to hold the blade until it breaks. If they’re limited by pain, such as in the presence of a mandible fracture, the patient won’t be able to hold the blade until it breaks.
This is an observational study enrolling 190 eligible patients for the tongue blade test in the presence of suspected mandible fracture. 66 patients had negative (normal) tongue blade tests, while 124 had positive (abnormal) tests. All patients received a CT for definitive diagnosis. There were 5 false negatives and 29 false positives. Therefore, the sensitivity of the test is 95% and specificity 68%. These results are consistent with some prior reviews of this test’s characteristics.
Not a “zero miss” test, but, depending on the pre-test likelihood based on other clinical factors, a very useful screening test.
“Re-evaluating the diagnostic accuracy of the tongue blade test: still useful as a screening tool for mandibular fractures?”
www.ncbi.nlm.nih.gov/pubmed/23490109