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The utility of the tongue blade test for the diagnosis of mandibular fracture

Three Part Question

In [patients with mandibular trauma] is [the tongue blade test] a good diagnostic test for [mandibular fracture]?

Clinical Scenario

You are evaluating a patient who has just been punched on the jaw. He is having difficulty opening his mouth and talking but you can see no step deformity or loose teeth. You recall that while you were on elective you saw the tongue blade test being used routinely in America to select patients for mandibular imaging. For this test the patient is asked to bite on the tongue blade and if the examiner can break the blade while the patient grips it, the patient does not need a radiograph. You wonder whether this is a sensitive test to use in this patient.

Search Strategy

Medline 1966-07/03 using the OVID interface.
[(mandibular fracture.mp.OR exp Mandibular Fractures/) OR {(exp fractures OR fracture$.mp) AND (exp mandible OR mandible$.mp or mandibular.mp)}] AND exp diagnosis OR diagnosis.mp AND maximally sensitive RCT filter LIMIT to human AND English.

Search Outcome

Altogether 269 papers were found of which 2 were relevant and are listed in the table.

Relevant Paper(s)

Author, date and country Patient group Study type (level of evidence) Outcomes Key results Study Weaknesses
Alonso LL & Thomas TB,
1995,
USA
110 consecutive patients in the emergency department with jaw pain Exculsion criteria: Patients unable to cooperate because of age, language barrier, inability to open mouth because of pain, intoxication or head injuryDiagnostic studyPatient ability to grasp a tongue blade/depressor between his teeth and hold the blade against a twisting motion, with the ability to crack the tongue blade on both sides defined a negative testSensitivity of tongue blade test: 45 positive of 47 fractures, sensitivity 95.7%, Cl (85.5-99.5%)No sample size estimates- sample used too small "Gold standard" radiologist interpretation sensitivity measured in an other study in this hospital and was found to be only 95.5% Single radiologist to report X-Rays no double reporting
Inability to crack tongue blade on both sides of the mandible defined positive testSpecificity of tongue blade test: 23 positive TBT of 63 non-fractures, specificity 63.5% CI (50.4-75.3%)
Robert A et al,
1998,
USA
119 patients with jaw pain after trauma presenting at the emergency department Exculsion criteria: Airway compromise, inability to perform or co-operate with clinical examination, edentulousnessDiagnostic studyPatient ability to grasp a tongue blade/depressor between his teeth by and then to hold the blade against mild resistance by the examinerSensitivity of tongue blade test: 42 positive of 44 fractures, sensitivity 95%No OPG despite panoramic series known to be more sensitive than mandibular series in detecting mandibular fracture Single radiologist to report X-Rays no double reporting No interobserver variability measurements No CIs calculated Incorrect use of Chi 2 test no. too small should have used Fisher's exact test No sample size estimates- sample used too small
Inability to hold tongue blade against resistance on either hemimandible defined as a positive testSpecificity of tongue blade test: 25 positive TBT of 75 non-fractures, specificity 67%

Comment(s)

No confidence intervals have been reported by Roberts et al, for the reported sensitivity of the tongue blade test so we calculated this ourselves; sensitivity 95.4% (CI 84.53% - 99.44%). The confidence intervals are comparatively wide and so the tongue blade test could not stand on its own as a single diagnostic tool in screening for mandibular fractures since missing these fractures can lead to serious long-term complications. The high sensitivities reported by both these studies do suggest, however, that the tongue blade test is a useful screening tool in evaluating patients with mandibular fracture but other clinical predictors must also be considered.

Clinical Bottom Line

The tongue blade test is useful in evaluating patients with possible mandibular fracture.

Level of Evidence

Level 3 - Small numbers of small studies or great heterogeneity or very different population.

References

  1. Alonso LA, Purcell TB. Accuracy of the tongue blade test in patients with suspected mandibular fracture. J Emerg Med 1995;13:297-304.
  2. Robert A, Schwab MD et al. Clinical predictors of Mandibular Fractures. Am J Emerg Med 1998;16:304-5.