Mandible Dislocation Clinical Presentation

Updated: Apr 08, 2016
  • Author: Meher Chaudhry, MD; Chief Editor: Trevor John Mills, MD, MPH  more...
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Presentation

History

Most patients present with jaw pain and trismus after extreme mouth opening or after a direct blow to the jaw. In addition, patients describe difficulty with speaking or swallowing, and malocclusion. [11, 17]

A history of previous dislocations, hypermobility syndromes, or injury to the TMJ joint should be elicited from patients.

In rare cases of multisystem trauma, head injuries, intoxication, or other causes of altered mental status, the patient may not be able to give a history suggestive of mandible dislocation.

Malocclusion is not unique to mandible fractures or dislocations, and maxillary fractures should be considered in the differential diagnosis in patients with malocclusion and pain. [14]

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Physical

A thorough examination of the head, neck, and nervous system should be performed in patients with suspected mandible dislocation. Usually pain and difficulty with jaw movement is present in all patients with mandible injury.

Anterior mandible dislocations usually result in a visible and palpable periauricular depression from displacement of the condyle. Unilateral dislocations result in a deviation of the jaw away from the dislocation. When both mandibular condyles are dislocated anteriorly, the patient appears to have an underbite, or prognathia, with pain over both TMJ areas. [17]

A thorough examination of the central nervous system, especially cranial nerves V and VII, should be performed in all patients with suspected jaw dislocations. This is vital, especially in cases of superior jaw dislocation.

External auditory canal should be inspected, and hearing should be assessed in patients with suspected posterior mandible dislocation.

The condylar head can sometimes be felt in the temporal space in cases of lateral dislocation.

Inspect the oral cavity for gingival lacerations, which may signal an open fracture.

A "tongue blade test" can be performed in subtle cases of jaw injury. A tongue blade is placed between the molars, and the patient is asked to bite down. If the patient can stabilize the tongue blade sufficiently for the examiner to twist it until it breaks, a mandibular fracture is unlikely. [18, 14] Alonso et al and Schwab et al reported that the tongue blade test is 95% sensitive. It should be performed on both sides.

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Causes

Risk factors for mandible dislocation include the following:

  • Shallow mandibular fossa

  • Previous TMJ trauma or dislocation that disrupted the joint capsule

  • Dystonic reactions

  • Hypermobility syndromes, such as Marfan syndrome or Ehlers-Danlos syndrome, which predisposes the TMJ to dislocation due to increased laxity of surrounding connective tissue [19, 14, 20]

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