Mandible dislocation

Background

Anterior Dislocation

• Most common
• Mandibular condyle is forced in front of the articular eminence
• Risk factors: Prior dislocation, weak capsule, torn ligaments
• Often occurs spontaneously while patient is yawning, "popping" ears, or laughing

Posterior Dislocation

• Follows a blow to the mandible that may or may not break the condylar neck
• Condylar head may prolapse into the external auditory canal

Lateral Dislocation

• Often associated with mandibular fracture

Superior Dislocation

• Occur from blow to the partially opened mouth
• Associated with cerebral contusions, facial nerve palsy, deafness

Clinical Features

• Inability to close mouth
• Difficulty speaking or swallowing
• Malocclusion
• Pain localized anterior to the tragus
• Prominent-appearing lower jaw
• Preauricular depression
• Condylar head palpable in the temporal space (in lateral dislocation)

Posterior Dislocation

• Must examine the external auditory canal

Differential Diagnosis

Jaw Spasms

• Acute tetanus
• Akathisia
• Conversion disorder
• Drug toxicity (anticholinergic, phenytoin, valproate, carbamazepine)
• Dystonic reaction
• Electrolyte abnormality
  • Hypocalcemic tetany
  • Magnesium
• Mandible dislocation
• Meningitis
• Peritonsillar abscess
• Rabies
• Seizure
• Strychnine poisoning
• Stroke
• Temporomandibular disorder
• Torticollis

Evaluation

• Generally a clinical diagnosis
• For traumatic etiology, obtain CT face to evaluate for fracture
  • Also obtain CT IAC if concern for posterior dislocation
• Examine external auditory canal, especially in posterior dislocation
• Evaluate the cranial nerves to rule out concomitant injury

Management

• Closed reduction in the emergency department (if no concern for fracture)
  • If dislocation is bilateral, may be easier to relocate one side at a time.
• Pain control or anxiolysis
  • Consider local analgesia - inject local anesthetic into the preauricular depression just anterior to the tragus.
• Consider procedural sedation

Syringe Reduction Technique

1. Have the patient place an empty 5 or 10 mL syringe between the upper and lower molars on one side of the mouth
2. Direct the patient to roll the syringe back and forth until reduction is achieved
3. If the opposite side does not spontaneously (it generally will), may repeat same technique on the opposite side

'Note that this technique is preferred in a cooperative patient as it avoids sedation and placing the practitioner's hands inside the patient's mouth'

Wrist Pivot Method

• Place patient in seated position
• While facing the patient, grasp the mandible with your thumbs at the apex of the mentum and fingers on the occlusal surface of the inferior molars.
• Apply cephalad force with the thumbs and caudad pressure with the fingers
• Then pivot your wrists.
• Note: This is a more physiologic reduction technique for the provider, allowing greater and more sustained force to be exerted.

Older "Traditional" Technique

Posterior position

• Place patient in seated position (anterior approach) or supine (posterior approach)
  • Advisable to wrap thumbs in gauze to guard against accidental bite
• Placed gloved thumbs in patient's mouth over the occlusal surfaces of the molars, or lateral to patient's molars in buccal fold (to avoid being bitten)
• Apply pressure downward (toward the feet) and then backward (posteriorly)

Disposition

• Generally may be discharged if uncomplicated and successfully reduced
  • Instruct patient to use soft diet, not to open mouth wider than 2cm for 2 weeks, and to support mouth when yawning
• Admit for:
  • Open dislocation
  • Superior dislocation
  • Fracture
  • Nerve injury
  • Inability to reduce