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Correspondence |
Sree Chitra Tirunal Institute for Medical Sciences & Technology, Trivandrum, India. E-mail: unnikp{at}sctimst.ac.in
To the Editor:
Yawning during iv anesthetic induction is an occasional clinical occurrence without known untoward effects. During iv induction, the typical sequence of clinical endpoints consists of loss of response to verbal command, followed by loss of eyelash reflex, occasional yawning, then apnea. We experienced an unusual complication of yawning in a patient during anesthetic induction.
A 31-yr-old, 52-kg man with a recent history of head injury secondary to a motor vehicle accident was referred to our hospital. He had progressive proptosis and reduced vision (diagnosed as post-traumatic bilateral carotico-cavernous fistulae) for which endovascular embolization of the fistulae was scheduled. On examination the patient was conscious, cooperative, and breathing spontaneously though a tracheostomy tube which had remained in situ since his last hospitalization. He had a residual left hemiparesis and both eyes were covered because of bleeding from episcleral vessels and exposure keratitis. He was able to communicate in writing, and routine laboratory investigations were within normal limits. In the neuroradiology suite standard monitoring was applied and the anesthesia circuit was connected to the tracheostomy tube with the patient spontaneously breathing 100% O2. General anesthesia was induced with fentanyl 2 µg·kg–1 iv and propofol 2 mg·kg–1 iv. We could not elicit standard clinical endpoints such as loss of response to verbal command and eyelash reflex, although the patient was observed to yawn during induction. Pancuronium 8 mg iv was administered, and anesthesia was maintained with 50% N2O in O2 and 1% isoflurane while the patient’s lungs were mechanically ventilated. To our surprise, the patient’s mouth remained in a locked open position, and several attempts to close his mouth passively were unsuccessful. Immediately, fluoroscopic examination of the patient’s head and neck was undertaken which revealed anterior dislocation of both temperomandibular joints (TMJ). A closed reduction of mandible was performed under fluoroscopic guidance and both TMJs were strapped with an elastic bandage. Thereafter, anesthesia and the embolization procedure were uneventful, and the patient made a good recovery. Later questioning revealed that the patient had experienced two previous episodes of jaw dislocation within the past two years, information which had not been disclosed during the preanaesthetic evaluation.
Although TMJ dislocation is not uncommon, a search of the anesthetic literature revealed very few reports1–4 in relation to the perioperative setting. The majority of TMJ disclocations were related to a jaw thrust maneuver during mask ventilation, placement of an oral airway or nasogastric tube, or in association with direct laryngoscopy. This is the first report of TMJ dislocation occurring during anesthetic induction with yawning as an isolated precipitating factor.
The TMJ represents the articulation of the condyloid process of the mandible with the glenoid fossa of the temporal bone. It is unique amongst synovial joints since it can be dislocated without external force.5 On mouth opening, the condyloid process moves for- ward and is usually limited by the articular tubercle (eminentia articularis). Laxity of supporting ligaments will allow the condyle to move anteriorly past its normal position. This results in dislocation that may be self-reducing or require manipulation for reduction. This may occur when the jaw is forcibly opened during general anesthesia, or rarely, spontaneously while yawning, as occurred in our patient. A more subtle degree of dislocation might have gone unnoticed in a patient whose airway was managed with an existing tracheostomy. Failure to promptly reduce a dislocated mandible could later result in severe pain, parotiditis, spasm of external pterygoid muscles, and ankylosis of the TMJ secondary to joint hematoma and subsequent intra-articular adhesion formation.
To conclude, yawning during induction of anesthesia may prompt TMJ dislocation in the patient with pre-existing TMJ laxity. Early diagnosis of TMJ dislocation and prompt reduction are important in view of potential complications.
Footnotes
Accepted for publication August 10, 2006.
References
1 Sosis M, Lazar S. Jaw dislocation during general anaesthesia. Can J Anaesth 1987; 34: 407–8.
2 Gambling DR, Ross PL. Temporomandibular joint subluxation on induction of anesthesia. Anesth Analg 1988; 67: 91–2.
3 Rastogi NK, Vakharia N, Hung OR. Perioperative anterior dislocation of the temporomandibular joint. Anesth Analg 1997; 84: 924–6.[Medline]
4 Rattan V, Arora S. Prolonged temporomandibular joint dislocation in an unconscious patient after airway manipulation. Anesth Analg 2006; 102: 1294.
5 Aiello G, Metcalf I. Anaesthetic implications of temporomandibular joint disease. Can J Anaesth 1992; 39: 610–6.
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