Abstract

Temporomandibular joint (TMJ) dislocation can occur whenever the mouth is opened wide during upper airway manipulation, even without external force. In the perioperative period, the majority of TMJ dislocations occur during anesthetic induction. We report the occurrence and management of bilateral TMJ dislocation upon orotracheal extubation in a 35-year-old woman. At the end of an otherwise unremarkable uterine myomectomy under general anesthesia, with the patient having regained consciousness in the operating room, we asked the patient to open her mouth so we could extubate her. Immediately after orotracheal extubation, however, the patient was found to be unable to close her mouth. The diagnosis of bilateral TMJ dislocation was made. The bilateral TMJ dislocation was reduced with the traditional transoral approach under morphine analgesia/sedation. The dislocation possibly occurred in consequence of her compliance with our request to open her mouth excessively before she was fully awake. As TMJ dislocation is a possible complication of upper airway manipulation, anesthesiologists should be prepared for its occurrence and to manage it competently.

Keywords

anesthesia, general; anesthesia recovery period; dislocations; intubation, intratracheal; temporomandibular joint;

1. Introduction

Dislocation of the temporomandibular joint (TMJ) is not an uncommon event. It can occur without exter-nal force when the mouth is opened excessively wide during upper airway manipulation for anesthesia and therapeutic management of trauma. In the periop-erative  period,  the  majority  of  TMJ  dislocations  that  occur  during  anesthetic  induction  could  be  evoked  by  yawning,¹⁻³  jaw  thrust  maneuvers,⁴⁻⁶ direct  laryngoscopy,^4,7  or  the  use  of  a  laryngeal  mask airway (LMA).⁸

We report here a case whose bilateral TMJ dislo-cation was noted immediately after orotracheal ex-tubation. Manual reduction of the dislocation was successfully accomplished under morphine analge-sia/sedation.

2. Case Report

A  35-year-old,  48-kg  woman,  who  had  suffered  menorrhagia-induced anemia, was admitted to our hospital  for  uterine  myomectomy.  Preanesthetic  evaluation revealed that she had undergone hem-orrhoidectomy  smoothly  under  spinal  anesthesia,  otherwise  her  past  history  was  unremarkable.  On  examination, there were no airway problems. Her mouth  opening  was  good  and  her  dentition  was  normal.
In  the  operating  room,  she  was  given  fentanyl  100 μg,  thiopental  250  mg,  and  atracurium  25  mg  intravenously for induction of general anesthesia. Orotracheal intubation with an endotracheal tube (Hi-Contour  tracheal  tube;  Mallinckrodt  Medical,  Athlone,  Ireland)  of  6.5  mm  internal  diameter  and  8.8 mm outer diameter was performed under direct laryngoscopy easily and uneventfully at the first at-tempt, without the need to open the mouth wide. A Berman oral airway, 80 mm in length (Cheen Houng Enterprise, Taipei, Taiwan) with a body thickness of 9 mm was inserted into the oropharyngeal cavity to act as a bite block. Thereafter, the patient’s upper and lower incisors were kept in close contact with the  Berman  airway  placed  in  between,  i.e.,  the  interincisor  distance  (IID)  was  9  mm.  Inhalational  desflurane in oxygen was used for anesthetic main-tenance. No additional muscle relaxant was given throughout  the  operative  course.  Morphine  4  mg  was given intravenously for postoperative analge-sia  before  the  completion  of  surgery.  Muscle  re-laxation was reversed using neostigmine 2 mg and atropine 1 mg intravenously. The patient recovered well  from  anesthesia.  Neither  bucking,  coughing  nor retching was noted when the endotracheal tube was  still  in situ.  When  the  patient  regained  con-sciousness, she was asked to open her mouth for oral endotracheal  tube  extubation.  The  endotracheal tube was then removed along with the Berman air-way.  Immediately  after  extubation  in  the  operat-ing  room,  however,  the  patient  was  found  to  be  unable  to  close  her  mouth.  Her  jaw  was  locked  wide open in a protracted position, with an IID of about 30 mm and without deformed configuration. Any active effort to correct the problem by herself was  unsuccessful.  She  also  complained  of  pain  in  the bilateral preauricular regions. Bilateral empty glenoid  fossae  and  spasmodic  masseter  muscles  were noted by palpation. The diagnosis of bilateral TMJ dislocation was made. Morphine 2 mg was slowly given  intravenously  to  provide  analgesia/sedation  for bimanual transoral reduction of the dislocation. The patient was then placed in a semi-recumbent position. The operating anesthesiologist stood be-side  the  patient,  with  his  left  and  right  thumbs  placed  onto  the  occlusal  surface  of  the  patient’s  right and left lower posterior molars, respectively, while his fingers grasped the patient’s mandibular angle  and  body.  Upward  rotation  of  the  patient’s  chin  (by  downward  pressure  exerted  with  the  thumbs and upward elevation from below the chin with the fingers) followed by force applied poste-riorly  to  the  entire  mandible,  was  carried  out  to  generate  the  reduction.  This  manipulative  ap-proach  was  similar  to  that  described  by  Stakesby  Lewis,9  which  could  readily  correct  the  bilateral  TMJ dislocation simultaneously.

Upon inquiry, the patient denied any prior history of  TMJ  dislocation.  She  made  a  good  recovery  and  was discharged 3 days later.

3. Discussion

The  TMJ  is  a  unique,  modified  hinge  joint  whose  motion allows two kinds of movement to take place. Besides  the  familiar  hinge-like  rotation  between  the mandibular condyle and the inferior surface of the  articular  disc,  an  anterior  gliding  movement  of the condylar process of the mandible along with the superior disc surface toward the articular tu-bercle  of  the  temporal  bone  can  occur  to  enable  the mouth to open widely.^4,10 As the glenoid fossa is shallow, an “overshot” anterior movement of the mandibular condyle can result in anterior TMJ dislo-cation, which is by far the most common type of TMJ dislocation.

As  upper  airway  management  is  an  important  item in the daily practice of anesthesiologists, it is no  wonder  that  TMJ  dislocation  is  liable  to  be  a  source of a lawsuit for anesthesiologists. An analysis of  266  claims  for  airway  injury  by  the  American  Society  of  Anesthesiologists  (ASA)  Closed  Claims  Project  database¹¹  showed  that  27  claims  (10%)  were  filed  for  TMJ  injuries,  with  a  median  com-pensation  of  US$10,000.  Among  these  27  claims,  11  were  for  TMJ  dislocation  and  16  were  for  TMJ  pain. These TMJ injuries were associated with non-difficult tracheal intubation, patients younger than 60 years of age, and ASA physical status 1−2. The circumstances  of  our  patient  fit  exactly  with  all  the conditions mentioned above.

Although  TMJ  dislocation  is  a  well-recognized  complication following general anesthesia, in this context  it  is  usually  diagnosed  on  a  retroactive  basis and it may be difficult to ascertain when the dislocation  actually  occurred,  partly  because  its  diagnosis can be difficult with an orotracheal tube or an LMA in situ,^2,12 and partly because palpating the patient’s glenoid fossae after airway manage-ment is a far from routine procedure in a patient without a past history of TMJ dislocation. For ex-ample,  three  cases  of  perioperative  TMJ  disloca-tions were reported by Prasad and Agrawal⁵ and by Rastogi  et  al.¹³  Prasad  and  Agrawal⁵  presented  a  case in whom TMJ dislocation was diagnosed after removal of an LMA: a jaw thrust maneuver to fa-cilitate LMA insertion was considered to have evoked the dislocation. Rastogi et al¹³ reported two cases without pinpointing the causative events: one pa-tient was extubated awake in the operating room, but TMJ dislocation was not diagnosed until the pa-tient was found to be unable to close her mouth in the postanesthesia care unit (PACU); the other was extubated in the PACU but TMJ dislocation was diag-nosed  as  late  as  about  24  hours  postoperatively  in  the ward.

As  to  when  TMJ  dislocation  occurred  in  our  pa-tient,  a  few  possibilities  existed:  (1)  the  patient  might have had preexisting dysfunction or hypermo-bility of the TMJ but appeared normal or was over-looked  preoperatively;  (2)  TMJ  dislocation  could  occur during anesthetic induction. Possible precip-itating  factors  included  the  effect  of  the  muscle  relaxant (which was given only once and was effec-tive),  direct  laryngoscopy,^4,7  and  placement  of  an  oral  airway;¹⁴  (3)  TMJ  dislocation  occurred  as  our  patient opened her mouth excessively in compliance with our request to open her mouth for orotracheal extubation.

The last supposition was supported by three con-siderations: (1) when the mouth is opened too wide, the  ligaments  supporting  the  articular  disc  of  the  TMJ  must  lie  lax  and  thus  predispose  the  TMJ  to  dislocation;⁴ (2) reduced muscle tone caused by re-sidual effects of general anesthesia and muscle re-laxant might have weakened the protection around the TMJ^4,15 and thus contributed to TMJ dislocation during  emergence  from  anesthesia  in  this  patient;  (3) spontaneous movement (if at all) of a dislocated mandible is usually limited¹⁴ or restricted to pure rotation.⁹

However,  our  patient’s  upper  and  lower  incisors  remained  in  close  contact  with  the  Berman  airway  until we asked her to open her mouth, which resulted in her IID increasing from 9 mm to about 30 mm, and then  her  mandible  remained  in  that  position  and  could not be moved at all. Therefore, the possibility that  the  TMJ  dislocation  had  already  occurred  be-fore our patient opened her mouth seemed remote.

Accordingly, while other possibilities could not be completely  ruled  out,  wide  mouth  opening  for  oro-tracheal  extubation  was  the  most  likely  causative  event  for  TMJ  dislocation  in  our  patient.  Even  if  partial dislocation of the TMJ had occurred before emergence from anesthesia, mouth opening for ex-tubation would induce spasm as well as pain of the muscles of mastication, aggravate the dislocation, and lock the condylar process of the mandible.

TMJ dislocations should be quickly diagnosed and promptly  reduced  to  minimize  following  sequelae  (such  as  fibrosis  of  the  joint  capsule)  and  to  avoid  the need for surgical intervention.¹³ Various methods of manual reduction for acute TMJ dislocation have been  employed  in  clinical  practice  for  years.  The  transoral  approach  described  by  Stakesby  Lewis⁹ is  traditionally  preferred.  Shun  et  al¹⁶  and  Chen  et  al¹⁷  separately  introduced  novel  extraoral  ap-proaches,  and  each  claimed  their  technique  to  be  effective,  analgesia/sedation/relaxation-free,  and  safer  for  the  clinicians  because  finger  insertion into the patient’s mouth was avoided. We success-fully treated our patient using the traditional trans-oral  maneuver  because  we  thought  it  was  much  more straightforward.

Employing drugs for analgesia/sedation or even general anesthesia (with or without a muscle relax-ant) may be needed to counteract pain and spasm of  the  masticatory  muscles  and  to  lower  the  clini-cian’s risk of bite injury during manual reduction of a dislocated TMJ. The necessity of these pharmaco-logical  regimens  should  be  judged  individually.  In  our  patient,  the  effects  of  residual  anesthesia  and  the supplemental morphine were adequate to allow successful reduction of TMJ dislocation.

To  reduce  a  bilaterally  dislocated  TMJ,  some  physicians^9,16,18 advise that reduction be done one side at a time because it is easier and less painful. Fortunately, we successfully reduced bilateral dis-location simultaneously in our patient.

In conclusion, we have reported a case of bilat-eral  TMJ  dislocation  that  possibly  occurred  during  orotracheal extubation and was successfully reduced under  mild  analgesia/sedation.  This  case  reminds  us that TMJ dislocation is a potential complication of  upper  airway  manipulation.  Anesthesiologists  should be aware of this problem and be prepared for its occurrence and management.