Yawning is often seen during induction of
anesthesia with propofol. I report an episode of
dislocation of the temporo-mandibular joint
caused by forceful yawning during induction
with propofol.
A 26-year-old, healthy (ASA physical status
1) woman was scheduled for aspiration of oocytes
for in vitro fertilization. During the slow
induction of anesthesia with propofol
(AstraZeneca, London, UR) to a total dose of 2
mg/kg the patient yawned forcefully. During the
procedure, the patient was breathing
spontaneonsly through a facemask (70% nitrous
oxide in oxygen), and at the end of surgery she
was fully conscious. It was then noticed that
her mouth was sliglitly opened (approximately 1
cm) and that she could not open, nor close it.
Dislocation of the right teimporo-mandibular
joint (TMJ) was the diagnosis. This was
explained to the patient and she agreed to
undergo reduction of the TMJ under anesthesia.
After administration of 1 mg/kg propofol the jaw
was easily reduced by pushing the mandible
inferiorly and posterior. The patient wokeup
within 1 to 2 minutes. She then complained about
pain in the right TMJ. The rnouth opening was
good with stable closure, and both TMJs were
moving freely. A gauze bandage was applied
around her face to prevent any further
inadvertent wide mouth opening for the next 24
hours, and she was instructed to eat a soft diet
only. Further follow-up was not necessary
because the patient did not have any history of
previous TMJ dislocation.
It is well known that forced volontary
opening of the mouth (stich as yawning,
laughing, or even passionate kissing) may lead
to TMJ dislocation. Forced passive opening of
the mouth (e.g. during larygoscopy.) inpatients
with or without hypermobility of the TMJ may
also lead to dislocation. Yawning during
induction of anesthesia is frequently seen with
propofol. The slow injection of propofol
transforms the patient from the awake state
through sedation to anesthesia. In the stage
of sedation, forceful yawning may occur. The
dislocation of the TMJ is caused by displacement
oftlic mandibular head out of the glenoid fossa.
Anterior dislocation, such as was seen in this
case, is the most common presentation, where
posterior, lateral, and superior dislocations
are rarer and usually associated with coexistant
fractures of the base of skull,mandible, or the
glenoid fossa
Early reduction of the dislocatedjoint is
important in reducing permanent sequelae. The
goal is to bring thecondylar head down and
around the articular eminence of the TMJ. This
action is achieved by pushing the mandible
inferiorely and posterioly and it can be
performed while standing before or behind the
patient: The lateral pterygoid muscle is the
main muscle of involvement. Although the
reduction may be performed while the patient is
conscious, decrease of the muscle spasm
facilitates the joint reduction and reduces the
pain. This can be achicved with direct injection
of local anesthetics into the muscle or under
sedation. Totten and Zambito describe the use of
propofol to reduce dislocated TMJ in two
patients. It is interesting to note that in one
patient the TMJ had to be reduced twice: the
patient dislocated the TNJ a second time while
yawning during propofol sedation alter the TMJ
was reduced the first time. Although propofol is
an excellent sedative drug, its use may be
contraindicated in reducing TMJ dislocations.
Forceful yawning during induction of anesthesia
with propofol should be avoided.
