Yawning is a common phenomenon that until
recently had received little attention in the
medical literature. Although abnormalities may
be associated with brain disorders yawning is
generally considered of little clinical
significance, and complications are rare.
Yawning is associated with depression of the
lower mandible and in our patient induced
At the age of 25 years, 6 months after the
birth of her daughter, the patient was sitting
at the kitchen table drinking a cup of coffee
when she yawned. Her jaw became locked in that
position, deviated to the left, so that she was
unable to close her mouth or speak. Pain was
prominent. After about 30 minutes her husband
struck the left side of her jaw, which restored
the mandible to its normal position.
Three months later the problem recurred, and
about 15 minutes elapsed before she was able to
manipulate her jaw back into position.
Subsequently she learned to suppress yawning by
voluntary effort and by cupping her hand
underneath the jaw when the urge to yawn
occurred. Before this, yawning had always been a
relaxing experience, during which the patient's
back would stretch and arch backwards, and her
arms, flexed at the elbow, would be raised and
her shoulders pushed back. Now the patient
became afraid of yawning. She would look away if
someone yawned and immediately take measures to
suppress any urge to yawn.
Despite these precautions there were four
occasions over the ensuing 34 years during which
subluxation of the jaw recurred, always as a
result of yawning. To restore the jaw to its
correct position the patient learned to make a
forced yawn and simultaneously push on her jaw.
We subsequently learned of a family history of
jaw-related anomalies. The patient's daughter
and grandson had complaints about their
temporomandibular joint function but declined
In a review of the literature on yawning,
including a Medline search and examination of
current textbooks of surgery, we were unable to
find any reference to subluxation of the lower
jaw induced by yawning, other than one briel
passing mention . Given the generality of the
phenomenon of yawning, we suspect this
complication is more common than is apparent
from the literature.
Grassino A, Thavundayil JX et al: A simple
method for the study of yawning in man induced
by the dopamine receptor agonist, apomorphine.
Prog Neuropsychopharmacol Biol Psychiatry 1987;