A 66-year-old female with a past history of
hypertension, who initially presented with four
limbs weakness for a duration of 3 h, poor
visual acuity, ataxia and slurred speech at ER
and progressed to drowsiness, tetraplegia with
episodes of unjustified excessive and repetitive
yawning and acute respiratory failure within few
hours.
On admission, the patient was drowsy and
showed a positive doll s eye sign and positive
gag reflex. Her uvula and tongue deviated to the
left and weakness of facial muscle caused
drooling. The right upper and lower extremity
strength were rated 3+/5 and 2+/5 separately.
The left upper and lower extremity strength were
rated reflexes were enhanced and bilateral
Babinski signs were present. A brain magnetic
resonance imaging (MRI) scan showed an infarct
in most parts of the pons and another small
lesion in right medial occipital lobe appearing
as increased signal intensity on DWI with
corresponding low ADC. MRI showed total
occlusion of the middle and distal thirds of
basilar artery. Besides, the left posterior
cerebral artery arose from the left internal
carotid artery with focal stenosis at its
proximal portion and there was an aneurysm about
3 mm in size located at the anterior
communicating artery (Fig. 1).
The patient developed acute respiratory
failure and progress to flaccid tetraplegia
several hours after admission. The frequency of
excessive yawning persisted despite adequate
sleep at night. An endotracheal tube was
inserted as a prerequisite of subsequent
ventilatory support. Several days later, she
still had limitationswith regards to eyeball
movement, prominent hypomimia, bilateral
masticatory spasms and persistent trismus and
more frequent yawning with an extreme opening of
the mouth. The patient developed anarthria and
dysphagia and had soft palate paresis, and brisk
gag reflexes. Ten days after admission, she
received tracheostomy under local anaesthesia at
bedside in the intensive care unit.
After the tracheostomy tube was secured, the
patient s breathing tube was removed. She made
an uneventful recovery after the procedure. To
our surprise, the frequency of yawning gradually
decreased and returned to normal within hours
after the tracheostomy. The duration of
excessive pathological yawning persisted only
for 10 days.
Discussion The precise role of
yawning in human physiology remains unclear, but
the central neural structures that control
yawning are presumably located in the brain stem
close to or within other respiratory and
vasomotor centres [1]. The earliest
appearance of yawning was observed in a
15-week-old embryo [2]. Frequency of
yawning decreases with brain maturation when the
connections between the limbic system and the
forebrain areas are already established
[3]. Besides, another factor
contributing to yawning is total dead space of
the respiratory system which would be relatively
larger in paediatric subjects [4].
Because it is interesting to note that the
frequency of yawning gradually decreased and
returned to normal within hours after the
tracheostomy was performed in our patient
presented with locked-in syndrome, we
hypothesized that initial enlarged dead space
after endotracheal tube intubation would be
another trigger of yawning because our patient s
dead space was reduced by tracheostomy which may
be one of the major factors capable of
terminating the pathological yawning. Others
postulated that repetitive yawning in cardiac
tamponade might be secondary to phrenic nerve
irritation [5,6].
Another hypothesis is that yawning
stimulates a haemodynamic compensatory response
to tamponade [7]. However, there was no
tamponade found in our patient. However, there
was possibility that the phrenic nerve of the
patient might be influenced by vagus nerve
manipulation or stimulation during the
tracheostomy similar to the reports proposed by
Eldridge and Millhorn who demonstrated that 0.5
min duration of vagus nerve stimulation induces
a reduction (<1 min duration) in phrenic
amplitude and frequency after stimulation
[8].
Besides, Zhang et al. [9] suggested
that a relatively longer post-stimulation
inhibitory memory is possible if using episodic
and longer vagus nerve stimulation. For many
years, episodic vagus nerve stimulation has been
applied clinically as a treatment for patients
with refractory epilepsy [11]. However,
the mechanisms and the consequence of long-term
vagus nerve stimulation remain unclear
[10]. We postulate that perioperative
vagus nerve manipulation or stimulation might
occur during the tracheostomy, which probably
played a role in the triggering or even
termination of pathological yawning because
there have been similar treatments using
tracheostomy and cauterization applied in the
treatment of epilepsy in the early 19th century
[11].
References
1. Barbizet
J. Yawning. Journal of Neurochemistry 1958;
21: 203&endash;209.
3. Fogel A. The effect of brief separations
on 2- month-old infants. Infant Behavior &
Development 1980; 3: 315&endash;330.
4. Numa AH, Newth CJ. Anatomic dead space in
infants and children. Journal of Applied
Physiology 1996; 80: 1485&endash;1489.
5. Krantz MJ,
Lee JK, Spodick DH. Repetitive yawning
associated with cardiac tamponade. American
Journal of Cardiology 2004; 94:
701&endash;702.
6. Moore KL, Dalley AF. Clinically Oriented
Anatomy, 4th edn. Philadelphia, PA: Lippincott,
Williams and Wilkins, 1999: 149&endash;150.
7.
Askenasy JJ. Is yawning an arousal defense
reflex? Journal of Psychology 1989; 123:
609&endash;621.
8. Eldridge FL, Millhorn DE. Oscillation,
gating, and memory in the respiratory control
system. In: Cherniack NS, WiddicombeJG, eds.
Handbook of Physiology, Vol. II, The Respiratory
System, Control of Breathing. Bethesda, MD:
American Physiological Society, 1986:
93&endash;114.
9. Zhang Y, McGuire M, White DP, Ling L.
Episodic phrenic-inhibitory vagus nerve
stimulation paradoxically induces phrenic
long-term facilitation in rats. Journal of
Physiology 2003; 551: 981&endash;991.
10. Schachter SC. Vagus nerve stimulation
therapy summary: five years after FDA approval.
Neurology 2002; 59: S15&endash;S20.
11. DeGiorgio CM, Amar A, Apuzzo MLJ.
Surgical anatomy, implantation technique, and
operative complications. In: Schachter SC,
Schmidt D, eds. Vagus Nerve Stimulation. London:
Martin Dunitz Ltd, 2003: 31&endash;50.
mise à
jour
le 11 juin
2009
Medical
implications of excessive yawning in relation to
thermoregulatory dysfunction
A. C. Gallup and G. G. Gallup
Jr
Department of Biological
Sciences,
Binghamton University, Binghamton,
NY
Recently Chang et al. describe how
pathological yawning was extinguished following
tracheostomy in a patient with locked-in
syndrome. In response, Prasad
described a connection between the amelioration
of symptoms and selective brain cooling via the
upper respiratory tract.
He suggests that the cerebral cooling
stimulated by the nasal air passage might be
strong enough to inhibit mechanisms that would
normally trigger yawning. We are in agreement
with these points; however, we think it is
important to set the archival record straight by
summarizing the current literature on yawning,
brain cooling, and abnormal thermoregulation.
Prasad suggests that research is needed to
connect yawning with nasal breathing, but he
neglects to mention a recent study, which showed
that nasal breathing eradicated contagious
yawning in humans.
Also, Prasad brings to light evidence of
selective brain cooling via nasal breathing in
sheep, but it is important to note that Mariak
et al. and more recently, Harris et al. have
both found a direct reduction in human brain
temperature following nasal air flow .
Therefore, these are not novel interpretations.
In addition, Chang et al. report the blocking of
basilar arteries prior to treatment, and Zenker
and Kubik report the importance of brain artery
function for cerebral cooling in humans.
Excessive yawning has been identified as a
symptom of abnormal thermoregulation.
For example, multiple sclerosis, epilepsy,
and migraine headaches are all related to
temperature regulation/ dysfunction, and each
have been linked to yawning. Likewise, drugs
that increase brain temperature often produce
excessive yawning, whilst drugs that produce
hypothermia inhibit yawning. We emphasize that
excessive yawning is not necessarily associated
with inadequate sleep, as evidenced by Chang et
al., and may in fact be indicative of abnormal
thermoregulation.
