McMaster University,
Radiation Oncologist Hamilton Regional Cancer
Centre
Abstract
Persistent and excessive yawning (greater
than 1 to 4 yawns/minute) is a pathological
process associated with a variety of conditions
including central nervous system disorders,
opiate withdrawal and drug side effects. This
report describes a patient with a brain tumour
who presented with persistent excessive yawning.
She was successfully treated with medical
acupuncture. A possible mechanism involving the
autonomic nervous system is discussed.
Presentation
A 51 year-old lady presented with a one and
half year history of headache, with no abnormal
neurological signs on physical examination. An
MRI scan of the brain showed an aggressive
tumour in the right parietal lobe, but without
significant surrounding cerebral oedema or
midline shift. The paraventricular area and the
brain stem were not involved. Subsequently, she
underwent gross total resection of the tumour.
The pathology result was an anaplastic
oligodendroglioma. She was offered thirty-three
radiation treatments for adjuvant therapy to the
brain to improve the probability of local tumour
control. The radiation volume included the
postoperative tumour bed and adjacent areas. The
right hypothalamus, midbrain and upper pons were
included in the high dose volume (> 95% of
the total dose of 5940 cGy), while correspondent
areas on the left side were included in a lower
dose volume (<60% of total dose). She
tolerated the treatment quite well without
significant side effects, except that her blood
pressure was elevated during treatment to
180/110 mm Hg. On the day of her 24th treatment
she presented with persistent yawning. The
yawning had continued for more than six hours,
with a frequency of 15 20 yawns per minute,
before she was seen for her condition. A
tingling sensation around her mouth was also
noted. She denied any snoring or previous
history of apnoea. Her past history was not
significant apart from a hysterectomy. Her
medication included dexamethasone 2 mg o.d.,
ranitidine 150 mg b.i.d., paracetamol 650 mg
p.r.n. q. 6 h., and dilantin 200 mg o.d. (she
was on a dose reducing schedule for dilantin).
Physical examination showed an obese lady
weighing 140kg with no abnormal neurological
signs. She was mentally alert and orientated in
time and space. A Traditional Chinese Medical
examination revealed weak proximal (both
superficial and deep) pulses bilaterally, but
normal middle and distal pulses. Her tongue was
slightly swollen but pink with no coating. The
latter was brushed off in the morning.
Treatment and Result
As there is no clear guidance in either
Western Medicine or Traditional Chinese Medicine
in the treatment of non-drug induced
pathological yawning, the patient was offered
empirical treatment with medical acupuncture.
PC6 acupoint (2 cun [body inch] above
the transverse crease of the wrist, between the
tendons of musculus palmaris longus and musculus
flexor radialis) in her left forearm was
punctured with a 0.25mm thick stainless steel
needle, to a depth of approximately one
centimeter. At this point a 'grasping' sensation
of the needle was felt, without any manipulation
or 'de qi" sensation. Within one minute, the
patient described a sensation of tingling
involving her face and forehead on both sides
but not affecting the pinnas. Then her yawning
stopped instantly. The needle was left in place
for 10 minutes. No other acupoint was used in
the treatment. She has suffered no relapse
since. Her radiation treatment was completed
uneventfully. At two-months following completion
of her radiation treatment, she had no further
persistent yawning.
Discussion
Yawning involves a wide opening of the mouth
with concurrent deep inhalation followed by a
slow expiration.' This complex coordinated motor
output process resembles a classical reflex
since once initiated, it goes to completion
without significant influence from sensory
feedback.2 The exact neuronal mechanism through
which yawning occurs is still unknown. It
appears that the complex neuronal network
involved in yawning may be situated in the
reticular brain stem area. It may be closely
associated with motor nuclei of the trigeminal
nerve in the pons, the facial nuclei, the dorsal
and ventral group nucleus of the 'respiratory
center' in the medulla oblongata, and other
nuclei constituting the autonomic nervous system
in the brain stem and hypothalamus. This is
supported by the interesting observation that
yawning also occurs in anencephalic newborns,
and that involvement of the autonomic nervous
system in yawning has been demonstrated by micro
neu rograph ic examination of the sympathetic
nervous system.';' A close link of this complex
yawning neural network to a large associative
cortical area has also been proposed.
The physiological triggers of yawning are
not clearly known. Involuntary programmed
cortical activities in response to a relatively
nonstimulating environment have been suggested.
This is supported by the observation that
yawning occurs more often at bed or waking times
and in boring situations. It can also be
triggered by just reading or thinking about it
or seeing somebody yawn.5 Yawning can also be
observed in patients suffering from brain
hypoxemia, epilepsy, brain tumours or lesions,
intracranial hemorrhage, infections, multiple
sclerosis, and progressive supranuclear
palsy.6° Morphine withdrawal and the
consumption of a variety of drugs that affect
neurotransmitters, such as dopamine, are also
found to be associated with excessive
yawning.";" Other neurotransmitters and
neuropeptides are thought to be involved in the
yawning process including adrenocorticotropin,
alpha melanocyte stimulating hormone,
actetylcholine, serotonin, excitatory amino
acids, nitric oxide, oxytocin and opioid
peptides."
In the patient presenting in this report,
the trigger of her pathological yawning was not
clear, but could be due to the presence of the
brain tumour, and the effect of radiation
treatment involving the relevant brain stem
areas. As there is still no clear clinical
guideline regarding the urgent management of
non-drug induced pathological yawning, in either
Traditional Chinese Medicine or Western
Medicine, the choice of treating this lady with
medical acupuncture was largely empirical. The
choice of using the acupoint PC6 was based on
the clinical evidence of its usefulness in
controlling nausea and vomiting. The 'emesis
center' is located in the brain stem between the
obex and the retrofacial nucleus, including the
region extending from the nucleus of the
solitary tract through the lateral tegmental
field of the reticular formation to the
ventrolateral medulla.
These areas are closely related to the areas
involved in the yawning process and the
autonomic nervous system. The exact mechanism of
the negative modulation of nausea and vomiting
with PC6 stimulation is not clear. Inhibition of
serotonin receptors at a central level has been
postulated, since it is recognized that
serotonin receptor antagonists reduce nausea and
vomiting in clinical studies." Serotonin has
also been shown to exert a positive modulating
effect on yawning." It is possible that the
therapeutic effect of PC6 acupoint stimulation
on yawning, as demonstrated in this patient, may
work through a similar mechanism of serotonin
receptor inhibition within the central nervous
system. The observation in this patient, that a
tingling sensation expanded from around the
mouth to the face, suggests a trigeminal nerve
sensory distribution. This suggests that PC6
stimulation may have exerted an effect on
corresponding areas of the pons where the
trigeminal nuclei are situated. This again
relates closely to the areas controlling yawning
and emesis.
The finding that an increase in
parasympathetic activity seems to precede the
expression of nausea and the observation that an
increase in parasympathetic activity occurs in
response to yawning, suggests that the autonomic
nervous system is probably involved in both
processes.';" PC6 acupoint stimulation may be
viewed as a regulator, possibly modulating the
parasympathetic component, of the autonomic
nervous system. In fact the Yin and Yang
patterns, as described in Traditional Chinese
Medicine, may correlate with relative changes in
parasympathetic and sympathetic activities in
disease. Further studies in this context will be
necessary to clarify the physiological basis of
Traditional Chinese Medicine.
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