Zebian B, Hogg FR, Fu RZ, Sivakumaran R,
Stapleton S.
Department of Neurosurgery,
Atkinson Morley Wing, St. George's Hospital,
London
Yawning is thought to be a behavior
regulated by the brainstem. Although excessive
yawning has been reported in brainstem strokes,
progressive supranuclear palsy, demyelination,
and tumors, the featured cases are the first
reports of excessive yawning in Chiari
malformation Type I (CM-I).
We describe excessive yawning as a
presenting feature of CM-I in 2 adolescent
females. The classic headache of CM-I was much
less of a feature; instead, symptoms were
characterized by weakness in the limbs, lower
cranial nerve weakness, and pathological
yawning. Presentation was acute in the first
case and more chronic in the second. Imaging
showed brainstem edema in combination with CM-I.
Both patients underwent foramen magnum
decompression, which resulted in complete
cessation of the excessive yawning. Given the
role of the brainstem in yawning, we believe
that medullary compression at the craniocervical
junction and ensuing edema were implicated in
this curious symptomatology.
Case Reports
Case 1
History and Examination
A 12-year-old girl whose twin sister had
undergone foramen magnum decompression for CM-I
was referred to the pediatric neurology
department with a 2-week history of gait
disturbance and right-sided weakness. While
undergoing outpatient MRI, she was noted to be
lethargic with persistent yawning. She was
referred to the on-call neurosurgical service
for urgent review. History taking revealed that
she had been increasingly lethargic over the
2-week period and had been yawning increasingly
frequently despite sufficient rest.
Examination revealed mild right upper
limb weakness, right 11th and 12th cranial nerve
palsies, and dissociated sensory loss affecting
her upper limbs. She was yawning more than twice
a minute.
Magnetic resonance imaging
demonstrated tonsillar descent, an extensive
syringomyelic cavity in the cervicothoracic
cord, and signal change in the ventral and
central medulla without syringobulbia. Operation
Four days later, she underwent foramen magnum
decompression (bony decompression with
arachnoid-sparing opening of the dura
mater).
Postoperative Course
She made a good recovery with residual but
improving mild right upper limb weakness. Her
yawning and lethargy ceased postoperatively, and
at the 36-month follow-up she remained very
well.
Case 2
History
A 15-year-old girl presented to clinic with
a 2-year history of increasingly frequent
headache following a minor trauma. In addition,
she described an 8-month history of difficulty
swallowing and pooling of saliva in the mouth
and throat. A barium swallow had been performed
and failed to provide a diagnosis. She also
reported a 4-month history of "muffled speech"
and difficulty articulating her words.
Throughout the clinic appointment, frequent
yawning was noted. On further questioning, the
patient and her mother agreed that yawning had
been occurring with increasing frequency, even
preceding the symptoms described above. They
could not remember the onset of the frequent
yawning. On average, the yawning episodes would
occur once every 10 minutes and would last for
just 1 or 2 minutes with persistent yawning each
time. She denied feeling lethargic, and there
was no clear diurnal variation, although she had
not been observed as an inpatient during sleep.
Yawning was more frequent when she was suffering
from headache.
On examination, she was
neurologically intact.
Magnetic resonance imaging of the
neuraxis revealed a CM-I with retroversion of
the odontoid process causing severe crowding at
the foramen magnum and an associated
cervicothoracic syrinx with faint edema in the
medulla.
Operation She underwent expedited
foramen magnum decompression (bony decompression
with dural opening and sparing of the
arachnoid).
Postoperative Course
Postoperative recovery was uncomplicated,
and she was discharged home within a week. She
reported significant improvement in her
headache, improved speech due to reduced pooling
of saliva, improved swallowing, and cessation of
the excessive yawning. At the 30-month follow-up
she remained well with no further symptoms.
Discussion
Hans
Chiari (1851&endash;1916), an Austrian
professor of anatomy and pathology in Prague, is
credited with the first descriptions (1891 and
1896) of 4 types of hindbrain malformations
(CM-I, -II, -III, and -IV).
The exact definition of each has evolved
since. Two other entities have also been
described.
Chiari malformation Type 0 is characterized
by syringomyelia in the absence of hindbrain
malformation and responds to surgical
intervention in much the same way as CM-I.
Chiari malformation Type 1.5, on the other
hand, is characterized by descent of the
tonsils, as well as the brainstem and fourth
ventricle, through the foramen magnum but in the
absence of a myelomeningocele.
Although it used to be widely accepted that
CM-I presents in the 2nd or 3rd decade of life,
the disorder is being diagnosed more frequently
in the younger population since the advent of
MRI. The most common presenting symptom is
occipital and/or cervical pain that is often
caused or exacerbated by straining; however, the
pain may have a more constant dull element.
Other presenting symptoms are, in order of their
frequency, limb weakness, numbness, dissociated
sensory loss, unsteadiness, and cranial nerve
palsies. Other much less common symptoms such as
hiccoughs and fainting have also been
reported.
To our knowledge, these are the first
reported cases of CM-I presenting with
yawning
The function of yawning remains a topic of
debate. Some believe that it increases vigilance
in states of low arousal; others, that it serves
a role in social communication and in
synchronizing the physiological and behavioral
state of a group. The "deep inhalation" phase of
yawning may serve as a respiratory reflex
designed to increase oxygenation in states of
hypercarbia, although experimental evidence does
not support this theory. It is, however,
accepted that yawning is a common human response
to states of fatigue or boredom.
It consists of 3 phases: The first, or
"inspiratory phase," involves wide mouth opening
and deep inspiration. The nostrils and soft
palate are elevated, the nasopharynx dilates,
the tongue moves posteroinferiorly, and the
vocal cords abduct. At the peak of inspiration
there are associated facial movements and often
arm and/ or trunk extension. The second phase,
or "acme," is where inspiration is maintained.
Lacrimation and salivation may occur in tandem
with eye closure. Eustachian tube closure
precipitates transient hypoacusis. Maximal arm
and/or trunk extension can alter proprioception.
The final phase, or "expiratory phase," involves
rapid exhalation followed by a brief apneic
episode.
Yawning occurs in neonates with anencephaly,
indicating that the brainstem plays a key role
in this automatism. Cattaneo et al. concluded in
their review of the published literature that
the circuit responsible for yawning involves the
hypothalamus, midbrain, and reticular formation
of the pons and medulla. Although dopamine and
oxytocin play a central part, it seems that
other substances are also involved, including
nitric oxide, acetylcholine, orexins, and
serotonin as well as opioids. Effector centers
that generate the yawn include the bulbar
respiratory center; the motor nuclei of cranial
nerves V, VII, X, and XII; the phrenic nerve;
and the nerves supplying the accessory muscles
of respiration.
Pathological or excessive yawning is defined
as a "compulsive, repetitive action that is not
triggered by appropriate stimuli such as boredom
or fatigue." A literature search for
"pathological yawning" showed it has been
observed in various neurological pathologies
including basal ganglia disorders, multiple
sclerosis, progressive supranuclear palsy,
infarcts, and tumors but not in the context of
CM-I.
Conclusions
The anatomical pathways controlling yawning
are not fully understood, but there is clear
evidence that the brainstem plays a key role.
Excessive yawning has been reported in brainstem
stroke, tumor, and demyelination, but these are
the first reports of excessive yawning in
patients with CM-I.
The presence of brainstem edema on imaging
is unusual in patients with CM-I. We believe
that the weakness of the limbs, lower cranial
nerve weakness, and pathological yawning in our
patients resulted from compression of the
brainstem at the craniocervical junction with
ensuing edema. Although disturbed sleep was not
reported in either of the featured cases, the
well-known relationship between CM-I and sleep
disorders (particularly sleep apnea syndrome
[SAS]) may have contributed to the
yawning.
A literature search was performed to see if
a relationship between SAS and excessive yawning
was documented, but no reports were found to
support this. However, neither of the patients
was observed during sleep as we performed
expedited foramen magnum decompressions on both,
which precluded us from being able to perform
sleep studies. These cases highlight the
probable involvement of the brainstem in yawning
and the potential for CM-I to present with
excessive yawning.
We propose that when this occurs, urgent
decompression is indicated to relieve brainstem
compression.
Gamper
E. Arhinencephalie mit Encephalocele and
yawning. Zeitschrift
für die Gesamte Neurologie und Psychiatrie.
1926;104:49-120
Walusinski
O. Yawning
in diseases. European
Neurology 2009;62(3):180-187
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