Yawning
and stroke
Abstract. Yawning during
hyperventilation occurred in certain patients
post-thalamotomy. It was found that all of the
lesions which elicited yawning (during the
routine recording of electroencephalograms) were
localized te, the medial portion of the
center-median nucleus. Yawning was noted to
persist up to 31/2 years postsurgery. Another
group of patients who yawned when
hyperventilated were patients with a history of
a recent head injury whe showed post-traumatic
behavioral changes. Patients in both groups were
young. There was no direct relationship between
yawning and EEG abnormality. It was suggested
that yawning during hyperventilation may serve
as a sign of brain damage, especially at the
brain stem level, in young patients.
Following surgery certain patients who had
stereotaxic lesions placed in the thalamus were
observed to yawn while hyper-ventilating.
During the routine recording of
electroencephalograms it was discovered that
these patients began to yawn during
hyperventilation and they stopped yawning when
hyperventilation was terminated. It was found
that all of the lesions which elicited this
yawning were located in the medial portion of
the center-median nucleus and that all of the
patients were young. Another group of patients
who yawned when hyperventilated provided a
provocative comparison with the lesion patients.
These were patients with a history of a recent
head injury who showed post-traumatic behavioral
changes. It is considered significant that all
of these patients were also young.
Six patients undergoing thalamotomy for
seizure and behavioral disorders were observed
to yawn when hyperventilated post-surgery. Three
of the patients were 21-23 years old, 2 patients
were 15 years old and 1 patient was age 11
years. Examination of the scattergram reveals
that all of the yawners had lesions 8 mm or less
laterally from the midline. A comparison of the
number of patients who yawned with lesion
placements within 8 mm from the midline to those
lesions beyond 8 mm was highly significant by
Fisher's exact probability test (p=0.003).
Further examination of the scattergram shows
that all of the yawners had lesions in the
centermedian lesions was also, significant
(p=0.014). This leads one to conmedian lesions
was also significant (p=0.014). This leads one
to conclude that lesions in the medial part of
the center-median nucleus are more likely to,
result in yawning than lesions in the lateral
center-median or other areas of the thalamus.
Moreover, lesions in the young are more 'A'
student, but afterwards he barely passed. The
patient's memory was impaired; he did not
remember what he was told. He had altered
reaction to pain consisting of decreased
awareness of pain. For example, he sustained
second- and third-degree burns on his calf
unaware that he was too close to a radiant
heater. After the accident, when spanked, he
laughed rather than crying or screaming. Two
EEGs taken 24 days apart, 1 year after injury,
revealed a mildly abnormal 7- to 10-eps
background frequency with the slower frequencies
predominating. Yawning was precipitated by
hyperventilation during both EEG recordings. In
figure 2 the three episodes of yawning which
occurred during hyperventilation in the second
EEG are illustrated. Note the first yawn at 18
sec, the second at 65 sec, and the third at 107
sec.
Yawning and EEG Abnormality : All of
the surgery patients had abnormal presurgery
EEGs. Three of the patients had spike-wave
discharges in their EEGs, 2 patients showed
generalized (theta range) slowing, and 1 patient
had focal delta left frontal. For the trauma
patients, 5 patients had a slow background
frequency (4 with biocciptal sharp waves and 1
with 14 sec positive spikes), 1 patient had
generalized spike-wave discharges, 1 patient
showed focal spikewave left frontal, and 1
patient had a normal EEG. Although 13 of the 14
yawners had abnormal EEGs, there was no direct
relationship between yawning and the severity of
the EEG abnormality.
Yawning and Persistence in Time : The
surgery patients were seen 5 days postoperative
and at 2- to 6-month intervals. Yawning was
elicited during hyperventilation in all of these
patients at the fifth postoperative day. Three
of the patients continued to show yawning 2-31/2
years following surgery; 3 patients still yawned
1 year postoperatively, and 1 patient yawned at
2 months but did not yawn when seen 6 months
later. Six of the 8 trauma patients were
followed 1-3 years after the initial
examination. The number of EEGs obtained ranged
from 2 to 8 EEGs and yawning occurred in at
least two thirds of the EEGs. In 2 cases which
were followed for 2 months there was yawning in
2 out of 3 EEGs in the first case, and yawning
in 1 of the 2 EEGs in the second case. It should
be noted that in one of the patients yawning did
not occur until 18 months after the initial
examination (26 months after injury) and then
was present in all of the 3 EEGs done within the
next year. It appears that for both surgery and
trauma patients there is a persistence of
yawning following its first appearance. The mean
number of yawns per 3-min hyperventilation was
3.0 for the surgery patients and 4.3 for the
trauma patients.
Discussion : Yawning is a
well-established response in the emotional
pattern of sub-human primates and rnan. It may
occur in human beings in such mild conflict
states as boredom and embarrassment and is even
simulated in nonverbal communication. Although
primates as the chimpanzee and the gorilla may
yawn in response to disturbance, yawning is so
prominently displayed in the baboon that it may
be regarded as a stereotyped response. Both
threat yawns and tension yawns have been
described. This increased frequency of yawning
in the less highly developed baboon is of
interest when contrasted with our finding that
yawning in hyperventilation was confined to the
young brain-injured patient. These maturational
aspects are further highlighted in the
descriptions of yawning in young chimpanzees
which typically occurred when they were unable
to take bananas in the presence of their
superiors.
The findîng that surgical lesions in
the medial part of the center-median nucleus
produced yawning, whereas lateral lesions
did not, is compatible with other evidence for
functional specificity in the center-median
nucleus. For Necker cube reversal rates it was
found that lesions placed medially in the
center-median nucleus increased reversal rate in
contrast to laterally placed lesions which
decreased the rate of reversal. Another study
indicated that the lesion site within the
center-median nucleus was related to the degree
of improvement for specifie behavioral
categories. For aggression maximum improvement
occurred for medially placed lesions, whereas
there were no differences in degree of
improvement for hyperkinesia and patho-affect
relative to medially or laterally placed
lesions.
Yawning was elicited by bilateral stimulation
of the cingulurn in two 17-year-old
brain-damaged patients. Motor and behavioral
responses such as restlessness and screaming
also occurred. The authors suggest that they
were chiefly stimulating the fibers that connect
the cingulurn to the temporal lobe and other
structures of the limbic system. They emphasized
that the two patients were significantly
brain-darnaged and their behavior, as a rule,
was destructive and aggressive. Their report is
compatible with cour observations and lends
support to the speculation that young patients
who yawn while hyperventilating, particularly
those with behavioral symptorns, may well have
brain damage involving subcortical structures,
especially at the brain stem level. If this is
the case then having the patients
hyperventilated and observing yawning might be a
simple, though useful, diagnostic tool.
