A patient with recurrent cerebral
ischemia induced by yawning is reported. The
patient had undergone a superficial
temporal-middle cerebral bypass operation
previously, and the cause of the cerebral.
ischemia was found to be a kink in the donor
artery by an action of opening the mouth widely.
Surgical revascularization of the brain is a
currently stimulating-though
controversial-subject in neurosurgery. The
superficial temporal artery-middle cerebral
artery (STA-MCA) anastomosis has been most
widely performed among the several modes of
extracranial-intracranial bypass operations, and
its mortality and morbidity are acceptably low.
Recently, a patient developed a rare
complication after STA-MCA anastomosis, namely,
recurrent cerebral ischemic attacks induced by
yawning.
Case Report : This 19-year-old,
right-handed man had been healthy until October
15, 1981, when he was found unpurposefully
crawling around in his apartment. His speech was
incoherent, but he refused to see a doctor. When
he was first seen by us 2 days later, he ddi not
respond to verbal commands. His pupils were
bilaterally miotic (1 mm in diameter), but
promptly reacted to light. The funduscopic
examination was normal. Babinski sign was
positive on the right side. Otherwise there was
no definitive neurologic deficit. A computed
tomography (CT) scan showed a large
subcortical hematoma in the left temporal
lobe associated with a marked shift of the
midline structures toward the right. An
anglogram of the left carotid artery showed an
avascular infrasylvian mass. The proximal
segment of the middle cerebrai artery was
severely stenotic, but the cortical branches
were still filled in a normograde fashion.
Neither cerebral anevrysm nor vascular
malformation was found. The hematoma was
evacuated through a left frontotempoal
craniotomy, and the patient recovered smoothly.
The cause of the hemorrhage could not be
clarified at operation.
After surgery, an anglogram of the left
carotid artery showed a disappearance of the
mass effect, but the stenosis of the middle
cerebral artery remained unchanged. Angiography
of the right carotid artery was performed for
the first time after an evacuation of the
hematoma, and it showed a severe stenosis of the
proximal segment of the middle cerebral artery
on this side also. The fillingof the anterlor
cerebral artery and several frontal branches of
the rniddle cerebral artery did not occur during
the 10-second period of serial filming. In
addition, the ahnormal vascular networks as seen
in the Moyamoya disease were found at the base
of the brain as well as in the peripheral
territory of the hypertrophied choroidal
artery.
Dyamic CT scanning after a rapid intravenous
injection of iodinated contrast medium showed a
marked slowing of circulation in the
frontoparital region.We performed anSTA_MCA
anastomosis on the right side. In addition, we
inserted a flap of the temporal muscle into the
subdural space, expecting the formation of
collateral routes between the vasculatures of
the muscle and those of the brain. The patient
did well after the operation, and he was
discharged on December 8, 1981, with a residual
right homonymous upper quadrantanopsia and a
mild fluent dysphasia.
When he gave a big yawn one day in the
beginning of january 1982, he noticed for the
first time a transient numbness in the left side
of the face and the left hand. Thereafter,
similar sensory episodes recurred on several
occasions, always triggered by yawning or
otherwise opening his mouth widely.
When he was readmitted on February 23, 1982,
neurologic examinations were noncontributory
except for the persistent visual-field defect
and a minimal impairment of recent memory. The
results of routine laboratory examinations were
within normal limits. The right superficial
temporal artery pulsated well. A subsequent
dynamic CT scan showed a marked improvement of
circulation in the right parietofrontal region
.
Digital compression of the right superficial
temporal artery in the preauricular region
caused similar sensory effects. When he was
forced to open his mouth maximally, a slowing of
the electroencephalograrn was noted in the right
frontal leads. Selective angiography of the
right external carotid artery was repeated,
first with his mouth closed and then with his
mouth opened. The right superficial temporal
artery had hypertrophied from 1.2 mm to 2.8 mm
in diameter during the intervening 3 months. The
anastomosis was patent. A loop of the
superficial temporal artery was seen in the
preauricular region. When angiography was
repeated with his mouth opened, the arterial
loop became more stressed with a small
interruption of the contrast medium.
Unfortunately, the sensory episode did not occur
at the time of this study, probably because of
an insufficient effort of the patient to open
his mouth maximally. Finally, the doppler-flow
studies demonstrated a marked decrease in the
velocity of flow through the right superficial
temporal artery during the act of opening his
mouth. On one occasion, a cessation of flow was
seen in association with the sensory deficits.
He was discharged without further surgery.
Thereafter, his peculiar sensory symptoms abated
gradually and he is working full-time as an
electrical engineer.
Discussion : Since 1967 when Donaghy
and Yasargil performed the first STA-MCA
anastomosis, the microvascular
extracranial-intracranial arterial bypass
operation has becorne an acceptable alternative
in the treatment of inaccessible cerebrovascular
occlusive lesions. It has also been performed
successfully as a useful adjunctive procedure in
the management of certain neurosurgical
conditions that may involve ligation of the
major cerebral arteries such as giant aneurysms
and tumors at the base of the brain.
Among several modes of microvascular
extracranialintracranial bypass operations, the
STA-MCA anastomosis has been most widely used.
In patients with definite indications, the
operative mortality is negligible when performed
by experienced surgeons, and the morbidity is
very low. Ischemic necrosis of the skin flap,
wound infection, thrombotic occlusion at the
site of the anastomosis, formation of a
subgaleal fluid collection or an intracranial
hematoma, hemorrhage in a recent infarct, and
several other major or minor complications have
been reported, but they are mostly avoidable by
surgical skill and adequate selection of the
timingof the operations. The compression of the
temple area by the tightly fitted sides of a
pair of spectacles, or by one's arm or a firm
pillow during a nap may occasionally cause an
interruption of the blood flow through the donor
superficial temporal artery with resultant
cerebral ischemic symptoms. To our knowledge,
however, recurrent cerebral ischemic attacks
induced by opening the mouth as seen in the
present case have not been reported as a
complication of the STA-MCA anastomosis.
As this patient apparently had had no
definitive cerebral ischemic symptoms and the
stenosis of the middle cerebral arteries had
remained asymptomatic before his first
admission, the indication to perform the
extracramal-intracranial bypass operation may
seern to have been problematic.
However, we have seen several other patients
harboring similar stenosis of the internal
carotid or middle cerebral artery and an
abnormal vascular network at the base of the
brain, in whom the stenosis progressed with time
and finally caused severe ischernia of the
brain. In this particular patient, the stenosis
of the middle cerebral artery was very tight. In
addition, the angiogram showed that the
collateral blood flow was very poor in the right
frontoparietal region, and the dynarnic CT scan
also demonstrated a marked delay in perfusion in
the same region. Based on these findings, we
decided to perform the STA-MCA anastomosis on
the right side in the hope of preventing
possible cerebral ischemic attacks in the
future.
Unfortunately the patient began having the
transient sensory events atter the STA-MCA
anastomosis. Initially, his peculiar complaints
seemed to us hard to believe. As his complaints
were nothing but subjective phenomena, we
performed several tests in an attempt to
substantiate them. When we found that his
symptoms were reproduced by digital compression
of the vigorously pulsating right superficial
temporal artery, we came to believe that the
anastomosis had become an important source of
blood supply to the right cerebral hemisphere,
and at the same time the source of his ischemic
events. We assumed further that the action of
opening his mouth widely might have somehow
caused a significant reduction of flow through
the donor artery and hence the ischemic cerebral
symptoms. This assumption was substantiated by
several provocative tests, and angiography with
and without opening his mouth pinpointed the
kink of the superficial temporal artery as the
organic cause of his complaints.
Although how a kink forms is not entirely
clear, two factors seem to deserve serious
consideration in this particular patient: the
excessive length of the dissected superficial
temporal artery and the subdural insertion of
the flap of the temporal muscle. At surgery, the
superficial temporal artery and a narrow fringe
of supporting connective tissues were dissected
to the extent of 8 cm or longer, and used as a
donor artery. This was probably too long for the
anastomosis in this patient. Furthermore, a fiap
of the temporal muscle, approximately 5 cm * 6
cm, was fashioned, and its distal portion was
inserted beneath the dura mater through a
horizontal dural incision. It was loosely fixed
to the dural edge with a few stay sutures.
Accordingly, the redundant superficial temporal
artery with a loop formation was put between the
temporal muscle outside and the dura mater
inside.
Under these conditions, the sandwiched
superficial temporal artery would become adhered
at random eihter to the dura mater, to the
temporal muscle, or to both. When the patient
opens his mouth widely, the muscular process of
the mandible moves downward, and the temporal
muscle flap is pulled downward because it has
lost its original firm attachment to the
temporal squama. If the distal segment of the
superficial temporal artery has tightly adhered
to the overelying muscle flap, it would be also
displaced downward. When the proximal portion of
the artery is fixed to the underlying dura mater
and therefore is less movable, a kink of the
artery with a cessation of the blood flowmay
occur. Although such a complication appears to
be rare, it should be avoided.
