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mise à jour du
18 juillet 2002
Surg Neurol
1983; 19; 46-50  
Transient cerebral ischemia evoked by yawning: an experience after superficial temporal artery-middle cerebral artery bypass operation  
Jyoji Handa, Yoko Nakasu, and Minoru Kidooka
Department of Neurosurgery, Shiga University of Medical Science, Ohtsu, Japan


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.