Two cases of azygos anterior cerebral artery aneurysm (author's transl)]

Two cases with azygos anterior cerebral artery were reported from an analysis of 37 cases of distal anterior cerebral artery aneurysm. Case 1 was a 57-year-old woman. She had an attack of subarachnoid hemorrhage two months before admission to our clinic. The anterior cerebral artery was not demonstrated on the right carotid angiogram, and an azygos anterior cerebral artery was visualized on the left carotid angiogram. The aneurysm was situated at the distal end of the azygos artery. Case 2 was a 71-year-old hypertensive woman. Subarachnoid hemorrhage occurred 6 days before admission to our clinic. The left carotid angiography with contraleteral compression revealed an azygos artery and an aneurysm in its middle part. The azygos arteries in both cases were confirmed at operation and aneurysmal necks were managed without any serious deficit. The distal anterior cerebral artery aneurysm is frequently accompanied by azygos artery. This vascular anomaly may cause a hemodynamic change and may be one of the factors of aneurysmal formation at this part.     

Accessory middle cerebral artery and duplication of middle cerebral artery--terminology, incidence, vascular etiology, and developmental significance.

A series of 455 bilateral carotid angiographies included 14 accessory middle cerebral arteries (Acc-MCAs) and seven duplication of middle cerebral arteries (Dup-MCAs). The branching patterns of Dup-MCA could be classified as "direct bifurcation" from the internal carotid artery, since most lacked the essential bifurcation or trifurcation at the distal end of the M1 portion. On the other hand, Acc-MCAs are probably residual congenital arteries. These anomalous MCAs were apparently associated with epilepsy. Five Acc-MCAs were associated with anterior communicating artery aneurysm at the origin. In addition, a rare case of Dup-MCA with arteriovenous malformation at its origin was found.     

Multiple intracranial mycotic aneurysm. Report of a case (author's transl)]

A case of intracranial mycotic aneurysm was reported, in whom repeated cerebral angiographies demonstrated the seccessive appearance of multiple aneurysms in a short term after the septic cerebral infection, and the importance of repeated angiography in the treatment of the intracranial mycotic aneurysm was stressed. A 44-year old male who had heart failure developed suddenly a left hemiparesis with irritable meningial signs on Nov. 3, 1973. The right carotid angiography carried out on Nov. 16 in an admitted hospital showed partial obliteration of cortical branches of the middle cerebral shift of the anterior cerebral artery due to the cerebral infarction. No aneurysm was demonstrated in the angiogram. The second angiography of the right carotid and vertebral artery was done on the admission of Dec. 18. The previously shown contralateral shift of the anterior cerebral artery was remarkably decreased, and an aneurysm of 3 mm in diameter was recognized at the cortical branch of the right middle cerebral artery on the parietal region. Any aneurysm was not revealed by the vertebral angiography. The third angiography of bilateral carotid and vertebral artery was performed on Dec. 25. The previously revealed aneurysm increased in size. Multiple aneurysms was demonstrated at the anterior branches of the insular artery. The vertebral angiography demonstrated multiple aneurysms at the peripheral portion of the bilateral posterior cerebral arteries. The patient was improved neurologically after the administration of antibiotics, and was discharged on Dec. 27 on the convenience of his family and would be followed in conservative cares.     

Three cases of infra-optic course of the anterior cerebral artery

Three cases of rare anomalous cerebral artery originating from internal carotid at the level of ophthalmic artery to join the anterior cerebral artery were presented. Case 1. A 32-year-old woman was admitted following subarachnoid hemorrhages. Cerebral angiography disclosed the anterior communicating artery aneurysm and the anomalous vessel originating at rt. carotid siphon to join anterior cerebral artery. Case 2. A 37-year-old woman was admitted with rt. hemiparesis and aphasia. Cerebral angiography revealed the anomalous vessel originating at rt. carotid siphon to join contralateral anterior cerebral artery. Case 3. A 22-day-old male infant with enlarged head was admitted and cerebral angiography was performed. Anomalous vessel originating from internal carotid at the level of ophthalmic artery joined to the azygos anterior cerebral artery. There were only sixteen reported cases of this anomaly including our three cases. Seven aneurysms were associated in six cases, in which four were located in anterior communicating system. The fact that among the cases of this anomaly, ophthalmic artery used to not have normal stem but be fed from middle meningeal or middle cerebral artery suggested that the anomalous vessel had the common stem with ophthalmic artery at certain embryonic stage. These considerations led us to the conclusion that this anomalous vessel might originate from the remnant of anastomotic loop between primitive dorsal and ventral ophthalmic artery.     

Ruptured aneurysm at the origin of the accessory middle cerebral artery: case report

The accessory middle cerebral artery is a rare vascular anomaly of the brain. We describe a case of a ruptured aneurysm at the junction of the accessory middle cerebral artery and the horizontal portion of the anterior cerebral artery. The lesion was demonstrated by angiography and confirmed at surgery. No perforating arteries arising from this accessory artery were found. There have been only four previous reports of aneurysms located at the origin of the accessory middle cerebral artery. The relevant literature is briefly reviewed.     

Relationship between the calibre of carotid arteries and the configuration of the circle of Willis in healthy older persons

AIM: Recent papers have pointed out that the severity of brain damage that follows carotid occlusion is largely influenced by the state of integrity and functionality of the circle of Willis. In spite of this, duplex scanning investigation of carotid arteries has traditionally been focused on the assessment of the degree of the stenosis, while other features, such as the calibre of carotid arteries and their possible asymmetry, have often been neglected. The aim of the present paper was to verify, in a cohort of older persons, whether, based on the calibre of internal carotid arteries and their possible asymmetry, abnormalities of the circle of Willis can be predicted. Such information could be used to identify high risk patients in whom the status of the circle of Willis should be investigated by MR angiography. METHODS: We studied 118 healthy older persons with both duplex scanning investigation of carotid arteries and MR angiography of the circle of Willis. RESULTS: We found that the finding of abnormal internal carotid artery calibres was always associated with abnormalities of the precommunicating segments either of the anterior or of the posterior cerebral arteries. Abnormalities of communicating arteries did not affect the calibre of internal carotid arteries, but abnormalities of anterior communicating arteries could always be detected by contralateral common carotid artery compression manoeuvres. CONCLUSION: In conclusion our findings show that, in healthy older persons, duplex scanning investigation of carotid arteries may provide useful information about the integrity and functionality of the circle of Willis. Future studies should confirm our findings in patients with atherosclerotic lesions of internal carotid arteries.     

A case of accessory middle cerebral artery associated with internal carotid artery aneurysm (author's transl)

A case of accessory middle cerebral artery associated with internal carotid artery aneurysm was reported. A 50-year-old female was admitted to our hospital with complaints of headache, nausea, vomiting and conciousness disturbance. Lumbar puncture showed bloody CSF. Right carotid angiogram revealed saccular aneurysm of the internal carotid-posterior communicating artery and accessory middle cerebral artery originating from the horizontal portion of the right anterior cerebral artery. No other vascular lesion was observed on other angiograms. Operation was performed 2 days after admission. The neck of the aneurysm was clipped. Postoperative aseptic meningitis was cured by frequent lumbar punctures, and her course was uneventful. The etiological hypothesis of these cerebral vascular anomalies was briefly discussed.     

Hypoplasia of the internal carotid artery--report of an unusual case.

We present a rare case of unilateral internal carotid artery (ICA) hypoplasia associated with arterial anomalies in the circle of Willis. The ipsilateral middle cerebral artery was supplied via anomalous arteries from the posterior cerebral artery and the ICA. The ipsilateral common carotid artery also originated from the anomalous brachiocephalic trunk. The etiology of the hypoplastic ICA is uncertain, but the associated multiple vascular anomalies support the congenital origin.     

A case showing the infraoptic course of the anterior cerebral artery associated with anterior cerebral artery aneurysm

A ruptured anterior cerebral artery aneurysm with anomalous right infraoptic course of the anterior cerebral artery (ACA) was reported. A 40-year old male was admitted because of SAH episode, and computerized tomography (CT) on the day of admission revealed hemorrhage in both Sylvian and interhemispheric fissures. Four-vessel angiography was performed on the same day. A saccular aneurysm was demonstrated in the region of the anterior communicating artery (ACoA), and anomalous artery, which originated from the intradural right carotid artery at the level of the right ophthalmic artery was found to be running medially and superiorly. It supplied the bilateral callosomarginal arteries and the unpaired pericallosal artery. The fenestration of the vertebral artery, duplication of bilateral superior cerebellar arteries, and an occipital artery arising from the right internal carotid artery at the C3 level were found. Surgery was performed on the first day of admission, and the anterior interhemispheric approach was selected. The anomalous branch of the right ICA ran beneath the right optic nerve, ascended between the optic nerves, and supplied the ACoA system. The left hypoplastic A1 segment entered the ACoA. However, the right A1 segment could not be found. The aneurysmal neck, situated between the bilateral callosomarginal arteries and the unpaired pericallosal artery, was clipped with Sugitas curved clip. The postoperative course was uneventful and a follow-up angiograph revealed successful obliteration of the aneurysm.     

Aneurysm rupture at an anomalous collateral artery that extended from the proximal A2 segment to the middle of the M1 segment, bypassing atresia of the internal carotid artery bifurcation. Case report

The authors report the first known case in which an anomalous collateral artery was found to connect the proximal A2 segment with the middle of the M1 segment. This rarity was associated with atresia of the T-shaped internal carotid artery bifurcation. Two aneurysms had developed on a tortuous and tangled portion of the anomalous artery; one of them had ruptured, producing a subarachnoid hemorrhage and an intracerebral hematoma in the area of the putamen. The aneurysms were clipped and the intracerebral hematoma was removed via an emergency craniotomy. Possible causes of the anomaly and the differences between it and accessory and duplicated middle cerebral arteries are reviewed.     

Surgical manipulation of primate cerebral arteries in established vasospasm

It is generally believed that surgery in the face of angiographic vasospasm is dangerous due to an increased incidence of postoperative cerebral ischemia. One theory is that arterial narrowing is exacerbated by surgical manipulation of vasospastic vessels during aneurysm dissection and clipping. This theory was tested in a primate model of cerebral vasospasm and the results reported. Six monkeys underwent baseline cerebral angiography, followed by induction of subarachnoid hemorrhage (SAH) on both sides of the circle of Willis. An equal amount of fresh autologous blood clot was placed around each internal carotid, anterior cerebral, and middle cerebral artery. Six days later, angiography was repeated and the right craniectomy was reopened for clot evacuation and surgical manipulation of the right cerebral arteries, including placement of a temporary aneurysm clip on the right middle cerebral artery. The left cerebral arteries were not exposed or manipulated, and served as controls. Twenty-four hours later angiography was repeated, then the animals were killed. Equal and significant vasospasm (greater than 40% reduction in vessel caliber compared to baseline, p less than 0.05) was seen in the middle cerebral arteries on both sides of the circle of Willis in all animals 6 and 7 days after SAH. There was no significant change in the severity of vasospasm on Day 7 compared with Day 6 in the right cerebral arteries. Increased risk of postoperative cerebral ischemia for surgery in the peak vasospasm period may be due to mechanisms other than increased arterial narrowing precipitated by surgical manipulation.     

Changes in blood flow of anterior and middle cerebral arteries following carotid endarterectomy: a transcranial Doppler study

AIM: The aim of the present study was to evaluate the changes in blood flow of anterior and middle cerebral arteries following carotid endarterectomy, using transcranial Doppler (TCD) flow studies. PATIENTS AND METHODS: This study included 100 patients (72 men, mean age 65 years) who underwent carotid endarterectomy because of high-grade carotid stenosis or symptoms of ischemic stroke. Endarterectomy was performed by a distal shunt between the common carotid and internal carotid arteries. Blood flow in the anterior and middle cerebral arteries was assessed by TCD preoperatively and also in the postoperative period (1st and 4th day; 1st, 6th, and 12th month). Collateral circulation in the Willis circle was evaluated by common carotid compression. RESULTS: Patients with bilateral carotid stenosis > or =70% exhibited a significantly increased flow velocity in the ipsilateral anterior cerebral artery (ACA), middle cerebral artery (MCA), and in the contralateral ACA. Patients with entirely occluded contralateral internal carotid artery showed the most pronounced changes in cerebral hemodynamics. Blood flow velocities returned to the preoperative values at 1 to 12 months following endarterectomy. Hyperperfusion syndrome was manifested in 14 patients, who exhibited significantly higher flow velocities in the ipsilateral MCA compared with asymptomatic patients. CONCLUSIONS: A transient bilateral increase of blood flow velocity in the anterior part of the Willis circle may often occur in the immediate postoperative period following carotid endarterectomy. Although its clinical significance is not entirely understood, this increase may be associated with cerebral hyperperfusion syndrome.     

Ruptured aneurysm at the origin of the median artery of the corpus callosum associated with accessory middle cerebral artery--case report

A 62-year-old male presented with ruptured anterior communicating artery (ACoA) aneurysm manifesting as severe headache associated with the rare combination of median artery of the corpus callosum (MACC) and accessory middle cerebral artery (MCA). Computed tomography demonstrated diffuse subarachnoid hemorrhage. Left carotid angiography demonstrated an anomalous vessel originating from the ACoA complex and passing forward in the interhemispheric fissure between the two companion A2 segments. This vessel was identified as the MACC. Another anomalous vessel originated from the left A1-A2 segment and passed into the sylvian fissure. This vessel was identified as the accessory MCA. Left frontotemporal craniotomy was performed to clip the neck of the aneurysm. After identifying both A1 and A2 segments, accessory MCA, and the MACC, the aneurysm neck was occluded successfully. The ACoA complex is one of the most frequent sites of vascular anomalies. Preoperative and intraoperative care is required to identify the presence of anomalies of the ACoA complex prior to clip placement, to avoid accidental damage or clipping, which may result in severe neurological deficits.     

Influence of the Collateral Function of the Circle of Willis on Hemispherical Perfusion During Carotid Occlusion as Assessed by Transcranial Colour-coded Duplex Ultrasonography

OBJECTIVES: to investigate the collateral potential of the circle of Willis with transcranial colour-coded duplex ultrasonography and common carotid artery (CCA) compression. MATERIALS AND METHODS: in 46 atherosclerotic patients without cerebrovascular disease, the functional patency of the collaterals of the circle of Willis, the anterior and posterior communicating arteries, was assessed. The Peak Systolic Velocity (PSV) decrease in the middle cerebral artery (MCA) during CCA compression between complete and incomplete circles was compared. RESULTS: in 10 (22%) patients a complete and in 36 (78%) patients an incomplete circle of Willis was found, mainly due to non-functioning posterior communicating arteries. In hemispheres with collateral supply through both the anterior and the posterior communicating artery, the median PSV decrease in the MCA during CCA compression was 43%. When the posterior, anterior or both communicating arteries (1 hemisphere) were missing the PSV decrease was 58% (p =0.003), 70% (p =0.001) and 75%, respectively. CONCLUSIONS: collateral flow from the basilar to the carotid territory is often hampered by non-functioning posterior communicating arteries. A non-functioning anterior communicating artery is rare. A complete collateral circulation provides better perfusion of the MCA during carotid occlusion as compared with collateral supply through only the anterior or the posterior communicating artery in the case of an incomplete circle of Willis.     

Connective tissue analysis of the canine circle of Willis in hypertension

The collagen and elastin contents of the major arterial components of the canine circle of Willis (basilar artery, posterior cerebral artery, internal carotid artery, middle cerebral artery, and anterior cerebral artery) were determined as measures of the passive mechanical properties of these vessels. Studies were carried out in seven normotensive dogs and seven dogs in which experimental renal hypertension of 3 months duration had been induced. In the normotensive animals, the collagen content of the middle cerebral artery exceeded that of the other vessels considered. The elastin content and the total connective tissue were not significantly affected by arterial site. The middle cerebral artery collagen to elastin ratio was greater than corresponding values for the basilar, posterior cerebral, and internal carotid arteries. Connective tissue differences were less pronounced in the hypertensive animals. No component of the canine circle of Willis in the hypertensive dogs showed a significantly different collagen content, elastin content, total connective tissue content, or collagen to elastin ratio. In comparing cerebral vessels from normotensive and hypertensive dogs, total connective tissue values were greater in hypertension for all arterial sites considered. These acute physiological changes in connective tissue content over small distances in intracranial blood vessels from normotensive animals, together with unique connective tissue responses of these vessels to short term hypertension, may suggest additional possible factors important in the natural history of cerebrovascular pathological conditions.     

The value and limitations of magnetic resonance angiography of the circle of Willis in patients undergoing carotid endarterectomy

Magnetic resonance angiography is a useful technique to determine the patency of the circle of Willis when compared with conventional four-vessel angiography. The purpose of this study is to determine whether the integrity of the circle of Willis, assessed by magnetic resonance angiography, provides adequate collateral cerebral circulation during carotid endarterectomy and correlates with internal carotid artery back pressure. Over a recent 20-month period, 35 patients were studied preoperatively with magnetic resonance angiography of the carotid bifurcations of the circle of Willis and the vertebrobasilar system. All patients underwent standard carotid endarterectomy with intraoperative measurement of internal carotid artery back pressure. Patients with an internal carotid artery back pressure < 50 mmHg had an intraluminal shunt placed. Deficiencies in branches of the circle of Willis, the carotid bifurcation and the vertebrobasilar system determined by magnetic resonance angiography were correlated with internal carotid artery back pressure using Fisher's exact test. Only one patient had a completely intact circle of Willis. Eleven of 16 patients (69%) who had an internal carotid artery back pressure < 50 mmHg had an occluded A1 segment of the anterior cerebral artery combined with an occluded posterior communicating artery, whereas only five of 19 patients (26%) who had an internal carotid artery back pressure > 50 mmHg had similar findings (P < 0.03). Severity of occlusive disease of the contralateral internal carotid artery and the basilar artery did not independently predict internal carotid artery back pressure. An occluded anterior branch of the circle of Willis in combination with an occluded posterior branch of the circle of Willis is associated with an internal carotid artery back pressure < 50 mmHg. Although magnetic resonance angiography of the circle of Willis may provide valuable anatomic information, it is not sufficiently accurate to predict the need for carotid shunting and therefore its use cannot be justified on a routine basis.     

Surgical anatomy of the cerebral arteries in patients with subarachnoid hemorrhage: comparison of computerized tomography angiography and digital subtraction angiography.

OBJECT: The purpose of this study was to compare computerized tomography (CT) angiography and digital subtraction (DS) angiography studies in patients with subarachnoid hemorrhage (SAH) to assess their vascular anatomy relevant to cerebral aneurysm surgery. METHODS: From a prospective series of 100 patients with SAH, the authors selected 73 patients whose CT angiography studies were of adequate quality and in whom DS angiography of both carotid arteries had been performed. Eleven patients with no DS angiographic studies of the vertebrobasilar artery were only evaluated for the anterior half of the circle of Willis. Anterior communicating arteries (ACoAs), both precommunicating anterior cerebral arteries (A1 segments), both posterior communicating arteries (PCoAs), and both precommunicating posterior cerebral arteries (P1 segments) were assessed on CT angiography and DS angiography by two independent observers. CONCLUSIONS: Computerized tomography angiography compares well with DS angiography for visualizing normal-sized arteries, and is superior for visualizing ACoAs and hypoplastic A1 and P, segments. Important preoperative aspects such as dominant A1 segments and PCoAs are equally well seen using either modality. Neither method enabled the authors to visualize more than 50% of PCoAs. Use of CT angiography can provide the required preoperative anatomical information for aneurysm surgery in most patients with SAH.     

A case of anterior communicating artery aneurysm with occlusion of the bilateral middle cerebral arteries

A patient with ruptured anterior communicating artery aneurysm associated with occlusion of the bilateral middle cerebral arteries is presented. A 70-year-old woman was hospitalized for sudden onset of severe headache and vomiting. She was alert, and no neurological deficit was found. CT scan showed a subarachnoid hemorrhage. Cerebral angiogram demonstrated occlusion of the bilateral middle cerebral arteries and ruptured anterior communicating artery aneurysm. After operation, she fully recovered and was able to walk at the time of discharge. In aneurysmal formation, we know from the literatures that hemodynamic stress plays an important role. In this case, occlusion of the bilateral middle cerebral arteries caused hemodynamic stress on the anterior cerebral arteries and anterior communicating artery. It is suggested that this is a causative factor of aneurysmal formation under systemic hypertension.     

Spontaneous middle cerebral artery occlusion leading to moyamoya phenomenon and aneurysm formation on collateral arteries

BACKGROUND: Spontaneous middle cerebral artery occlusion associated with moyamoya phenomenon is distinct from moyamoya disease. The hemodynamic stress on the collateral channel occasionally leads to aneurysm formation, which may manifest as hemorrhage. The etiology of this disease has not been fully understood. CASE DESCRIPTION: A 63-year-old woman presented with left putaminal hemorrhage. The cerebral angiogram revealed a significant stenosis in the proximal segment of the left middle cerebral artery. Collateral arteries originating from the horizontal segment of the ipsilateral anterior cerebral artery and the ambient segment of the ipsilateral posterior cerebral artery supplied the middle cerebral artery distal to the stenosis. Both of the collateral channels had associated aneurysms that were surgically obliterated. The aneurysm on the collateral artery from the posterior cerebral artery was responsible for the putaminal hemorrhage. CONCLUSIONS: Spontaneous middle cerebral artery occlusion may lead to focal moyamoya phenomenon and aneurysmal intracerebral, intraventricular, or subarachnoid hemorrhage. The presence of a co-existing anomalous collateral artery in the present case suggests a congenital etiology of the focal middle cerebral artery occlusion.