Agenesis of the internal carotid artery with transcavernous anastomosis presenting with an anterior communicating artery aneurysm--a case report and review of the literature

Arterial communication between cavernous segments of the carotid arteries associated with unilateral agenesis of the internal carotid artery (ICA) is extremely rare. We herein present a case of unilateral ICA agenesis with transcavernous anastomosis that presents with an anterior communicating artery (ACoA) aneurysm, and discuss its embryogeny and clinical implications. A 55-year-old woman with no significant medical history was admitted to our hospital for further examination of agenesis of the left ICA, which was detected in a routine medical examination. She was free of clinical symptoms and had no neurological deficits. Radiological evaluation revealed agenesis of the left ICA with transcavernous anastomosis. Moreover, an incidental multilobulated aneurysm was detected at the ACoA. She underwent microsurgical clipping for this aneurysm, and the post-operative course was uneventful. Investigation of collateral pathways helps our understanding of the segmental nature of carotid artery development. Recognition of this anomaly also has important implications in the surveillance and detection of associated cerebral aneurysms.     

Dysgenesis of the carotid artery associated with congenital ipsilateral Horner syndrome

We report a case with dysgenesis of the carotid artery associated with congenital Homer syndrome. A 6-year-old boy, who had undergone surgical repair for pulmonary atresia, ventricular septal defect, and patent ductus arteriosus at 20 months of age, presented with miosis of the left eye, and anhidrosis of the left face, neck, and shoulder girdle. Since the anhidrosis was obvious in early childhood, he was suspected as having congenital Horner syndrome. Cranial and cervical CT showed unpredicted abnormalities of the left carotid arteries, including the absence of an internal carotid artery (ICA), and hypoplasia of the common carotid and external carotid arteries. The anterior and middle cerebral arterial flow was supplied through the communicating arteries. Congenital agenesis of the ICA was highly suspected, because the left carotid canal could not be discerned at all. The concurrence of agenesis of ICA with ipsilateral Horner syndrome is accounted for by simultaneous organogenesis of the carotid artery and cervical sympathetic nerve, both of which are derived from neural crest cells. Developmental anomalies of the cervical neural crest, though rare, should be included in the differential diagnosis of congenital Homer syndrome.     

Unilateral internal carotid artery absence in trisomy 18

BackgroundInternal carotid artery (ICA) absence (agenesis or aplasia) is a rare congenital anomaly that is usually asymptomatic and found coincidentally. There has been no report showing a specific chromosomal abnormality causes ICA absence.Case reportsMR angiography in a Japanese male infant with trisomy 18 revealed left ICA absence with the left middle cerebral artery (MCA) and anterior cerebral artery (ACA) supplied from the ipsilateral posterior communicating artery and anterior communicating artery (ACoA), respectively, type A in Lie’s classification. Another Japanese male infant with trisomy 18 showed right ICA absence with the right ACA and MCA supplied from the ACoA, that is, type B in Lie’s classification.ConclusionThere have been no pathological or radiological reports of ICA absence in trisomy 18, however, it may be underestimated because the anomaly usually causes no clinical symptoms. It is necessary to evaluate further patients to clarify whether or not unilateral ICA absence is a characteristic congenital malformation.     

Internal carotid artery agenesis: diagnosis,clinical spectrum,associated conditions and its importance in the era of stroke interventions

Abstract

Background: Internal carotid artery (ICA) agenesis has been usually reported as an asymptomatic condition in association with other congenital anomalies. However, it is less well described in the context of clinical neurological syndromes.

Method: Five cases of ICA agenesis are reviewed. The diagnosis of ICA agenesis was based on the absence of bony carotid canal on computed tomography. Brain CT and magnetic resonance image (MRI) scans were done in all the patients and four vessels digital angiograms were obtained in two. Clinical presentation, coexistent radiological findings and associated abnormalities are reviewed.

Findings: The initial presentations were pulsatile tinnitus, ischemic stroke, migraine, Horner's syndrome, and subarachnoid hemorrhage. Collateral circulation was supplied via the posterior communicating artery and the anterior communicating artery. Ophthalmic artery was supplied by meningeal arteries. On CT, all cases demonstrated agenesis of the bony carotid canal. Smaller cavernous sinus were detected in all cases, enlargement of the foramen spinosum was found in three patients and hyper-pneumatization of the petrous apex was detected in two cases. In one patient a cerebral aneurysms was detected and treated with an endovascular approach. Other associated vascular abnormalities were aortic origin of the vertebral artery in two patients, ICA coiling in two cases and fenestration of basilar artery in one case.

Conclusion: ICA agenesis is usually asymptomatic but occasionally may be associated with ischemic stroke. Collateral supply is usually effective in preventing stroke but may become inefficient leading to ischemia. Associated anomalies such as cerebral aneurysms are commonly depicted on the same side as the ICA agenesis and may represent a potential life-threatening condition.     

Internal carotid artery-to-posterior cerebral artery bypass for revascularization of the brainstem

We describe a novel bypass technique used to revascularize the brainstem by anastomosing the internal carotid artery (ICA) to the posterior cerebral artery (PCA) using a radial artery graft, effectively creating a functional alternative to the posterior communicating artery. A 72-year-old male patient presented with rapidly progressive neurological symptoms attributable to brainstem compression; imaging showed a giant, fusiform, partially thrombosed, vertebrobasilar artery aneurysm. An Alcock’s test revealed no significant collateral circulation from the posterior communicating arteries. To revascularize the top of the basilar artery, we performed an ICA-to-PCA bypass using a radial artery interposition graft. Specifically, we used the radial artery graft to connect the supraclinoid ICA to the P2 segment of the PCA. The basilar artery was subsequently occluded during the same operation by placing a clip below the superior cerebellar arteries. Although the bypass remained patent, the patient suffered an acute thrombosis of the aneurysm, resulting in fatal pontine infarction.     

Ischaemia-induced vascular vulnerability resulting in intracerebral haemorrhage with ipsilateral internal carotid artery occlusion

Intracerebral haemorrhage accompanied with cervical internal carotid artery (ICA) occlusion on the same side without moyamoya-like vessels is rare. A 73-year-old man with left ICA occlusion and no presence of moyamoya disease criteria underwent xenon-enhanced computed tomography with acetazolamide challenge test. The findings showed hypoperfusion and no vasoreactivity in the territory of the left middle cerebral artery. During follow-up he suffered bleeding in the left frontoparietal lobe. Cerebral angiography showed left ICA occlusion and cross flow via the anterior communicating artery without moyamoya vessels. Long-term ischaemia would make perforating or anastomotic arteries vulnerable. These arteries were easily ruptured by hypertension, resulting in intracerebral haemorrhage.     

Agenesis of the left internal carotid artery associated with anterior communicating artery aneurysm: case report

We present a rare case of agenesis of the left internal carotid artery in a 43-year old woman, associated with an aneurysm of the anterior communicating artery and presenting with subarachnoid hemorrhage. The left internal carotid artery was not visualized on the left carotid angiogram. The left middle cerebral artery was perfused from the basilar artery via the dilated posterior communicating artery on vertebral angiogram. Absence of the left carotid canal was proven on temporal bone computed tomography. Absence of the left internal carotid artery was verified at operation. Absence of internal carotid artery is discussed in relation to aneurysm formation.     

Agenesis of left internal carotid artery associated with megadolichobasilar anomaly and olivopontocerebellar atrophy

A case of agenesis of the left internal carotid artery associated with megadolichobasilar anomaly (MDBA) and olivopontocerebellar atrophy (OPCA) was reported. A 73-year-old female had a three-year history of slowly progressing gait disturbance. On admission neurological examination revealed bilateral cerebellar ataxia and dysarthria with increased muscle stretch reflexes and extensor planter response in the left. CT and MRI showed marked atrophy of the brain stem and cerebellum with brain stem rotation and deviation to the right. Total absence of the left internal carotid artery was demonstrated angiographically. The left anterior and middle cerebral arteries were fed by the tortuous megadolichobasilar artery through the enlarged posterior communicating artery. The left ophthalmic artery was fed by the left middle meningeal artery. By the high resolution CT at the skull base, the lack of the carotid canal was demonstrated on the left side. The interesting clinical features of a case of agenesis of the left internal carotid artery were discussed. This case showed a clinical and radiological signs and symptoms of OPCA though any influences by MDBA could not be excluded.     

Infarction in the territory of the anterior choroidal artery due to embolic occlusion of the internal carotid artery--report of two cases

A case with infarction in the territory of the anterior choroidal artery (AChA) due to embolic occlusion of the internal carotid artery (ICA) is rare. We described two cases and investigated the mechanism of the territory of the AChA. Case 1 was a 69-year-old man. Case 2 was a 71-year-old woman. The neurological examination in both cases showed left homonymous hemianopsia, left facial palsy, left hemiparesis and left hemisensory disturbance. CT scan in these cases showed infarctions of the right uncus, amygdaloid nucleus, genu and posterior limb of the internal capsule, globus pallidus, lateral geniculate body and tail of the caudate nucleus. The right common carotid angiogram showed a complete occlusion of the ICA at its cervical segment in case 1 and at its carotid siphon in case 2. In both cases, the left carotid injection visualized the right anterior cerebral artery and right middle cerebral artery via the anterior communicating artery well, but the right AChA was not visualized. In case 1, the collateral pathways from the right external carotid artery (ECA) and the right posterior communicating artery (PCoA) to the right ICA were not supplied and the precommunicating segment of the right posterior cerebral artery was hypoplastic. In case 2, the collateral pathway from the right ECA to the right ICA was not supplied.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ophthalmic artery fed by posterior communicating artery after trapping of the internal carotid artery

The authors report a 50-year-old man with a ruptured large carotid-ophthalmic aneurysm on the right side and an unruptured anterior communicating artery (A Com) aneurysm. The A Comm aneurysm was clipped and the carotid-ophthalmic aneurysm was managed by combining internal carotid artery (ICA) trapping with an interposed radial artery graft from the external carotid artery (ECA) to the middle cerebral artery (MCA). The patient had an uncomplicated postoperative recovery. Postoperative carotid angiography demonstrated no aneurysms and excellent flow through the bypass graft. Postoperative vertebral angiography showed the right ophthalmic artery to be fed by the posterior communicating artery. It is speculated that collateral circulation from the angular artery of the ECA to the ophthalmic artery did not develop because of high flow graft from the ECA to MCA and ICA trapping.     

颈内动脉球囊闭塞术后产生对侧新生动脉瘤

目的 在国内献中首次报道1例床突旁动脉瘤(AN)病人在行载瘤动脉球囊闭塞术后5年出现对侧后交通AN并破裂。方法 行急诊手术夹闭该新生动脉瘤。结果 病人仍死于严重的颅内高压。回顾献共发现29例35个因颈动脉闭塞术后出现的新生AN，主要位于前、后交通动脉。结论 颈动脉闭塞后对侧血流代偿性增加可能是导致AN的原因，对大型AN应尽量采用保留载瘤动脉的方法；如闭塞载瘤动脉，应进行长期的影像学随访。     

Cerebral hemodynamics in relation to patterns of collateral flow.

BACKGROUND AND PURPOSE: We sought to investigate the relation between collateral flow via different pathways and hemodynamic parameters measured by dynamic susceptibility contrast-enhanced MRI in patients with severe carotid artery disease. METHODS: Dynamic susceptibility contrast-enhanced MRI was performed in 66 patients and 33 control subjects. Patients had severe stenosis (>70%, n=12), unilateral occlusion (n=38), or bilateral occlusion (n=16) of the internal carotid artery (ICA). Cerebripetal flow and collateral flow via the circle of Willis were investigated with MR angiography. Collateral flow via the ophthalmic artery was investigated with transcranial Doppler sonography. RESULTS: Patients with ICA stenosis had well-preserved cerebral perfusion and were in general not dependent on collateral supply. Patients with unilateral ICA occlusion had impaired cerebral perfusion. However, appearance time, peak time, and mean transit time in white matter were less increased in patients with than in patients without collateral flow via the circle of Willis (P<0.05). Furthermore, patients with collateral flow via both anterior and posterior communicating arteries had less increased regional cerebral blood volume than patients with collateral flow via the posterior communicating artery only (P<0.05). Patients with bilateral ICA occlusion had severely compromised hemodynamic status despite recruitment of collateral supply. CONCLUSIONS: In patients with unilateral ICA occlusion, the pattern of collateral supply has significant influence on hemodynamic status. Collateral flow via the anterior communicating artery is a sign of well-preserved hemodynamic status, whereas no collateral flow via the circle of Willis or flow via only the posterior communicating artery is a sign of deteriorated cerebral perfusion.     

The formation and regression of a flow-related cerebral artery aneurysm

The authors report a patient with an aneurysm of the right cerebral posterior communicating artery (PCoA) developing after thrombotic pseudo-occlusion of the right internal carotid artery (ICA). The aneurysm regressed spontaneously subsequent to ipsilateral ICA endarterectomy and reversal of blood flow in the PCoA. The formation and regression of the aneurysm was well documented by repeat cerebral digital subtraction angiography studies, computed tomography and magnetic resonance imaging. The authors conclude that the formation and regression of this 'flow-related' aneurysm was associated with hemodynamic changes in blood flow of the right PCoA and the right ICA.     

Absent anterior communicating artery and varied distribution of anterior cerebral artery

During the cerebral dissection of a 67-year-old male cadaver, a unique combination of variations at the circle of Willis and anterior cerebral artery (ACA) distribution were encountered. The A1 segment of both ACA were fused without an anterior communicating artery (ACoA), forming an X shape and giving rise to a common pericallosal artery (CPA), an incomplete distal ACA, and an incomplete distal anterior cerebral artery (IACA). The IACA had an unusual course, which may be important from the surgical point of view. The CPA continued as the A2 and A3 segments, and bifurcated into 2 pericallosal arteries. Branching patterns of the varied arteries to the interhemispheric region were evaluated, and results were discussed. Additionally, both posterior communicating arteries were hypoplastic. There was no aneurysm formation at the circle of Willis and its branches.     

Intra-arterial thrombolysis of embolic middle cerebral artery using collateral pathways

BACKGROUND AND PURPOSE: Cervical internal carotid artery (ICA) occlusion associated with middle cerebral artery (MCA) embolic occlusion requires prompt revascularization to prevent devastating stroke. With the advent of endovascular techniques for chemical and mechanical thrombolysis, the clinical outcome of patients with major arterial occlusions will improve. Finding the most expedient pathway to the site of end organ occlusion for thrombolysis is important. METHODS: We present two cases of acute stroke secondary to thrombotic occlusion of the cervical ICA associated with MCA embolic occlusion treated with intra-arterial thrombolysis via catheter navigation through the posterior communicating artery to the site of MCA arterial occlusion. No attempt was made to transverse the occluded ICA. RESULTS: Near complete restoration of flow was achieved in one patient and minimal vessel reopening was observed in the other patient. Both patients had good outcomes. CONCLUSION: Intra-arterial thrombolysis via Circle of Willis collaterals such as the posterior communicating artery for the treatment of acute thrombotic occlusion of the cervical internal carotid artery associated with embolic occlusion of the middle cerebral artery is a therapeutic option. This treatment option avoids the potential complications of navigating through an occluded proximal internal carotid artery and may expedite reopening of the MCA.     

Patterns of cerebral perfusion in patients with asymptomatic internal carotid artery disease

BACKGROUND: The perfusion profile of patients with asymptomatic internal carotid artery (ICA) disease has not been well studied. The purpose of this study is to describe the perfusion patterns of patients with asymptomatic ICA disease using computed tomography perfusion (CTP) and its potential value in identifying patients at higher risk for transient ischemic attacks (TIAs) or strokes. METHODS: We analyzed 32 patients with asymptomatic high grade ICA disease who had CTP and computed tomography angiography (CTA) of the head and neck. Twenty-four patients had severe ICA stenosis and eight had ICA occlusion. The degree of ipsilateral external carotid artery (ECA) and contralateral ICA stenosis, patency of the anterior communicating artery (ACOM), A1 segment and posterior communicating artery (PCOM) were evaluated in all patients. RESULTS: Sixteen patients had normal CTP and the other 16 patients had cerebral hypoperfusion, characterized by abnormalities in one or more of the three perfusion maps. Ipsilateral hypoplastic A1 segment was more frequent in the group with cerebral hypoperfusion (p = 0.025). Ipsilateral TIAs occurred in two patients, both with cerebral hypoperfusion. CONCLUSION: Cerebral hypoperfusion is present in half of the patients with asymptomatic ICA disease, predominantly in patients with a hypoplastic ipsilateral A1 segment. These patients likely represent a higher-risk group for symptomatic brain ischemia.     

A case of transient blindness due to severe stenosis of the internal carotid artery with persistent primitive hypoglossal artery (PPHA)]

We report a patient having transient blindness due to severe stenosis of the internal carotid artery (ICA) with persistent primitive hypoglossal artery (PPHA). This 73 year-old man was admitted because of the transient visual impairment. At first, he had bilateral blindness for a several minutes and after that the right amaurosis continued for an hour. MRI showed an old lacunar infarction of the right caudate nucleus. Carotid duplex ultrasonography and conventional angiography demonstrated severe stenosis of the origin of the right ICA, and PPHA was arising from the right ICA at the level of 2nd cervical spine. The left ICA was normal. Because of the aplasia of the right vertebral artery and hypoplasia of the left vertebral artery, almost all blood flow of the basilar artery was supplied from the right ICA via PPHA. We considered that transient ischemia of both the bilateral posterior cerebral arteries and the right ocular artery occurred due to stenosis of the right ICA which branching PPHA. When ischemic neurological symptoms of multiple vascular territories occurr at the same time, we often think that ischemic mechanism was cardiogenic embolism. But we should recognize that stenosis of the ICA with PPHA cause the complex neurological deficits.     

Internal carotid-posterior communicating artery aneurysm associated with unusually short posterior communicating artery

We report two cases of a ruptured internal carotid-posterior communicating artery aneurysm in which the ipsilateral posterior communicating artery is short and the P1 and P2 segments of the posterior cerebral artery are long. Unique angiographic and operative findings are described. Vertebral angiography with carotid compression is recommended to diagnose this rare variation. Recognition of this variation is important to avoid an inadvertent occlusion of arteries behind the aneurysm at the time of clipping.     

Agenesis of the internal carotid artery--report of a case combined with arachnoid cyst in a child]

A case of agenesis of the internal carotid artery combined with arachnoid cyst is reported. This 11-year-old boy had occasionally complained headache and nausea since he was of 9 years old. He was admitted to our hospital because of an epileptic seizure. Physical and neurological examinations on admission were normal. A CT scan showed a cystic mass in retrocerebellar region. MRI suggested absence of flow void area indicating internal carotid artery in the cavernous sinus on left side. Left common carotid angiogram showed absence of the internal carotid artery. Bilateral A2 segments were supplied by right A1 with tortuous anterior communicating artery. Left middle cerebral artery and left ophthalmic artery were supplied via dilated left posterior communicating artery on left vertebral angiogram. Thin slice, axial target image of the CT revealed absence of the left bony carotid canal. MRI by 3D TOF method confirmed no blood flow in this area. MR angiography provided sufficient information about cervical vessels non-invasively. 123I-IMP SPECT image ascertained no hypoperfusion area in left cerebral hemisphere. Convulsion was controlled with sodium valproate. Association of agenesis of the internal carotid artery and arachnoid cyst could be a coincidence.