Carotid artery dissections presenting as isolated posterior cerebral artery infarctions

A spontaneous dissection of the carotid artery is a well-known cause of cerebral infarction, mostly due to an embolus from the affected vessel segment. For haemodynamic and anatomical reasons the territories of the middle and anterior cerebral arteries are usually involved. We report two cases of carotid artery dissections resulting in infarctions exclusively in the territory of the posterior cerebral artery. The underlying anatomical conditions were a fetal origin of the posterior cerebral artery and an embolic supra-ophthalmic occlusion of the internal carotid artery. To our knowledge similar cases have not previously been documented. Received: 7 August 1996 Received in revised form: 30 October 1996 Accepted: 17 January 1997     

The arterial patterns associated with internal carotid disease and cerebral infarcts

In 20 necropsies with 15 stenosed and 17 thrombotic occluded internal carotid arteries there were 46 cerebral infarcts larger than 1 cm diameter. Using portmortem arteriographic and pathological techniques the patterns of the neck and brain artery systems were correlated with the situation and extent of the brain infarcts. Massive infarcts involving two major cerebral artery territories were associated with distal internal carotid artery occlusion and grossly ineffective cervical and circle of Willis anastomoses. Isolated middle cerebral artery territory infarcts were associated with internal carotid occlusion or stenosis and impairment of the circle of Willis anastomoses, perhaps with middle cerebral artery stenosis. The pattern of adequate size arteries determined if these infarcts were total, deep central, anterior, medium or posterior partial territory infarcts. Boundary zone infarcts were associated with internal carotid artery disease and limitation of anterior or posterior circle of Willis anastomoses. These limitations determined which boundary zones were affected. Isolated anterior cerebral artery territory infarcts were associated with bilateral internal carotid disease and an anterior cerebral artery stenosis or small caliber anterior communicating artery. Isolated posterior cerebral artery territory infarcts were associated with internal carotid disease and a direct impairment of the ipsilateral posterior cerebral artery capability.     

The distribution of the internal carotid circulation in the brain of the macaque monkey (Macaca mulatta)

The distribution of the internal carotid circulation of the macaque brain was studied by using a method of intracarotid dye injections which produced no appreciable disturbance of the dynamics of the cerebral circulation. The areas in cortical and diencephalic structures supplied by the carotid circulation are described and displayed semidiagrammatically in a set of figures. The carotid artery supplies most of the lateral and mesial surfaces of the cerebral hemisphere, whereas the hemispherical portion supplied by the posterior cerebral artery is confined to the occipital and inferior temporal region. Left and right internal carotid territories overlap widely across the midline in cortical areas due to the existence of a single pericallosal arterial trunk formed by the junction of both anterior cerebral arteries. In the diencephalon the segregation of the territories of the left and right internal carotid arteries is sharp, except in its anterior-most portion. The pattern of internal carotid supply to the thalamus is somewhat variable, the most lateral structures are most consistently supplied by this vessel, whereas the more medial structures, even those lying far rostral within the thalamus, are supplied by the posterior cerebral artery. The territories of the two vessels overlap considerably within the thalamus. In a certain number of animals, the posterior cerebral artery is part of the internal carotid, rather than of the vertebral-basilar system.     

颈内动脉分叉上间隙的显微外科解剖

目的 探讨颈内动脉分叉上间隙的解剖特征及其手术意义。方法 在30侧尸体标本上观察该间隙的显微解剖。结果 该间隙狭小、深在，血管多，90％呈三角形、A1段为前下边，M1段为外下边，前穿质为上边。10％呈四边形，视交叉或视束构成其内侧边。间隙内常有Heubner回返动脉和大脑中深静脉等走行，经间隙可见下方的诸多小血管。结论 在至少1／3的间隙内容易展开显微操作，多数需慎重处理间隙内的小血管。     

Anastomoses among the perforating arteries of the brain. Microanatomy and clinical significance

Anastomoses among the perforating arteries were examined in 50 human brains using injection technique with India ink and gelation, or methylmethacrylate. Anastomoses were not found among the perforators of the internal carotid artery and the thalamogeniculate branches. Anastomotic channels involving perforating branches of the anterior choroidal, middle cerebral, and anterior cerebral arteries were noted in 1% of the cases. Vascular connections of the premamillary arteries were observed in 30% of the brains. They varied from 60 to 280 microns) in diameter, and from 0.3 to 3.6 (mean 1.5 mm) in length. Anastomoses among the interpeduncular (thalamoperforating) branches of the posterior cerebral artery were present in 79% of the cases. They ranged from 80 to 400 microns (mean 146 microns) in caliber, and from 0.9 to 6.1 mm (mean 3.3 mm) in length. Since anastomoses among the interpeduncular and the premamillary arteries are much more frequent than those among other perforators, thalamic, subthalamic, and midbrain's infarctions seem to be less frequent than capsular and ganglionic ischemic lesions.     

Arterial patterns of the rat rhinencephalon and related structures

Course and distribution information on arteries in the rat rhinencephalon was not found in the literature. Such data are useful for designing experiments and interpreting findings, tracing nerve fibers on or to intracerebral vessels, and in considering routes for diffusion or transport of intracerebral injected agents. Adult rats were perfused with silicone rubber and many brains were cleared in glycerin. The major arteries to the olfactory bulb stem from the anterior cerebral artery. A middle cerebral arterial ramus could provide a collateral source. The septum receives supply exclusively from the anterior cerebral artery. A rostral lesion in the medial septum would most likely involve arteries supplying more caudal structures including hippocampal afferent and efferent fibers. No anastomoses between septal arteries or with middle or posterior cerebral arterial rami were observed. The cingulate cortex receives anterior cerebral arterial branches with the middle cerebral artery being a collateral source. The amygdala and overlying cortex receive branches of the internal carotid and middle cerebral arteries. Transverse arteries in the hippocampal fissure stem from the longitudinal hippocampal artery, a branch of the posterior cerebral artery, to nourish the hippocampus and portions of the fascia dentata. Other branches supply the remainder of the fascia dentata, entorhinal and subicular structures, and certain vessels anastomose with middle cerebral arterial rami. A transverse artery occlusion would probably result in a lesion: No intracerebral arterial anastomoses were observed. Vascular compensation may occur following occlusion of the longitudinal artery via supply from the middle cerebral artery.     

Occipital infarction with hemianopsia from carotid occlusive disease

Extracranial internal carotid artery occlusive disease usually produces stroke in the middle cerebral artery territory or the border zone between the middle and anterior cerebral arteries. It is unusual for occipital infarction in the posterior cerebral artery territory to be caused by internal carotid artery disease despite the fact that the posterior cerebral artery may arise directly from the internal carotid artery as an anatomic variation. We describe a patient with a fetal posterior cerebral artery originating from the internal carotid artery, and the initial manifestation of his extracranial internal carotid artery occlusive disease was hemianopsia from occipital infarction.     

Occlusive cerebrovascular disease in young adults

13 patients under 40 years of age had cerebral infarction and angiographic evidence of arterial stenosis or occlusion. None of them had cardiac disorders prone to cerebral embolism. Five patients had occlusion at the origin of the internal carotid artery, one had occlusion of the common carotid artery and one each had stenosis at the origin of the internal carotid and common carotid arteries, respectively. Two patients had unilateral occlusion of the supraclinoid portion of the carotid artery with basal collaterals that had some resemblance to the Moyamoya disease. Three patients demonstrated stenosis or occlusion of the middle and/or anterior cerebral arteries. Three patients had hypercholesterolemia, one of whom was hypertensive. None had confirmed diabetes mellitus. One female, who died, had taken oral contraceptives for 3 years. A male, with internal carotid artery occlusion, had serological evidence for syphilis.     

Infarcts in the territory of the deep perforators from the carotid system

We studied risk factors and presumed causes of infarct in 100 consecutive patients with a first stroke, who had an appropriate CT-proven infarct in the territory of the deep perforators from the carotid system (ITDPCS). The infarct involved the territory of the lenticulostriate arteries in 65 cases, the anterior choroidal artery in 23 cases, watershed zones between these two territories in four cases, and another territory in eight cases. In 42% of the patients, we felt the cause of the infarct to be small-artery disease. In 36%, at least one source of embolism was present (in 27% from the internal carotid artery, in 17% from the heart), either with (25%) or without (10%) associated hypertension (HT) and diabetes mellitus (DM). Other possible less common etiologies included migraine, syphilitic angiitis, and systemic diseases. We have confirmed that HT or DM are the most common etiologic factors of ITDPCS. However, large-artery disease and cardioembolism may be more important than previously assumed.     

Hemiplegia during carbon monoxide poisoning revealing multiple cerebral artery abnormalities including the hypoglossal artery

Hemiplegia after carbon monoxide (CO) poisoning is rare since only 9 such lesions have been reported from among 1480 cases of poisoning. The patient reported was a 43 year-old man with a left hemiplegia with coma following CO poisoning. Right carotid angiography demonstrated a hypoglossal artery supplying both posterior cerebral arteries. Left carotid angiography showed a dolichocarotid artery supplying the territories of the anterior and middle cerebral arteries on both sides. Complete regression of the hemiplegia occurred after 2 months following rapid administration of hyperbaric oxygen. Normal CT scan images and cerebral blood flow rates on follow-up examination suggest that the left hemiplegia was due to the combined effects of arterial anomalies and CO poisoning.     

Neuroradiological analysis of small infarcts in deep subcortical structure detected by CT

We studied angiographic findings of 56 patients who were diagnosed as lacunar infarcts in the basal ganglia or deep subcortical white matter based on clinical symptomatology and brain computed tomography. In 26 patients with CT lesions less than 15 mm in diameter, only eight (31%) showed minor angiographic findings. In 30 patients with lesion of 15 mm or more, however, 22 (73%) had abnormal angiographic findings. Fourteen of the 22 patients had minor irregularities, three had 25-75% stenosis, five had 75% less than stenosis at the bifurcation of the common carotid artery or the horizontal portion of the middle cerebral artery. Our findings support the notion that a small lesion on CT can result from an occlusion of the perforating artery itself and a larger lesion is much related to the major vessel or heart diseases, i.e., emboli from the parent artery or heart, obstruction of perforators at their origin by an atheromatous plaque of the horizontal portion of the middle cerebral artery, or terminal zone infarct due to hemodynamically significant stenotic lesion. In patients with a larger deep infarct on CT, further investigation of the arteries in the carotid-axis and heart is important for determination of therapeutic indication.     

Origins and pathways of cerebrovascular vasoactive intestinal polypeptide-positive nerves in rat

In order to clarify the origins and pathways of vasoactive intestinal polypeptide (VIP)-containing nerve fibers in cerebral blood vessels of rat, denervation experiments and retrograde axonal tracing methods (true blue) were used. Numerous VIP-positive nerve cells were recognized in the sphenopalatine ganglion and in a mini-ganglion (internal carotid mini-ganglion) located on the internal carotid artery in the carotid canal, where the parasympathetic greater superficial petrosal nerve is joined by the sympathetic fibers from the internal carotid nerve, to form the Vidian nerve. VIP fiber bridges in the greater deep petrosal nerve and the internal carotid nerve reached the wall of the internal carotid artery. Two weeks after bilateral removal of the sphenopalatine ganglion or sectioning of the structures in the ethmoidal foramen, VIP fibers in the anterior part of the circle of Willis completely disappeared. Very few remained in the middle cerebral artery, the posterior cerebral artery, and rostral two-thirds of the basilar artery, whereas they remained in the caudal one-third of the basilar artery, the vertebral artery, and intracranial and carotid canal segments of the internal carotid artery. One week after application of true blue to the middle cerebral artery, dye accumulated in the ganglion cells in the sphenopalatine, otic and internal carotid mini-ganglion; some of the cells were positive for VIP. The results show that the VIP nerves in rat cerebral blood vessels originate: (a) in the sphenopalatine, and otic ganglion to innervate the circle of Willis and its branches from anterior and caudally and (b) from the internal carotid mini-ganglion to innervate the internal carotid artery at the level of the carotid canal and to some extent its intracranial extensions.     

Influence of anatomic origin on intracranial distribution of micro-emboli in the baboon

The purpose of this study was to investigate whether the anatomic origin of micro-emboli influences their intracranial distribution. In twenty-two baboons, we examined the distribution of 99-Technetium labelled albumin aggregates (5 to 40 microns in size) after injection into the circulation at the left atrium (LA), carotid trifurcation (CA), and anterior and posterior common carotid artery (CCI). In a further subgroup, the emboli were introduced at the carotid trifurcation with the contralateral carotid artery ligated (CA + L). The results of this study demonstrated that aggregates introduced at the carotid artery lodged preferentially in the ophthalmic (p = 0.032) and middle cerebral artery territories (p = 0.016). If the contralateral common carotid artery was ligated, however, more aggregates were found in the ipsi- and contralateral anterior cerebral artery territories (p = 0.01, p = 0.003). Aggregates introduced into the cardiac circulation were equally distributed throughout the brain. This experimental model determined patterns of flow that might be analogous to the human situation where unilateral or bilateral carotid stenosis or stenosis with contralateral occlusion has occurred or embolus from cardiac source has occurred. The results do not imply that the 40 micron microaggregates do cause TIA. These experimental findings support clinical observations that cardiac lesions may cause transient ischemic attacks (TIA) anywhere in the brain. In contrast, those of carotid artery origin cause predominantly middle cerebral or ophthalmic artery territory TIAs unless the contralateral carotid artery is severely stenosed or occluded.     

Three-Dimensional Reconstruction of the Power Flow Doppler Imaging of Intracranial Vascular Structures in the Neonate

Three-dimensional (3D) ultrasonography reconstructing from power flow Doppler imaging (PF) is able to image the 3D structures of the vascular systems. We tried to display the 3D images of intracranial vascular structures in 5 neonates with a portable data processor. Data acquisition was performed using PF through the anterior fontanel. We succeeded in reconstructing vivid 3D images of the anterior cerebral arteries (ACA), basilar artery (BA), internal carotid arteries (ICA), middle cerebral arteries (MCA), lenticulostriate arteries (LSA), internal cerebral vein (ICV), the vein of Galen (GV) and straight sinus (SS) in all subjects. The MCA could be displayed in only a proximal portion. The images of the LSAs were fainter than the other vessels. These problems are based on the character of PF; the flow signal, sampling from the small sized vessels and the perpendicular vessels to ultrasonic beam, is weak. The images of these vessels are fainter than other vessels. These limitations of PF performance directly influence the quality of the 3D images. The benefits and limitations of 3D ultrasonography system are discussed.     

Balloon Angioplasty of lntracranial Arteries for Stroke Prevention

Stroke from surgically inaccessible intracranial atherostenosis remains a formidable clinical challenge. While antithrombotic or antiplatelet therapy may prevent distal embolism, there is no effective program for plaque stabilization preventing progression of atherosclerotic stenosis. In patients with isolated circulations (single vertebral with absent posterior communicating arteries, single carotid with contralateral internal carotid artery occlusion, or single carotid with an absent anterior communicating artery), occlusion of the stenotic vessel may produce a low flow–mediated stroke. Fifteen patients with atherosclerotic intracranial stenoses were treated by balloon angioplasty after medical therapy with warfarin failed. Treated territories included the distal internal carotid, proximal middle cerebral, distal vertebral, and basilar arteries. Dilation was successful in all vessels, with residual stenoses averaging less than 30%. Two complications included one paramedian pontine stroke and a single vessel rupture that proved fatal. There was no recurrence of transient ischemic attacks and no restenosis at the angioplasty site over a follow–up period of more than 24 months. In this small series, balloon angioplasty of intracranial vessels provided a therapeutic option for secondary stroke prevention in highly selected patients. Further studies will be necessary to establish the efficacy and safety of endovascular treatment in larger series.     

Microanatomy of the perforators of the anterior communicating artery complex

We describe the microanatomy of the perforating arteries arising from the anterior communicating artery complex (5 mm distal of the anterior cerebral artery, the anterior communicating artery, and 5 mm proximal of the distal anterior cerebral artery). Thirteen unfixed human brains were used in this study. The origin and number of perforators are described, as is the site of brain penetration, and results are correlated with previous studies. The hemodynamics of blood flow ib relation to the formation of an anterior communicating artery aneurysm and different surgical approaches are mentioned. The neuropsychological outcome after aneurysm clipping with regards to the pattern of blood supply from the anterior cerebral artery complex is also discussed. [Neural Res 1997; 19: 577-587]     

Morphometric Study of the Anterior Thalamoperforating Arteries

Objective

To evaluate the morphometry of the anterior thalamoperforating arteries (ATPA).

Methods

A microanatomical study was performed in 79 specimens from 42 formalin-fixed adult cadaver brains. The origins of the ATPAs were divided into anterior, middle, and posterior segments according to the crowding pattern. The morphometry of the ATPAs, including the premammillary artery (PMA), were examined under a surgical microscope.

Results

The anterior and middle segments of the ATPAs arose at mean intervals of 1.75±1.62 mm and 5.86±2.05 mm from the internal carotid artery (ICA), and the interval between these segments was a mean of 3.17±1.64 mm. The posterior segment arose at a mean interval of 2.43±1.46 mm from the posterior cerebral artery (PCA), and the interval between the middle and posterior segments was a mean of 3.45±1.39 mm. The mean numbers of perforators were 2.66±1.19, 3.03±1.84, and 1.67±0.98 in the anterior, middle, and posterior segments, respectively. The PMA originated from the middle segment in 66% of cases. A perforator-free zone was located >2 mm from the ICA in 30.4% and >2 mm from the PCA in 67.1% of cases.

Conclusion

Most perforators arose from the anterior and middle segments, within the anterior two-thirds of the posterior communicating artery (PCoA). The safest perforator-free zone was located closest to the PCA. These anatomical findings may be helpful to verify safety when treating lesions around the PCoA and in the interpeduncular fossa.     

Sphenoid and optic nerve sheath meningioma revealed by recurrent brain infarctions

Meningioma, though benign, may invade adjacent structures such as bone, soft tissues, dural sinuses and arteries. However brain infarctions secondary to meningioma involving the cavernous sinus and encasing and narrowing the intracranial carotid artery are rare. We report the case of a young man with recurrent left carotid artery infarctions due to a left sphenoid meningioma infiltrating the posterior optic nerve sheath through the optic canal and circumscribing the intracranial carotid artery. The patient had a gradually progressive occlusion of the middle cerebral artery, the distal internal carotid artery and finally the anterior cerebral artery ipsilateral to the sphenoid meningioma.     

A patient with Moyamoya-like vessels after radiation therapy for a tumor in the basal ganglia]

A patient with Moyamoya-like vessels after radiation therapy for treatment of a tumor in the basal ganglia is reported. He was diagnosed as Down syndrome at birth. He had a tumor in the left basal ganglionic region at 12 years of the age. The tumor increased in size at age 14. He underwent cerebral angiography, which did not show a stenosis nor occlusion of the internal carotid artery, anterior cerebral artery, nor the middle cerebral artery. He received radiation therapy with a total dose of 56 Gy. He presented a dressing apraxia at age 19. MRI showed cerebral infarction in the left temporo-occipital region. Right internal carotid angiography revealed a severe stenosis of the internal carotid artery and anterior cerebral artery as well as a severe stenosis of the middle cerebral artery on the right side. Moyamoya-like vessels were seen in the basal ganglionic region. Left internal carotid angiography also showed a stenosis of the internal carotid artery and anterior cerebral artery as well as a severe stenosis of the middle cerebral artery on the left side. Moyamoya-like vessels were seen in the basal ganglionic region. Leptomeningeal anastomose and transdural anastomose were bilaterally seen. These arterial occlusion and stenotic phenomenon corresponded to a previous radiation field. These Moyamoya-like vessels with arterial stenosis and occlusion were thought to be due to radiation-induced vasculopathy, because a previous cerebral angiography showed a normal caliber of cerebral arteries. This patient showed that patients with radiation therapy in their early childhood should be carefully observed considering the possibility of this phenomenon.     

Transcranial Doppler in cerebrovascular disease

Doppler analysis of flow in intracranial arteries is now possible using a 2 MHz probe allowing sufficient penetration of bone to obtain signals noninvasively. Thirty-two normal subjects, and 11 patients with cerebrovascular diseases including vasospasm following subarachnoid hemorrhage, middle cerebral artery stenosis, and extracranial internal carotid artery stenosis were studied by transcranial Doppler. Increased peak velocity and spectral broadening of the reflected signal corresponded to clinical and angiographic evidence of middle cerebral artery vasospasm or stenosis. Decreased peak velocity and blunted waveforms occurred in the middle cerebral artery ipsilateral to severe extracranial internal carotid stenosis with poor crossfilling from the contralateral carotid artery. Abnormalities resolved following carotid endarterectomy. Transcranial Doppler identifies vasospasm or stenosis of the middle cerebral artery and may allow noninvasive evaluation of collateral flow across the anterior circle of Willis in patients with extracranial carotid artery stenosis.