Microsurgical anatomy of the anterior choroidal artery

Segmental agenesis of the internal carotid artery without proximal regression: an embryological clue for a new segment of the internal carotid artery?

PURPOSE

The paper aims to explore the complexities of the internal carotid artery (ICA) segmentation, particularly in the context of segmental agenesis, by presenting a unique case of ICA segmental agenesis without proximal regression. This case prompts a reevaluation of existing embryological classifications and suggests the need for an updated segmentation model.

METHODS

A 63-year-old woman underwent brain Magnetic Resonance Imaging (MRI) and MR Angiography due to hypoacusis, revealing incidental findings of vascular anomalies, including a focal absence of contrast in the left ICA. Subsequent imaging techniques, including Computed Tomography Angiography (CTA) and Digital Subtraction Angiography (DSA), confirmed the segmental agenesis while also identifying associated vascular anomalies, such as a triplicated anterior communicating artery and a saccular aneurysm. The study employs a detailed analysis of embryological development and existing ICA classification systems to contextualize these findings.

CONCLUSIONS

The case highlights a previously unreported segmental agenesis of the ICA between the posterior communicating artery and the anterior choroidal artery, suggesting the existence of a new segment. The findings indicate that collateralization through a hyperplastic anterior choroidal artery and a complex anterior communicating system may offer compensation. This case advocates for an update in the ICA segmentation framework to accommodate emerging embryological insights and improve understanding of vascular anomalies.

Distribution of branches of anterior choroidal artery in the uncus: an anatomical study

The aim of our study was to examine the relationship between uncus and uncal branches of anterior choroidal artery (AChA) and to observe the morphological and morphometric features of these branches. 124 hemispheres from 62 fresh cadavers were included in the study. Measurement of the length of AChA and the distances of the uncal branches to the origin of AChA were measured by ImageJ software. Morphological variations of uncal branches originating from AChA were observed. The length of AChA was found as mean 26.24 ± 4.34 mm. It was determined that the average distance of these uncal branches arising from the AChA was 13.48 ± 7.31 mm. In 4 out of 124 AChAs, no branches were observed. 594 branches originating from 120 were detected. 130/594 branches appeared to be terminal branches. AChAs of 80/120 hemispheres have been reported to have uncal branches. Thirty of 130 uncal branches were observed to originate as the first branch of AChA. It was found that uncal branches may originate from AChA with a variability between 1 and 4. When evaluated according to the origin of each branch from the AChA, it was observed that the uncal branches originated from the midpoint of the AChA on average. Also, in 64 hemispheres, morophological variations were detected regarding the origin of uncal branches. We believe that the morphological and morphometric data we obtained from the uncal branches of the AChA are of clinical importance in terms of understanding this complex region and minimizing errors in surgical procedures.

Role of the anterior choroidal artery in the endovascular treatment of brain arteriovenous malformations

The anterior choroidal artery (AchA) is a very important vessel that supplies certain crucial structures that have poor collateral circulation. When the AchA is recruited to supply brain arteriovenous malformations (BAVMs), can the AchA act as a safe path through which endovascular treatment (EVT) be performed? As few studies or reports have investigated this matter, we performed a review to expound upon the role of the AchA in the EVT of BAVMs. In this review, we discussed the anatomy and variation of the AchA, the angioarchitecture of BAVMs fed by the AchA, the status of EVT for BAVMs and its associated problems and their solutions, the choice of embolic materials, new EVT techniques, the complications and prognoses of EVT through the AchA, etc. The review revealed that although EVT of BAVMs through the AchA is challenging and can result in unpredictable complications, it may be an appropriate option prior to surgery and radiation therapies or serve as a curative procedure. A complete and thorough understanding of the functional anatomy and variant of the AchA and proper EVT techniques are crucial for successful embolization of BAVMs via the AchA.

Endovascular Treatment and Angiographic Characteristics of Aneurysms at the Origin of the Anterior Choroidal Artery

Background

The information available about the variations and anatomy of the anterior choroidal artery (AchA) with aneurysm at the origin of the vessel and the outcomes of endovascular treatment (EVT) for AchA aneurysms is incomplete.

Materials and Methods

A retrospective study of 54 consecutive patients who were admitted to our hospital with a diagnosis of AchA aneurysm and treated with EVT was performed. The variations and anatomy of the AchA and the outcomes of EVT for AchA aneurysms were analyzed.

Result

The 54 patients were aged 35-82 years (mean age, 56.1 ± 19.7 years) and included 32 females (59.3%, 32/54). Regarding AchA anatomy, 63.5% of AchAs had a typical S-shaped course. The diameter of the AchA origin averaged 0.8 ± 0.3 mm. Of all the AchA aneurysms, 51.9% were ruptured. The diameter of AchA aneurysms averaged 4.1 ± 2.4 mm. Moreover, 40.7% of 54 cases had multiple aneurysms. EVT was assisted with stenting for 25.9% of 54 AchA aneurysms. An immediate Modified Raymond-Roy Classification grade of I was obtained in 96.3% of AchA aneurysm cases. After EVT, the ischemic complication rate was 13%. In total, 83% of patients had good outcomes, with a Glasgow Outcome Scale score of 4-5. Follow-up angiography showed acceptable treatment results in this study.

Conclusion

The study showed that the AchA had a complex angiographic anatomy in cases with aneurysms at the origin of the vessel and that the anatomical features can be helpful in EVT. EVT for aneurysms at the origin of the AchA had good outcomes.

Case Report: “Clipping” an Internal Carotid Artery Aneurysm With a Duplicated Middle Cerebral Artery and the Anterior Choroidal Artery Arising From the Dome

Background

A duplicated middle cerebral artery (DMCA) is an anatomical variant that includes duplication of the middle cerebral artery (MCA) and an anomalous vessel originating between the anterior choroidal artery (AChA) and the distal end of the internal carotid artery (ICA). Here, we present a case report of an ICA aneurysm with a DMCA and the AChA originating from the dome, which was successfully treated with clipping.

Case Description

In a 64-year-old man, preoperative angiography revealed an unruptured right ICA aneurysm with a maximum diameter of 4.3 mm, and fusion three-dimensional computer graphics revealed that a DMCA and the AChA originated from the dome. The aneurysm enlarged; therefore, clipping was performed. The closure of the aneurysm while preserving the patency of the DMCA and AChA was identified using intraoperative microvascular Doppler ultrasonography and indocyanine green video angiography. The postoperative course was uneventful, and no ischemic lesions were confirmed on MR imaging.

Conclusion

To the best of our knowledge, this is the first report of an ICA aneurysm with a DMCA and the AChA arising from the dome. In such cases, the anatomy of the DMCA and AChA should be well-characterized before treatment.

Kissing Aneurysms: Radiological and Surgical Difficulties in 30 Operated Cases and a Proposed Classification

OBJECTIVE

The first aim of this study is to bring up the radiological and surgical difficulties of kissing aneurysms and to present solutions. The second aim is to develop a classification that can help to predict the difficulties encountered during surgery.

METHODS

The records of 817 patients who were operated on for aneurysm were reviewed retrospectively to identify kissing aneurysms. The radiological and clinical databases of these patients were evaluated in detail.

RESULTS

Kissing aneurysms were detected in 30 patients (3.6%). Radiologically correct diagnosis rate of kissing aneurysms was 80% throughout the series. The most common locations were the anterior communicating artery (12 cases, 40%) and the middle cerebral artery (12 cases, 40.0%). The ruptured aneurysm could not be detected preoperatively in 24% of the patients. Intraoperative rupture occurred in 4 patients (13.3%). Accompanying vascular anomaly/variation was seen in 16 patients (53.3%). As detailed in the text, kissing aneurysms were divided into 3 types according to their position with each other on the parent artery from the surgeon's point of view during surgery: type I (proximal/distal), type II (superior/inferior), and type III (right/left).

CONCLUSIONS

Despite advanced angiographic techniques, even today, kissing aneurysms can be misinterpreted as a single bilobular aneurysm. The ruptured aneurysm may not be detectable preoperatively. These complex aneurysms have a high intraoperative rupture risk. Accompanying vascular anomalies are more common than expected. Clip selection and sequencing are important. Proposed classification helps the surgeon to be aware of intraoperative difficulties that he/she may encounter in advance.

Differential Hemispheric Lateralization of Emotions and Related Display Behaviors: Emotion-Type Hypothesis

There are two well-known hypotheses regarding hemispheric lateralization of emotions. The Right Hemisphere Hypothesis (RHH) postulates that emotions and associated display behaviors are a dominant and lateralized function of the right hemisphere. The Valence Hypothesis (VH) posits that negative emotions and related display behaviors are modulated by the right hemisphere and positive emotions and related display behaviors are modulated by the left hemisphere. Although both the RHH and VH are supported by extensive research data, they are mutually exclusive, suggesting that there may be a missing factor in play that may provide a more accurate description of how emotions are lateralization in the brain. Evidence will be presented that provides a much broader perspective of emotions by embracing the concept that emotions can be classified into primary and social types and that hemispheric lateralization is better explained by the Emotion-type Hypothesis (ETH). The ETH posits that primary emotions and related display behaviors are modulated by the right hemisphere and social emotions and related display behaviors are modulated by the left hemisphere.

Duplicated Anterior Choroidal Arteries: Literature Review and Clinical Implications

The anterior choroidal artery supplies important cerebral structures. One important variation of this vessel is duplication. However, little is reported on this anatomical variant and moreover, the prevalence of such a finding varies widely. Therefore, here, we review the literature regarding duplicated anterior choroidal arteries. Clinicians reviewing imaging of the brain, interventionalists, or neurosurgerons should be knowledgeable of variations of the anterior choroidal artery, including its duplication. A better understanding of this anatomy and embryology can improve diagnoses and patient outcomes following interventional or open neurosurgical techniques.

Lesion Trapping with High-Flow Bypass for Ruptured Internal Carotid Artery Blood Blister-Like Aneurysm Has Little Impact on the Anterior Choroidal Artery Flow: Case Series and Literature Review

OBJECTIVE

To examine the relationship between trap location and cerebral infarction in the anterior choroidal artery (AChA) region and associated risks in ruptured internal carotid artery blood blister-like aneurysm (BLA) treatment with high-flow bypass and lesion trapping.

METHODS

We included 26 patients diagnosed with BLAs and treated with high-flow bypass and trapping. We examined clinical characteristics including age, aneurysm trap location, final prognosis, cerebral infarction on postoperative magnetic resonance imaging, and modified Rankin Scale score at discharge. We also searched the literature for similar studies.

RESULTS

The modified Rankin Scale score at discharge was 0-2 in 20 patients, 3-5 in 2 patients, and 6 in 2 patients. In 19/26 patients (73.1%), the trapped segment was between the posterior communicating (PcomA) and the ophthalmic arteries. In 2 patients (7.7%), the trapped segment included the PcomA and the AChA; in 4 patients (15.4%), the trapped segment was within the PcomA. In these patients, the PcomA was occluded, and blood from the high-flow bypass flowed out to the AChA alone. No patient showed cerebral infarction. Our systematic review identified 70 patients. Of all 96 patients, 12 had AChA cerebral infarction; however, the infarction affected the prognosis of only 2 patients.

CONCLUSIONS

When treating BLAs with high-flow bypass and lesion trapping, the frequency of AChA cerebral infarction is low even when the PcomA is occluded, leaving the AChA as the only outflow vessel during high-flow bypass. However, PcomA occlusion may be associated with risks when treating patients with advanced arteriosclerosis near C1-2.

Preoperative obliteration of choroidal arteries in the treatment of large hypervascular tumors in the lateral ventricle

Background

Removal of large hypervascular tumors in the lateral ventricle still poses a surgical challenge. These tumors are usually fed from choroidal arteries, and vascular control is typically performed late during the removal. We aimed to evaluate the clinical efficacy of our strategy for persistent preoperative obliteration of feeders from the choroidal arteries to manage large hypervascular tumors in the lateral ventricle.

Methods

We retrospectively analyzed six patients with hypervascular tumors in the lateral ventricle. We first attempted to obstruct feeders using endovascular treatment, and, if unavailable, performed initial microsurgical occlusion through the temporal horn for the staged tumor removal.

Results

In all patients, feeder obliteration was successfully performed; the anterior choroidal arteries were occluded by the endovascular treatment and microsurgical occlusion in one and five patients, respectively, while the lateral posterior choroidal arteries were occluded via endovascular treatment in four patients. No patients had permanent symptoms due to feeder obliteration, and tumor devascularization was achieved at the mean rate of 69.9%. During the tumor removal, the mean blood loss volume was 253 ml. No postoperative hemorrhage had occurred, and all patients scored ≤ 2 on the modified Rankin Scale at six months post-removal.

Conclusions

Although further studies are warranted, persistent feeder obliteration of choroidal arteries could be an effective treatment strategy against large hypervascular tumors in the lateral ventricle.

Fusiform vertebral artery aneurysms involving the posterior inferior cerebellar artery origin associated with the sole angiographic anterior spinal artery origin: technical case report and treatment paradigm proposal

Fusiform aneurysms of the vertebral artery (VA) involving the posterior inferior cerebellar artery (PICA) origin are uncommon and challenging. The anterior spinal artery (ASA) commonly originates from a unilateral ramus just distal to the PICA. Occlusion of an unpaired ASA can result in bilateral medial medullary syndrome. The authors propose a treatment paradigm for ASA preservation based on the artery's proximity to fusiform VA aneurysms, and they present 3 representative cases. In the first case, they performed a V3-PICA bypass using an interposition graft and then performed endovascular coil embolization of the parent VA. A complete occlusion of the aneurysm and VA was complicated by ASA thrombosis. The subsequent cases were treated with PICA-PICA bypass and subsequent endovascular embolization of the VA. Filling of the sole angiographic ASA remote from the aneurysm was preserved in both cases. The anatomy of the ASA is the most critical determinant of treatment recommendations for fusiform VA aneurysms involving PICA. When the ASA originates from the aneurysm, proximal occlusion with or without a PICA bypass is suggested. In cases in which the ASA is removed from the aneurysm, the authors recommend revascularization followed by endovascular sacrifice. When the aneurysm is immediately adjacent to the ASA, revascularization and open trapping should be considered.

Mirroring with Indocyanine Green Angiography in Aneurysm Surgery: Technical Note and Case Presentations

OBJECTIVE

The authors used a micromirror under a microscope with an indocyanine green (ICG) imaging system to assess clipped aneurysms and the blood flow in hidden regions during aneurysm surgery. This study then investigated the usefulness of such mirroring with ICG angiography (MICGA).

METHODS

A micromirror was used during aneurysm surgery on 25 patients, and MICGA was performed on 10 of these 25 patients to inspect the hidden region after clipping. The mirrored aneurysms were located at the posterior communicating artery (n = 4), anterior choroidal artery (n = 4), proximal A1 segment (n = 1), and middle cerebral artery (n = 1).

RESULTS

In all 10 cases, MICGA was successful in assessing the state of the clipped aneurysm and blood flow of the vessels in the hidden region after clipping. This led to clip repositioning in 3 patients (30.0%) because of incomplete clipping of a hidden aneurysm or occlusion of a hidden perforator. Complete occlusion of the aneurysm was achieved in 8 patients, and the other 2 patients showed near complete occlusion because of an intentional residual aneurysm to avoid a small vessel adherent to the posterior wall of the aneurysm base.

CONCLUSIONS

MICGA can provide useful and reliable information on the state of a clipped aneurysm and the blood flow of associated vessels and perforators in a hidden region after aneurysm clipping.

Microsurgical Angioarchitectonics of Deep Brain Structures and Deep Arterial Anastomoses

BACKGROUND

Surgeries for deep and eloquent cerebral lesions require a detailed knowledge of normal brain anatomy and accurate planning. Important parts of brain anatomy are the cerebral blood supply and collateral circulation system. In addition to well-known cortical and basal (circle of Willis) anastomoses, there is also a deep interarterial anastomotic circle that is not described in the literature.

METHODS

Twenty brain specimens were studied for deep arterial anastomotic connections between branches of the anterior and posterior choroidal arteries.

RESULTS

We have marked 3 symmetric zones of deep arterial anastomoses that form an epithalamic circle.

CONCLUSIONS

Epithalamic anastomoses provide an additional mechanism of blood distribution that may play a role during surgical interventions or stroke.

Hemodynamic ischemia of the anterior choroidal artery and reversal by carotid artery stenting 10 years after ipsilateral superficial temporal artery-middle cerebral artery bypass for symptomatic left middle cerebral artery stenosis

The pathogenesis of anterior choroidal artery (AChA) territory infarction includes various mechanisms, but hemodynamic causes are rare and difficult to diagnose. 77- year-old man, who had moderate left ICA stenosis and he had treated with STA-MCA bypass surgery for severe symptomatic left MCA stenosis 10 years earlier, was admitted with right hemiparesis and confused state. On admission, magnetic resonance imaging and angiography demonstrated patent bypass, but severe stenosis of left ICA with no opacification of the left AChA and A1 portion of the left ACA. Diffusionweighted imaging demonstrated ischemic lesion in the left corona radiata. Together with clinical findings, hemodynamic ischemia of the AChA region was suspected and left carotid artery stenting resulted in prompt improvement of symptoms. Hemodynamic ischemia of the AChA territory is rare, however, should be considered as a potential target of treatment when the ipsilateral ICA, A1 and M1 show stenoocclusive lesions.

The cisternal segment of the anterior choroidal artery: an anatomical study using magnetic resonance imaging

PURPOSE

The topography of the anterior choroidal artery (AChA) has infrequently been delineated on neuroimages. The present study aimed to explore the cisternal segment of the AChA using magnetic resonance imaging.

METHODS

A total of 50 sides of the AChA obtained from 25 patients were included in this study. A constructive interference in steady-state (CISS) sequence was performed in thin-sliced axial sections. Furthermore, the cisternal AChA and relevant neurovascular structures were observed through cadaveric dissections in two heads.

RESULTS

In the cadaveric dissections, all the AChAs were exposed only in the proximal part even after extensive arachnoid dissections and cerebral retraction. In the examinations with the CISS sequence, the original site of the AChA was identified on the right side in 88% and on the left side in 96%. In 70% of the 50 sides, the AChA arose from the posterolateral wall of the internal carotid artery, distally to that of the posterior communicating artery. The cisternal course of the AChA was delineated on the right side in 96% and on the left side in 100%; it crossed over the optic tract in variable manners with the middle third as the most frequent site found in 60% of the sides.

CONCLUSIONS

The cisternal AChA shows a morphological variability. The CISS sequence is useful for delineating the cisternal AChA.

The cerebral circulation and cerebrovascular disease I: Anatomy

In this paper, which is the first in a three-part series that reviews cerebrovascular anatomy, pathogenesis, and stroke, we lay the anatomical foundation for the rest of the series. Beginning with its origin in the branches of the aorta, we start by describing the arterial system. This system is partitioned into two major divisions (anterior and posterior circulations) that differ significantly in features and pathogenic potential. The systems, and the major branches that comprise them, are described. Description of the arterial system proceeds to the point of the fulfillment of its function. This function, the exchange of gases and nutrients with the cerebral parenchyma, is the subject of a subsequent section on the microcirculation and blood-brain barrier. Finally, the cerebral venous system, which is composed of cerebral veins and dural venous sinuses, is described. Thus, an anatomical context is supplied for the discussion of cerebrovascular disease pathogenesis provided by our second paper.

Patency of the anterior choroidal artery covered with a flow-diverter stent

OBJECT

The concept of the flow-diverter stent (FDS) is to induce aneurysmal thrombosis while preserving the patency of the parent vessel and any covered branches. In some circumstances, it is impossible to avoid dangerously covering small branches, such as the anterior choroidal artery (AChA), with the stent. In this paper, the authors describe the clinical and angiographic effects of covering the AChA with an FDS.

METHODS

Between April 2011 and July 2013, 92 patients with intracranial aneurysms were treated with the use of FDSs in the authors’ institution. For 20 consecutive patients (21.7%) retrospectively included in this study, this involved the unavoidable covering of the AChA with a single FDS during endovascular therapy. AChAs feeding the choroid plexus were classified as the long-course group (14 cases), and those not feeding the choroid plexus were classified as the short-course group (6 cases). Clinical symptoms and the angiographic aspect of the AChA were evaluated immediately after stent delivery and during follow-up. Neurological examinations were performed to rule out hemiparesis, hemihypesthesia, hemianopsia, and other cortical signs.

RESULTS

FDS placement had no immediate effect on AChA blood flow. Data were obtained from 1-month clinical follow-up in all patients and from midterm angiographic follow-up in 17 patients (85.0%), with a mean length of 9.8 ± 5.4 months. No patient in either group complained of transient or permanent symptoms related to an AChA occlusion. In all cases, the AChA remained patent without any flow changes.

CONCLUSIONS

The results of this study suggest that when impossible to avoid, the AChA may be safely covered with a single FDS during intracranial aneurysm treatment, irrespective of anatomy and anastomoses.

An unusual, duplicate origin of the anterior choroidal artery with aneurysm: a case report

BACKGROUND AND IMPORTANCE

Aneurysms of the anterior choroidal artery (AChoA) are rare and often difficult to treat. Variations may be present and must be identified prior to treatment. We report a unique case of a ruptured aneurysm located at the origin of a duplicate branch of the AChoA.

CLINICAL PRESENTATION

A 56-year-old male was admitted to our university hospital for coma. A brain CT scan showed a subarachnoid hemorrhage, and CT angiography revealed a duplication of the right AChoA, with an aneurysm located at the branch's origin. We decided to embolize this aneurysm. Four weeks later, our patient was able to transfer to the rehabilitation unit.

CONCLUSION

To the best of our knowledge, this is one of the first descriptions of an aneurysm located at the origin of a duplicate branch of the AChoA.

Common features of the cerebral perforating arteries and their clinical significance

BACKGROUND

The perforating vessels supply very important regions of the brain stem and diencephalon, as well as the basal ganglia and internal capsule. Some of their micro-anatomical characteristics are still not well known. The aim of this study was to examine and evaluate the features of all the perforating vessels.

METHODS

The arteries of 24-32 cerebral hemispheres, diencephalons and halves of the brain stem were injected with India ink mixture or methylmethacrylate, and microdissection was performed or the vascular casts were produced and examined under the sterescopic microscope.

RESULTS

It was noticed that the perforators ranged from 0 to 14 in number, with the smallest mean value (1.1) for the diencephalic perforators and the largest one (8.1) for the lenticulostriate arteries. The smallest mean diameter (175 μm) was found in the group of the perforators of the anterior communicating artery, whereas the largest one is related to the Heubner's artery (668 μm), the diencephalic thalamoperforating vessels (562 μm), the premamillary vessel (489 μm) and the lenticulostriate arteries (469 μm). The perforators most frequently originated from the pial branches of the basilar artery (91.7 %) and of the posterior cerebral artery (59.4 %). The common stems were most often formed by the perforators of the basilar (79.2 %), posterior cerebral (75.0 %) and middle cerebral arteries (40.6 %). Some perforators arose close to or from the terminal divisions, the branching sites or the junctions of the parent arteries, where the saccular aneurysms most often develop. The anastomoses among the perforators were present in a range from 6.3 % to 53.2 %.

CONCLUSIONS

The micro-anatomical data obtained may be useful for neurosurgeons when operating at the base of the brain, as well as for a neurological and radiological evaluation of the perforators in the occlusive cerebrovascular disease, or in the cases of an aneurysm, arteriovenous malformation (AVM) or tumour presence.

Microsurgical anatomy of the cisternal anterior choroidal artery with special emphasis on the preoptic and postoptic subdivisions

Object

The object of this study was to delineate the microsurgical anatomy of the cisternal segment of the anterior choroidal artery (AChA). The authors also propose a new classification of this segment on the basis of its complicated course within the carotid and crural cisterns in relation to important neurovascular structures, and the site of origin, course, and areas of supply of perforating arteries.

Methods

Thirty cadaveric cerebral hemispheres injected with colored latex were dissected under surgical magnification to view the cisternal segment of the AChA and its perforators. Fiber dissections using the Klingler technique were performed in two additional latex injected hemispheres to follow the penetration points, courses, and terminal areas of supply of perforating branches that arise from the cisternal segment of the AChA.

Results

The cisternal segment of the AChA was divided into pre- and postoptic parts that meet at the artery's genu, the most medial extension point of the cisternal segment where the artery makes an abrupt turn after passing under the optic tract. The preoptic part of the AChA extended from its origin at the inferomedial side of the internal carotid artery to the artery's genu, which is commonly located just inferomedial to the initial part of the optic tract. The postoptic part coursed within the crural cistern and extended from the genu to the inferior choroidal point. The genu of the AChA was 8 mm medial to the artery's origin and was located medial to the optic tract in 13% of the hemispheres. The postoptic part was longer than the preoptic part in all hemispheres and had more perforating arteries supplying critical deep structures (preoptic 3.4 per hemisphere vs postoptic 4.6 per hemisphere), and these results were statistically significant (p = 0.01). At the preoptic part, perforating arteries arose from the superolateral portion of the artery and coursed laterally; at the postoptic part, perforators arose from the inferomedial portion of the artery and coursed medially. Perforating arteries from both segments passed most commonly to the optic tract, followed by the anterior segment and apex of uncus in the preoptic part and the cerebral peduncle in the postoptic part.

Conclusions

Both parts of the cisternal segment of the AChA come into surgical view during surgeries for different pathologies in and around the perimesencephalic cisterns. However, attending to the artery's genu and defining pre- and postoptic parts during surgery may help the surgeon locate the origin and eventual course of these perforators, and even estimate the terminal areas of supply of most of the perforating arteries. The proposed classification system can prove helpful in planning any operative procedure along the crural cistern and may reduce the probability of inadvertent injury to perforating branches of the cisternal segment.

Endovascular embolization of distal anterior choroidal artery aneurysms associated with moyamoya disease. A report of two cases and a literature review

We evaluated the feasibility of endovascular embolization for the management of distal anterior choroidal artery (AChA) aneurysms associated with moyamoya disease and performed a literature review to summarize their clinical features and treatment. We describe two cases of moyamoya disease-associated distal AChA aneurysms treated by endovascular embolization. In both cases, a good outcome was observed. We performed a MEDLINE (1980-2010) search which identified 13 similar cases. Our analysis of the clinical data from these 15 cases led us to conclude that (i) endovascular embolization is an effective and feasible treatment for distal AChA aneurysms associated with moyamoya disease; (ii) aneurysm location and the preservation of the parent artery are two major prognostic factors for moyamoya disease-associated distal AChA aneurysms subjected to craniotomy or endovascular therapy; (iii) the parent artery should be preserved when the aneurysm is located in the temporal horn of the lateral ventricle, but sacrificed when it is located in the trigone of the lateral ventricle.

Microvascular anatomy of the medial temporal region: part 1: its application to arteriovenous malformation surgery

BACKGROUND

The medial temporal region (also called the temporomesial or mediobasal temporal region) is the site of the most complex cortical anatomy.

OBJECTIVE

To investigate the anatomic variability of the arterial supply and venous drainage of each segment of the medial temporal region (MTR), and to discuss and illustrate the implications of the findings for surgery of arteriovenous malformations (AVM) of the MTR.

METHODS

Forty-seven cerebral hemispheres and 10 silicon-injected cadaveric heads were examined using x3 to x40 magnification. Illustrative surgical cases of MTR AVMs were selected.

RESULTS

The anterior choroidal artery (AChA) gave rise to an anterior uncal artery in 83% of hemispheres and a posterior uncal or unco-hippocampal artery in 98%. The plexal segment of the AChA gave off neural branches in 38%. The MCA was the site of origin of anterior uncal, unco-parahippocampal, or anterior parahippocampal arteries in 94% of hemispheres. An anterior uncal artery arose from the internal carotid artery (ICA) in 45% of hemispheres. The posterior cerebral artery (PCA) irrigated the entorhinal area through its anterior parahippocampal or hippocampo-parahippocampal branches in every case. A PCA bifurcation was identified in 89% of hemispheres, typically at the middle segment of the MTR. The most common pattern of bifurcation was by division into posteroinferior temporal and parieto-occipital arterial trunks. The anterior segment of the basal vein had a predominant anterior drainage in 35% of hemispheres, and the middle segment had a predominant inferior drainage in 16%.

CONCLUSION

An understanding of the vascular variability of the MTR is essential for accurate microsurgical resection of MTR AVMs.

Anomalous medial origin of the anterior choroidal artery with associated aneurysm

Injury to the anterior choroidal artery (AchA) can be devastating owing to the importance of the territory it supplies. The AchA is a known site of aneurysm formation, and is often exposed during various surgical and endovascular procedures. We report a patient with an aneurysm at the origin of the AchA, and an anomalous medial take off of the artery from the internal carotid artery, then a sharp lateral turn followed by a normal course toward the choroidal fissure, unreported to date to our knowledge. The aneurysm was treated successfully by endovascular therapy. The typical anatomy of the AchA, and reported variations in its origin are discussed. Thorough knowledge of the normal cerebrovascular anatomy and attention to variations play an important role in the successful management of patients with neurological vascular conditions.

Endovascular coil embolization of anterior choroidal artery aneurysms. Clinical article

OBJECT

Anterior choroidal artery (AChA) aneurysms are difficult to treat, and the clinical outcome of patients is occasionally compromised by ischemic complications after clipping operations. The purpose of this study was to document the outcome and follow-up results of endovascular coil embolization in patients with AChA aneurysms.

METHODS

Between July 1999 and March 2008, 88 patients with 90 AChA aneurysms (31 ruptured and 59 unruptured aneurysms) were treated with endovascular coil embolization in 91 sessions. There were 87 small aneurysms (< 10 mm) and 3 large aneurysms, with a mean aneurysm volume of 60.9 +/- 83.3 mm(3). Preprocedural oculomotor nerve palsy associated with AChA aneurysms was noted in 8 patients. Efficacy and safety were evaluated based on the degree of initial occlusion, procedure-related complications, patient outcome based on the Glasgow Outcome Scale score, and follow-up results.

RESULTS

The degree of angiographic occlusion of the aneurysms was complete for 15 aneurysms (17%), near complete for 69 aneurysms (77%) and partial for 6 aneurysms (7%). There were 4 (4.4%) symptomatic procedure-related complications (3 thromboembolic events and 1 procedural hemorrhage). The procedural hemorrhage resulted in death; however, the thromboembolic events only caused transient deficits. A favorable outcome (Glasgow Outcome Scale score of 5 or 4) was achieved in 90% (79 of 88) of the patients at the time of discharge. No patient showed signs of bleeding or rebleeding during the follow-up period (mean 25 months). Major aneurysm recanalization occurred in 2 cases. The AChA aneurysm-associated oculomotor nerve palsy tended to become aggravated transiently after coil embolization and then completely recovered over the course of 2-9 months.

CONCLUSIONS

Coil embolization is a safe and effective treatment modality in cases of AChA aneurysms. Coil embolization enables procedural recognition of arterial compromise and immediate reestablishment of flow, thus contributing to a favorable outcome.

Distal anterior choroidal artery aneurysms

BACKGROUND

Distal AChoA aneurysms are quite rare. Only 12 operated cases have been reported in the English medical literature. Treatment of these aneurysms is also difficult because of their deep location, small size, and angioarchitecture.

METHODS

The authors report 2 additional patients with aneurysms, arising from the distal AChoA and located within the temporal horn of the lateral ventricle. In the first patient, the aneurysm could also be visualized with CTA, which is the first demonstration in the literature.

RESULTS

The aneurysms were explored and resected via a transtemporal/ventricular approach in both patients. One patient was discharged as neurologically intact and the other died because of severe vasospasm.

CONCLUSIONS

The conclusions drawn from our experience and a comprehensive review of the literature include the following: (1) A distal AChoA aneurysm should be considered in patients with isolated medial temporal intracerebral hematoma with intraventricular extension. (2) These aneurysms are frequently very small (<5 mm). Therefore, they cannot be detected on initial angiograms in some cases. (3) These small aneurysms cannot be usually clipped without sacrificing the parent artery. (4) Sacrificing distal AChoA (beyond the plexal point) does not usually cause any neurological deficit, but, whenever possible, this artery should be preserved.

[Microsurgical anatomy of the human basal anterior perforated substance]

The anterior perforated substance (APS) is a landmark in the basal forebrain. It has a basal face located above the carotid bifurcation in the subarachnoid space, and an interhemispheric one. It is the site of passage of the arteries to the caudate nucleus, putamen, internal capsule, adjacent areas of the globus pallidus and thalamus. Fifty hemispheres from twenty-five adult cadavers were obtained. The arteries were perfused with colored latex, Batsons resin and gelatin colored with carmine. Using a surgical microscope we have determined the origin, local and number of origin from the parent vessel. The sites of penetration in the mediolateral and anteroposterior direction were also recorded. The anterior communicating artery contribution to the basal APS was reviewed. Significant vascular variations and anastomoses were encountered mainly involving middle cerebral and anterior choroidal arteries. The precise understanding of these vessels has surgical and clinical implications in the management of vascular and tumoral maladies related to the anterior perforated substance.

Microanatomy of the intrachoroidal vasculature of the lateral ventricle

OBJECTIVE

Intraventricular surgery requires a detailed knowledge of the microanatomy of the choroid plexus vasculature.

METHODS

Twenty choroid plexuses were microdissected, and two additional plexuses were prepared for microscopic examination.

RESULTS

The choroid plexus was perfused primarily by the anterior choroidal artery (AChA) and the lateral posterior choroidal artery (LPChA). The AChA, which averaged 650 microm in diameter, most often (in 75% of cases) divided into the medial and lateral trunks, which averaged 450 microm in diameter. The medial trunk gave off the bush-like intrachoroidal branches, whereas the lateral trunk divided into the parallel arteries. The inferior LPChA was present in 50% of the hemispheres, both the inferior and superior LPChAs in 40%, and their common trunk in 10%. In 40%, the LPChA, which averaged 670 microm in diameter, divided into the terminal trunks, with a mean diameter of 490 microm. The anastomoses involving the trunks of the LPChA and other choroidal arteries averaged 310 microm in diameter. All primary intrachoroidal branches of the AChA and LPChA were divided into three groups. The parallel branches, which averaged from 220 to 230 microm in diameter, coursed along the lateral part of the choroid plexus. The tortuous glomus vessels, which averaged 310 microm in size, originated from the AChA (45%), the LPChA (15%), or both (40%). The bush-like vessels, with a mean diameter between 155 and 190 microm, ramified into smaller twigs, up to the intrachoroidal capillaries.

CONCLUSION

The data obtained on the microanatomy of the intrachoroidal vasculature may have certain neurosurgical implications.

Microanatomy of the subependymal arteries of the lateral ventricle

BACKGROUND

Scarce information about the anatomy of the subependymal arteries (SEAs) is present in the scientific literature.

METHODS

Twenty cerebral hemispheres with injected arteries were microdissected, and the magnetic resonance imaging scans of 100 patients with lacunar infarcts were examined.

RESULTS

The SEAs were found to range in diameter from 40 to 490 microm (mean, 149 microm) and in number between 3 and 12 (average, 5.2). Of these, numbers from 1 to 3 originated from the anterior choroidal artery (AChA), between 1 and 10 from the lateral posterior choroidal artery (LPChA), 1 from the medial posterior choroidal artery (MPChA), and 1 from the internal carotid artery. The SEAs most often arose from the choroidal branches (90%) and less frequently from the thalamic (30%), caudate (35%), or thalamocaudate twigs (20%). The SEAs of the AChA supplied the walls of the temporal horn (100%), the occipital horn (85%), and the atrium (35%). Those of the LPChA perfused the walls of the occipital horn (15%), the atrium (65%), the body of the ventricle (100%), and partially the frontal horn. The SEAs of the MPChA partially nourished the body and the frontal horn (10%). The SEAs may also occasionally supply the caudate nucleus (20%) and the stria terminalis. The anastomoses involving the SEAs were absent. In spite of this, ischemia in the territory of a single SEA was noticed in only 1% of our patients.

CONCLUSIONS

The SEAs are tiny vessels that supply the walls of the lateral ventricle, as well as the caudate nucleus and the stria terminalis occasionally. The obtained anatomic data can have important neurosurgical implications in intraventricular operations.

Ruptured distal anterior choroidal artery aneurysm presenting with right intracerebral haematoma: clipping aided by subpial uncal resection

This report describes a rare case of a distal right anterior choroidal artery aneurysm which developed a right intracerebral haematoma and intraventricular haemorrhage and was treated by surgical exploration and clipping with the aid of a limited subpial resection of the uncus and ambient gyrus. The technique of limited subpial uncal resection allows the surgeon to follow the anterior choroidal artery without much difficulty, achieves proximal control early and aids in the eventual clipping procedure.

Microsurgical anatomy of the temporal lobe: part 1: mesial temporal lobe anatomy and its vascular relationships as applied to amygdalohippocampectomy

OBJECTIVE

We review the anatomy of the mesial temporal lobe region, establishing the relationships among the intraventricular, extraventricular, and surrounding vascular structures and their angiographic characterization. We also demonstrate the clinical application of these anatomic landmarks in an anatomic temporal lobectomy plus amygdalohippocampectomy.

METHODS

Fifty-two adult cadaveric hemispheres and 12 adult cadaveric heads were studied, using a magnification ranging from 3x to 40x, after perfusion of the arteries and veins with colored latex.

RESULTS

The intraventricular elements are the hippocampus, fimbria, amygdala, and choroidal fissure; the extraventricular elements are the uncus and parahippocampal and dentate gyri. The uncus has an anterior segment, an apex, and a posterior segment that has an inferior and a posteromedial surface; the uncus is related medially to cisternal elements and laterally to intraventricular elements. The anterior segment is related to the proximal sylvian fissure, internal carotid artery, proximal M1 segment of the middle cerebral artery, proximal cisternal anterior choroidal artery, and amygdala. The apex is related to the oculomotor nerve, uncal recess, and amygdala; the posteromedial surface is related to the P2A segment of the posterior cerebral artery inferiorly, to the distal cisternal anterior choroidal artery superiorly, and to the head of the hippocampus and amygdala intraventricularly. The choroidal fissure is located between the thalamus and fimbria; it begins at the inferior choroidal point behind the head of the hippocampus and constitutes the medial wall of the posterior two-thirds of the temporal horn.

CONCLUSION

Not only is the knowledge of these relations useful to angiographically characterize the mesial temporal region, but it has also proven to be of extreme value during microsurgeries involving this region.

The surgical anatomy of the perforating branches of the anterior choroidal artery

BACKGROUND

The available information about certain microanatomic features of the AChA perforators is incomplete. Precise knowledge of these vessels is necessary to understand the consequences of their occlusion and to safely operate in their region.

METHODS

The AChA perforators were microdissected and examined under the stereoscopic microscope in 10 vascular casts and in 20 hemispheres injected with india ink or radiopaque substance.

RESULTS

The perforating branches ranged in number from 2 to 9 (mean, 4.6) and in diameter between 90 microm and 600 microm (mean, 317 microm). The most proximal perforator arose 3.2 mm on average caudal to the AChA origin. The most distal (capsulothalamic) perforator varied in size from 200 microm to 610 microm (mean, 431 microm). One or more of the perforators always originated from the AChA (100%), but some of them also from the uncal (33.3%) or parahippocampal branch (10%) of the AChA, either as individual vessels only (70%) or from common trunks (30%). The perforators gave off the peduncular (20%), optic (23.3%), or uncal side branches (26.7%).

CONCLUSIONS

Our findings concerning the origin, position, number, size, branching, penetration site, and relationships of the AChA perforators gave the anatomic basis for safe operations in patients with AChA aneurysms or mediobasal limbic epilepsy.

Microanatomic and vascular aspects of the temporomesial region

OBJECTIVE

The aim of this work was to provide a detailed description of the arterial vascularization of the temporomesial region (TMR), correlated with the definitions of the macroscopic and cytoarchitectonic subdivisions of this area.

METHODS

Selective colored arterial injections were performed in 16 hemispheres to study their blood supply. Four hemispheres were used to illustrate the macroscopic aspect of the TMR and were then cut into thin sections and stained with Nissl's stain to study the cytoarchitectonic areas.

RESULTS

The surface of the TMR is subdivided into several areas: anteriorly, the lateral olfactory gyrus is covered by prepiriform cortex; dorsomedially, the semilunar gyrus and uncus hippocampi consist, respectively, of cortical amygdaloid nucleus and hippocampal cytoarchitectonic fields; and ventrolaterally, the anterior part of the parahippocampal gyrus is covered by periamygdaloid cortex, entorhinal, and transentorhinal areas and its posterior part is covered by Fields TH and TF per Von Economo and subicular complex. Six cortical arterial groups were defined: Group I, anterosuperior parahippocampal arteries (mean, 3.9 arteries) vascularize the ambiens, semilunar, and lateral olfactory gyri (origins: middle cerebral artery, anterior choroidal artery [AChA], posterior cerebral artery [PCA], and internal carotid artery); Group II, anteroinferior parahippocampal arteries (mean, 2.8 arteries) irrigate the anterior ventrolateral region of the parahippocampal gyrus (origins: middle cerebral artery, PCA, and AChA); Group III, medial uncal arteries (mean, 1.9 arteries) supply the medial part of uncus hippocampi (origins: AChA and PCA); Group IV, lateral uncal arteries (mean, 2.9 arteries) vascularize the lateral part of the uncus hippocampi (origins: AChA and PCA); Group V, several small posterior parahippocampal arteries irrigate Fields TF and TH per Von Economo (origins: PCA and AChA); and Group VI, posterior hippocampal arteries (mean, 3.2 arteries) irrigate the posterior part of hippocampal formation (origin: PCA). Many anastomoses are found among these arteries, particularly in the ventrolateral part of the TMR. Three groups of amygdaloid arteries were defined: Group I, the anterolateral group (mean, 5.7 arteries) (origin: middle cerebral artery); Group II, the medial group (mean, 6.4 arteries) (origins: AChA, internal carotid artery, and PCA); and Group III, the posterolateral group (mean, 5 arteries) (origins: AChA and internal carotid artery).

CONCLUSION

We hope that this work will be useful for any microneurosurgical procedures on the TMR. We have clarified the macroscopic and histological definitions of the cortical and nuclear areas of the TMR and the arterial groups closely related to them. The systematic analysis of the variability of the arterial vascularization of this area was our second goal; such a goal, however, requires more observations to be exhaustive. The numerous interterritorial anastomoses found inside the TMR imply that a selective presurgical injection of short-acting barbiturates to evaluate its functions (Wada test) may well result in its diffusion to other areas of the TMR.

Microsurgical anatomy of the anterior choroidal artery

In this study, the authors present the results of 50 dissections of the anterior choroidal a. in man. Fifty cerebral hemispheres were prepared with the classic techniques of preservation and vascular injection. An ectopic origin was observed in 4% of cases. The intracisternal segment of the anterior choroidal a. forms a neurovascular bundle with the optic tract and basal v. Most of its intraparenchymatous branches arise from the cisternal segment, while branches supplying the optic tract, lateral geniculate body and thalamus arise from the intraplexual segment. Constant anastomoses exist with the vertebrobasilar system, specially the postero-lateral choroidal and posterior cerebral aa. We discuss the importance of an adequate knowledge of the anatomy of the anterior choroidal a. and its relations in the surgical approach to arterial aneurysms and arteriovenous malformations of the region.

Superselective intra-arterial amytal (Wada test) in temporal lobe epilepsy: basics for neuroradiological investigations

We describe the angioarchitecture of the medial temporal region as a basis for modified superselective Wada tests in patients with temporal lobe epilepsy. Possible functional deficits following the injection of amytal, depending on the superselective placement of the microcatheter in the medial temporal arteries, are discussed. The individual blood supply in each patient determines the ideal super-selective positioning of the micro-catheter.

The surgical anatomy of the relationships between the perforating and the leptomeningeal arteries

OBJECTIVE

Despite detailed studies of the perforating arteries, their relationships with the leptomeningeal arteries are almost unknown. These relationships can be of great significance during neurosurgical operations.

METHODS

The arteries of the hemispheres, which ranged in number from 17 to 36, were injected with india ink or methylmethacrylate.

RESULTS

The perforating vessels were noted to arise from the following leptomeningeal arteries: the subcallosal branch of the anterior communicating artery (26.6%); the median artery of the corpus callosum (6.6%); the medial orbitofrontal (6.6%) and the olfactory branch (3.3%) of the anterior cerebral artery; the accessory middle cerebral artery (3.3%); the frontal and temporal branches of the middle cerebral artery (66.6%); the temporal branches of the internal carotid and the anterior choroidal arteries (25% each); the peduncular branch of the posterior communicating artery (4.8%); the peduncular, collicular and medial posterior choroidal branches of the posterior cerebral artery (40%); the cerebellar branches (100%); the long pontine branches (20-26.6%); the anterolateral branches (33.3%) of the basilar artery; and the anterolateral or the lateral medullary branches (35.3%) of the vertebral artery. From 19.4 to 100% of some leptomeningeal vessels originated in the large perforating arteries.

CONCLUSION

From 4.8 to 100% of certain groups of the perforating vessels originated in the leptomeningeal arteries. Occlusion of a leptomeningeal artery that gives rise to the perforating vessel(s) may lead to superficial and deep infarcts in the same patient.

A proposed modification of the Wada test for presurgical assessment in temporal lobe epilepsy

We report experience with a modification of the Wada test used before temporal lobe resection in patients with drug-resistant epilepsy. Our procedure consists of injection of amytal via a microcatheter into the anterior choroidal artery or the P2 segment of the posterior cerebral artery and simultaneous presentation of verbal and figural memory test material before, during and after the injection. Pros and cons of the modification and inherent shortcomings of the amytal test are discussed on the basis of the results in ten patients.

Unilateral amnesic stroke. Six new cases and a review of the literature

BACKGROUND AND PURPOSE

Although persistent amnesia due to bilateral limbic system infarction is well described, reports of amnesic syndromes due to unilateral stroke have appeared infrequently and unsystematically. We report six new cases and review previously published reports to expand and consolidate knowledge regarding amnesic stroke.

CASE DESCRIPTIONS

Six patients developed acute amnesia associated with unilateral stroke. Brain computed tomography or magnetic resonance imaging revealed lesions in limbic structures, which accounted for the memory deficit. Based on these as well as similar cases in the literature, we delineate three distinct syndromes of unilateral amnesic stroke involving the territories of the posterior cerebral, anterior choroidal, and thalamic penetrating arteries. Eighty-five percent of reported cases have involved the left hemisphere.

CONCLUSIONS

Persistent as well as transient amnesia may be the sole or primary manifestation of unilateral hemispheric stroke. The vascular mechanisms of amnesic stroke are diverse. Patients presenting with acute amnesia possibly related to cerebral ischemia should be classified by documented or presumed lesion site as well as the involved vascular territory. Left amygdalohippocampal or diencephalic dysfunction may produce a particular vulnerability to global amnesia.

Anterior choroidal artery syndrome after surgery for internal carotid artery aneurysms

We report five patients with anterior choroidal artery syndrome after surgery for internal carotid artery aneurysms. All patients suffered hemiparesis, and hemisensory loss and homonymous hemianopsia were identified in 2 patients. The characteristic triad of the syndrome was recognized in only 1 patient. Dominant and nondominant cerebral hemisphere signs have been reported in association with this syndrome, and 2 patients had a speech disturbance in our series. In previous reports, neurological deficits were mild and patient prognosis was good in anterior choroidal artery infarct, in spite of the fact that the artery supplied the corticobulbar and corticospinal tracts. This report suggests the possible causes of this syndrome after surgery for internal carotid aneurysms, which involve vasospasm after subarachnoid hemorrhage, mechanical obstruction, thromboembolism, and distortion of the aneurysm clip.

Microvascular anatomy of the hippocampal formation

The hippocampal vessels were examined in 25 forebrain hemispheres injected with india ink or methylmethacrylate. There were two to seven hippocampal arteries, which measured 200-800 microns in diameter. The anterior hippocampal artery (AHA), which was present in 88.2% of the hemispheres, most often originated from the posterior cerebral and the anterior temporal arteries, that is, within the rostral hippocampo-parahippocampal arterial complex. It arose from the anterior choroidal artery in 29.4% of the hemispheres. The AHA extended between the uncus and the parahippocampal gyrus, and it supplied the head of the hippocampus. The middle hippocampal artery was constant. It most often arose from the posterior cerebral and the common temporal arteries. The middle hippocampal artery coursed just caudal to the uncus, in close relationship with the lateral posterior choroidal artery, and it usually supplied the middle part of the hippocampal formation. The posterior hippocampal artery, which existed in 94.1% of the hemispheres, most often arose from the posterior cerebral and the splenial arteries. It irrigated the caudal part of the hippocampal formation. The anastomoses connecting the posterior, middle, and the anterior hippocampal arteries were present in 29.4% of the hemispheres. The hippocampal arteries gave rise to the straight vessels, which divided into the large and the small intrahippocampal arteries. The highest density of the capillary network was noted in the pyramidal and molecular layers of the hippocampal formation. The clinical significance of the obtained microanatomical findings is discussed.

[Microsurgical anatomy of the anterior choroidal artery]

Microdissection of 100 hemispheres from human cadavers were performed in order to study the anatomic characteristics of the anterior choroidal artery (AChA). One AChA per hemisphere was found. In 98% of hemispheres the AChA arose from the internal carotid artery (ACI) 2.4mm distal to the origin of the posterior communicating artery (ACoP) and 4.7mm proximal to the carotid bifurcation. One or more perforating branches arose from communicating segment of ACI in 29% of hemispheres. The average calibre of the cisternal portion was 0.9mm and the plexal portion 0.7mm. The most frequent branches of the cisternal portion pass to the optic tract, cerebral peduncle, uncus and lateral geniculate body. Anastomosis were found between branches of the AChA and posterior cerebral artery, ACoP, middle cerebral artery and ACI. The results are discussed.