Proximal Anterior Cerebral Artery Aneurysms Research Articles

Classification of anatomy and treatment approaches for aneurysms originating from the proximal of the A1 segment of the anterior cerebral artery in clinical settings.

To explore the spatial relationship between A1 segment proximal anterior cerebral artery aneurysms and their main trunks, classify them anatomically and develop targeted treatment strategies. This single-center retrospective analysis involved 39 patients diagnosed with aneurysms originating from the proximal of A1 segment of the anterior cerebral artery (2014-2023). Classify the patient's aneurysm into 5 types based on the location of the neck involving the carrier artery and the spatial relationship and projection direction of the aneurysm body with the carrier artery, and outcomes from treatment methods were compared. Among 39 aneurysms, 18 cases underwent endovascular intervention treatment, including 6 cases of stent assisted embolization, 1 case of flow-diverter embolization, 5 cases of balloon assisted embolization, and 6 cases of simple coiling. At discharged, the mRS score of all endovascularly treated patients was 0, and the GOS score was 5 at 6 months after discharge. At discharge, the mRS score of microsurgical clipping treated patients was 0 for 15 cases, 3 for 1 case, 4 for 1 case and 5 for 2 cases. Six months after discharge, the GOS score was 5 for 16 cases, 4 for 2 cases, 3 for 2 cases, and 1 for 1 case. GOS outcomes at 6 months were better for endovascularly treated patients (p = 0.047). Results showed better outcomes for the endovascular treatment group compared to microsurgical clipping at 6 months after surgery. The anatomical classification of aneurysms in this region may be of help to develop effective treatment strategies.

Morphological and Hemodynamic Risk Factors for the Rupture of Proximal Anterior Cerebral Artery Aneurysms (A1 Segment).

ObjectiveThe treatment of unruptured small intracranial aneurysms remains controversial. A distinguishing characteristic of A1 segment aneurysms is that they tend to rupture when they are small, which may be related to their distinctive morphology and hemodynamics. Our study sought to investigate the rupture risk factors of A1 segment aneurysms by analyzing the clinical risk factors, morphology, and hemodynamic characteristics of A1 segment aneurysms.MethodsWe retrospectively enrolled 49 (23 ruptured, 26 unruptured) consecutive patients presenting to our institute with A1 segment aneurysms between January 2010 and March 2020. Independent risk factors associated with the rupture of A1 segment aneurysms were analyzed by multivariate regression analysis in the ruptured group and unruptured group.ResultsClinical risk factors, including age, sex, hypertension, smoking history, and SAH family history revealed no difference between the ruptured and unruptured groups. The ruptured group presented a significantly larger size (Size, P = 0.007), aspect ratio (AR, P = 0.002), size ratio (SR, P = 0.001), bottleneck index (BN, P = 0.016), dome-to-neck ratio (DN, P = 0.001), and oscillatory shear index (OSI) (P = 0.001) than the unruptured group. The normalized wall shear stress (NWSS) of the ruptured aneurysms was lower than the unruptured group (P = 0.001). In the multivariate regression analysis, only SR (OR = 3.672, P = 0.003) and NWSS (OR = 0.474, P = 0.01) were independent risk factors in the A1 segment aneurysm rupture.ConclusionA higher SR and lower NWSS revealed a close connection with the rupture of A1 segment aneurysms in our study, thus providing a reference for clinical decision-making in treating A1 segment unruptured aneurysms.

The Special Considerations in the Surgical Management of Proximal Anterior Cerebral Artery Aneurysms

Proximal anterior cerebral artery (A1) aneurysms are difficult to clip because of their frequent proximity to perforators, location behind the parent artery, or adherence to surrounding structures. We retrospectively reviewed a consecutive series of patients with A1 aneurysms and report the clinical status, radiologic findings, treatment methods, and outcome. This series included 19 male and 12 female patients with a mean age of 50 years. The morphology of the A1 aneurysms was fusiform in 2 patients and saccular in the remaining 29 patients. Multiple aneurysms were presented in 9 patients (29.0%). On admission, 26 patients (83.9%) presented with subarachnoid hemorrhage, 3 of whom had an additional intracerebral hematoma. All surgeries were performed with a standard pteriomal craniotomy. The mean Glasgow Outcome Scale score at final follow-up was 4.8 (interquartile range, 5, 5), with 26 patients (83.9%) rated as 5. The mean follow-up time was 38.5 months (range, 12-60 months). A1 aneurysms are rare but have their own complex characteristics and are difficult to treat. Meticulous analysis of the relevant angiographs is needed for their diagnosis. An important consideration in surgery is the preservation of perforators and prevention of rupture. Wide opening of the sylvian fissure and temporary control of the parent artery can facilitate dissection of the A1 aneurysms dome. Multiple intraoperative monitoring methods, such as microvascular Doppler ultrasonography and somatosensory and motor evoked potential monitoring, can reduce the relevant complications of surgery.

Microsurgical clipping of a ruptured A1 segment aneurysm.

Background:Proximal anterior cerebral artery aneurysms are usually rare small aneurysms, mostly arising at the origin of perforating arteries on the A1 segment. They account for <1% of all intracranial aneurysms and may be treated by microsurgical or endovascular procedures. The microsurgical approach requires careful evaluation of the imaging. The 3D configuration and orientation of the aneurysm related with the anatomical landmarks (optic chiasm and the adjacent structures of the skull base) might be useful for the navigation. The dominancy, length, deep, and course of the ipsilateral A1 are also important features for planning the temporary and definitive clipping. The presence of vascular abnormalities and space-occupying hematoma should be also evaluated. Intraoperatively, the identification of the medial lenticulostriate branches and the recurrent artery of Heubner, which can originate from the distal A1 in around 10% of cases, might be essential aiming to carry a safe procedure.Technique:The patient was placed in supine position. The head, positioned above the cardiac level, was slightly rotated (20°–30°) and tilted to the opposite side with minimal extension. A right lateral supraorbital approach followed by a frontal ventricular drainage was applied to reduce intracranial pressure before dura opening. Intradurally, the carotid cistern was opened to release some extra cerebrospinal fluid (CSF) and to expose the internal carotid artery bifurcation and the A1 segment. Once, some surrounding adherences and clots indicated the probable location of the aneurysm, a temporary clip was applied on the proximal A1 segment to facilitate the dissection of the aneurysm base, the A1 artery, and the evolved perforators. A ruptured aneurysm arising at the origin of an aberrant fronto-orbital artery was discovered. Initial pilot clip was applied in the aneurysm base and the temporary clip was released. With a controlled aneurysm and after a careful vascular dissection, a definitive clip was placed under temporary trapping. After careful evaluation of some residual neck, a second definitive clip was applied under the first one by a double-clip technique. Intraoperative angiography determined complete occlusion of the aneurysm. The orbitofrontal branch was occluded as well, and small pieces of surgicel embedded in papaverine were applied over its surface. Finally, after opening the lamina terminalis, an external third ventriculostomy was placed for additional CSF removal, replacing the frontal external ventriculostomy.Conclusion:Skillful microneurosurgery is required for the management of challenging small ruptured A1 segment aneurysms.Videolink:http://surgicalneurologyint.com/videogallery/ruptured-a1-aneurysm

Management of Proximal Anterior Cerebral Artery Aneurysms: Anatomical Variations and Technical Nuances

The proximal segment of the anterior cerebral artery (A1) is among the most uncommon locations for occurrence of an intracranial aneurysm. These aneurysms may be missed if small or misinterpreted when they are near the internal cerebral artery bifurcation or Anterior Communicating Artery region. The association with congenital vascular anomalies and multiplicity makes them unique. Seventeen A1 aneurysms were diagnosed in sixteen patients between January 2000 and October 2014 in our institution. A retrospective review of the clinical, radiological, and management (microsurgical and endovascular) details of these patients was conducted. The incidence of A1 aneurysm was 1.71% of all patients harboring aneurysms and 1.19% of all aneurysms. Half of these patients exhibited subarachnoid hemorrhage. Fourteen aneurysms underwent microsurgical or endovascular intervention. All patients recovered well, except for one patient who died in the postoperative period. A1 aneurysms are rare, with wide anatomic variations. In this article, we discuss those variations in detail with illustrative cases and pictures. We also discussed the microsurgical and endovascular strategies to encounter them highlighting the technical challenges.

Proximal Anterior Cerebral Artery Aneurysm: Case Presentation and Review of the Literature

Purpose: Aneurysms involving the proximal segment of the anterior cerebral artery (A1) are relatively rare. We report two cases we encountered and review the literature. Cases: Two female patients were referred to our hospital. The first, a 71-year-old woman, was found unconscious and semicomatose at home. Computed tomography (CT) revealed diffuse subarachnoid hemorrhage (SAH) with intraventricular and intracerebral hemorrhage. Cerebral angiography (CAG) showed a saccular aneurysm in the right A1 and unruptured right middle cerebral artery aneurysm. The second patient was a 76-year-old woman in whom an unruptured right A1 aneurysm was found incidentally. During a 3-year observation period, the aneurysm enlarged and changed its shape. Both patients underwent surgical clipping. The first patient showed moderate disability due to SAH insult while the second showed no neurological deficits. Conclusions: A1 aneurysms are rare intracranial aneurysms, but reportedly show strong correlations with vascular anomalies. When planning surgery, use of CAG and other radiological modalities are warranted to precisely assess the origin of the aneurysm neck and any accompanying anomalies. Anatomical speculations must be confirmed intraoperatively while paying attention to perforating arteries from the A1 segment. ACTA MEDICA NAGASAKIENSIA 57: 79－83, 2012

Posterior projecting carotid bifurcation aneurysms

Posteriorly projecting carotid bifurcation aneurysms are rare. Proximal anterior cerebral artery aneurysms are even more uncommon. Distinguishing between true posteriorly projecting carotid bifurcation aneurysms and carotid A1 aneurysms can be difficult but it is important because small posteriorly projecting carotid bifurcation aneurysms may need a contralateral approach for adequate exposure. We report our experience with a recent case that illustrated this problem.

A1-A2 interposition grafting for surgical treatment of a giant “unclippable” A1 segment aneurysm

Background Although various bypass options for the surgical treatment of middle cerebral artery aneurysms have been described, little has been reported about similar options for complex aneurysms of the anterior cerebral artery. Case description We report the case of a 15-year-old adolescent girl, in whom a giant A1 segment aneurysm was successfully treated with aneurysm resection followed by saphenous vein interposition grafting. Conclusion Recognizing the option for a bypass can be the key to success in the surgical management of complex intracranial aneurysms. A potential donor vessel of appropriate size (either arterial or venous) should be prospectively identified. Interposition grafting is technically feasible for proximal anterior cerebral artery aneurysms, although technically demanding.

Microsurgical treatment of proximal anterior cerebral artery aneurysms

To explore clinic characteristics of proximal anterior cerebral artery aneurysms and analyzed operative techniques. A review was performed of a total of 362 patients whose aneurysms were surgically treated from June 1995 to December 2003, the morbidity of A(1) aneurysms was 2.2%. To reviewed clinical data of 8 proximal anterior cerebral artery aneurysms patients. All of the aneurysms developed at the takeoff point of perforating arteries, the recurrent artery of Heubner in three cases, the medial proximal lenticulostriate artery in five cases. Six cases aneurysms projected posteriorly, two cases projected inferiorly in the surgical field. The shape of the aneurysms was saccular in all cases and diameter no larger than 5 mm in six cases. Patients were clipped satisfactorily, excellent condition in 7 patient, good condition in one. It is important to preserve the perforating arteries and use suitable clip by avoiding cerebral ischemia.

前大脳動脈水平部 (A1) 脳動脈瘤の検討

Proximal anterior cerebral artery aneurysms (A1 An) are rare and occupy 0.88-4% of all cerebral aneurysms. They are characterized by both vascular anomalies and high incidences of multiplicity. We had 288 patients, including some with multiple surgeries, resulting in a total of 339 operations in our hospital from November 1991 through November 1996. Of the 339 operations, 6 cases (1.8%) were of the A1 An type. We outline the characteristics of A1 An, the diagnoses and operations.Patients were 60 years old on average. Two cases suffered from subarachnoid hemorrhage and the remaining 4 had unruptured aneurysms. All A1 An were saccular and occurred at the origin of perforators. The sizes of 6 cases were 3.0mm on average. In 5 of 6 cases, the location of the A1 An was within one-third of the length of Al on the proximal side. Vascular anomaly existed in none of our cases, but in 1 case multiple aneurysms existed. All cases were approached via ipsilateral frontotemporosphenoidal craniotomy. To avoid excess compression of the frontal base, we set up the patient's head in the vertex down position, taking care to avoid kinking of perforators of Al at the clipping.The size of ruptured A1 An in our cases were 3.4mm and 3.5mm, which is smaller than the average 8.2mm size of aneurysms in other regions. Therefore, it can be said that one of the characteristics of A1 An is the high risk of the rupture in spite of its small size.When we diagnose A1 An, it is important to understand its characteristics. We should not miss the vascular anomaly and the other anuerysms. It is also important to avoid compression of the frontal base and kinking of perforators of Al at the operation.Finally we suggest that operation of A1 An should be positively considered unless it is of belowaverage size as there is a high risk of rupture in such cases.