Anterior Inferior Cerebellar Artery Aneurysm Research Articles

A rare dissecting anterior inferior cerebellar artery aneurysm treated with flow diversion using a silk vista baby device.

Dissecting intracranial pseudoaneurysms represent a challenge for treatment both endovascularly and surgically. We review the treatment course of a ruptured anterior inferior cerebellar artery (AICA) dissecting pseudoaneurysm in a 50-year-old patient and review the history of dissecting aneurysms and AICA aneurysms treatment. An aneurysm cure was achieved using flow diversion in the AICA. The recent introduction of flow diversion devices that can be deployed through 0.017" microcatheters represents a new avenue for treatment of aneurysms. To the best of our knowledge this is the first published case of flow diversion in the(?) AICA to treat a dissecting aneurysm. The introduction of Silk Vista Baby and similar future devices is likely to widen the scope of aneurysm treatment utilizing flow diversion in distal distribution with small parent arteries.

Flow Diversion for Treatment of Anterior Inferior Cerebellar Artery Aneurysms: Mechanism and Pitfalls from a Novel Management Strategy

Anterior inferior cerebellar artery (AICA) aneurysms present a challenge for neurosurgeons and neurointerventionalists alike. Cases of AICA aneurysms managed with endovascular flow diversion at our institute are reviewed with their angiographic outcomes. Both direct and indirect flow diversion provide complete aneurysm occlusion at follow-up. We propose a stratified method of approaching AICA aneurysms based on location, rupture status, and neck size. Careful evaluation of preoperative parameters is paramount in deciding between a surgical or a neuroendovascular approach. Low-profile stents in the future may assist in direct flow diversion of AICA trunk aneurysms. In addition, neurosurgeons need to be well versed in endovascular approaches.

Anterior Inferior Cerebellar Artery Aneurysm in Internal Auditory Canal: A Case of Hemorrhage Caused by Misdiagnosis.

Anterior Inferior Cerebellar Artery Aneurysm in Internal Auditory Canal: A Case of Hemorrhage Caused by Misdiagnosis.

Anterior inferior cerebellar artery (AICA) aneurysms: a radiological study of 15 consecutive patients.

The aneurysms of the anterior inferior cerebellar artery (AICA) are rare lesions of the posterior circulation and to treat them is challenging. We aim to present anatomical and morphological characteristics of AICA aneurysms in a series of 15 patients. The DSA and CT angiography images of AICA aneurysms in 15 consecutive patients were analyzed retrospectively. Different anatomical characteristics were quantified, including morphology, location, width, neck width, length, bottleneck factor, and aspect ratio. Eighty percent of the patients were females. The age was 52.4 ± 9.6 (mean ± SD) years. 11 patients were smokers. Ten patients had a saccular aneurysm and five patients had a fusiform aneurysm. Aneurysm in 10 patients were located in the proximal segment, in three patients in the meatal segment, and in two patients in the distal segment. Ten out of 15 patients presented with a ruptured aneurysm. The size of AICA aneurysms was 14.8 ± 18.9 mm (mean ± SD). The aspect ratio was 0.92 ± 0.47 (mean ± SD) and bottleneck factor was 1.66 ± 1.65 (mean ± SD). AICA aneurysms are rare lesions of posterior circulation predominantly found in females, present predominantly with subarachnoid hemorrhage, and are mostly large in size.

Treatment and Outcome of Anterior Inferior Cerebellar Artery (AICA) Aneurysms: Helsinki Series of 15 Consecutive Patients.

Objective Anterior inferior cerebellar artery (AICA) aneurysms are rare posterior circulation lesions that are challenging to treat. This article presents the treatment and clinical outcome of AICA aneurysms in an unselected cohort of patients. Methods A retrospective analysis of patient record files, digital subtraction angiography, and computed tomography angiography images of 15 consecutive patients harboring AICA aneurysms treated between 1968 and 2017. Results Of the 15 AICA aneurysm patients reviewed, 12 (80%) were females. Twenty percent had intracerebral hemorrhage and 40% presented with intraventricular hemorrhage. Eleven out of 15 (73%) patients presented with subarachnoid hemorrhage (SAH); 82% of SAH patients had a good-grade SAH (Hunt and Hess grade 1-3). Eleven patients (73%) were treated surgically, three (20%) were treated conservatively, and one (7%) had coil embolization. In 27% of patients, a subtemporal approach with anterior petrosectomy was performed. A retrosigmoid approach was used in the remaining 73%. In 18% of the patients, a parent vessel occlusion was necessary to occlude the aneurysm. Five out of 11 (47%) of the patients developed postoperative cranial nerve deficits. Twenty-seven percent developed shunt-dependent hydrocephalus. All patients who presented with an unruptured AICA aneurysm had good clinical outcome (modified Rankin scale [mRS] 1-2). In patients with SAH, 82% achieved good clinical outcome and 18% had poor clinical outcome (mRS 3-6) after 1 year. Conclusion Surgical treatment of AICA aneurysms has a high rate of cranial nerve deficits but most of patients have a good long-term clinical outcome.

Heavily T2-weighted image of a cerebellar infarction due to thrombosed occlusion of an anterior inferior cerebellar artery aneurysm: a case report

68歳女性．右聴力低下とめまいを主訴に前医を受診し，頭部MRIで右前下小脳動脈（anterior inferior cerebellar artery: AICA）領域に新規梗塞を認めた．アテローム血栓性脳梗塞として抗血小板療法を開始したが，1カ月後のMR angiography（MRA）で椎骨動脈合流部近傍に高信号域を認めた．DSAではAICAは描出されず，basi-parallel anatomical scanning（BPAS）でも椎骨動脈合流部近傍の高信号部位と脳底動脈との連続性は明らかでなかった．そこでくも膜下腔の詳細な評価目的にthin sliceでのheavily T2強調画像を撮像し，右AICAと高信号部位が連続していることを証明できたため，AICA血栓化動脈瘤によるAICA閉塞が脳梗塞の原因と診断した．AICAの血栓性動脈瘤の評価に，thin sliceでのheavily T2強調画像が有用な可能性がある．

Microsurgical Clipping of the Ruptured Meatal Segment Anterior Inferior Cerebellar Artery Aneurysm.

Microsurgical Clipping of the Ruptured Meatal Segment Anterior Inferior Cerebellar Artery Aneurysm.

Endovascular treatment of anterior inferior cerebellar artery trunk aneurysms.

The anterior inferior cerebellar artery (AICA) is a very slender and anatomically variable artery that gives off many important perforating arteries that feed the brainstem and nerve-related arteries that feed the inner ear and labyrinth. AICA trunk aneurysms are rare entities that are also difficult to manage. At present, endovascular treatment (EVT) is the preferred choice; however, the understanding of EVT for AICA trunk aneurysms is limited. In this article, we present a literature review on EVT for AICA trunk aneurysms. To promote understanding, we would also provide some illustrative educational cases of our institute. Aneurysms along the AICA trunk can occur alone (isolated AICA aneurysm) or secondary to cerebrovascular shunts (flow-related AICA aneurysm). According to their anatomical location, they can also be divided into proximal and distal types. At present, EVT is the mainstream treatment, mainly including selective coiling with parent artery preservation and parent artery occlusion. Both coils and liquid embolization materials can be used. For AICA trunk aneurysms, EVT is a reasonable choice and should be based on the specific anatomical location, pathology, and collateral circulation. However, there is still controversy as to the specific type of treatment that should be chosen.

Surgical Clipping of a Ruptured Distal Anterior Inferior Cerebellar Artery Aneurysm: A Technical Note.

Aneurysms of the distal anterior inferior cerebellar artery (AICA) are uncommon. They can present with subarachnoid hemorrhage (SAH), cerebellopontine angle syndrome, or a combination of the two. We describe the technique and nuances of microsurgical clipping of a ruptured distal AICA aneurysm using a retrosigmoid approach.After performing the craniotomy, the AICA was exposed in a distal to proximal fashion and the aneurysm and the proximal parent vessel were identified. After establishing proximal control, a clip was placed across the neck of the aneurysm to obliterate it while maintaining flow within the parent vessel. Finally, the flow within the parent vessel was confirmed and the final clip position was checked to ensure that it was not compressing any of the cranial nerves in the vicinity. The aneurysm was completely obliterated, and the parent vessel remained patent.Distal AICA aneurysms are rare and challenging to treat. The retrosigmoid approach is commonly used to treat these aneurysms. Careful planning, which includes studying the vascular anatomy and the aneurysm characteristics, and proficient execution of the procedure can increase the safety and improve outcomes of surgical clipping of these aneurysms.

Challenges in Using the Posterior Inferior Cerebellar Artery for Revascularization of the Anterior Inferior Cerebellar Artery: A Microsurgical Anatomic Study

A bypass is usually required to prevent ischemia during the treatment of anterior inferior cerebellar artery (AICA) aneurysms. The intracranial (IC)-to-IC bypass provides several advantages over the extracranial-to-IC bypass in the posterior fossa. However, there are only 2 case reports about AICA revascularization with the posterior inferior cerebellar artery (PICA). We aimed to investigate the microsurgical anatomical challenges for PICA to AICA anastomosis. Ten cadaveric heads injected with colored silicone were inspected on both sides using a lateral transcondylar approach. After the donor and recipient arteries were examined from the posterior side, neurovascular contents of the posterior fossa were excised and the origin, course, and variations of both arteries were investigated from the anterior view. The diameters of the AICA and PICA segments and the intersegment distance were measured. PICA variations and posteromedial origins from the vertebral artery were identified in 8 of the 20 right and 6 of the 20 left sides, and the first segment of the PICA was not present in 7 sides. Furthermore, in 18 sides, the PICA was trapped between the lower cranial nerves and dentate ligaments. Therefore the donor artery could not be brought closer than 1 cm to the recipient artery in 19 sides. Moreover, AICA variations were identified in 6 sides, and in 12 sides, the diameter of the recipient artery was <1 mm. The mostly PICA-related issues made PICA-to-AICA anastomosis unfeasible in all cadaveric heads included in the study.

Limited Intradural Anterior Petrosectomy for Upper Basilar Aneurysms: A Technical Note

The extradural anterior petrosectomy is a widely used skull base approach to the upper petroclival region, basilar trunk, and ventral pons. However, there is significant procedure-related morbidity and a complete petrosectomy is required, as the intradural structures are not in view at the time of drilling. We describe an intradural anterior petrosectomy for aneurysms of the basilar trunk and anterior inferior cerebellar artery with intraoperative photographs and artwork to illustrate the approach. A temporal craniotomy is made at the root of the zygoma and middle fossa floor. After opening dura, the trochlear nerve is identified at the tentorial edge. The tentorium is incised posterior to the trochlear nerve and the incision is carried forward across the cisternal segment of the trigeminal nerve toward V3 and the superior petrosal sinus. The petrous apex is identified and drilled lateral and posterior to V3 with a diamond bur. Intraoperative navigation is useful to confirm its location. Once posterior fossa dura is identified, the superior petrosal sinus may be safely cauterized and divided, connecting the tentorial incision with an incision in the posterior fossa dura, and exposing the upper basilar trunk and its branches. Additional bone is removed only as needed. Two patients underwent successful treatment of a basilar trunk perforator and anterior inferior cerebellar artery aneurysm with a subtemporal approach and tailored intradural petrosectomy. The intradural anterior petrosectomy allows limited drilling of the petrous apex and provides sufficient exposure of upper basilar artery aneurysms.

An a3-Anterior Inferior Cerebellar Artery to p3-Posterior Inferior Cerebellar Artery Bypass With Thrombectomy and Trapping of an Anterior Inferior Cerebellar Artery Aneurysm: 3-Dimensional Operative Video.

In situ bypasses to the anterior inferior cerebellar artery (AICA) are unusual because, with only one artery in the cerebellopontine angle (CPA), no natural intracranial donors parallel its course. In rare cases, the posterior inferior cerebellar artery (PICA) may have the tortuosity or redundancy to be mobilized to the AICA to serve as a donor. This video demonstrates this p3 PICA-to-a3 AICA in situ side-to-side bypass. A 75-yr-old woman presented with ataxia and hemiparesis from a large thrombotic right AICA aneurysm compressing the brainstem. Strategy consisted of bypass, trapping, and brainstem decompression. Written informed consent for surgery was obtained from the patient. A hockey-stick incision was made to harvest the occipital artery as a backup donor, but its diminutive caliber precluded its use. The bypass was performed through an extended retrosigmoid craniotomy. The aneurysm was trapped completely and thrombectomized to relieve the pontine mass effect. Indocyanine green videoangiography confirmed patency of the bypass, retrograde filling of the AICA to supply pontine perforators, and no residual aneurysmal filling. This unusual in situ bypass is possible when redundancy of the AICA and PICA allow their approximation in the CPA. The anastomosis is performed lateral to the lower cranial nerves in a relatively open and superficial plane. The extended retrosigmoid approach provides adequate exposure for both the bypass and aneurysm trapping. In situ AICA-PICA bypass enables anterograde and retrograde AICA revascularization with side-to-side anastomosis. The occipital artery-to-AICA bypass and the V3 vertebral artery-to-AICA interpositional bypass are alternatives when intracranial anatomy is unfavorable for this in situ bypass.1-6 Used with permission from Barrow Neurological Institute, Phoenix, Arizona.

Anterior Inferior Cerebellar Artery Bypasses: The 7-Bypass Framework Applied to Ischemia and Aneurysms in the Cerebellopontine Angle.

Aneurysms of the anterior inferior cerebellar artery (AICA) are rare. Primary clip reconstruction of these lesions is a challenge because of the limited surgical exposure and frequent nonsaccular aneurysm morphology. Endovascular treatment options exist, but outcomes are equivalent to those for open surgery. Historically, AICA aneurysms not amenable to clipping or primary coiling have been treated with parent vessel sacrifice. To determine whether an AICA revascularization strategy would afford for the safe treatment of AICA aneurysms and other posterior circulation pathologies without compromising perfusion of the AICA territories. We describe a series of AICA bypasses to treat 4 AICA aneurysms and 3 vertebral artery/AICA occlusions. We used 7 types of bypasses to revascularize the AICA territory. Bypass types included extracranial-to-intracranial (EC-IC) bypass without an interpositional graft, EC-IC with an interpositional graft, in situ bypass, reanastomosis, reimplantation, intracranial-to-intracranial bypass with interpositional graft, and combination bypasses. In particular, we performed the following 7 bypasses: OA-a3 AICA, OA-RAG-a3 AICA, p3 PICA-a3 AICA, a2 AICA reanastomosis, V4 VA-a3 AICA, V3 VA-SVG-a3 AICA, and a combined OA-a3 AICA bypass and p3 PICA reanastomosis. AICA revascularization allows for the safe treatment of AICA aneurysms and other posterior circulation pathologies without compromising perfusion of the AICA territories. All 7 AICA bypasses are feasible for application to AICA aneurysms and ischemic disease. Our experience with the 7-bypass framework demonstrates the utility of the framework as a decision-making tool and the breadth of bypass innovation possible in this anatomically challenging region.

Retrosigmoid Clip Anterior Inferior Cerebellar Artery Aneurysm: 2-Dimensional Operative Video.

Aneurysms of the anterior inferior cerebellar artery (AICA) are rare and require a considerate approach to facilitate successful and safe clipping. Surgical approaches vary and are dependent on the relation of the aneurysm to the internal acoustic meatus. An anterior approach should be considered for lesions medial to the meatus. Lesions adjacent to the meatus can be approached via a retrosigmoid or translabyrinthine approach. Lesions lateral to the meatus can be approached via a retrosigmoid or far lateral approach. This patient had a previously ruptured AICA aneurysm in the meatal region for which a retrosigmoid approach was selected. The approach involved locating the AICA distally and tracking it proximally to the origin off the basilar artery. A clip was applied across the aneurysm neck to facilitate occlusion while preserving parent vessel flow. The patient gave informed consent for surgery and video recording. Institutional review board approval was deemed unnecessary. Used with permission from Barrow Neurological Institute, Phoenix, Arizona.

A giant anterior inferior cerebellar artery aneurysm in the guise of a cerebellopontine angle tumour: A case report and review of literature

Giant intracranial aneurysms, and aneurysms in the posterior circulation of the brain, are each rare entity when considered separately. It is more uncommon to find both coexisting. Aneurysms usually present when they rupture and haemorrhage, and for one to present with non-haemorrhagic symptoms, is rarer. The authors present an unusual case of a giant aneurysm of the anterior inferior cerebellar artery masquerading as a cerebellopontine angle tumour with cerebellar signs. The patient was treated with a retromastoid suboccipital craniectomy and microsurgical clipping and excision, with excellent results. A PubMed search of existing literature was carried out and reviewed and has been discussed.

The future of open vascular neurosurgery: perspectives on cavernous malformations, AVMs, and bypasses for complex aneurysms.

Despite the erosion of microsurgical case volume because of advances in endovascular and radiosurgical therapies, indications remain for open resection of pathology and highly technical vascular repairs. Treatment risk, efficacy, and durability make open microsurgery a preferred option for cerebral cavernous malformations, arteriovenous malformations (AVMs), and many aneurysms. In this paper, a 21-year experience with 7348 cases was reviewed to identify trends in microsurgical management. Brainstem cavernous malformations (227 cases), once considered inoperable and managed conservatively, are now resected in increasing numbers through elegant skull base approaches and newly defined safe entry zones, demonstrating that microsurgical techniques can be applied in ways that generate entirely new areas of practice. Despite excellent results with microsurgery for low-grade AVMs, brain AVM management (836 cases) is being challenged by endovascular embolization and radiosurgery, as well as by randomized trials that show superior results with medical management. Reviews of ARUBA-eligible AVM patients treated at high-volume centers have demonstrated that open microsurgery with AVM resection is still better than many new techniques and less invasive approaches that are occlusive or obliterative. Although the volume of open aneurysm surgery is declining (4479 cases), complex aneurysms still require open microsurgery, often with bypass techniques. Intracranial arterial reconstructions with reimplantations, reanastomoses, in situ bypasses, and intracranial interpositional bypasses (third-generation bypasses) augment conventional extracranial-intracranial techniques (first- and second-generation bypasses) and generate innovative bypasses in deep locations, such as for anterior inferior cerebellar artery aneurysms. When conventional combinations of anastomoses and suturing techniques are reshuffled, a fourth generation of bypasses results, with eight new types of bypasses. Type 4A bypasses use in situ suturing techniques within the conventional anastomosis, whereas type 4B bypasses maintain the basic construct of reimplantations or reanastomoses but use an unconventional anastomosis. Bypass surgery (605 cases) demonstrates that open microsurgery will continue to evolve. The best neurosurgeons will be needed to tackle the complex lesions that cannot be managed with other modalities. Becoming an open vascular neurosurgeon will be intensely competitive. The microvascular practice of the future will require subspecialization, collaborative team effort, an academic medical center, regional prominence, and a large catchment population, as well as a health system that funnels patients from hospital networks outside the region. Dexterity and meticulous application of microsurgical technique will remain the fundamental skills of the open vascular neurosurgeon.

Meatal Anterior Inferior Cerebellar Artery Aneurysm with AICA-PICA Complex: Endovascular Coiling and Parent Artery Preservation

AbstractSecondary stroke prevention requires early initiation of antiplatelet; therefore, stroke mimics need to be ruled out particularly in circumstances when antiplatelet therapy can be of disastrous consequences. A 54-year-old female patient presented to the emergency department with symptoms of sudden-onset deviation of angle of mouth to the right side, left eye ptosis, and occipital headache for past 4-hour duration. Neurologic examination revealed right-sided gaze-dependent torsional nystagmus and left lower motor neuron facial weakness. An embolic posterior circulation stroke secondary to vertebral artery dissection was suspected. Diffusion-weighted imaging (DWI) did not show any acute infarcts, and careful review of susceptibility-weighted imaging (SWI) scans showed hemorrhage in the fourth ventricle. Subsequent digital subtraction angiography (DSA) was done, which showed left anterior inferior cerebellar artery (AICA) aneurysm involving its intrameatal segment with AICA-posterior inferior cerebellar artery (PICA) complex. Retrospective review of computed tomographic (CT) angiography images showed small aneurysm in the internal auditory meatus, which is difficult to discern secondary to adjacent bony structure and smaller size of the aneurysm. The patient underwent endovascular coiling of the aneurysm with preservation of the parent artery. Our experience concluded that these clinical features suggest remote subarachnoid hemorrhage secondary to the ruptured of AICA intrameatal segment aneurysm with left facial nerve paralysis and peripheral cochlear vestibular changes secondary to either compression (mechanical or pulsations of the aneurysm sac) or ischemia of vestibular apparatus. The neurointerventionist should consider the possibility of aneurysmal rupture, especially in cases of atypical location of hemorrhage and no signs of infarct on neuroimaging of posterior circulation stroke.

Revascularization of the Anterior Inferior Cerebellar Artery Using Extracranial and Intracranial Donors: A Morphometric Cadaveric Study

Anterior inferior cerebellar artery (AICA) aneurysms are rare, accounting for 0.2%-1.3% of all intracranial aneurysms. The standard treatment is often endovascular embolization or neck clipping; however, sacrifice of the parent vessel is sometimes necessary. Addition of revascularization procedures is a subject of controversy. The occipital artery (OA) has been used as a donor for bypass, but recently there has been a trend toward intracranial-intracranial approaches. The posterior inferior cerebellar artery (PICA)-AICA side-to-side bypass may serve as a safe alternative. To characterize the PICA-AICA side-to-side bypass and the OA-AICA end-to-side bypass and review the literature relevant to AICA revascularization. We performed a far-lateral approach on 12 cadaveric specimens and analyzed the regional anatomy. On this basis, we performed either an OA-AICA or a PICA-AICA bypass and took morphometric measurements relevant to the technique. PICA-AICA bypass was successful in 6/12 specimens. The length of the flocculopeduncular segment was 42.6 ± 15.8 mm in the specimens in which the bypass was feasible and 26.2 ± 7.2 mm in those in which the bypass was not feasible (P= 0.04). Mean distance between AICA and PICA was 5.3 ± 4 mm in the specimens in which side-to-side bypass was feasible and 11.6 ± 4.2 mm in the specimens in which it was not (P= 0.02). OA-AICA end-to-side bypass was feasible in all the specimens (75% in the flocculopeduncular segment; 25% in the cortical segment). This is the first cadaveric study analyzing the PICA-AICA side-to-side bypass for AICA revascularization. Our analyses provide evidence for the feasibility of this bypass and document the anatomic variations that may indicate its use.

Middle Meningeal Artery to Premeatal Anterior Inferior Cerebellar Artery Bypass via Anterior Petrosectomy: An Anatomic Feasibility Study

Anterior inferior cerebellar artery (AICA) aneurysms are rare with no optimal consensus on management strategies. When treatment requires parent artery occlusion, postoperative ischemic or neuropathic complications can occur. This study evaluated the feasibility of direct revascularization of premeatal AICA using the middle meningeal artery (MMA) as the donor through an anterior petrosectomy window. Ten specimens were used for surgical simulation of MMA-AICA bypass. MMA was harvested from the dura down to the foramen spinosum. An anterior petrosectomy approach was performed on each specimen, and AICA was exposed up to its origin from the basilar artery. The lateral pontine (A2) segment was mobilized laterally, and the end-to-end anastomosis was completed. Measurements of the required length of the AICA, MMA, and their calibers at the anastomotic site were recorded. MMA-AICA bypass was feasible in all specimens. The mean length of AICA from the origin at the anastomotic site was 7.3 ± 1.7 mm, and mean length of MMA from the foramen spinosum was 34.6 ± 5.1 mm. Mean calibers of MMA were 2.1 ± 0.2 mm at the foramen spinosum and 1.7 ± 0.2 mm at the anastomosis. A2 caliber was 1.6 ± 0.3 mm with average lateral mobilization of 7.6 ± 2.7 mm. This study establishes the feasibility of MMA-AICA bypass via a middle fossa approach. The matching caliber of the 2 arteries makes end-to-end anastomosis easy to achieve. The MMA is a suitable donor artery that avoids the use of an interposition graft and the complications of extracranial-intracranial bypass.

Ruptured partially thrombosed anterior inferior cerebellar artery aneurysms: two case reports and review of literature.

ABSTRACTAneurysms arising from the distal anterior inferior cerebellar artery (AICA) are very rare. When the parent artery is an AICA−posterior inferior cerebellar artery (PICA) variant, occlusion of the artery, even distal to the meatal loop, leads to a significant area of cerebellar infarction. We report two cases of ruptured partially thrombosed distal AICA aneurysms. In both cases, the parent artery was an AICA−PICA variant. The aneurysms were clipped in one case and trapped following occipital artery (OA)−AICA anastomosis in another case. It is important to keep the OA as a donor artery for revascularization in the treatment of the AICA−PICA variant aneurysms, especially when the absence of intra-aneurysmal thrombus is not comfirmed preoperatively.