Anatomical Study of Anterior Inferior Cerebellar Artery and Its Reciprocal Relationship with Posterior Inferior Cerebellar Artery Based on Angiographic Data

Is Common Trunk Anomaly Frequent in Hemifacial Spasm? Comparison with Normal Subjects Using Magnetic Resonance Imaging

OBJECTIVE

Hemifacial spasm (HFS) results from vascular compression at the root exit of the facial nerve. Although the underlying etiology has yet to be identified, it has been suggested that congenital vascular anomalies are involved. We have hypothesized common trunk anomaly of the anterior inferior cerebellar artery (AICA) and posterior inferior cerebellar artery (PICA) which may play a role in HFS. However, no previous studies have directly compared the incidence of this anomaly between HFS patients and normal subjects. The present study was designed to address this gap in the literature.

METHODS

This case-control study compared magnetic resonance angiography data from 65 HFS patients and 65 normal subjects. Dominant AICA/PICA is defined as the absence of PICA/AICA, with the remaining AICA/PICA supplying both vascular territories. The term "common trunk" encompasses both dominant AICA and dominant PICA. The frequency of common trunk and dominant AICA/PICA was compared between the 2 groups.

RESULTS

There were no significant differences in the incidence of a common trunk (68.5% and 64.6%), dominant AICA (30.8% and 32.3%) and dominant PICA (37.7% and 32.3%) between the 2 groups. Additionally, no differences were found in the frequency of atherosclerosis risk factors.

CONCLUSIONS

There was no apparent association between common trunk anomaly and HFS. It is suspected that some vascular anomalies other than a common trunk are involved in HFS.

Embolization of an arteriovenous malformation using the "pressure cooker" technique in the AICA via a marathon microcatheter: A case report

INTRODUCTION AND IMPORTANCE

Embolization of an arteriovenous malformation (AVM) via the anterior inferior cerebellar artery (AICA) is difficult. The "pressure cooker" technique in the AICA via a marathon microcatheter can be effective.

CASE STUDY

A 43-year-old man with a cerebellar hematoma involving the brainstem. Angiography revealed an AVM supplied by the right AICA. Embolizing the AVM by casting an Onyx-18 liquid embolic system assisted by the "pressure cooker" technique was planned. An Apollo microcatheter was used for Onyx casting, and a Marathon microcatheter was used to establish a coiling plug to prevent Onyx reflux. The AVM was obliterated. Postoperatively, burr hole drainage of the cerebellar hematoma was performed. Postoperative computed tomography showed that the cerebellar hematoma and hydrocephalus had resolved. Magnetic resonance imaging revealed that there was no new serious infarction from damage to the cerebellum or brainstem. The patient recovered well.

CLINICAL DISCUSSION

During Onyx casting, the drawback is that reflux can occlude normal vessels. The "pressure cooker" technique was useful for preventing Onyx reflux and for driving the Onyx to penetrate the AVM. However, it was difficult to use this technique in slim AICA; the Marathon microcatheter had a thinner tip than other microcatheters, and it can be used to establish the "pressure cooker" technique. This technique provides more solutions for AVMs in transarterial embolization through small feeding arteries.

CONCLUSION

In a selective case, it was feasible to use the "pressure cooker" technique in the AICA via a Marathon microcatheter to embolize the AVM.

An Uncommon Coexistence of Ischemic Stroke in a Multiple Sclerosis Patient With Duplicated Superior Cerebellar Artery: A Case Report From Saudi Arabia

The case describes a middle-aged man with well-managed multiple sclerosis who experienced an acute ischemic stroke attributed to a rare anatomical variant - a duplicated left superior cerebellar artery (SCA). Despite his prior lack of neurological issues, the patient presented with severe headaches and walking difficulties. Imaging confirmed the ischemic stroke in the left SCA territory and revealed the duplicated left SCA. This case highlights the importance of considering cerebrovascular anatomy in stroke risk assessment, especially in individuals with unique vascular features such as duplicated SCAs, which can predispose to vascular complications.

Current research status and future of endovascular treatment for basilar artery aneurysms

Aneurysms occurring along the basilar artery (BA) account for <1% of all intracranial aneurysms. Endovascular treatment (EVT) in particular is recommended for large unruptured BA aneurysms and ruptured BA aneurysms. Given that EVT techniques vary, a detailed review of EVT for BA aneurysms is necessary. In this review, the following issues were discussed: the anatomy and anomalies of the BA, the classification of BA aneurysms, the natural history of BA aneurysms, the status of open surgery, the use of EVT for various types of BA aneurysms and the deployment of new devices. According to the findings of this review and based on our experience in treating BA aneurysms, traditional coiling EVT is still the optimal therapy for most BA aneurysms. However, in some BA aneurysms, flow diverter (FD) deployment can be used. In addition, there are also some new devices, such as intrasaccular flow disruptors and stent-like devices that can be used to treat BA aneurysms. In general, EVT can yield good clinical and angiographic outcomes for patients with BA aneurysms. In addition, recent new devices and techniques, such as new-generation FDs generated via surface modification and virtual reality simulation techniques, show promise for EVT for BA aneurysms. These devices and techniques may further improve EVT outcomes for BA aneurysms.

The Anterior Inferior Cerebral Artery Variability in the Context of Neurovascular Compression Syndromes: A Narrative Review

The anterior inferior cerebellar artery (AICA) is situated within the posterior cranial fossa and typically arises from the basilar artery, usually at the pontomedullary junction. AICA is implicated in various clinical conditions, encompassing the development of aneurysms, thrombus formation, and the manifestation of lateral pontine syndrome. Furthermore, owing to its close proximity to cranial nerves within the middle cerebellopontine angle, AICA's pulsatile compression at the root entry/exit zone of cranial nerves may give rise to specific neurovascular compression syndromes (NVCs), including hemifacial spasm (HFS) and geniculate neuralgia concurrent with HFS. In this narrative review, we undertake an examination of the influence of anatomical variations in AICA on the occurrence of NVCs. Significant methodological disparities between cadaveric and radiological studies (CTA, MRA, and DSA) were found, particularly in diagnosing AICA's absence, which was more common in radiological studies (up to 36.1%) compared to cadaver studies (less than 5%). Other observed variations included atypical origins from the vertebral artery and basilar-vertebral junction, as well as the AICA-and-PICA common trunk. Single cases of arterial triplication or fenestration have also been documented. Specifically, in relation to HFS, AICA variants that compress the facial nerve at its root entry/exit zone include parabola-shaped loops, dominant segments proximal to the REZ, and anchor-shaped bifurcations impacting the nerve's cisternal portion.

How I do it: endoscopic microvascular decompression for hemifacial spasm associated with anterior inferior cerebellar artery-posterior inferior cerebellar artery common trunk

BACKGROUND

Multiple vessels from the anterior inferior cerebellar artery-posterior inferior cerebellar artery common trunk (APC) variation of the posterior circulation can cause hemifacial spasm (HFS).

METHOD

Endoscopic microvascular decompression (eMVD) was performed using 0° and 30° endoscopes through a retrosigmoid keyhole. The root exit zone (REZ) was decompressed by transpositioning the offending anterior inferior cerebellar artery (AICA) and posterior inferior cerebellar artery (PICA) arising from the APC under excellent endoscopic view.

CONCLUSION

eMVD is an advanced, minimally invasive and reliable technique to resolve the neurovascular conflict (NVC) in HFS due to offenders from APC.

Endovascular treatment for anterior inferior cerebellar artery-posterior inferior cerebellar artery (AICA-PICA) common trunk variant aneurysms: Technical note and literature review

The Anterior Inferior Cerebellar Artery-Posterior Inferior Cerebellar Artery (AICA-PICA) common trunk is a rare variant of cerebral posterior circulation in which a single vessel originating from either the basilar or vertebral arteries supplies both cerebellum and brainstem territories. We present the first case of an unruptured right AICA-PICA aneurysm treated with flow diversion using a Shield-enhanced pipeline endovascular device (PED, VANTAGE Embolization Device with Shield Technology, Medtronic, Canada). We expand on this anatomic variant and review the relevant literature. A 39-year-old man presented to our treatment center with vertigo and right hypoacusis. The initial head CT/CTA was negative, but a 4-month follow-up MRI revealed a 9 mm fusiform dissecting aneurysm of the right AICA. The patient underwent a repeat head CTA and cerebral angiogram, which demonstrated the presence of an aneurysm on the proximal portion of an AICA-PICA anatomical variant. This was treated with an endovascular approach that included flow diversion via a PED equipped with Shield Technology. The patient's post-procedure period was uneventful, and he was discharged home after two days with an intact neurological status. The patient is still asymptomatic after a 7-month follow-up, with MR angiogram evidence of stable aneurysm obliteration and no ischemic lesions. Aneurysms of the AICA-PICA common trunk variants have a high morbidity risk due to the importance and extent of the territory vascularized by a single vessel. Endovascular treatment with flow diversion proved to be both safe and effective in obliterating unruptured cases.

Vascular supply of the hindbrain: Basic longitudinal and axial angioarchitecture

The basic pattern of arterial vascularization is highly conserved across vertebrates and develops under neuromeric rules. The hindbrain has an angioarchitecture that is homologous to that of the spinal cord, and the hindbrain vascular system can be analyzed at the longitudinal and axial structures. During development, there are two main longitudinal arteries: the longitudinal neural artery and primitive lateral basilovertebral anastomosis. This review discusses the basic pattern of the blood supply of the hindbrain, the development of vascularization, and the anatomical variations, with a special reference to the embryological point of view of two main longitudinal anastomoses (longitudinal neural artery and primitive lateral basilovertebral anastomosis). The formation of commonly observed variations, such as fenestration and duplication of the vertebrobasilar artery, or primitive trigeminal artery variant, can be explained by the partial persistence of the primitive lateral basilovertebral anastomosis. Understanding the pattern and the development of the blood supply of the hindbrain provides useful information of the various anomalies of the vertebrobasilar junction and cerebellar arteries.

Endovascular treatment of posterior inferior cerebellar artery trunk aneurysm

BACKGROUND

The posterior inferior cerebellar artery (PICA) generally originates from the vertebral artery (VA) and is the most complex cerebellar artery. Aneurysms can occur at any site along the PICA trunk. Although most PICA aneurysms are located at the VA-PICA junction, a small proportion is located at the PICA trunk. Endovascular treatment (EVT) of aneurysms in the PICA trunk may be difficult and complex.

METHODS

We performed a review to expound upon EVT of PICA trunk aneurysms.

RESULTS

The PICA can be divided into five segments (p1-5); the p1-3 segments are proximal segments, and the p4-5 segments are distal segments. Most PICA trunk aneurysms are dissecting aneurysms. Sometimes, the PICA can give rise to flow-related aneurysms in association with cerebellar arteriovenous malformations. Most aneurysms of the PICA trunk require aggressive treatment, especially those that have ruptured. Currently, the EVT mainly includes selective coiling with/without stent assistance and parent artery occlusion. Recently, some new devices, such as flow diversion and Barricade and Kaneka ED coils, can be used to treat PICA trunk aneurysms. The risk of complications with EVT seems to be higher; however, most complications are only transient or mild, and some are even clinically silent. In addition, open surgery is still an important option.

CONCLUSION

For PICA trunk aneurysms, the treatment choice should be assessed on a case-by-case basis. The rate of permanent morbidity of the EVT is low. EVT is an effective method for treating PICA trunk aneurysms.

Abducens nerve palsy in a congenital anomalous neurovascular development of the sixth cranial nerve and anterior inferior cerebellar artery: A case report

Abducens nerve palsy is a common ocular motor paralysis with a broad set of etiopathogenetic causes. Magnetic resonance imaging is a key diagnostic technique to investigate organic causes of sixth nerve palsy, as it allows a detailed representation of the course of the nerve, particularly in its intracisternal tract. Anatomical variants of the sixth cranial nerve comprise duplications and fenestrations in various traits. Anatomical variants of cerebellar arteries have also been described. We report the case of a patient with abducens nerve palsy presumably related to a neurovascular conflict due to a peculiar anatomical variant, which consists in a cerebellar artery passing through the intracisternal duplication of the abducens nerve.

Endovascular treatment of anterior inferior cerebellar artery trunk aneurysms

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Case Report: Can Ruptured Aneurysms in the Hypoplastic and Plexiform Posterior Inferior Cerebellar Arteries Be Safely Occluded?

Aneurysms arising from the posterior inferior cerebellar artery (PICA) are not rare and may originate from the proximal or peripheral segment of the PICA. However, when the affected PICA is hypoplastic and plexiform, it is difficult to occlude the aneurysm without sacrificing the parent vessel, the PICA. This type of aneurysm is rare, and whether it is safe to occlude the aneurysm and the parent artery, in cases of a ruptured aneurysm of the hypoplastic and plexiform PICA, has not been adequately studied and is still open to debate. In this report, two patients with ruptured aneurysms in the hypoplastic and plexiform PICA were presented. Both patients were admitted to our hospital for subarachnoid hemorrhage. After team discussions between the neurosurgeons and neurointerventionalists, the aneurysm and parent PICA had to be occluded via endovascular treatment under general anesthesia. One of the patients developed postprocedural brainstem infarction and exhibited favorable recovery. The other patient died of pulmonary infection, although improvement in the postoperative state was observed. Although rare, aneurysms can originate from the hypoplastic and plexiform PICA. Occluding the aneurysm and hypoplastic parent PICA via endovascular treatment might be a reasonable option.

The cerebral artery in cynomolgus monkeys (Macaca fascicularis)

Cerebral artery structure has not been extensively studied in primates. The aim of this study was to examine the cerebrovascular anatomy of cynomolgus monkeys (Macaca fascicularis), which are one of the most commonly used primates in medical research on human diseases, such as cerebral infarction and subarachnoid hemorrhage. In this study, we investigated the anatomy and diameter of cerebral arteries from 48 cynomolgus monkey brain specimens. We found three anatomical differences in the vascular structure of this species compared to that in humans. First, the distal anterior cerebral artery is single. Second, the pattern in which both the anterior inferior cerebellar artery and posterior inferior cerebellar artery branch from the basilar artery is the most common. Third, the basilar artery has the largest diameter among the major arteries. We expect that this anatomical information will aid in furthering research on cerebrovascular disease using cynomolgus monkeys.

Recurrent vertebrobasilar strokes and transient-ischemic attacks with challenging workup: Case report

Detecting the stroke etiology in young patients can be challenging. Among others, determining causality between ischemic stroke and patent foramen ovale (PFO) remains a complicated task for stroke neurologists, given the relatively high prevalence of PFOs. Thorough diagnostic workup to identify incidental vascular risk factors and rare embolic sources is crucial to avoid premature PFO closure suggesting successful secondary stroke prevention. In this paper, we report on a 38-year-old patient with recurrent vertebrobasilar territory, especially right posterior inferior cerebellar artery (PICA) territory strokes. After the initial suspicion of a left vertebral artery (VA) dissection was not confirmed by ultrasound and magnetic resonance imaging (MRI) and other major risk factors were excluded, a PFO was detected and closed. Successful PFO closure was confirmed by transesophageal echocardiography, yet recurrent transient-ischemic attacks and vertebrobasilar strokes, especially during nighttime and in the early morning, occurred despite various antiplatelet and antithrombotic regimes and a persistent right-to-left shunt was detected by bubble transcranial Doppler. Finally, MRI after another vertebrobasilar infarction detected a transient left VA occlusion that finally led to the diagnosis of a left VA pseudoaneurysm from an incident emboligenic dissection in the atlas segment. This pseudoaneurysm together with an anatomical variant of the right PICA originating with the right anterior inferior cerebellar artery from the basilar artery finally explained the recurrent ischemic events of the patient. After successful treatment with coil occlusion, the patient suffered no further stroke and recovered completely. In summary, stroke in the young remains a diagnostic challenge. The incidental finding of a PFO should not deter from thorough stroke workup and the follow-up of these patients including PFO closure verification should be performed under the guidance of vascular neurologists.

Progression in Moyamoya Disease: Clinical Feature, Neuroimaging Evaluation and Treatment

Moyamoya disease (MMD) is a chronic cerebrovascular disease characterized by progressive stenosis of the arteries of the circle of Willis, with the formation of collateral vascular network at the base of the brain. Its clinical manifestations are complicated. Numerous studies have attempted to clarify the clinical features of MMD, including its epidemiology, genetic characteristics, and pathophysiology. With the development of neuroimaging techniques, various neuroimaging modalities with different advantages have deepened the understanding of MMD in terms of structural, functional, spatial, and temporal dimensions. At present, the main treatment for MMD focuses on neurological protection, cerebral blood flow reconstruction, and neurological rehabilitation, such as pharmacological treatment, surgical revascularization, and cognitive rehabilitation. In this review, we discuss recent progress in understanding the clinical features, in the neuroimaging evaluation and treatment of MMD.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

The mostly PICA-related issues made PICA-to-AICA anastomosis unfeasible in all cadaveric heads included in the study.

In situ suturing of a post-meatal segment of the anterior inferior cerebellar artery dissected by an aneurysm: A technical note

Aneurysms originating along the peripheral portion of the anterior inferior cerebellar artery (AICA) are rare entities. As a result of the small diameter of the AICA, it is very challenging to preserve the parent artery during endovascular treatment for a peripheral AICA aneurysm. In this report, we present a rare case of aneurysm in the a2 segment of the right AICA. During surgery, the aneurysm was found to be a dissecting aneurysm. As the tissue of the aneurysm neck had a similar thickness to that of the adjacent normal vessel, interrupted suturing of the vessel was performed after partial removal and trimming of the aneurysm wall. The patient experienced an uneventful postoperative recovery. No other neurological deficit was noted. Magnetic resonance imaging three days after surgery revealed no acute ischaemia in the brainstem and cerebellum. Catheter angiography nine months later showed no recurrence of the aneurysm or stenosis of the AICA. The a2 segment of the AICA runs tortuously along the subarachnoid space of the cerebellopontine angle, which permits higher vascular mobility. In selected cases, in situ suturing or re-anastomosis could be considered for a2 segment aneurysms.

Endovascular treatment for the flow-related aneurysm originating from an anterior inferior cerebellar artery supplying the cerebellar arteriovenous malformation

BACKGROUND

When a flow-related aneurysm originates from an anterior inferior cerebellar artery (AICA) supplying the cerebellar arteriovenous malformation (AVM), the management becomes very complicated. Endovascular treatment (EVT) was an option, but no consensus has been achieved.Methods and materials: A retrospective investigation was performed for patients with flow-related aneurysm originating from an AICA supplying the cerebellar AVM.

RESULTS

Ten patients, harboring 13 aneurysms, were identified. Of the 5 a1 aneurysms, 2 underwent stent assisted coiling, 2 underwent parent artery occlusion (PAO), and 1 was intact. Of the 8 a2 aneurysms, 3 underwent coiling with preservation of the AICA, 3 underwent PAO with Onyx, 1 underwent PAO with coils, and 1 was intact. Seven patients underwent partial embolization of the cerebellar AVM, 3 were intact. One patient died 6 hours postoperatively for cerebellar AVM rebleeding. During a follow-up from 6 months to 6 years, 9 patients had favorable recovery.

CONCLUSION

For the flow-related aneurysm originating from an AICA supplying the cerebellar AVM, the EVT depends on the specific circumstances. When the aneurysm is located at the a1 segment, coiling of the aneurysm with preservation of the parent AICA should be performed. PAO is the last resort. When the a2 aneurysm is proximal to the internal auditory artery, coiling of the aneurysm with preservation of the AICA is preferred. When the aneurysm is distal to the internal auditory artery, PAO can be safely performed.

Morphologic characterization of the anterior inferior cerebellar artery: a direct anatomic study

OBJECTIVE

An adequate knowledge of the anterior inferior cerebellar artery (AICA) is oriented to the morphological sciences, clinical management and surgical planning of the posterior fossa. We aimed to determine the morphology of AICA in a sample from Colombian population.

METHOD

We studied 92 AICA from fresh cadavers. For each specimen, the vertebral arteries were injected with 100 cc of semi-synthetic resin (a mixture of Palatal E210® BASF 80 cc and Styrene 20 cc) dyed with mineral red. The biometrics and morphological variables of AICA were registered.

RESULTS

AICA originated at 9.9 ± 3.2 mm from the vertebrobasilar junction. In 12 samples (8.1%), we observed a common trunk between AICA and posterior inferior cerebellar artery, which presented a caliber of 1.56 ± 0.23 mm and a length of 11.3  ± 3. 53 mm. In 80 (51.3%) specimens, AICA was originated from the proximal segment of basilar artery, while in 76 (48.7%) of them emerged from the medium segment. The AICA bifurcation distance from its origin was less than 20 mm in 20.5% of cases; between 20 and 40 mm in 62.3%. In its trajectory, AICA passed ventral to the facial nerve in 85 samples (53.2%), dorsal to the facial nerve in 68 samples (43.6%) and between the roots in 5 samples (3.2%).

CONCLUSIONS

The origin of the AICA from the proximal segment of the basilar artery is confirmed in this study, which disagrees with reports that point out its origin in the middle segment.

Endovascular Treatment of Traumatic Transection of the Vertebral Artery Caused by Penetrating Injury to the Oropharynx in a Pediatric Patient

BACKGROUND

Pediatric isolated penetrating traumatic vertebral artery injuries require urgent multidisciplinary management as they may lead to potentially fatal posterior circulation ischemia.

CASE DESCRIPTION

We present a 19-month-old patient with an isolated penetrating vertebral artery injuries at the V2 segment of the right vertebral artery and report our strategy for her endovascular treatment which involved simultaneous coil embolization and foreign body removal.

CONCLUSION

Endovascular treatment can be considered first line treatment of oral penetrating injuries to the vertebral artery, where the penetrating object has an anterior to posterior trajectory.