Origin Of Posterior Inferior Cerebellar Artery Research Articles

A Prevalence Anatomic-Imaging Study of the Posterior Inferior Cerebellar Artery's Origin.

Background and Objectives: Typically, the vertebral arteries (VAs) enter the posterior fossa through dural rings and further unite, forming the basilar artery. The posterior inferior cerebellar artery (PICA) is usually a branch of the V4 segment of the VA (intradural origin). It may also leave the V3 suboccipital segment of the VA (extradural origin). The transdural origin of the PICA within the VA's dural ring has been consistently overlooked. A study was designed to determine the topographical patterns of the PICA's origin. Materials and Methods: Determinations were performed in a retrospective sample of 225 computed tomography angiograms. Four types of PICA origin were documented: type 0, absent PICA; type 1, the extradural origin of the PICA from the V3 segment of the VA; type 2, the transdural origin of the PICA within the dural ring; and type 3, the intradural origin of the PICA from the V4 segment of the VA. The bilateral symmetry of types was also investigated. Results: Out of 450 VAs, type 0 (absent PICA) was found in 36%, type 1 (extradural) in 0.44%, type 2 (transdural) in 5.56%, and typical type 3 in just 58%. In types 1 and 2, the PICA entered the posterior fossa through the dural ring and the marginal sinus. In the overall group (N = 225), the type combinations 1_1, 1_2 and 1_3 were not found. Bilaterally absent PICAs occurred in 18.67%. The bilateral combinations 0_1/0_2/0_3/2_2/2_3/3_3 were found, respectively, in 0.89%/3.11%/30.67%/1.78%/4.44%/40.44%. Four of the seventy-eight PICAs opposite to an absent one, three intradural and one transdural, were true bihemispheric PICAs. Conclusions: The PICAs with extradural or transdural origins are facultative contents of the dural ring and are at risk during neurosurgical approaches in the foramen magnum. Rare bihemispheric PICAs could originate either intradurally or within the dural ring.

End-to-end revascularization between the occipital Artery(OA) and the p1 segment of posterior inferior cerebellar Artery(PICA) for a patient with posterior circulation ischemia via a far-lateral approach:2-Dimensional Operative video

Vertebral artery （VA）Aneurysms involving the origin of the posterior inferior cerebellar artery (PICA) ,occasionally, induce cerebellum and brainstem infarction due to intraluminal thrombus and calcific VA stenosis. At times, vessel occlusion and revascularization is necessary for successful obliteration of these aneurysms.2 The occipital artery (OA) is often the preferred donor graft for lesions of the posterior fossa. Although most OA-PICA bypasses can be performed using the p3 segment as the recipient site for an end-to-side anastomosis, a more feasible alternative to conventional OA-p3 PICA bypass in cases of high-riding caudal loops , aberrant anatomy or p3 multiple perforators is to free the p1 PICA, transpose it away from the lower cranial nerves, and perform an end-to-end OA-p1 PICA bypass instead. This video captures the dissection of the OA using an orientational anterograde harvesting technique and the end-to-end anastomosis of the OA to the PICA at the p1 segment. This was performed in a 56-year-old man who presented with posterior circulation ischemia from a fusiform aneurysm with calcific vertebral artery stenosis located at the origin of the right PICA. The patient tolerated the procedure well and suffered no major complications related to the operation. He did experience some mild, posterior neck rigidity at the time of his 6-month follow-up, likely due to nerve injury that occurred while harvesting the OA. Overall, the patient remains in good neurologic status 1 year after the operation. The operation proved the feasibility of end-to-end bypass in OA-p1 PICA.

Ruptured thrombosed vertebral artery dissecting aneurysm treated with staged flow diverter after prediction of the rupture point by vessel wall MRI.

The safety and feasibility of using staged flow diverter (FD) for ruptured cerebral aneurysms, in which coil embolization is performed in the acute phase and FD is deployed in the subacute phase, has recently been reported. This strategy requires assuming the rupture point and performing coil embolization. Although vessel wall magnetic resonance imaging (VW-MRI) has been reported to be useful in predicting the rupture point of aneurysms, its use with staged FD has not yet been reported. We report the first case of staged FD with preoperative contrast-enhanced VW-MRI to predict the rupture point for partially thrombosed vertebral artery dissecting large aneurysm involving posterior inferior cerebellar artery (PICA) origin. This approach achieved a very good outcome, not only completely occluding the aneurysm, but also reconstructing the parent artery while maintaining the patency of the PICA.

Ruptured vertebrobasilar junction aneurysm supplied by reversed flow from the anterior spinal artery: Illustrative case report.

In patients with vertebral artery (VA) occlusion, spontaneous flow reversal may occur in the anterior spinal artery (ASA) as a source of compensatory supply to the posterior circulation. Turbulent flow and increased flux through these small arteries may predispose to luminal damage and intracranial aneurysm formation. We report a novel case of a ruptured ASA-VA junction aneurysm in a patient with chronic bilateral VA occlusion, successfully treated with endovascular embolization. A 62-year-old female with uncontrolled hypertension presented with acute-onset headache, emesis, neck stiffness, and decreased level of consciousness. Head computed tomography demonstrated diffuse cisternal subarachnoid hemorrhage with intraventricular extension and ventriculomegaly. Computed tomography angiography showed left VA atresia and chronic right VA occlusion just distal to the posterior inferior cerebellar artery origin, as well as a complex, bilobed aneurysm at the ASA-VA junction. Angiography demonstrated flow reversal from the ASA into the distal stump of the occluded right VA, which in turn filled the aneurysm. Of note, the patient's posterior circulation was predominantly supplied by the dilated ASA, and associated collaterals from ASA and right VA stump. The aneurysm was accessed and embolized using superselective microcatheterization over a soft microguidewire through the right cervical VA perforators supplying retrograde flow into and through the ASA. ASA-VA aneurysms are exceedingly rare, and generally associated with atypical flow dynamics. Dynamic treatment strategies may be needed, especially in the setting of subarachnoid hemorrhage.

Telovelar/Transcerebellomedullary Fissure Approach: Giant Distal Posterior Inferior Cerebellar Artery Aneurysm, Epidermoid Cyst, and Brainstem Cavernoma: 2-Dimensional Operative Video.

The telovelar or transcerebellomedullary fissure approach can provide wide exposure of the cerebellomedullary fissure and fourth ventricle by separating the natural plane between the medulla and cerebellum.1-5. The cerebellar tonsil is attached to the adjacent cerebellum only by the tonsillar peduncle at its superolateral edge.2 The posterior inferior cerebellar artery (PICA) runs in the cerebellomedullary fissure, usually making its caudal and cranial loops.6,7. After widely opening the foramen magnum, the tonsil is gently elevated by shearing the tela choroidea up to the lateral recess from the taenia, where the vein of the inferior cerebellar peduncle courses.8,9. The developed occipital sinus, posterior condylar vein, and anomalies of the vertebral artery and PICA origin can obstruct the exposure. Detailed neuromonitoring is essential for accomplishing the procedure safely.10,11. This exposure can be extended to the lower cerebellopontine angle and can also be applied to the dorsal brainstem surgery.2,12 The patients consented to the procedure and to the publication of their images.Image Credits: Department of Neurosurgery, Tokyo Medical University logo used by permission. Image at 0:10, 1:02, 2:46, 6:22, and 7:10 from Matsushima and Kohno,1 used by permission from Medical View Co., Ltd.Right image at 0:14 and also upper image at 0:46, image at 1:26, and for left and lower right images at 1:54 from Matsushima et al,2 by permission from Journal of Neurosurgery Publishing Group (JNSPG). Left image at 0:14, from Matsushima et al,4 used by permission from the Congress of Neurological Surgeons. Lower image at 0:46 reprinted from Matsushima et al,9 by permission from Elsevier. Left image at 1:06 from Matsushima et al,8 used by permission from the Congress of Neurological Surgeons.Image at top right at 1:54 from Lister et al,6 used by permission from the Congress of Neurological Surgeons. Image in center at 6:56 from Matsushima et al,11 used by permission from Springer Nature. Image at right at 6:56 from Matsushima et al,10 used by permission from JNSPG. Images at 9:48, by year: 1982 article screenshot and figure from Matsushima et al,4 by permission from the Congress of Neurological Surgeons; 1992: article title screenshot from Matsushima et al,3 by permission from the Congress of Neurological Surgeons; 1996: used with permission of McGraw-Hill Health Professions Division, from Microsurgical Anatomy of the Fourth Ventrical, Matshushiam T and Rhoton AL Jr, in Neurosurgery, eds Wilkins and Rengachary, vol 1, 1996, permission conveyed through Copyright Clearance Center, Inc.; 2000: article title screenshot from Mussi et al,5 reused with permission from JNSPG; 2001: article title screenshot from Matsushima, Transcerebellomedullary fissure approach with special reference to methods of dissecting the fissure, J Neurosurg, vol 91, 2001, p. 257-264, by permission from JNSPG; 2021: article title screenshot from Matsushima et al,12 by permission from Springer Nature. Images at 11:05 from Inoue T et al, "Surgical approach to the mesencephalic vascular malformation" [in Japanese], Surg Cereb Stroke, vol 26, 1998, p 288-289, by permission from the Japanese Society on Surgery for Cerebral Stroke. Cadaveric image at 11:56 from Matsushima T et al, "Exposure of the wide interior of the fourth ventricle without splitting the vermis: importance of cutting procedures for the tela choroidea" Neurosurg Rev, vol 35, 2012, p 563-571, used with permission from Springer Nature.

Bow Hunter Syndrome Involving Rare PICA Variant (P3-5.032)

<h3>Objective:</h3> NA <h3>Background:</h3> Rotational vertebrobasilar insufficiency, also known as bow hunter’s syndrome (BHS), is a rare cause of dynamic vertebral artery stenosis or occlusion during rotation of the head resulting in posterior circulation ischemia. It is potentially a reversible condition which can remain undetected and cause multiple ischemic strokes in the posterior fossa leading to significant disabilities. A 78-year-old male presented with a two-year history of transient episodes of dysarthria, vertigo, and gait disturbance lasting several minutes. These symptoms occurred after exercise or upon turning his head to the left. Dynamic transcranial doppler (TCD) revealed a significant decline in PCA flow velocities with leftward head turn followed by a hyperemic response after moving his head to a neutral position. Dynamic cerebral angiogram showed the presence of a congenitally anomalous origin of the right posterior inferior cerebellar artery (PICA) which originated at the level of C1 transverse foramen and extended under the C1 lamina. Upon neck rotation, there was near occlusion of the vertebral artery at the PICA origin. Hemilaminectomy of C1 was performed with near resolution of the patient’s symptoms. A follow up TCD confirmed improvement in blood flow parameters post-operatively. <h3>Design/Methods:</h3> NA <h3>Results:</h3> NA <h3>Conclusions:</h3> This case report describes a rare presentation of BHS involving an anomalous cervical origin of right PICA. The patient underwent multiple diagnostic studies including MRIs, inner ear physiology tests, and EEGs without any formal diagnosis. The TCD provided an effective and noninvasive diagnostic modality for position related transient neurological symptoms. Frequent use of such test can help diagnose patients with BHS and improve their quality of life. <b>Disclosure:</b> Miss Trujillo has nothing to disclose. Miss Otero-Bell has nothing to disclose. Dr. Girotra has nothing to disclose.

Clinical characteristics, endovascular choices, and surgical outcomes of intracranial vertebral artery dissecting aneurysms: a consecutive series of 196 patients.

The authors aimed to evaluate the clinical features, endovascular strategy selection, and outcomes of vertebral artery (VA) dissecting aneurysms (VADAs) near the origin of the posterior inferior cerebellar artery (PICA). Clinical data were obtained from 196 patients with 202 VADAs who had been surgically treated at the authors' hospital between 2005 and 2021. The patients' medical records, imaging data, and follow-up outcomes were retrospectively analyzed. All 196 patients (148 male, 48 female; mean age 53 years) underwent endovascular therapy for VADA. The most common chief complaints were headache (56.6%), dizziness (40.8%), and other occasional symptoms (18.4%). Twenty-six patients experienced posterior circulation ischemia, and 25 patients experienced subarachnoid hemorrhage (SAH). On DSA images, 37 aneurysms were found in the dominant VA, and 165 aneurysms were found on the nondominant side. Eighty-eight VADAs had stenosis. Regarding the VADA location, there were 59 distal, 51 proximal, 23 ventral, 64 PICA, and 5 obliteration types. Single-stent implantation (10.9%), overlapping stent implantation (23.8%), flow diverter (FD) implantation (11.9%), single stent-assisted coil (SAC) embolization (31.7%), overlapping SAC embolization (12.9%), parent artery occlusion (PAO) (8.4%), and FD-assisted coil embolization (0.5%) were chosen. The follow-up rate was 82.7%. The modified Rankin Scale (mRS) score was 0.5 ± 1.1. Ninety-six patients underwent DSA. The complete occlusion rates were 100%, 81.4%, 56.7%, and 76.5% in the PAO group, SAC reconstruction group, stent implantation group, and FD implantation group, respectively. Young patients showed a higher probability of SAH, and elderly patients showed a higher probability of posterior circulation infarction. The surgical plan selection should be based on the SAH history, VA dominant side, and PICA origin location.

Vertebrobasilar dissecting aneurysms: microsurgical management in 42 patients.

Vertebrobasilar dissecting (VBD) aneurysms are rare, and patients with these aneurysms often present with thromboembolic infarcts or subarachnoid hemorrhage (SAH). The morphological nature of VBD aneurysms often precludes conventional clip reconstruction or coil placement and encourages parent artery exclusion or endovascular stenting. Treatment considerations include aneurysm location along the vertebral artery (VA), the involvement of the posterior inferior cerebellar artery (PICA), and collateral blood flow. Outcomes after endovascular treatment have been well described in the neurosurgical literature, but microsurgical outcomes have not been detailed. Patient outcomes from a large, single-surgeon, consecutive series of microsurgically managed VBD aneurysms are presented, and 3 illustrative case examples are provided. The medical records of patients with dissecting aneurysms affecting the intracranial VA (V4), basilar artery, and PICA that were treated microsurgically over a 19-year period were reviewed. Patient demographics, aneurysm characteristics, surgical procedures, and clinical outcomes (according to modified Rankin Scale [mRS] scores at last follow-up) were analyzed. Forty-two patients with 42 VBD aneurysms were identified. Twenty-six aneurysms (62%) involved the PICA, 14 (33%) were distinct from the PICA origin on the V4 segment of the VA, and 2 (5%) were located at the vertebrobasilar junction. Thirty-four patients (81%) presented with SAH with a mean Hunt and Hess grade of 3.2 at presentation. Six (14%) of the 42 patients had been previously treated using endovascular techniques. Nineteen aneurysms (45%) underwent clip wrapping, 17 (40%) were treated with bypass trapping, and 6 (14%) underwent parent artery sacrifice. The complete aneurysm obliteration rate was 95% (n = 40), and the surgical complication rate was 7% (n = 3). The 8 patients with unruptured VBD aneurysms were significantly more likely to be discharged home (n = 6, 75%) compared with 34 patients with ruptured aneurysms (n = 9, 27%; p = 0.01). Good outcomes (mRS score ≤ 2) were observed in 20 patients (48%). Eight patients (19%) died. These data demonstrate that patients with VBD aneurysms often present after a rupture in poor neurological condition, but favorable results can be achieved with open microsurgical repair in almost half of such cases. Microsurgery remains a viable treatment option, with the choice between bypass trapping and clip wrapping largely dictated by the specific location of the aneurysm and its relationship to the PICA.

A growing aneurysm of the posterior inferior cerebellar artery complicated with cerebellar infarction: A case report.

Introduction and importanceHereby we describe an instructive patient with cerebellar infarction and a growing aneurysm at the posterior inferior cerebellar artery (PICA), which was not a true cause of infarction.Case presentationA 50-year-old female presented with dizziness and posterior neck pain at our hospital (Mitaka city, Tokyo, Japan). Diffusion weighted magnetic resonance (MR) images showed cerebellar infarction in the left PICA territory and MR angiography study showed an aneurysm at the origin of the left PICA, which grew in 2 weeks. Since we considered cerebellar infarction was caused by thrombosis from the aneurysm, trapping of the PICA and occipital artery-PICA bypass was performed to prevent recurrent cerebellar infarction and rupture of the aneurysm by neurosurgeons. During the operation, dissection was observed at the distal PICA, which was diagnosed to be the true cause of cerebellar infarction. By the follow-up for 12 months at an outpatient, there was no recurrence of cerebral infarction.Clinical discussionA specimen of the artery showing the findings of dissection was not obtained, and the pathological diagnosis could not be made. It would be controversial whether a surgical procedure presented here was the most optimal.ConclusionThis is a first reported case of growing aneurysms and cerebral infarction due to arterial dissection. Even if cerebral infarction is accompanied by growing aneurysms, arterial dissection should be included in the differential diagnoses of a cause of infarction. Posterior cervical pain can be a clue for early appropriate diagnosis in such a case.

Extended Retrosigmoid Craniotomy and Approach Through the Glossopharyngeal Cochlear Triangle for Clipping of a High-Riding Vertebral-Posterior Inferior Cerebellar Artery Aneurysm: 2-Dimensional Operative Video.

The far lateral transcondylar (FL) craniotomy is the standard approach for posterior inferior cerebellar artery (PICA) aneurysm exposure through microsurgical dissection in the vagoaccessory triangle (VAT).1,2 However, the extended retrosigmoid (eRS) craniotomy and dissection through the glossopharyngeal-cochlear triangle (GCT) may be more appropriate when the patient has an aneurysm arising from a high-riding vertebral artery (VA)-PICA origin.3-5 We present a case of a 41-yr-old woman with hypertension presenting with left occipital pain and left-side hearing loss and past facial spasm and pain. Computed tomography angiography and digital subtraction angiography demonstrated an unruptured 8.4×9.0×10.2 mm saccular aneurysm at the left VA-PICA junction. Surgical clipping was chosen over endovascular therapy given the relationship of the PICA origin to the aneurysm neck as well as the history of cranial neuropathy. It was noted that the VA-PICA junction and aneurysm was high-riding at the level of the internal auditory canal. An eRS craniotomy was performed with dissection through the GCT, and the aneurysm was clipped as shown in the accompanying 2-dimensional operative video. Postoperative angiography demonstrated complete occlusion of the aneurysm and patency of the left VA and PICA without stenosis, and the patient had a favorable postoperative course although her left-sided hearing remained diminished. The eRS craniotomy allowed direct exposure via the GCT for clipping of the high-riding VA-PICA junction aneurysm and decompression of the cranial nerves. The traditional FL craniotomy and exposure through the VAT would likely have resulted in a less desirable inferior trajectory. The patient gave informed consent for the operation depicted in the video. Animation at 2:43 in video is used with permission from Barrow Neurological Institute, Phoenix, Arizona.

Radiological anatomy of the intracranial vertebral artery in a select South African cohort of patients

The intracranial segment of the vertebral artery (VA) is the unique part of the artery where the two VAs join to form a single vascular channel, viz. the basilar artery. In addition to this typical description, anatomical variations have been described; the presence of anatomical variation has been associated with some pathological processes, neurological complications, and the risk of vascular diseases in the posterior circulatory territory. We evaluated the typical anatomical features and variations of the VA4 component of the VA in a South African population to provide useful data on the prevalence of variation and morphometry of the distal VA. The study is an observational, retrospective chart review of 554 consecutive South African patients (Black, Indian, and Caucasian) who had been examined with multidetector computed tomography angiography (MDCTA) from January 2009 to September 2019. We observed various anatomical variations in the VA4 segment of the VA. We report the incidence of VA hypoplasia, hypoplastic terminal VA, and atresia. Fenestration and duplicate posterior inferior cerebellar artery (PICA) origin were also observed. The left intracranial VA was significantly larger than the right. Our study shows that anatomical variation of the intracranial VA is common in the population studied, with a total prevalence of 36.5%. Understanding the patterns of anatomical variations of the VAs will contribute significantly to the interpretation of ischemic areas and diagnosis of various diseases in the posterior circulatory territory.

Subarachnoid Hemorrhage Due to Rupture of Vertebral Artery Dissecting Aneurysms: Treatments, Outcomes, and Prognostic Factors

Mortality rate after subarachnoid hemorrhage due to rupture of vertebral artery dissecting aneurysms (VADAs) is high; endovascular coil trapping is the first-line therapy to prevent rerupture. To select optimal treatments, the positional relationship between the VADA and posterior inferior cerebellar artery (PICA) and the morphology of the contralateral vertebral artery must be considered, and outcome predictors of different treatment methods and their possible complications must be identified. We retrospectively studied 44 patients with ruptured VADAs who had undergone endovascular or surgical treatment. VADA morphology was assessed on conventional preoperative angiograms, and VADAs were categorized based on their site in relation to the PICA. VADA site, treatment method, and complications were used to identify prognostic factors. The sites of the 44 VADAs were PICA-proximal (n= 3), PICA-distal (n= 22), PICA-absent (n= 7), and PICA-involved (n= 12). Treatments included internal coil trapping (n= 30), proximal coil occlusion (n= 5), and stent placement (n= 3); surgical flow alteration via an occipital artery-PICA bypass and ligation at the proximal vertebral artery and the PICA origin was performed in 6 patients. Periprocedural rebleeding was associated with a poor outcome. Internal coil trapping prevented the rerupture of PICA-proximal and PICA-absent VADAs, and flow alteration prevented rerupture of PICA-involved VADAs; there were no complications directly attributable to these procedures. Periprocedural rebleeding was a poor prognostic factor. Internal trapping of PICA-proximal and PICA-absent VADAs and flow alteration in PICA-involved VADAs prevented rerupture.

The Glossopharyngo-Cochlear Triangle-Part II: Case Series Highlighting the Clinical Application to High-Riding Posterior Inferior Cerebellar Artery Aneurysms Exposed Through the Extended Retrosigmoid Approach.

Use of the far lateral transcondylar (FL) approach and vagoaccessory triangle is the standard exposure for clipping most posterior inferior cerebellar artery (PICA) aneurysms. However, a distal PICA origin or high-lying vertebrobasilar junction can position the aneurysm beyond the vagoaccessory triangle, making the conventional FL approach inappropriate. To demonstrate the utility of the extended retrosigmoid (eRS) approach and a lateral trajectory through the glossopharyngo-cochlear triangle as the surgical corridor for these cases. High-riding PICA aneurysms treated by microsurgery were retrospectively reviewed, comparing exposure through the eRS and FL approaches. Clinical, surgical, and outcome measures were evaluated. Distances from the aneurysm neck to the internal auditory canal (IAC), jugular foramen, and foramen magnum were measured. Six patients with PICA aneurysms underwent clipping using the eRS approach; 5 had high-riding PICA aneurysms based on measurements from preoperative computed tomography angiography (CTA). Mean distances of the aneurysm neck above the foramen magnum, below the IAC, and above the jugular foramen were 27.0 mm, 3.7 mm, and 8.2 mm, respectively. Distances were all significantly lower versus the comparison group of 9 patients with normal or low-riding PICA aneurysms treated using an FL approach (P<.01). All 6 aneurysms treated using eRS were completely occluded without operative complications. The eRS approach is an important alternative to the FL approach for high-riding PICA aneurysms, identified as having necks more than 23 mm above the foramen magnum on CTA. The glossopharyngo-cochlear triangle is another important anatomic triangle that facilitates microsurgical dissection.

Ruptured vertebral artery dissecting aneurysms involving a dominant posterior inferior cerebellar artery origin: A preferred indication for bypass surgery in clinical practice

BackgroundIn clinical practice, the optimal treatment approach for ruptured vertebral artery dissecting aneurysm (VADA) involving a posterior inferior cerebellar artery (PICA) remains unclear. Here, we report two cases of ruptured VADA involving a dominant PICA that were successfully treated with surgical occlusion with occipital artery (OA) to PICA bypass, while avoiding postoperative ischemia. Case descriptionThe first patient was a 47-year-old woman who presented with a Hunt–Hess grade III, diffuse subarachnoid hemorrhage (SAH) due to a ruptured right VADA involving a PICA. The PICA was dominant, supplying a wide vascular territory in the right cerebellum (the “PICA–anterior inferior cerebellar artery” variant). The second patient was a 56-year-old man who presented with a Hunt–Hess grade II, localized SAH due to a ruptured right VADA involving a PICA. The PICA was also dominant, supplying a wide vascular territory in the bilateral cerebellum (the “bihemispheric PICA” variant). Both patients were treated with OA–PICA bypass, which was followed by surgical trapping of the VADA in the first patient and proximal clipping in the second patient on the day of the SAH onset. The postoperative course was uneventful, and magnetic resonance imaging showed no apparent ischemic change in the brainstem and cerebellum in either patient. ConclusionsFor ruptured VADA involving a PICA, dominance of the involved PICA may be a practically preferred indication for bypass surgery because of the severity of ischemia when a dominant PICA is sacrificed and because the vascular anatomy of a dominant PICA makes anastomosis feasible.

Endovascular sacrifice of the proximal posterior inferior cerebellar artery for treatment of ruptured intracranial aneurysms

BackgroundRuptured aneurysms of the intracranial vertebral artery (VA) or posterior inferior cerebellar artery (PICA) are challenging to treat as they are often dissecting aneurysms necessitating direct sacrifice of the diseased...

Blind-Alley Formation and Occipital Artery-Posterior Inferior Cerebellar Artery Bypass for the Treatment of Unclippable Vertebral Artery Aneurysms with Posterior Inferior Cerebellar Artery Involvement

Unclippable vertebral artery aneurysms (UVAs) are difficult to treat with direct clipping, especially in cases involving the origin of the posterior inferior cerebellar artery (PICA). Bypass with trapping is the common procedure used for these conditions. The authors used the blind-alley formation technique, which is a simpler method than trapping and can avoid some complications. To report 7 cases of UVA with PICA involvement treated with blind-alley formation and occipital artery (OA)-PICA bypass as well as their surgical outcomes and complications and to describe the operative techniques. Seven patients with UVA and PICA involvement underwent OA-PICA bypass and blind-alley formation (occlusions of the PICA origin and vertebral artery proximal to the aneurysm). Vertebral artery dissecting aneurysms and fusiform atherosclerotic vertebral artery aneurysms were detected in 6 patients and 1 patient, respectively. All patients presented with subarachnoid hemorrhage, and 71.4% of them were classified into the poor-grade group. Good bypass patency and complete aneurysm obliteration were achieved in all cases. Six aneurysms (85.7%) were completely obliterated according to computed tomography angiography performed immediately postoperatively. Another aneurysm was 50% and 100% thrombosed immediately and at 7 days after the operation, respectively. Surgical complications were found in 1 patient (14.3%) who had postoperative diparesis with dysphagia. Three patients (42.9%) achieved a Glasgow Outcome Score of 4 or 5 one month after the operation. Blind-alley formation and OA-PICA bypass are simple, safe, and effective for the treatment of patients with UVA with PICA involvement.

Anatomical Analysis of the Vagoaccessory Triangle and the Triangles Within: The Suprahypoglossal, Infrahypoglossal, and Hypoglossal–Hypoglossal Triangles

Rootlets of the lower cranial nerves create a web that limits microsurgical maneuverability in the cerebellomedullary cistern (CMC). The vagoaccessory triangle (VAT) and 2 triangles within it were defined to identify surgical routes to aneurysms of the posterior inferior cerebellar artery (PICA). Dividing the VAT into 2 triangles (suprahypoglossal [SHT] and infrahypoglossal [IHT]), although elegant, oversimplifies CMC anatomy. The triangle formed by the superior and inferior hypoglossal rootlets (hypoglossal-hypoglossal triangle [HHT]) needs consideration as well. Far-lateral craniotomy was performed on 10 cadaveric heads bilaterally. Areas of CMC triangles were calculated. Relationships between the PICA origin and the adjacent triangles were analyzed. Vertebral artery (VA) exposure and clipping lengths were recorded for each triangle. The area of SHT was almost twice those of IHT and HHT. The average VA depth relative to VAT increased significantly when moving distally from proximal VA (P < 0.001), but VA exposure and clipping lengths were not significantly different between triangles. IHT, HHT, and SHT defined VA subsegments (V4i, V4h, and V4s), with PICA most commonly originating from V4h. Based on our cadaveric measurements, the V4 subsegments were identified with 76% accuracy in angiograms. Based on this study, VAT should be divided into 3 triangles, not 2. Splayed rootlets of cranial nerve XII and multiple outlet foramina create an important space different from the previously recognized SHT and IHT. These triangles provide corridors to vascular pathologies. V4 subsegments may be approximated from imaging studies and may help with preoperative planning.

Treatment of posterior inferior cerebellar artery aneurysms using flow-diverter stents: A single-center experience.

The effectiveness and reliability of flow-diverter stents, which are commonly used in aneurysms of the anterior circulation, have been demonstrated previously. However, the use of these devices is associated with higher rates of perforator and branch ischemia following the treatment of aneurysms of the posterior circulation. This work involved a single-center; retrospective study reviewing eight patients who had aneurysms related to the posterior inferior cerebellar artery (PICA) and who were treated with flow-diverter stents from September 2013 to May 2017. The mean aneurysm diameter was 7.6 mm (range, 5 to 11 mm). The types of aneurysm included five aneurysms that were saccular, two that were fusiform, and one that was dissecting. All saccular aneurysms in the neck involved the PICA origin, and one dissecting aneurysm was localized in the proximal part of the PICA. Procedural success was 100% (8/8), and there were no ischemic complications. One patient with subarachnoid hemorrhage died because of rebleeding (modified Rankin Scale (mRS), 6). Other than this patient all of the patients' mRS scores were zero at discharge and at the clinical follow-up period (mean, 2.5 years). All of the aneurysms were completely occluded according to the latest angiographic controls (mean follow-up period of 19.5 months). Treatment of PICA aneurysms with flow-diverter stents showed positive results with a high rate of technical success and low complication and mortality rates. The use of flow-diverter stents in the treatment of PICA aneurysms should be considered a safe and effective endovascular treatment option.

Persistent hypoglossal artery aneurysm: Case report and qualitative systematic review

A persistent hypoglossal artery was first described in 1889 and is one of the more common anatomical variations arising from aberration in normal development. Endovascular coiling has been recognised as a robust treatment for acutely ruptured intracranial arterial aneurysms, although specific data regarding an aneurysm arising from a persistent hypoglossal artery is lacking due to the low incidence. Here we report both the oldest patient reported to be treated with a persistent hypoglossal artery-associated aneurysm and also explicitly report endovascular treatment of a persistent hypoglossal artery aneurysm arising at the posterior inferior cerebellar artery origin. Qualitative systematic review of the available medical literature demonstrates limited evidence regarding treatment of persistent hypoglossal artery-associated aneurysms with the majority being carried out via open surgery. Ruptured posterior inferior cerebellar artery aneurysm arising from a persistent hypoglossal artery can be successfully and safely treated by endovascular therapy via the persistent hypoglossal artery. Randomised study of this situation is unlikely to be feasible; however, qualitative review of the literature reveals six such aneurysms that have been treated surgically, and this case appears to be the first via an endovascular means.

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.