Posterior Inferior Cerebellar Research Articles

Course of the V3 segment of the vertebral artery relative to the suboccipital triangle as an anatomical marker for a safe far lateral approach: A retrospective clinical study

Background: The third segment of the vertebral artery (V3) is vulnerable during far lateral and retrosigmoid approaches. Although the suboccipital triangle (SOT) is a useful anatomical landmark, the relationship between V3 and the muscles forming the triangle is not well-described. We aimed to demonstrate the relationship between the V3, surrounding muscles, and SOT in clinical cases.Methods: Operative videos of patients with the vertebral artery (VA) and posterior inferior cerebellar artery (PICA) aneurysms treated with occipital artery-PICA bypass through the far lateral approach were examined. Videos from January 2015 to October 2021 were retrospectively reviewed to determine anatomy of the V3 and the SOT.Results: Fourteen patients were included in this study. The ipsilateral V3 was identified without injury in all patients using the bipolar cutting technique. The lateral 68.2% of the horizontal V3 segment, including the V3 bulge, was covered by the inferomedial part of the superior oblique muscle (SO). The medial 23.9% was covered by the inferolateral part of the rectus capitis posterior major muscle. The inferomedial part of the horizontal V3 segment is located within the SOT.Conclusion: Most of the V3, including the V3 bulge, were located beneath the SO and the inferomedial part of V3 located within the SOT. Elevation of the SO should be performed carefully using the bipolar cutting technique to avoid injury to the V3. To the best of our knowledge, this is the first description of the V3 relative to the SOT in the clinical setting.

Topography and etiologies of cerebellar infarcts presenting as isolated acute vestibular syndrome

To investigate the topography and etiologies of acute cerebellar infarcts (ACIs) that presented as isolated acute vestibular syndromes (AVSs). ACI was ascertained on magnetic resonance diffusion-weighted imaging combined with apparent diffusion coefficient sequence and was categorized into the simple (territory and small infarct) and the complicated (concomitant infarcts in territories of posterior circulation besides cerebellum). Infarct topography and etiologies were compared between ACI patients with isolated AVS and non-isolated AVS (general and/or local neurological symptoms and/or signs with or without AVS). We enrolled 129 ACI patients, and 53 patients (53/129, 41.1%) had isolated AVS. In isolated AVS, the infarct lesions could be territory infarcts, small infarcts involving cortical, subcortical, and areas directly related to vestibular structures, and the primary etiologies were of large artery atherosclerosis and small vessel disease. Compared with the patients with non-isolated AVS, those with isolated AVS had more prevalence of small vessel disease (OR 6.30, 2.16-18.39; p = 0.001) and more probability of small infarcts (OR 6.04, 95%CI 2.31-15.76; p < 0.0001). In isolated AVS patients, the small infarct located more frequently in cerebellar hemispheres than the areas directly related to vestibular structures (27/35 vs 8/35), and the territory infarct located more frequently in the area supplied by posterior inferior cerebellar artery than the other areas (9/13 vs 4/13). Our study found that ACI could be presented as isolated AVS, which occurred more frequently in patients with small hemisphere infarct or infarct in the territory supplied by posterior inferior cerebellar artery.

Posterior Inferior Cerebellar Artery Stenosis Presenting as Recurrent Orthostatic Dizziness

We report a unique case of vertebrobasilar transient ischemic attacks manifesting as isolated, recurrent, orthostatic dizziness with posterior inferior cerebellar artery (PICA) stenosis. A 57-year-old male patient without past medical history, presented with brief orthostatic dizziness for 2 weeks. There was no associated nausea, vomiting, diplopia, or weakness. On neuro-otologic examination, the patient did not show spontaneous, positional, or gaze-evoked nystagmus. Vestibular function tests such as caloric test, head impulse test, video-oculography, and tilt table test were normal. Brain diffusion-weighted images showed multiple small high signal intensities in the bilateral cerebellar hemispheres. Brain magnetic resonance angiography revealed hypoplasia of the right vertebral artery without focal intracranial focal stenosis. Four-vessel cerebral angiogram showed severe stenosis at the right PICA artery. Our patient’s clinical scenario appears unique hemodynamic spells without symptoms or signs of posterior circulation ischemia. Physicians should also consider cerebrovascular ischemic when the patient suffers repeated orthostatic dizziness that is not explained clinically.

Isolated posterior inferior cerebellar artery dissection with ischaemic stroke: evaluating the radiological features and diagnostic feasibility of high-resolution vessel wall imaging

To evaluate the radiological features of isolated posterior inferior cerebellar artery dissection (PICAD) and the feasibility of using high-resolution vessel-wall imaging (HR-VWI) for diagnosing PICAD. Three hundred and nine patients with arterial dissection involving the posterior cerebral circulation, who underwent HR-VWI between March 2012 and July 2019 were reviewed retrospectively. Among them, 44 patients (14.2%) were diagnosed with isolated PICAD in consensus among a neuroradiologist, a neurointerventionist, and a neurologist. Two neuroradiologists reviewed the vessel wall images independently for evidence of dissection (dissection flap, outer diameter enlargement on T2-weighted imaging [WI], mural haematoma). Diagnostic confidence was also scored on a five-point scale. Intra- and interobserver agreement for diagnosing PICAD and detecting evidence of dissection were evaluated. Dissection flaps were seen on T2WI in all cases (100%) and on contrast-enhanced T1WI in 34 patients (79.1%). Outer diameter enlargement of the steno-occlusive lesions on angiography was detected in most cases (97.7%). A mural haematoma was detected on three-dimensional (3D) contrast-enhanced motion-sensitised driven-equilibrium T1WI in 97.1% of the cases. The mean diagnostic confidence score derived by two neuroradiologists was 4.72. The two reviewers showed substantial to almost perfect agreement (weighted kappa coefficient: 0.62-0.97). Use of HR-VWI as a diagnostic tool for PICAD is feasible, and a dissection flap with outer wall enlargement on HR-T2WI allows confident dissection diagnosis. The present data suggest that PICAD might be considered as a stroke aetiology in patients with unexplained ischaemic stroke in the PICA territory, and that PICA evaluation with HR-VWI is both necessary and feasible.

Failure of Flow-Diverter Endothelization Visualized with Optic Coherent Tomography Technology

We report a case of an intracranial aneurysm of the left posterior inferior cerebellar artery, which was treated with a flow-diverting stent. One year later at follow-up, the patient presented with new symptoms due to mass effect in the posterior fossa and a 3-fold enlargement of the aneurysm. Digital subtraction angiography showed an increase in size of the aneurysm with jet flow into the sac. Optic coherent tomography was performed during the procedure, demonstrating a failure of endothelization of the stent with a focal 1-mm opening at the neck of the aneurysm, resulting in jet flow. Parent vessel sacrifice was performed by coiling of the left vertebral artery. The patient had a codominant right vertebral artery and tolerated the procedure well. Two years later, follow-up magnetic resonance angiography showed significant decrease of the size of the aneurysm and symptom regression, with a modified Rankin scale of 1 (functionally independent).

Symptomatic ischemic complications following endovascular treatment of vertebral artery dissecting aneurysms.

The aim of this study is to investigate the clinical and radiological features related to the symptomatic ischemic complications of vertebral artery dissecting aneurysm (VADA) following endovascular treatment (EVT). The clinical and radiological features of 127 VADAs, which were treated in a single tertiary institute between September 2008 and December 2020, were retrospectively reviewed. We defined a thrombosed aneurysm as being one which the thrombus was in the aneurysm in magnetic resonance imaging (MRI). Symptomatic ischemic complication was defined as a case in which acute infarction was confirmed on diffusion weighted image after EVT with associated clinical symptoms. Univariate and multivariate analyses were executed to demonstrate the associations between symptomatic ischemic complication and characteristics of VADA. The rate of symptomatic ischemic complication was 13.4% (17 of 127). The thrombosed aneurysms were observed in 24.4% (31 of 127) and posterior inferior cerebellar artery (PICA) involvement was shown in 38.6% (49 of 127). Multivariate logistic regression analysis demonstrated that thrombosed aneurysms (odds ratio [OR] = 8.54, 95% confidence interval [CI] 1.98-36.87, p = 0.004) and PICA involvement (OR = 4.26, 95% CI 1.03-17.68, p = 0.046) were significantly associated with symptomatic ischemic complications following EVT. This study showed that the VADAs with intra-aneurysmal thrombose and PICA involvement may be independent risk factors for symptomatic ischemic complications following EVT. Therefore, when the thrombosed VADAs with PICA involvement are observed, practitioners may consider close postoperative monitoring for early detection of ischemic complications.

Morphological characteristics associated with ruptured intracranial vertebral artery dissecting aneurysms

ObjectiveMorphological risk factors for the rupture of intracranial vertebral artery dissecting aneurysms (IVADAs) have not been well characterized. In this study, we aim to identify morphological characteristics associated with IVADA...

Microsurgical treatment of posterior inferior cerebellar aneurysms based on angioarchitecture supplemented by high-resolution vessel wall MRI: a case series report

BackgroundSurgical treatment of posterior inferior cerebellar artery (PICA) aneurysms is challenging because many are nonsaccular and atherosclerotic. We report our tailored approach to PICA aneurysms, which is based on angioarchitecture...

Microsurgical and endovascular treatment of posterior inferior cerebellar artery aneurysms: a systematic review and meta-analysis.

Posterior inferior cerebellar artery (PICA) aneurysms are uncommon vascular lesions of the posterior fossa. In addition to aneurysmal morphology, structural anatomic considerations may confer additional procedural risk, and as a result there is currently no consensus as to whether a surgical or endovascular approach offers greater safety and efficacy for patients. We systematically examined peer-reviewed literature describing PICA aneurysm treatment planning from January 2000 to May 2021 using the PRISMA methodology. A meta-analysis of proportions was performed. Certainty of the evidence was assessed using the GRADE approach. Fifty-eight studies including 1673 PICA aneurysms were analyzed. Overall treatment occlusion rate was 97% (95% confidence interval [CI]: 93-100%) for surgery and 85% (95% CI: 78-92%) for endovascular therapy. The recurrence rate was 6% in the endovascular group and 1% for surgery. Overall morbidity and mortality were 16% and 7%, respectively. Intraoperative complications occurred in 9% of the surgical patients. Despite a large body of literature, analysis indicates that 62% of studies had moderate or serious risk of bias, suggesting very-low certainty results. Therefore, treatment via either approach should be determined on a case-by-case basis and according to institutional experience.

Posterior Inferior Cerebellar Artery Infarction, Surgical Intervention and Outcome

Posterior Inferior Cerebellar Artery Infarction, Surgical Intervention and Outcome

Case Series for Gamma Knife Surgery for Arteriovenous Malformation Associated Intracranial Aneurysms

Abstract Objective The incidence of aneurysms coexisting with arteriovenous malformations (AVMs) ranges between 2.7% and 16.7%. The anatomical relationship between AVM and aneurysm is critical in deciding the best management. Methods Between October 1994 and August 2017, gamma knife surgery (GKS) was performed in six patients with AVMs and associated aneurysms. The patients consisted of four men and two women with a mean age of 37.8 years (range, 18−57 years). The mean follow-up was 34.2 months (range, 13−84 months). The mean maximal dose was 35.9 Gy and the mean margin dose to AVM was 18 Gy. Coil embolization was performed in one of the aneurysms prior to GKS. In our study, GKS was performed in six AVM-associated aneurysms. Of the six aneurysms, four were intranidal and two were pedicular. The mean volume of AVMs was 3.6 cm3 (range, 1.6−6.5 cm3). Results The locations of aneurysms are as follows: four on posterior cerebral artery (PCA), one on posterior inferior cerebellar artery (PICA), and one on middle cerebral artery (MCA). Sublocation sites were MCA M3 above, PCA P3 above, and PICA distal. There were no GKS-related complications. Complete obliteration of AVM and aneurysm was documented in all four patients with intranidal aneurysm-associated AVMs. Both the aneurysm and AVM were completely obliterated in the two patients with proximal pedicular aneurysms. Conclusion GKS is a possible treatment for AVM with associated intranidal or pedicular aneurysms located above P3 or M3, etc., in which there is less turbulent flow and jet flow.

Rupture of posterior meningeal artery aneurysm: case report

An aneurysm of the posterior meningeal artery is a rare pathology. However, rupture of this aneurysm can lead to serious consequences for the patient's health. For the surgical treatment, both microsurgical and endovascular methods are used. A 19-year-old patient was admitted to our hospital on day 21 after suffering a subarachnoid-ventricular hemorrhage from an aneurysm of the right posterior meningeal artery. On admission, the patient complained of a headache. Cerebellar symptoms were noted in the neurological status. According to digital subtraction angiography, the patient had an anastomosis between the posterior meningeal artery and the hypoplastic p1-segment of the right posterior inferior cerebellar artery distal to the aneurysm. Endovascular method was used to occlude the aneurysm with a detachable coil. The patient was discharged on the third day with total regress of neurological symptoms. Control cerebral angiography 3 months later showed thrombosis of the aneurysm with the supporting segment of the parent artery, as well as restructuring of the main blood flow of this basin through the previously hypoplastic posterior inferior cerebellar artery. In the literature, we found only 9 such cases. Endovascular treatment of this pathology is, in our opinion, effective and safe, and the presence of an anastomosis distal to the aneurysm made it possible to avoid disruption of blood supply in the vascular basin of the affected artery.Received 21 September 2021. Revised 11 October 2021. Accepted 18 October 2021.Funding: The study did not have sponsorship.Conflict of interest: Authors declare no conflict of interest.Contribution of the authors: The authors contributed equally to this article.

Intracranial-Intracranial Bypass for Aneurysms: Quantitative Intraoperative Assessment of Flow Preservation.

Intraoperative flow measurement has proven utility in extracranial-intracranial bypass, particularly in assessing the adequacy of donors by measurement of cut flow. The nature of intracranial-intracranial (IC-IC) bypass precludes cut flow measurement, but quantitative intraoperative flow measurements may evaluate augment assessment of the bypass. To retrospectively evaluate flow measurements performed in IC-IC bypass to determine the adequacy of the constructs in preserving flow. With institutional review board approval, we performed a retrospective review of our bypass database from 2001 to 2021 for aneurysms treated with IC-IC bypass and with intraoperative flow measurements. Patients' preoperative characteristics, bypass indications, prebypass and postbypass intraoperative flow measurements, and patient outcomes were recorded. Of 346 bypasses, 21 cases using 22 IC-IC bypasses were included. The median age was 55 years; 13 of 21 cases were ruptured aneurysms. Aneurysms involved posterior inferior cerebellar artery (n = 7), middle cerebral artery (n = 6), distal anterior cerebral artery (n = 5), and anterior communicating artery (n = 3). Six bypasses were end-to-side (ETS), 10 were side-to-side (STS), and 6 were excisional with reanastomosis (end-to-end, ETE). Intraoperatively, 21 of the bypasses were patent; the postbypass/prebypass flow index averaged 1.15 (±0.32): ETE (n = 6) 1.22 ± 0.34 and ETS/STS bypasses (n = 15) 1.11 ± 0.32. All intraoperatively patent bypasses were patent on postoperative angiography. One occluded on delayed angiography without clinical sequelae. Despite advances in endovascular therapy, IC-IC bypass remains essential to the treatment of large and fusiform aneurysms. We demonstrate quantitatively that IC-IC donors provide adequate direct (ETE) and redistributed (STS ETS) flow to the recipient territory. Flow measurement provides valuable information regarding the patency and adequacy of IC-IC bypass for flow preservation.

Surgical and Endovascular Treatment of Saccular Posterior Inferior Cerebellar Artery Aneurysms: Systematic Review and Meta-Analysis

The optimal treatment modality for saccular aneurysms of the posterior inferior cerebellar artery (PICA) remains unclear. A previous meta-analysis on the topic included a heterogenous study population, limiting the conclusions that can be drawn from its results. The aim of this study was to perform a systematic review and meta-analysis to compare outcomes of microsurgical and endovascular treatment (EVT) of these aneurysms. A search of 4 online databases was performed for studies describing the management of saccular PICA aneurysms. The primary outcome was complete aneurysm occlusion. Data were also collected on neurologic outcomes, cranial nerve palsies, and requirement for re-treatment. A random effects model was used for calculation of pooled proportions. Our protocol was registered with PROSPERO (CRD42021232784). A total of 17 studies were included in the final analysis, reporting the treatment outcomes of 455 aneurysms, with a mean follow-up of 20 months. The pooled occlusion rates were 94.8% (95% confidence interval [CI] 90.6%-97.8%) for surgical treatment and 69.1% (95% CI 55.0%-81.7%) for EVT. Pooled rates of good neurologic outcome (modified Rankin scale score ≤2, Glasgow Outcome Scale score ≥4) at last follow-up were 78.1% (95% CI 67.4%-87.1%) for surgery and 77.6% (95% CI 67.9%-86.0%) for EVT. This meta-analysis demonstrates that in the treatment of saccular PICA aneurysms, microsurgical clipping results in superior angiographic outcomes, similar functional outcomes, but higher rates of lower cranial nerve palsy compared with EVT. Further studies are required to assess the duration and severity of cranial nerve palsies following surgical treatment, and long-term aneurysm occlusion and the requirement for re-intervention following EVT.

Giant Posterior Inferior Cerebellar Artery Aneurysm Mimicking a Brainstem Tumor

Aneurysms from the vertebrobasilar system are rare, accounting for only 5%-10% of all intracranial aneurysms. The most common sites in which these lesions occur are the bifurcation of the basilar artery and the origin of the posterior inferior cerebellar artery (PICA). When the aneurysms present in the distal portion of the PICA, they represent from 0.5% to 6%. These aneurysms are called giant when they exceed 25 mm in diameter. We present a case of a 49-year-old male who presented with acute obstructive hydrocephalus, which required ventriculoperitoneal shunting and left hemispheric cerebellar syndrome. The magnetic resonance imaging study revealed an occupative mass located in the fourth ventricle, and diagnostic angiography showed a partially thrombosed giant saccular aneurysm in the posterior inferior cerebellar artery. He underwent surgical management via a lateral suboccipital approach. The aneurysm was remodeled and clipped successfully without complications, with an uneventful postoperative course.Although rare, PICA aneurysms should always be considered when posterior fossa syndrome occurs, including brainstem and cranial nerve compression symptoms. It can easily be misdiagnosed as a neoplastic lesion, especially when the aneurysm reaches big or giant size. Therefore, complete diagnostic studies, such as cerebral angiography, must be performed. Surgical clipping must be offered as the first line of treatment. It provides occlusion of the aneurysm and relieves compressive symptoms.

Bypass Surgery Management of Complex Proximal and Distal Posterior Inferior Cerebellar Artery Aneurysms.

For the complex posterior inferior cerebellar artery (PICA) aneurysms, standard microsurgical or endovascular technical options were not feasible. To determine the efficacy and outcomes of bypass surgery for complex PICA aneurysms, the authors herein review our recent surgical experience for complex PICA aneurysms. The authors retrospectively reviewed our experience of extracranial-intracranial bypass and intracranial-intracranial bypass surgery in treatment of proximal and distal complex PICA aneurysms at our institution from 2016 to 2020. Twelve patients harboring 12 complex PICA aneurysms received bypass surgery at our institution. Seven (58.3%) patients with proximal PICA aneurysms underwent extracranial-intracranial bypass. Five (41.7%) patients with distal PICA aneurysms accepted intracranial-intracranial bypass. The postoperative symptom improvement: Of the 6 patients with preoperative hypoperfusion or ischemic of the cerebellar hemisphere, the symptom resolved in 5 patients, improved in 1 patient, of 5 patients with preoperative mass effect, the symptom resolved in 5 patients. During the follow-up period, ten patients had a modified Rankin scale (mRS) score of 0 to 1, and 1 patient had an mRS score of 2. One patient had an mRS score of 3. The long-term graft patency rate was 91.7%. All patients had no recurrence of intracranial aneurysm. Base on the complexity of anatomy structure and the vascular architecture, an individualized strategy was proposed for each patient. The use of different types of bypass procedures (occipital artery-PICA end-to-end bypass, PICA-PICA end-to-end anastomosis, and/or occipital artery graft) can safely and effectively manage these complex PICA aneurysms.

Posterior Circulation Alberta Stroke Program Early Computed Tomography Score (pc-ASPECT) for the Evaluation of Cerebellar Infarcts.

Patients with cerebellar ischemic stroke may be misdiagnosed and may exhibit a delayed time to acute stroke treatment compared with patients with anterior circulation ischemic stroke. The posterior circulation Alberta stroke program early computed tomography score (pc-ASPECT) score has been used to evaluate hyperacute stroke, much as the ASPECT in anterior circulation stroke recently. Our main objective was to evaluate the associations of the clinical and etiological characteristics of ischemic cerebellar infarction patients on admission with their pc-ASPECT scores, as well as the correlations of the pc-ASPECT score with morbidity and mortality rates. We include 114 patients with cerebellar infarction who underwent 1 year of follow-up into the study. Patients with a pc-ASPECT score <7 were more likely to present with impaired consciousness ( P <0.001), multiple posterior circulation infarcts ( P <0.001), hydrocephalus ( P <0.001), lesions of the vermis ( P =0.028), and peduncle ( P =0.024), perfusion deficits in the total of posterior inferior cerebellar artery, anterior inferior cerebellar artery, superior cerebellar artery ( P <0.05), and basilar artery stenosis ( P =0.005), ischemia in additional anatomical structures in the posterior circulation ( P <0.001) compared with those with a score ≥7. Although the pc-ASPECT score alone is insufficient in some cases like vertebral artery dissection, using it together with the National Institutes of Health Stroke Scale (NIHSS) score and clinical findings may be beneficial during the hyperacute period of cerebellar ischemia. Presentation with impaired consciousness, basilar artery pathologies, vermian ischemia, and ischemia in additional anatomical structures in the posterior circulation other than the cerebellum appeared as important clinical and radiologic parameters predicting long-term prognosis.

Coiling Using Dual Microcatheter Technique—A Novel Approach

AbstractPosterior circulation aneurysms are difficult to treat, and if an incorporated artery is arising from the neck of aneurysm, management becomes much more challenging. Here, we are describing a novel technique used to treat a patient with a large, wide-necked left vertebral artery (VA)-posterior inferior cerebellar artery (PICA) junctional aneurysm. PICA seems to be arising from the aneurysm neck, but the aneurysm neck was not very clearly defined. So, we placed a second microcatheter into PICA, which not only allowed the coils to be placed in the aneurysm, without disrupting the flow through PICA but also helpful in assessing the aneurysmal occlusion. This technique allowed coils to be placed successfully without compromising flow through PICA.

Eosinophilic meningitis following suboccipital craniotomy without bovine dural graft: illustrative case.

BACKGROUNDEosinophilic meningitis is a rare known complication after brain surgery associated with duraplasty using artificial bovine graft. However, eosinophilic meningitis after craniotomy without bovine dural graft has not been reported.OBSERVATIONSA 48-year-old female presented with lateral medullary infarction caused by a vertebral artery dissecting aneurysm incorporating the posterior inferior cerebellar artery (PICA). The authors performed occipital artery–PICA anastomosis and repaired the dura by primary suture without bovine graft. Thereafter, endovascular internal trapping using coils was conducted. Severe headache developed at postoperative day 17, and the patient was diagnosed with eosinophilic meningitis. After administration of a high-dose corticosteroid for 2 weeks, her symptoms and laboratory findings were improved.LESSONSPostoperative eosinophilic meningitis is rarely related to craniotomy without using bovine graft. Neurosurgeons should consider the possibility of eosinophilic meningitis after craniotomy without a xenogeneic dural material.

Babinski-Nageotte Syndrome: Case Report of a rare variant of Lateral Medullary Infarction

Babinski-Nageotte Syndrome (BNS) is a rare variant of lateral medullary infarction, and only a few cases have been reported. In this case, a 52-year-old African-American gentleman presented with acute onset weakness on the left side of the body. On examination, there was a palpable right supraclavicular lymph node. Neurological examination showed right-sided gaze-evoked nystagmus and left hemiparesis with grade 3/5 power. Reflexes were normal except for extensor plantar responses on the left. MRI showed a subacute right-sided lateral brainstem infarct just below the pontomedullary junction with minimal progression in a repeat MRI after 24 hours. Workup for supraclavicular adenopathy with CT chest and CT abdomen and pelvis revealed neither neoplastic nor metastatic disease. Biopsy of supraclavicular lymph node was planned as an outpatient but was deferred as it was presumed to be reactive. He was conservatively managed with daily physiotherapy, aspirin, atorvastatin, and optimal blood pressure control. Babinski-Nageotte syndrome includes all symptoms of the Wallenberg syndrome with contralateral hemiparesis due to a spread of the lateral lesion to the pyramidal tract. Atherosclerotic occlusion and lipohyalinosis of the vertebral artery and posterior inferior cerebellar artery have been identified as the most common causes.