Posteroinferior Cerebellar Artery Aneurysms Research Articles

Posteroinferior Cerebellar Artery Aneurysms: Influence of Angioanatomy on the Safety of Flow Diversion Treatment.

Several anatomical variables critically influence therapeutic strategies for posteroinferior cerebellar artery (PICA) aneurysms and, specifically, the safety of flow diversion for these lesions. We review the microsurgical anatomy of the PICA, discussing and detailing these considerations in the treatment of aneurysms of this vessel from a theoretical perspective and in light of our previously published clinical results.

Case Presentation: Unusual Association Between Possible Bilateral Intraventricular Xanthogranulomas, Postero-inferior Cerebellar Artery Aneurysm and Thrombophilia

Abstract Introduction: Xanthogranulomas are rare, benign, usually asymptomatic, cutaneous tumors most frequently seen in children (juvenile xanthogranulomas). Some lesions can be found accidentally at randomly performed cerebral computer tomography (CT) or magnetic resonance imaging (MRI) or even on autopsy. Case report: We present the case of a 44 year-old woman, known with a thrombophilic disorder (PAI-1 gene mutation, MTHFR C677T and A1298C) on chronic anticoagulant treatment. The onset of symptoms was in 2010, when she presented paresthesia and lower limbs weakness. Two years later the patient presents with severe intermittent headache and left hemicrania and a cerebral angio-MRI is performed showing a left postero-inferior cerebellar artery aneurysm and two choroid plexus intraventricular masses in the lateral ventricles. The patient developed a new symptom, dysarthria in 2014 and in 2015 has multiple episodes of loss of consciousness, interpreted as epileptic seizures. Routine blood tests were within normal range, except for a high cholesterol level. The patient was tested for autoimmune, infectious, endocrine and metabolic diseases that were negative. Surgical treatment and biopsy from the lesion was proposed, however the patient refused both procedures. Conclusions: There is an association between xanthogranulomas localization and the choroid plexus, the most frequent CNS origin being in the trigon of the lateral ventricle. Our case does not resemble with any other case published, mostly because the unusual presentation, symptomatology and the association between xanthogranulomas, thrombophilia and postero-inferior cerebellar artery aneurysm which were never reported before in other cases of xanthogranulomas from the literature.

A Reminder for a Very Rare Entity: Massive Tongue Swelling after Posterior Fossa Surgery

The purpose of this study is to report a case of presumably neurogenic macroglossia that occurred after surgical trapping of a vertebral artery (VA)-posteroinferior cerebellar artery aneurysm, and to analyze its potential pathogenesis. A 53-year-old woman who suffered from headaches and intermittent loss of consciousness but without evidence of subarachnoid hemorrhage was admitted. Magnetic resonance imaging and angiography showed an irregular aneurysm in the fourth segment of a left dominant VA. Surgical treatment was indicated after discussion with the neuroradiology team. During surgery, in the prone position the aneurysm ruptured. The patient became hemodynamically instable. On the first postoperative day, macroglossia appeared and remained for 3 weeks until spontaneous regression. Macroglossia is a rare complication following neurosurgical procedures with very few cases reported so far. It has been attributed to the sitting position and venous flow congestion. We illustrate a case of macroglossia, which occurred following surgery in the prone position. Its etiology remains speculative, but a neurogenic explanation seems most plausible.

Aneurysms of the medullary segments of the posterior-inferior cerebellar artery: considerations on treatment strategy and clinical outcome

Proximal aneurysms of the medullary postero-inferior cerebellar artery (PICA) tract are peculiar due to critical anatomical location, small size and tortuosity of the parent vessel, close origin to brainstem perforators, and fragility of the sac wall. Moreover, most patients present after bleeding, increasing the challenges. Aim of this study is to evaluate the treatment modality and outcome of these patients during the last decade at the University Clinic of Torino. Databases of the Neurosurgical and Neuroradiological Department of the University of Torino were analyzed to retrieve patients treated for aneurysms of the medullary PICA tract. Charts and neuroradiological documentation were revised to complete the database. Of 621 patients treated for an intracranial aneurysm, 23 had PICA aneurysm, 18 located at the medullary tract. Only two were unruptured and 16 were ruptured aneurysms. Sixteen underwent endovascular treatment and two underwent surgery. In six cases the aneurysm was cured by parent vessel occlusion. At 6 months follow-up, the Glasgow outcome scale was high (5 and 4) in 16 patients; two patients had died in the acute phase, for reasons unrelated to the procedure. If not adequately compensated, parent vessel occlusion associates with high risks of ischemia and related brain swelling. In the present series sufficient collateral flow contributed to a good tolerance toward occlusion in all cases. Despite the small size of the present series, most treated cases presented a good outcome. Nevertheless, distal revascularization of the occluded artery would be indicated where collateral flow is insufficient.

Bilateral, Mirror-imaged, Postero-inferior Cerebellar Artery Aneurysms: Report of a Rare Case

A 60-year-old right-handed lady presented with the features of subarachnoid haemorrhage. The CT angiogram showed a pair of very rare bilateral, mirror-imaged distal postero-inferior cerebellar artery aneurysms. Both aneurysms were clipped via the midline posterior fossa craniectomy under general anaesthesia. The literatures is reviewed on the incidence, presentation, management and outcome of bilateral distal posterior-inferior cerebellar artery aneurysms.

Clinical outcomes of lower cranial nerve palsies caused by vertebral artery–posteroinferior cerebellar artery aneurysms after endovascular embolization

Objective: To report clinical outcomes of lower cranial nerve palsy (LCNP) caused by vertebral artery (VA) aneurysms.Methods: Seventy-two patients with VA aneurysms, who were treated endovascularly between 2001 and 2008, were retrospectively studied to identify patients presenting LCNP without hemorrhage.Results: LCNP occurred in 12 patients (16·7%) initially caused by VA aneurysms: four located at vertebral artery–posteroinferior cerebellar artery (PICA) complex, seven at distal to PICA segment and one at proximal to PICA segment. Among these patients, ten patients were diagnosed as having dissecting aneurysms of the intracranial VA, and two were diagnosed having saccular aneurysms. Two patients were treated by sole stent placement, five patients were treated by stent coil embolization and five were treated by vertebral artery occlusion. Nosocomial pneumonia did not occur in our patients. Post-operative LCNP resolved completely within 6 months in nine patients (75%) and within 9 months in ten patients (83%). Two (1·9%) patients died of aneurismal bleeding and brainstem ischemia, respectively.Conclusion: The results of this study can help to identify the effect and natural history of LCNP caused by VA aneurysms. These lesions can be effectively treated by endovascular embolization, even by VA occlusion.

THE CURRENT ROLE OF MICROSURGERY FOR POSTERIOR CIRCULATION ANEURYSMS

During the past decade, management of posterior circulation aneurysms has shifted away from microsurgery. Currently, microsurgical clipping is considered a primary, competitive alternative to endovascular coiling, or more commonly, a secondary alternative when endovascular therapy is unfavorable. We present a large, multidisciplinary team experience with posterior circulation aneurysms in an institution that continues to use microsurgery as a primary treatment modality for selected aneurysms. During a 9-year period, 217 patients with 228 posterior circulation aneurysms were treated microsurgically; they included 106 basilar bifurcation, 27 posterior cerebral artery, 23 superior cerebellar artery, eight anteroinferior cerebellar artery, five basilar trunk, 47 posteroinferior cerebellar artery, and 12 vertebral artery aneurysms. Overall, 81% of patients presented with hemorrhage, and 33% of the aneurysms were large or giant in size. Direct clipping was performed in 75% of cases, and the overall rate of angiographic aneurysm obliteration was 98.1%. Sixteen patients (7.4%) died after surgery, 25 patients (11.5%) experienced transient neurological deterioration, and 17 patients (7.8%) experienced permanent neurological deterioration. At late follow-up (mean duration, 13.6 mo), 144 patients had good outcomes (Glasgow Outcome Scale scores of 5 or 4, 66%), and 184 patients (85%) either improved or were unchanged relative to their preoperative baseline. Overall, mean Glasgow Outcome Scale scores improved from 3.60 to 3.97. Despite increasing reliance on endovascular therapy with posterior circulation aneurysms, there is a role for microsurgical therapy. Microsurgery remains a competitive, primary therapy for superior cerebellar artery, P1 posterior cerebral artery, distal anteroinferior cerebellar artery, and posteroinferior cerebellar artery aneurysms. Microsurgery has become a secondary therapy for P2 posterior cerebral artery, basilar trunk, proximal anteroinferior cerebellar artery, vertebrobasilar junction, and vertebral artery aneurysms when endovascular therapy is unfavorable. The preferred therapy for basilar bifurcation aneurysms remains unclear. Collaborative, multidisciplinary teams are strengthened and results are improved by offering competitive treatment alternatives for patients to consider and select. Rather than abandoning the posterior circulation prematurely, aneurysm surgeons should maintain technical proficiency with these lesions.

Far Lateral Suboccipital Approach for the Treatment of Proximal Posteroinferior Cerebellar Artery Aneurysms: Surgical Results and Long-Term Outcome

Far Lateral Suboccipital Approach for the Treatment of Proximal Posteroinferior Cerebellar Artery Aneurysms: Surgical Results and Long-Term Outcome

In Situ Bypass in the Management of Complex Intracranial Aneurysms: Technique Application in 13 Patients

Cerebral revascularization is an important part of the treatment of complex intracranial aneurysms that require deliberate occlusion of a parent artery. In situ bypass brings together intracranial donor and recipient arteries that lie parallel and in close proximity to one another rather than using an extracranial donor artery. An experience with in situ bypasses was retrospectively reviewed. Thirteen aneurysms were treated with in situ bypasses between 1997 and 2004. During this time, 1071 aneurysms were treated microsurgically and 46 bypasses were performed as part of the aneurysm treatment. Treated aneurysms were located at the middle cerebral artery (MCA) in five patients, posteroinferior cerebellar artery (PICA) in three patients, vertebral artery in three patients, and anterior communicating artery in two patients. Seven aneurysms were fusiform or dolichoectatic, and six aneurysms were saccular. Microsurgical revascularization techniques included side-to-side anastomosis of intracranial arteries in eight patients and aneurysm excision with end-to-end reanastomosis of the parent artery in five patients. In situ bypasses included A3-A3 anterior cerebral artery bypass in two patients, anterior temporal artery-MCA bypass in one patient, MCA-MCA bypass in one patient, and PICA-PICA bypass in four patients. Aneurysm excision with arterial reanastomosis included three MCA aneurysms and two PICA aneurysms. On angiography, all aneurysms were completely obliterated and 12 bypasses were patent. In situ bypass is a safe and effective alternative to extracranial-intracranial bypasses and high-flow bypasses using saphenous vein or radial artery grafts. Although in situ bypasses are more demanding technically, they do not require harvesting a donor artery, can be accomplished with one anastomosis, and are less vulnerable to injury or occlusion.

Vertebral Artery-Posteroinferior Cerebellar Artery Aneurysms: Clinical and Lower Cranial Nerve Outcomes in 52 Patients

To identify factors predictive of postoperative lower cranial nerve palsy (LCNP) among patients undergoing surgery for vertebral artery (VA)- posteroinferior cerebellar artery (PICA) aneurysms. The natural history of this LCNP is defined, and its effect on postoperative patient course is analyzed. No similar study has been described in the literature. Fifty-two patients with VA-PICA aneurysms, who were treated surgically between 1996 and 2002, were retrospectively studied to identify factors contributing to postoperative LCNP. The effect of LCNP on intensive care unit stay and development of nosocomial pneumonia also was analyzed. All analyses were performed with Fisher's exact test. Postoperative LCNP occurred in 25 patients (48.1%) with VA-PICA aneurysms. Of the factors investigated, the use of temporary or total occlusion was associated with increased incidence of postoperative LCNP (P <0.001). The average length of stay in the intensive care unit was 13.8 days for patients with LCNP defined as moderate to severe, compared with 7.92 days for patients with LCNP defined as none or mild (P=0.0014). Nosocomial pneumonia occurred only in patients with moderate to severe LCNP (P=0.022). Postoperative LCNP resolved completely within 3 months in 12 patients (48%) and within 6 months in 19 patients (76%) . The results of this study can help to identify the effect and natural history of LCNP after surgical clipping of VA-PICA aneurysms. This information may assist neurosurgeons in expediting treatment, decrease the cost and length of hospital stays, and result in improved outcomes.

Far Lateral Suboccipital Approach for the Treatment of Proximal Posteroinferior Cerebellar Artery Aneurysms: Surgical Results and Long-term Outcome

Proximal posteroinferior cerebellar artery (PICA) aneurysms are challenging to treat surgically, with high reported perioperative complication rates. We describe the perioperative course and long-term clinical outcomes obtained via a far lateral suboccipital approach in 20 consecutive proximal PICA aneurysms. Data were collected prospectively on the first 20 proximal PICA aneurysms treated surgically by a single surgeon (ESC) between December 1997 and April 2003. All aneurysms were clipped via a far lateral approach. Patients with unruptured aneurysms were assessed at 3 and 12 months after surgery. For all subarachnoid hemorrhage patients, a battery of outcome tests was performed at 3- and 12-month intervals. Outcomes were then compared with those of a contemporaneously managed population of ruptured right-sided posterior communicating artery aneurysms. The far lateral suboccipital approach achieved adequate exposure in all cases. There were no intraoperative complications or intraoperative aneurysm ruptures. All patients with unruptured aneurysms were fully functional at long-term follow-up. At 3 months of follow-up, 93% of the subarachnoid hemorrhage patients achieved a Glasgow Outcome Scale score of 1 to 2. At 12 months of follow-up, 92% achieved a Glasgow Outcome Scale score of 1 to 2. Compared with the patients with a ruptured right-sided posterior communicating artery aneurysm, no difference could be found in quality of life or activities of daily living at either time point. The favorable outcomes and low postoperative morbidity in this subset of patients argues that clipping via this approach be considered a first-line therapeutic option. When performed in this manner, PICA aneurysm surgery seems to have no greater morbidity than right-sided posterior communicating artery aneurysm surgery.

Posteroinferior cerebellar artery aneurysms: surgical results for 38 patients.

Posteroinferior cerebellar artery aneurysms have an incidence of approximately 0.49%. Reports in the literature are sparse concerning outcomes in this patient population. We report our results for 38 consecutive patients who were treated during the last 6.5 years. All patients (n = 38) with posteroinferior cerebellar artery aneurysms that were surgically treated at Zale-Lipshy University Hospital between January 1990 and May 1997 were retrospectively reviewed. Data were collected and analyzed relating to demographics, condition at presentation, lesion characteristics, associated medical problems, postsurgical complications, and outcome. Sixty-six percent of the patients (n = 25) experienced neurological sequelae, which included symptomatic vasospasm, hydrocephalus, dysarthria, paresis, diplopia, ataxia, and facial paralysis. Many, however, showed significant improvement during their hospitalization and during the course of the ensuing year. Seventy-four percent of the patients had a Glasgow Outcome Scale score of 1 or 2 at the time of discharge, 91% at 6 months after surgery, and 89% at 1 year after surgery. This review summarizes the presentations and outcomes of 38 consecutive surgical cases during a 6.5-year period and concludes that posteroinferior cerebellar artery aneurysms are not benign entities. The study does, however, also demonstrate that patients have significant recuperative potential after the treatment of these lesions.

Comments

OBJECTIVE: Posteroinferior cerebellar artery aneurysms have an incidence of approximately 0.49%. Reports in the literature are sparse concerning outcomes in this patient population. We report our results for 38 consecutive patients who were treated during the last 6.5 years. METHODS: All patients (n = 38) with posteroinferior cerebellar artery aneurysms that were surgically treated at Zale-Lipshy University Hospital between January 1990 and May 1997 were retrospectively reviewed. Data were collected and analyzed relating to demographics, condition at presentation, lesion characteristics, associated medical problems, postsurgical complications, and outcome. RESULTS: Sixty-six percent of the patients (n = 25) experienced neurological sequelae, which included symptomatic vasospasm, hydrocephalus, dysarthria, paresis, diplopia, ataxia, and facial paralysis. Many, however, showed significant improvement during their hospitalization and during the course of the ensuing year. Seventy-four percent of the patients had a Glasgow Outcome Scale score of 1 or 2 at the time of discharge, 91% at 6 months after surgery, and 89% at 1 year after surgery. CONCLUSION: This review summarizes the presentations and outcomes of 38 consecutive surgical cases during a 6.5-year period and concludes that posteroinferior cerebellar artery aneurysms are not benign entities. The study does, however, also demonstrate that patients have significant recuperative potential after the treatment of these lesions.

Ruptured vertebrobasilar aneurysms: frequency of the nonaneurysmal perimesencephalic pattern of hemorrhage on CT scans.

To determine the frequency of the computed tomographic (CT) pattern of nonaneurysmal perimesencephalic subarachnoid hemorrhage in the setting of ruptured posterior fossa aneurysms. Four neuroradiologists independently and retrospectively reviewed cranial CT scans of 169 patients with ruptured vertebrobasilar aneurysms (44 cases of posteroinferior cerebellar artery aneurysm, 20 cases of superior cerebellar artery aneurysm, and 105 cases of basilar-tip aneurysm). The mean frequency of nonaneurysmal perimesencephalic pattern of subarachnoid hemorrhage in ruptured vertebrobasilar aneurysms was 7.1% (48 of 676 readings) among the four readers. The mean frequency of aneurysms with the pattern of hemorrhage for each location was as follows: basilar tip, 9.8% (41 of 420 readings); superior cerebellar artery, 5.0% (four of 80 readings); and posteroinferior cerebellar artery, 0%. In 75% (six of eight) of the cases in which the CT pattern of hemorrhage was deemed compatible by all readers with nonaneurysmal hemorrhage, the clinical presentation was mild. Because ruptured posterior fossa aneurysms manifest with the nonaneurysmal pattern of hemorrhage in approximately 10% of cases, a high degree of suspicion should be maintained even if the pattern of subarachnoid hemorrhage suggests a nonaneurysmal origin and clinical symptoms are mild.