Ruptured Pseudoaneurysm after Gamma Knife Surgery for Vestibular Schwannoma

Ruptured distal anterior inferior cerebellar artery aneurysm years after stereotactic radiosurgery for vestibular schwannoma: A case report and literature review

Background

Aneurysmal formation after stereotactic radiosurgery (SRS) for vestibular schwannoma (VS) is a rare complication. Its characteristics and the best treatment strategies remain controversial, and the clinical course is especially unknown because reported aneurysms are first incidentally detected, or aneurysmal rupture occurs suddenly, and they are treated immediately.

Case Description

A 68-year-old man who underwent SRS for VS 20 years ago presented with subarachnoid hemorrhage (SAH) due to rupture of a radiation-induced fusiform anterior inferior cerebellar artery aneurysm. He was treated with parent artery occlusion, resulting in a modified Rankin scale grade 2. This report illustrates the first case of detected aneurysm formation before rupture with retrospective magnetic resonance imaging evaluation.

Conclusion

We describe the possible risk of rapid progression and rupture of aneurysms, focusing on the interval from SRS to aneurysmal formation. The period of formation of SRS-induced aneurysms is suspected to vary from years to decades regardless of radiation doses; however, aneurysms estimated as pseudoaneurysms have an extremely high risk of rupture within a few years, even when small in size. If aneurysms are discovered unruptured, there are some advantages in not only the prevention of poor prognosis due to SAH but also in the availability of optional therapeutic strategies using revascularization. Long-term annual follow-up, including vessel examination, is warranted not only to assess tumor status but also for early detection of any vascular lesions.

Radiation-induced anterior inferior cerebellar artery pseudoaneurysm after stereotactic radiosurgery for vestibular schwannoma: features observed by direct surgery

BACKGROUND

In vestibular schwannoma (VS) patients treated with stereotactic radiosurgery (SRS), radiation-induced pseudoaneurysm is a rare long-term complication. To the best of our knowledge, there has been only one report of direct surgery in ruptured cases, and the optimal strategy for direct surgery is yet to be clarified. This case report describes a case of ruptured VS-related SRS-induced pseudoaneurysm that was successfully treated by direct surgery.

CASE PRESENTATION

A 57-year -old man underwent SRS for VS, and the tumour was well controlled after the SRS. Nine years after the SRS, however, he developed subarachnoid haemorrhage, and a SRS-induced distal anterior inferior cerebellar artery aneurysm was detected on the surface of the tumour. During the trapping surgery, the aneurysm was embedded in the tumour, and it was difficult to separate the aneurysm and tumour. Besides, the facial nerve and tumour restricted exposure of the parent artery. The parent artery proximal to the aneurysm could only be exposed by resecting caudal part of the tumour. The aneurysm was trapped with permanent clips and it was pathologically diagnosed as pseudoaneurysm.

CONCLUSION

It was suggested that the VS-related SRS-induced pseudoaneurysm is tightly adhered with surrounding structures and exposure of the parent artery could be limited due to the tumour and facial nerve. In this case report, we describe detailed intraoperative findings that will be useful for developing strategies for trapping surgery in future.

Formation of internal carotid artery aneurysms following gamma knife radiosurgery for pituitary adenomas: a case series and literature review

Only two aneurysm formations in the internal carotid artery after gamma knife radiosurgery (GKRS) for pituitary adenomas are reported so far. Here, out of the 482 patients who underwent GKRS for pituitary adenomas at our institute, at least five developed aneurysms within the area of high single-dose irradiation. Three patients presented with epistaxis due to aneurysmal rupture and one presented with abducens paralysis due to nerve compression, while one was asymptomatic. The interval between irradiation and aneurysmal detection ranged from 14 to 21 years. Aneurysm formation in those conditions may be higher than previously thought.

Unruptured anterior Inferior cerebellar artery aneurysm following stereotactic irradiation for vestibular schwannoma: Case report and literature review

Background

The clinical features and therapeutic measures of vestibular schwannoma (VS) radiation-related aneurysm (RRA) have not been well described. We reported the first VS RRA case admitted for acute anterior inferior cerebella artery (AICA) ischemic symptoms. Literature was reviewed to present the research fruits about VS RRAs, and some therapeutic advices were given.

Materials and methods

A 54-year-old woman who had undergone GKS 10 years previously for a right VS was admitted to our hospital in 2018 because of sudden onset of severe vertigo and vomiting, accompanied with unsteady gait. During tumor resection, a dissecting aneurysm arose from the main trunk of AICA was encountered accidently within the tumor. The aneurysm was successfully treated with direct clip ligation, sparing the parent vessel. Data about this case were combined with those of other 11 radiation-related AICA aneurysm cases retrieved from the current literature. The following parameters were evaluated: Age, Sex, Diagnostic method, Location of aneurysm, Age of radiotherapy (Years)/Latency, Rupture, x-ray dosage, Type of radiotherapy, History of surgical resection of VS, Aneurysm Type, Morphology, Number, Treatment, Operative complications, Sequela, Outcome. VS RRAs mainly occurred in women (75%) with a median age of 62.5 years and were mainly located on AICA. Ruptured aneurysms accounted for 75.0% of the total cases. This paper reported the first VS case admitted with acute AICA ischemic symptoms. Cases with sacciform-like, irregular and fusiform-shaped aneurysms accounted for 50.0%, 25.0% and 25.0% of the total, respectively. After surgical treatment, 75.0% patients recovered, except for 3 patients who developed new ischemic consequence.

Conclusion

Patients should be informed of the risk of RRAs after receiving radiotherapy for VS. In these patients, RRAs should be suspected when subarachnoid hemorrhage or AICA ischemic symptoms occurred. Active intervention should be conducted considering the high instability and bleeding rate of VS RRAs.

Outcomes of stereotactic radiosurgery in young adults with vestibular schwannomas

PURPOSE

Vestibular schwannomas (VSs) are comparatively rare in younger patients, and stereotactic radiosurgery (SRS) outcome data are limited. We aimed to evaluate long-term SRS outcomes concerning sporadic VSs in patients aged ≤ 40 years.

METHODS

Of 383 patients with VS who had undergone SRS at our institution between 1990 and 2017, we retrospectively compared younger and older patients' tumor control and radiation-induced complication rates using case-control propensity score (PS) matching.

RESULTS

The mean follow-up was 83 and 92 months in older and younger patients, respectively. Compared with older patients, younger patients were more likely to have a history of resection (20% vs. 39%, p = 0.006) and be treated with higher marginal doses (median, 12 Gy vs. 14 Gy; p = 0.014). Cumulative 5- and 10-year tumor control rates were higher in older patients (97.7% and 93.9%, respectively) than in younger patients (90.2% and 85.4%, respectively, p = 0.024). After PS matching, younger patients' cumulative tumor control rates (93.6%, 85.4%, and 85.4% at 5, 10, and 15 years, respectively) were similar to those of older patients (p = 0.411). No significant between-cohort differences in hearing preservation rates or other cranial nerve complications were observed. Two younger patients had malignant tumors several years post-SRS, with one patient having confirmed histological transformation.

CONCLUSIONS

SRS is equally effective for younger and older patients. Complications other than hearing deterioration are uncommon. However, malignant transformation is possible, and long-term post-SRS surveillance MRI is important. These data are useful for decision-making involving young adults with VSs.

Intracranial Pseudoaneurysms: Evaluation and Management

Intracranial pseudoaneurysms account for about 1% of intracranial aneurysms with a high mortality. The natural history of intracranial pseudoaneurysm is not well-understood, and its management remains controversial. This review provides an overview of the etiology, pathophysiology, clinical presentation, imaging, and management of intracranial pseudoaneurysms. Especially, this article emphasizes the factors that should be considered for the most appropriate management strategy based on the risks and benefits of each treatment option.

Long-Term Outcomes of Sporadic Vestibular Schwannomas Treated with Recent Stereotactic Radiosurgery Techniques

PURPOSE

Vestibular schwannomas (VSs) are benign; thus, understanding long-term tumor control and late adverse radiation effects of stereotactic radiosurgery (SRS) through current radiosurgical techniques is important to inform treatment decisions. Our aim was to clarify long-term tumor control rates and incidence of late adverse radiation effects in patients with VSs followed for 5 years or longer after SRS.

METHODS AND MATERIALS

Altogether, 615 patients with VSs (excluding neurofibromatosis type 2 and partially treated tumors) followed for 5 years or longer after SRS using recent radiosurgical techniques were evaluated. All patients were treated at a margin dose of less than 14 Gy. All tumors were classified into 4 categories: type A (intracanalicular tumor, 87 patients [14%]), type B (cerebellopontine angle [CPA] tumor, 325 patients [53%]), type C (CPA tumor compressing the brain stem, 138 patients [22%]), and type D (CPA tumor compressing the brain stem with a deviation of the fourth ventricle, 65 patients [11%]). Median tumor volume was 2.0 cm³ and median marginal dose was 12 Gy.

RESULTS

Median follow-up period was 158 months. Actuarial 5-, 10-, and 15-year or longer local control (LC) rates were 93%, 91%, and 89%, respectively. Tumor type (P < .001, hazard ratio 2.389) and number of prior surgeries (P = .007, hazard ratio 1.698) were significant for LC. Depending on the tumor type, the actuarial 10-year LC rates were 100%, 93%, 88%, and 70% in type A, B, C, and D tumors, respectively. No patient developed persistent facial palsy. Twenty patients (3.3%) developed delayed cysts. One patient developed malignant transformation (0.2%).

CONCLUSIONS

SRS is a safe and effective treatment for VSs in the long term, excluding VSs compressing the brain stem with a deviation of the fourth ventricle. Delayed cysts such as cyst formation, enlarged preexisting cysts or extratumoral cysts, and malignant transformation should be considered possible causes of long-term treatment failures.

Gamma knife surgery-induced aneurysm rupture associated with tissue plasminogen activator injection: A case report and literature review

Background

Cases involving delayed development of intracranial aneurysms related to gamma knife surgery (GKS) have been recently reported. Here, we present a rare case of GKS-induced aneurysm rupture after intravenous injection of tissue plasminogen activator (t-PA) for occlusion of the middle cerebral artery (MCA). To the best of our knowledge, this is the first case in which t-PA-induced rupture of a GKS-related unruptured aneurysm.

Case Description

A 56-year-old woman underwent GKS for left trigeminal neuralgia. Eighteen years later, she suddenly experienced MCA occlusion with consciousness disturbance and right hemiparesis. She received an intravenous injection of t-PA and then was transferred to our hospital. We confirmed residual thrombus, and she underwent mechanical thrombectomy successfully. A postthrombectomy brain computed tomography scan revealed subarachnoid hemorrhage with a hematoma in the left cerebellar hemisphere. Cerebral angiography revealed a small irregular-shaped aneurysm at the branching site of the left circumflex branch at the distal position of the anterior inferior cerebellar artery, which was not detected on initial imaging. Coil embolization was performed. One month after the ischemic attack, she was transferred to a rehabilitation hospital, with a modified Rankin Scale score of 5.

Conclusions

The tendency to rupture is greater for GKS-induced aneurysms than for intrinsic unruptured aneurysms, according to previous reports. When performing acute treatment for cerebral infarction in patients with a history of GKS, the presence of aneurysms should be evaluated and we should keep in mind that GKS aneurysms are very small and tend to rupture.

Refractory De Novo Multiple Cerebral Aneurysms After Radiotherapy and Multistaged "Open" Surgical Treatment for Low-Grade Glioma During Long-Term Follow-Up: A Case Report and Review of the Literature

Background

Radiation-induced aneurysms have been previously reported; however, multiple and repeated de novo aneurysm formation chronologically and anatomically during long-term follow-up have not yet been observed. The pathogenesis of persistent radiation-induced vasculopathy is not fully understood.

Case Description

A 31-year-old woman presented with intraventricular hemorrhage due to rupture of a right internal carotid artery (ICA) aneurysm that developed 17 years after surgical resection of a low-grade glioma in the right frontal lobe and postoperative radiotherapy (focal, 50 Gy/25 fractions). During glioma follow-up, salvage surgery with adjuvant gamma knife therapy and chemotherapy (ranimustine, vincristine, temozolomide) were performed for recurrence of the glioma. The aneurysm was treated with endovascular coil embolization. However, she experienced repeated intraventricular hemorrhages, and angiography revealed a de novo ICA aneurysm. The de novo aneurysms were treated with endovascular surgery using coil embolization and stenting. At 2 years after the third hemorrhage, the surgical wound became dehiscent, probably due to wound infection, thus epicranial soft tissue reconstruction using vascularized skin flap was performed. Despite multistaged endovascular surgery for the ICA aneurysm, she experienced repeated subarachnoid and intraventricular hemorrhages. Angiography revealed a de novo aneurysm of the right posterior cerebral artery and basilar trunk. She underwent coil embolization and stenting. Despite active management with endovascular surgery and close follow-up, she died after an eighth consecutive intraventricular and intracerebral hemorrhage caused by a de novo large aneurysm of the posterior cerebral artery.

Conclusions

To the best of our knowledge, the present study is the first to report on of refractory and recurring de novo aneurysms treated by multistaged endovascular surgery during a long-term follow-up after radiotherapy and multistaged craniotomy for glioma.

Internal carotid artery aneurysms diagnosed after stereotactic radiosurgery for a growth hormone-secreting pituitary adenoma: a case report and literature review

Radiation therapy is associated with the subsequent development of cerebral aneurysms; however, stereotactic radiosurgery (SRS)-associated aneurysm cases have not been well documented, with only 18 cases reported to date. We present a case of intracranial aneurysms with the rupture occurring 20 years after SRS for a growth hormone-producing pituitary adenoma. This is the first report of aneurysms diagnosed following transsphenoidal surgery and SRS for pituitary adenoma. We believe that the aneurysm reported here is a consequence of the SRS treatment, and thus this may be a very rare long-term complication following radiation treatments.

Radiosurgery-Induced Anterior Inferior Cerebellar Artery Pseudoaneurysm Treated with Trapping and Bypass

BACKGROUND

Stereotactic radiosurgery (SRS) is an established modality for treatment of vestibular schwannomas (VSs). However, its long-term vascular complications have not been well studied. Among 360 patients who underwent SRS for VS in our institution and lived for >5 years thereafter, we identified only 1 patient who exhibited a complication secondary to a late-onset aneurysm for an estimated incidence of 0.3%.

CASE DESCRIPTION

A 78-year-old man who had undergone SRS 19 years previously for a right VS presented with right peripheral facial palsy. Radiographic examinations revealed a distal anterior inferior cerebellar artery (AICA) fusiform aneurysm that was embedded in the tumor and progressively enlarged over 17 months. Although the right AICA perfused a large area of the cerebellum, the aneurysm was successfully treated with AICA trapping in conjunction with an occipital artery-AICA bypass.

CONCLUSIONS

Distal AICA pseudoaneurysm formation is a rare but potentially severe late complication after SRS for VS. This pathology was successfully treated with AICA trapping with occipital artery-AICA bypass.