Unruptured intracranial aneurysm as a cause of cerebral ischemia

Treatment Strategy of Intracranial Anterior Circulation Aneurysm Presenting with Cerebral Ischemia: A Single-Center Experience

OBJECTIVE

To investigate the clinical characteristics and treatment strategy of anterior circulation aneurysm presenting with cerebral ischemia.

METHODS

We performed a retrospective review of patients with intracranial anterior circulation aneurysms presenting with cerebral ischemia examined in the Fifth Ward of the Neurosurgery Department of Tianjin Huanhu Hospital between September 2016 and September 2023. Data were reviewed for age, sex, presentation, type and size, location, treatment modalities, postoperative complications, clinical and imaging outcomes, and follow-up outcomes.

RESULTS

Among the 13 patients, there were 8 males and 5 females (1.6:1). Their presentations included ischemic stroke (69.23%, 9/13) and transient ischemic attack (TIA) (30.77%, 4/13). The aneurysms were dissecting (46.15%, 6/13), saccular (30.77%, 4/13), and saccular combined with thrombosis (23.08%, 3/13) in shape. There were 6 giant aneurysms, 4 large aneurysms, and 3 microaneurysms. Three (23.08%, 3/13) aneurysms were located at the internal carotid artery (ICA) and 10 (76.92%, 10/13) were located in the middle cerebral artery (MCA). A preoperative magnetic resonance perfusion (MRP) examination was performed in all patients, and 9 (69.23%, 9/13) patients showed hypoperfusion. Treatment modalities included stent-assisted embolization, direct clipping, clipping combined with bypass, resection combined with bypass, isolated combined with bypass, proximal occlusion combined with bypass, and the internal carotid artery constriction combined with bypass. Twelve (92.31%, 12/13) patients had no postoperative complications, and temporary complications occurred in 1 (7.69%, 1/13) patient. Aneurysms disappeared in 11 cases and shrank in 2 cases postoperatively. All patients were followed up for 1 to 72 months. We found no new cerebral infarction, no subarachnoid hemorrhage, and no recurrence or enlargement of aneurysms during the follow-up.

CONCLUSIONS

Intracranial anterior circulation aneurysm presenting with cerebral ischemia is rare. Saccular aneurysms with wide neck or thrombosis and dissected aneurysms of the anterior circulation may result in cerebral ischemic attack caused by distal vascular embolism. Individualized treatment should be performed, and cerebral revascularization is an effective treatment for patients with intracranial anterior circulation aneurysms presenting with cerebral ischemia.

A comprehensive assessment of self-reported symptoms among patients harboring an unruptured intracranial aneurysm

Background

Approximately 3.2%-6% of the general population harbor an unruptured intracranial aneurysm (UIA). Ruptured aneurysms represent a significant healthcare burden, and preventing rupture relies on early detection and treatment. Most patients with UIAs are asymptomatic, and many of the symptoms associated with UIAs are nonspecific, which makes diagnosis challenging. This study explored symptoms associated with UIAs, the rate of resolution of such symptoms after microsurgical treatment, and the likely pathophysiology.

Methods

A retrospective review of patients with UIAs who underwent microsurgical treatment from January 1, 2014, to December 31, 2020, at a single quaternary center were identified. Analyses included the prevalence of nonspecific symptoms upon clinical presentation and postoperative follow-up; comparisons of symptomatology by aneurysmal location; and comparisons of patient demographics, aneurysmal characteristics, and poor neurologic outcome at postoperative follow-up stratified by symptomatic versus asymptomatic presentation.

Results

The analysis included 454 patients; 350 (77%) were symptomatic. The most common presenting symptom among all 454 patients was headache (n = 211 [46%]), followed by vertigo (n = 94 [21%]), cognitive disturbance (n = 68[15%]), and visual disturbance (n = 64 [14%]). Among 328 patients assessed for postoperative symptoms, 258 (79%) experienced symptom resolution or improvement.

Conclusion

This cohort demonstrates that the clinical presentation of patients with UIAs can be associated with vague and nonspecific symptoms. Early detection is crucial to prevent aneurysmal subarachnoid hemorrhage. It is imperative that physicians not rule out aneurysms in the setting of nonspecific neurologic symptoms.

Acute middle cerebral artery occlusion caused by spontaneous thrombosis of a small internal carotid artery aneurysm: illustrative case

BACKGROUND

Spontaneous thrombosis of a saccular, unruptured, intracranial aneurysm is rare in nongiant aneurysms. Herein, the authors present a case of acute middle cerebral artery occlusion (MCO) caused by spontaneous thrombus of a small internal carotid artery (ICA) aneurysm.

OBSERVATIONS

A 68-year-old woman presented with increased somnolence, right-sided hemiplegia, hemispatial neglect, and total aphagia. Left MCO and a small left ICA aneurysm were suspected based on magnetic resonance angiography (MRA). The authors detected early ischemic lesions from diffusion-weighted imaging (DWI). The DWI–Alberta Stroke Program Early Computed Tomography Score was 6. T2*-weighted imaging (T2*WI) showed a thrombus, the so-called susceptibility vessel sign, at the left MCO site. Another suspected thrombus was also found in the ipsilateral ICA aneurysm. The authors treated acute phase MCO with mechanical thrombectomy (MT), after which secondary stroke prophylaxis consisting of warfarin potassium was started. Since follow-up T2*WI showed the thrombus had disappeared from the left ICA aneurysm and the whole aneurysm was clarified by MRA, coil embolization was performed. After coil embolization, there was no ischemic recurrence.

LESSONS

Aneurysms are infrequently found proximal to occlusion sites during MT. If the proximal aneurysm is a potential embolic source, treatment of the said aneurysm may prevent stroke.

Transient Ischemic Attack Due to Unruptured Basilar Artery Aneurysm

Intracranial aneurysms are typically asymptomatic. They are usually incidentally detected or detected only after rupture. Ischemic stroke or transient ischemic attack (TIA) due to unruptured intracranial aneurysms (UIAs) is rare. A 79-year-old male with well-controlled hypertension and hypothyroidism, presented with complaints of sudden-onset weakness of the right upper limb and lower limb, followed by altered sensorium and a fall. Two hours later, he had fully recovered. Neurologic examination was unremarkable. Computed tomography of the brain revealed a dilated and tortuous basilar artery, suggestive of an aneurysm compressing the left midbrain and pons, with no evidence of intracranial bleed. Further, magnetic resonance imaging with an angiogram revealed multiple lacunar infarcts in the posterior circulation, distal to the aneurysm. Finally, a cerebral angiogram confirmed a partially thrombosed, fusosaccular aneurysm, arising from the left vertebral and basilar arteries. In view of frailty and long vessel segment involvement, surgery was not advised. He was treated medically, with appropriate antiplatelets and prophylactic antiepileptics. On follow-up, he had no neurologic deficit and had suffered no later ischemic or hemorrhagic events. UIAs may cause brainstem strokes via thrombosis of the parent vessel, emboli from the thrombus, or compression of the parent artery. In our case, compression, the least common mechanism, appears to have caused the TIA, with emboli potentially responsible for the silent lacunar infarcts. Fusiform aneurysms of the vertebrobasilar system have a poor natural history. In elderly patients presenting with ischemic events due to UIAs of the vertebrobasilar system, surgical intervention can be risky. So, medical treatment with antiplatelets is recommended. UIAs should be considered in the differential diagnosis of patients with TIAs, and such patients should have a visualization of intracranial arteries.

Effect of Pulsatility on the Transport of Thrombin in an Idealized Cerebral Aneurysm Geometry

Computational models of cerebral aneurysm thrombosis are designed for use in research and clinical applications. A steady flow assumption is applied in many of these models. To explore the accuracy of this assumption a pulsatile-flow thrombin-transport computational fluid dynamics (CFD) model, which uses a symmetrical idealized aneurysm geometry, was developed. First, a steady-flow computational model was developed and validated using data from an in vitro experiment, based on particle image velocimetry (PIV). The experimental data revealed an asymmetric flow pattern in the aneurysm. The validated computational model was subsequently altered to incorporate pulsatility, by applying a data-derived flow function at the inlet boundary. For both the steady and pulsatile computational models, a scalar function simulating thrombin generation was applied at the aneurysm wall. To determine the influence of pulsatility on thrombin transport, the outputs of the steady model were compared to the outputs of the pulsatile model. The comparison revealed that in the pulsatile case, an average of 10.2% less thrombin accumulates within the aneurysm than the steady case for any given time, due to periodic losses of a significant amount of thrombin-concentrated blood from the aneurysm into the parent vessel’s bloodstream. These findings demonstrate that pulsatility may change clotting outcomes in cerebral aneurysms.

Brain ischemia due to direct vascular compression associate with rapid enlargement of unruptured middle cerebral artery aneurysm: A case report

Background

Acute cerebral infarction is a rare complication resulting from an unruptured cerebral aneurysm (UCA). There is presently no consensus on the optimal strategy for the management of UCAs with cerebral infarctions.

Case Description

A 53-year-old man presented with transient dysarthria and left hemiparesis. Magnetic resonance imaging (MRI) demonstrated the presence of a 7 mm UCA originating from the middle cerebral artery bifurcation, and diffusion-weighted imaging showed no evidence of cerebral infarction. One month later, his transient left hemiparesis recurred, and the patient was admitted to our hospital. Computed tomography angiography showed enlargement of the aneurysm. His left hemiparesis worsened 3 days later. MRI showed cerebral infarction in the area of perforating arteries and further enlargement of the aneurysm with surrounding parenchymal edema. Therefore, the rupture risk was considered to be rarely high and dome clipping was performed immediately. Postoperatively, his neurological status improved without any recurrent brain ischemia.

Conclusion

We report a rare case of a rapidly enlarging aneurysm that presented with cerebral infarction. This is the first report describing aneurysmal sac enlargement that can lead to perforating artery obstruction and brain ischemia. The case illustrates the importance of performing close follow-up examinations to confirm findings that suggest a high rupture risk.

Distal middle cerebral artery dissection with concurrent completely thrombosed aneurysm manifesting as cerebral ischemia. A case report and review of the literature

We report the case of a 70-year-old woman who presented with an acute ischemic stroke involving the left frontal operculum secondary to an M2 dissection and a concomitant completely thrombosed aneurysm of the left distal middle cerebral artery. Initial imaging work-up was inconclusive due to the lack of typical radiographic features and only repeated imaging studies pointed towards the presence of an arterial dissection combined with a completely thrombosed aneurysm. The aneurysm was partially clipped and wrapped with excellent clinical result at 1-year follow-up. The clinical, imaging and therapeutic challenges of this rare entity are discussed.

Complete spontaneous thrombosis in unruptured non-giant intracranial aneurysms: A case report and systematic review

BACKGROUND AND AIM

Spontaneous partial or complete thrombosis of saccular unruptured intracranial aneurysm (UIAs) is a known occurrence in giant aneurysms. However, spontaneous complete thrombosis of non-giant aneurysms is a rare event in the natural history of UIAs. The aim of this paper is to report on the cases from literature of complete spontaneous thrombosis with a view to identify possible factors associated with this phenomenon.

MATERIAL AND METHODS

We performed a systematic review of the current literature on spontaneous complete thrombosis of saccular, non-giant, unruptured UIAs, including a case that we treated at our institution. We analysed the possible risk factors for thrombosis, association with ischemic events, rupture and recanalization. We reviewed the possible management's strategies for this group of patients described in literature to date.

RESULTS

We identified 26 patients for a total of 27 thrombosed aneurysms from the literature review (including our case). Thrombosis was prevalent in women, in the anterior circulation and in larger aneurysms. Endovascular events in the parent artery, either spontaneous or iatrogenic, were associated with spontaneous thrombosis in 4 cases. In 47 % of cases an antiplatelet treatment (AP) was introduced. Rupture and recanalization of the aneurysm were observed in 14 % and 33 % respectively. A larger size was the only factor statistically associated with rupture (P = 0041). AP was not statistically associated with recanalization or rupture of the aneurysm.

CONCLUSION

Complete spontaneous thrombosis is not a curative event. Its natural history is associated with recanalization, rupture and ischemic stroke. Conservative treatment with a clinical-radiological follow up and treatment with AP is a safe option for small aneurysms. Definitive aneurysmal exclusion should be considered in medium and large aneurysms due to the significant risks associated with untreated aneurysms.

Thrombolysis in Acute Stroke Due to Thrombosed Aneurysm

We describe a case of a patient who presented with an acute stroke and thrombosed aneurysm of the same vessel. We review the literature on acute stroke management in the setting of an ischemic stroke caused by a thrombosed aneurysm, including intravenous thrombolysis and mechanical thrombectomy. We found that it is unclear whether thrombolysis is safe in these cases. Future case series may be helpful in answering the question.

Unruptured intracranial aneurysm growth trajectory: occurrence and rate of enlargement in 520 longitudinally followed cases

OBJECTIVE

As imaging technology has improved, more unruptured intracranial aneurysms (UIAs) are detected incidentally. However, there is limited information regarding how UIAs change over time to provide stratified, patient-specific UIA follow-up management. The authors sought to enrich understanding of the natural history of UIAs and identify basic UIA growth trajectories, that is, the speed at which various UIAs increase in size.

METHODS

From January 2005 to December 2015, 382 patients diagnosed with UIAs (n = 520) were followed up at UCLA Medical Center through serial imaging. UIA characteristics and patient-specific variables were studied to identify risk factors associated with aneurysm growth and create a predicted aneurysm trajectory (PAT) model to differentiate aneurysm growth behavior.

RESULTS

The PAT model indicated that smoking and hypothyroidism had a large effect on the growth rate of large UIAs (≥ 7 mm), while UIAs < 7 mm were less influenced by smoking and hypothyroidism. Analysis of risk factors related to growth showed that initial size and multiplicity were significant factors related to aneurysm growth and were consistent across different definitions of growth. A 1.09-fold increase in risk of growth was found for every 1-mm increase in initial size (95% CI 1.04-1.15; p = 0.001). Aneurysms in patients with multiple aneurysms were 2.43-fold more likely to grow than those in patients with single aneurysms (95% CI 1.36-4.35; p = 0.003). The growth rate (speed) for large UIAs (≥ 7 mm; 0.085 mm/month) was significantly faster than that for UIAs < 3 mm (0.030 mm/month) and for males than for females (0.089 and 0.045 mm/month, respectively; p = 0.048).

CONCLUSIONS

Analyzing longitudinal UIA data as continuous data points can be useful to study the risk of growth and predict the aneurysm growth trajectory. Individual patient characteristics (demographics, behavior, medical history) may have a significant effect on the speed of UIA growth, and predictive models such as PAT may help optimize follow-up frequency for UIA management.

Thrombosis in Cerebral Aneurysms and the Computational Modeling Thereof: A Review

Thrombosis is a condition closely related to cerebral aneurysms and controlled thrombosis is the main purpose of endovascular embolization treatment. The mechanisms governing thrombus initiation and evolution in cerebral aneurysms have not been fully elucidated and this presents challenges for interventional planning. Significant effort has been directed towards developing computational methods aimed at streamlining the interventional planning process for unruptured cerebral aneurysm treatment. Included in these methods are computational models of thrombus development following endovascular device placement. The main challenge with developing computational models for thrombosis in disease cases is that there exists a wide body of literature that addresses various aspects of the clotting process, but it may not be obvious what information is of direct consequence for what modeling purpose (e.g., for understanding the effect of endovascular therapies). The aim of this review is to present the information so it will be of benefit to the community attempting to model cerebral aneurysm thrombosis for interventional planning purposes, in a simplified yet appropriate manner. The paper begins by explaining current understanding of physiological coagulation and highlights the documented distinctions between the physiological process and cerebral aneurysm thrombosis. Clinical observations of thrombosis following endovascular device placement are then presented. This is followed by a section detailing the demands placed on computational models developed for interventional planning. Finally, existing computational models of thrombosis are presented. This last section begins with description and discussion of physiological computational clotting models, as they are of immense value in understanding how to construct a general computational model of clotting. This is then followed by a review of computational models of clotting in cerebral aneurysms, specifically. Even though some progress has been made towards computational predictions of thrombosis following device placement in cerebral aneurysms, many gaps still remain. Answering the key questions will require the combined efforts of the clinical, experimental and computational communities.

A wide-necked extracranial internal carotid artery saccular aneurysm with ipsilateral proximal compression

Extracranial internal carotid artery aneurysms (EICAA) are rare and can elicit various neurologic symptoms. Here, we present a case of a saccular EICAA compressing its proximal parent internal carotid artery (ICA). Ultrasonography demonstrated the proximal ICA stenosis and the "tardus-parvus" Doppler waveform downstream. The patient underwent aneurysmectomy and graft interposition. The histologic analysis highly supported an atypical fibromuscular dysplasia. Although this patient only showed a neck mass, the reduced ipsilateral cerebral blood supply was a potential cause for neurologic symptoms. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 45:116-120, 2017.

Spontaneous thrombosis of giant intracranial aneurysm and posterior cerebral artery followed by also spontaneous recanalization

Background:

Spontaneous complete thrombosis of a giant aneurysm and its parent artery is a rare event. Their spontaneous recanalization is even rarer, with few reports.

Case Description:

A 17-year-old male patient presenting blurred vision and headache, with a history of seizures, was referred to our service. After further investigation with cranial computed tomography, magnetic resonance imaging (MRI), and cerebral angiography (CAG), it was diagnosed a thrombosed aneurysm of the posterior cerebral artery (PCA) and also complete thrombosis of the PCA. Three years later, he experienced visual worsening. A new MRI scan indicated flow both through the aneurysm and the left PCA, which was further confirmed by CAG. We decided for a noninterventional treatment combined with strict clinical follow-up. The patient continues to present with the previous neurological deficit, without recurrence of headaches.

Conclusions:

Thrombosis is not the final event in the natural history of giant aneurysms, and partial thrombosis does not preclude the risk of rupture. Thrombosed aneurysms may display additional growth brought about by wall dissections or intramural hemorrhages. Their treatment may be either surgical or involve endovascular procedures such as embolization. Thrombosed giant aneurysms are dynamic and unstable lesions. A noninterventional treatment is feasible, but aneurysmal growth or recanalization may suggest the need for a more active intervention.

Computational modelling of clot development in patient-specific cerebral aneurysm cases

ESSENTIALS: Clotting in cerebral aneurysms is a process that can either stabilize the aneurysm or lead to rupture. A patient-specific computational model capable of predicting cerebral aneurysm thrombosis is presented. The different clotting outcomes highlight the importance of personalization of treatment. Once validated, the model can be used to tailor treatment and to clarify clotting processes in aneurysms.

BACKGROUND

In cerebral aneurysms, clotting can either stabilize the aneurysm sac via aneurysm occlusion, or it can have a detrimental effect by giving rise to embolic occlusion.

OBJECTIVE

The work presented in this study details the development of an in silico model that combines all the salient, clinically relevant features of cerebral aneurysm clotting. A comprehensive computational model of clotting that accounts for biochemical complexity coupled with three-dimensional hemodynamics in image-derived patient aneurysms and in the presence of virtually implanted interventional devices is presented.

METHODS

The model is developed and presented in two stages. First, a two-dimensional computational model of clotting is presented for an idealized geometry. This enables verification of the methods with existing, physiological data before the pathological state is considered. This model is used to compare the results predicted by two different underlying biochemical cascades. The two-dimensional model is then extended to image-derived, three-dimensional aneurysmal topologies by incorporating level set methods, demonstrating the potential use of this model.

RESULTS AND CONCLUSION

As a proof of concept, comparisons are then made between treated and untreated aneurysms. The prediction of different clotting outcomes for different patients demonstrates that with further development, refinement and validation, this methodology could be used for patient-specific interventional planning.

A completely thrombosed, nongiant middle cerebral artery aneurysm mimicking an intra-axial neoplasm

Background:

Few reports exist regarding thrombosed aneurysms where the initial work up was concerning for a neoplasm. To date, no published reports exist regarding a nongiant thrombosed middle cerebral artery aneurysm, where the primary workup and treatment plan was directed toward a preliminary diagnosis of intra-axial neoplasm.

Case Description:

We report a 43-year-old female who presented with a generalized tonic-clonic seizure attributed to a lesion along the right superior temporal gyrus. The lesion enhanced on initial magnetic resonance imaging (MRI) of the brain, as well as on follow-up MRI. Subsequent vascular studies and metastatic work up were negative. A craniotomy with image guidance was performed and an intraoperative diagnosis was made of a thrombosed aneurysm along a branch of the middle cerebral artery. The aneurysm was trapped and resected as there was no significant flow from the branch as seen on the prior cerebral angiogram. The patient had an uneventful postoperative course.

Conclusion:

Completely thrombosed, nongiant aneurysms can mimic an intra-axial neoplasm. Typical imaging features for thrombosed aneurysms may be missed, especially if the aneurysms are small, where imaging characteristics of the intraluminal contents is more difficult to appreciate. Although imaging may be consistent with a neoplastic lesion, there should be suspicion for a potential underlying aneurysm.

Investigation of the endovascularly treated and untreated unruptured vertebrobasilar artery aneurysms

BACKGROUND AND PURPOSE

The present study aimed to investigate the endovascular indication with close monitoring of both endovascularly treated and untreated unruptured vertebrobasilar aneurysms.

MATERIALS AND METHODS

In the past 2 years, 36 patients [7 women and 29 men with a mean age of 48.5 years (range, 13-75 years)] who had 40 unruptured vertebrobasilar artery aneurysms were reviewed. The decision of the endovascular treatment was not randomized. In both endovascularly untreated and treated patients, overall mortality and morbidity corresponding to Glasgow outcome scale (GOS) score III or worse was counted as unruptured aneurysm related event. The ratio of event free was compared between endovascularly treated and untreated patients using Log-rank test. In a univariate analysis, poor outcome was predicted by endovascularly untreated.

RESULTS

Thirty-six patients were followed with a mean period of 10.7 months (range, 0.7 months-21 months). In untreated cases, new neurological deficits caused by the aneurysm were noted in 2 cases. The annual deterioration rate of the untreated cases was 9.1%. In endovascularly treated cases, there was no mortality and morbidity. There was no SAH in all cases during follow-up period. When ratio of event free was compared, significant advantage of endovascular treatment was noted (X(2)=4.429, P=0.035).

CONCLUSIONS

The present results indicated that endovascular treatment has a benefit for the unruptured vertebrobasilar artery aneurysms.