Mirror Aneurysms Among Multiple Aneurysms: Lesser of the Two Evils

Multiple and mirror intracranial aneurysms: study of prevalence and associated risk factors

OBJECTIVE

Multiple intracranial aneurysms (MIA) account for 30% of all intracranial aneurysms, while mirror aneurysms, a subgroup of MIA, are present in 5% of all patients with cerebral aneurysms. We investigated the risk factors associated with the presence of multiple and mirror intracranial aneurysms.

METHODS

1404 patients, 314 males (22.4%) and 1090 female (77.6%) were enrolled for this study. Diagnosis was performed with a digital subtraction angiography (DSA). Multiplicity was defined as the presence of two or more aneurysms and mirror aneurysms as one pair of aneurysms involving bilateral corresponding arteries. Patients were followed-up from September 2009 till August 2018. Individuals' characteristics such as sex, age, smoking, hypertension and use of contraceptives were evaluated.

RESULTS

Five hundred and twelve patients (36.4%) were diagnosed with MIA, approximately 4%/year. We observed 203 pairs of mirror aneurysms, accounting for 406 aneurysms (13% of the population). There was an increased frequency of females with multiple (p < 0.001, OR = 1.883, 95% CI = 1.386-2.560) and mirror aneurysms (p < 0.001, OR = 2.828, 95% CI = 1.725-4.636). Smoking was associated with multiplicity (p< 0.001, OR = 1.458, 95% CI = 1.160-1.833), as well as advanced age (p < 0.001, OR = 1.938, 95% CI = 1.438-2.611), but there was no significant relation with presence of mirror aneurysms. We observed higher frequency of baby aneurysms (<3mm) in the group of patients with MIA, while giant aneurysms (>25 mm) were most found in patients with only one aneurysm (p < 0.001). No differences between patients who used contraceptives against patients who did not use were found (p = 0.600).

CONCLUSIONS

Gender and smoking, known risk factors to the development of a single intracranial aneurysm, are proportionally increased in patients with MIA. Hypertension and oral contraceptives were not associated with multiplicity.

Multiples of multiple: Case series of mirror aneurysms and review of literature

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Incidentally detected unruptured mirror intracranial aneurysms are on the rise due to advanced imaging modalities.

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Further studies are required to elucidate theories of development, inheritance pattern and the need for screening of 1st-degree relatives with twin aneurysms.

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Treatment strategy for mirror aneurysms should be customised based on the location, size, morphology and clinical manifestations of each patient.

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Randomised control trials that compare [single/multistage] clipping and coiling of mirror aneurysms are necessary to decide the best intervention strategy.

Introduction

Mirror aneurysms are a rare subtype of multiple aneurysms, located in identical or adjacent arterial segment bilaterally. We report a case series of 3 such patients amongst whom one of them had 3 sets of mirror aneurysms and the other patient had 2 sets of mirror aneurysm on the same arterial segment which has not been reported till date.

Methods

A retrospective analysis of 3 patients with incidentally detected multiple mirror aneurysms, who were treated with microsurgical clipping and coiling, was conducted. A systematic search was performed using the PUBMED database and relevant articles were reviewed with particular attention to incidence, associated conditions, risk factors and management strategies. Written informed consent was obtained from all of the patients for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request. This research work has been reported in line with the PROCESS criteria (Agha et al., 2018).

Results

All the 3 patients were females with incidentally detected multiple mirror aneurysms. All the 3 patients were known Hypertensives. All the aneurysms were successfully clipped by a multistage, bilateral craniotomy except the one in the cavernous ICA, for which an endovascular procedure is planned. All of them had an uneventful postoperative course with the CT angiogram showing obliteration of all the clipped aneurysms except the one in the cavernous ICA.

Conclusions

Multiple mirror aneurysms represent a rare occurrence of a diverse pathology. Both these described types of cases have not been reported so far in the literature. The treatment strategy for mirror aneurysms should be determined individually based on the location, size, and morphology of the aneurysms, as well as, on the clinical manifestations of each patient.

Intracranial Mirror Aneurysm: Epidemiology, Rupture Risk, New Imaging, Controversies, and Treatment Strategies

There are some controversies about the surgical treatment strategy of mirror aneurysms. Whether to choose 1-stage or 2-stage surgery, bilateral or unilateral craniotomy, or surgical or interventional treatment are the main points in dispute. In this review, the different surgery strategies faced by patients are discussed. Different surgical methods are adopted based on the patient's individual state and the location and size of the aneurysm. A new imaging method is introduced using 3D Slicer, which clearly recognizes the relationship among aneurysm, brain tissue, skull, and nerve. The 3D Slicer can help surgeons undertake adequate preoperative preparation. In addition, we also introduce some ruptured factors (e.g., age, gender, hypertension, morphologic, and hemodynamic) concerning mirror aneurysm. Systematic discussion of the controversies and methods in surgical treatment of mirror aneurysms may provide new perspectives in future research for the prevention and treatment of mirror aneurysms.

Surgical Treatment Strategy and Perioperative Analysis of Patients With Intracranial Mirror Aneurysms

OBJECT

Intracranial mirror aneurysm is a type of multiple aneurysms, which is rare in clinical and literature. There is no unified conclusion on the treatment strategy of mirror aneurysms. Therefore, our study evaluated the surgical approach and prognosis of a series of mirror aneurysms, and explored the clinical features and treatment strategies of mirror aneurysms.

METHODS

This study retrospectively analyzed the clinical features, imaging data, treatment methods and post-hospital results of 67 cases of mirror aneurysms admitted to our department from December 1997 to April 2018.

RESULTS

There were 20 males and 47 females with an average age of 53.6 years. Mirror aneurysms are mainly located in the posterior communicating artery and middle cerebral artery. Of 67 patients, 1-stage unilateral craniotomy with bilateral aneurysms in 18 cases, 1-stage bilateral craniotomy with bilateral aneurysms in 17 cases, staged treatment of bilateral aneurysms in 13 cases, and 19 cases only treated the responsible aneurysms. 57 cases with good recovery; 7 cases were self-care; 1 case was heavy disability; 2 cases were dead. In parallel, 8 cases had different degrees of cerebral infarction, 3 cases of hydrocephalus, 3 cases of oculomotor nerve injury, 2 cases died of cerebral hernia resulted from intracranial hypertension, and the remaining 53 cases were better.

CONCLUSIONS

The treatment of the mirror aneurysm should be based on the location, size, shape of the aneurysm, the patient's clinical manifestations and the surgeon's experience to choose a personalized treatment.

Flow diverter for endovascular treatment of intracranial mirror segment internal carotid artery aneurysms

BACKGROUND

To evaluate the feasibility and efficacy of the pipeline embolization device in the treatment of unruptured intracranial mirror segment aneurysms.

METHODS

Out of a total of 338 subjects, 14 were identified harboring a total of 32 internal carotid artery mirror segment aneurysms that were treated with the pipeline embolization device and were consecutively enrolled into our study. We collected data on patient demographics, modified Rankin scale (mRS) at admission, aneurysm characteristics, clinical outcome at discharge, 3-9 and at 12-18 months as well as angiography results at follow-up.

RESULTS

Patients' mean age was 52.9 years; baseline mRS was 0 in all subjects. Pipeline embolization device placement was successful in all cases. Post-treatment mRS remained 0 in 13/14 patients. One patient experienced a small intraparenchymal hemorrhage and subarachnoid hemorrhage, associated with a frontoparietal infarction resulting in right upper extremity weakness and aphasia (post-treatment mRS 3). His mRS evaluation remained stable at the 3-9-month follow-up. Three to 9-month follow-up angiography (13/14 subjects) showed complete aneurysm occlusion in 24/30 aneurysms (80%), near complete and partial occlusion in three of 30 (10%) aneurysms each. At the 9-month follow-up, one patient experienced a complete occlusion of the anterior temporal artery branch but did not present with any clinical deficits. No mRS changes were encountered over a median 6-month follow-up period. Mid-term follow-up angiography (12-18 months) available in eight of 14 subjects showed complete aneurysm occlusion in all patients. Mild intimal hyperplasia was observed in one patient.

CONCLUSIONS

Flow diversion technology can be used for the treatment of unruptured mirror segment aneurysms in selected patients.

Intracranial Mirror Aneurysms: Anatomic Characteristics and Treatment Options

Objective

Mirror aneurysms are generally considered as a subset of multiple aneurysms, defined as aneurysms occurring bilaterally and symmetrically on the same-named vessels. Although not infrequent, the characteristics of mirror aneurysms are not well studied. This investigation was conducted to elucidate the anatomic features of such lesions and examine treatment options.

Materials and Methods

A retrospective review was conducted, aimed at 172 patients treated for 344 mirror aneurysms between January 2007 and December 2015. Aneurysms of similar nature but in asymmetric locations on the same-named vessels were excluded. All available records were examined and lesion characteristics, as well as treatment outcomes were assessed.

Results

In study subjects (n = 172), mirror aneurysms most often involved middle cerebral artery bifurcation (n = 83), followed by a paraclinoid internal carotid artery (n = 50) and posterior communicating artery (n = 21). Most of the lesions (95.3%) measured ≤ 10 mm, and in 126 patients (74.6%), the size ratios were > 50%. Of the 344 aneurysms studied, coil embolization was undertaken in 217, surgical clipping in 62, and observation alone (no treatment) in 65. Coil embolization and surgical clipping were done bilaterally in 83 and 12 patients, respectively. In 12 patients, combined coiling and clipping were implemented on each side. Single-stage coil embolization of both the aneurysms was performed in 73 patients, with excellent post-procedural (85.6%) and follow-up (86.8%) occlusive results. There was no procedure-related morbidity or mortality.

Conclusion

By adopting different treatment strategies to different configurations and vascular sources, mirror aneurysms can be safely and effectively treated. If feasible, single-stage coil embolization should be considered as a reasonable treatment option for mirror aneurysms.