De Novo Aneurysm Formation and Growth of Untreated Aneurysms

Cerebral aneurysms: formation, progression, and developmental chronology

The prevalence of unruptured intracranial aneurysms (UIAs) in the general population is up to 3%. Existing epidemiological data suggests that only a small fraction of UIAs progress towards rupture over the lifetime of an individual, but the surrogates for subsequent rupture and the natural history of UIAs are discussed very controversially at present. In case of rupture of an UIA, the case fatality is up to 50%, which therefore continues to stimulate interest in the pathogenesis of cerebral aneurysm formation and progression. Actual data on the chronological development of cerebral aneurysm has been especially difficult to obtain and, until recently, the existing knowledge in this respect is mainly derived from animal or mathematical models or short-term observational studies. Here, we review the current data on cerebral aneurysm formation and progression as well as a novel approach to investigate the developmental chronology of cerebral aneurysms.

[Neuroimaging follow-up of cerebral aneurysms treated with endovascular techniques]

There are no specific recommendations in clinical guidelines about the best time, imaging tests, or intervals for following up patients with intracranial aneurysms treated with endovascular techniques. We reviewed the literature, using the following keywords to search in the main medical databases: cerebral aneurysm, coils, endovascular procedure, and follow-up. Within the Cerebrovascular Disease Group of the Spanish Society of Neuroradiology, we aimed to propose recommendations and an orientative protocol based on the scientific evidence for using neuroimaging to monitor intracranial aneurysms that have been treated with endovascular techniques. We aimed to specify the most appropriate neuroimaging techniques, the interval, the time of follow-up, and the best approach to defining the imaging findings, with the ultimate goal of improving clinical outcomes while optimizing and rationalizing the use of available resources.

Enlargement of small, asymptomatic, unruptured intracranial aneurysms in patients with no history of subarachnoid hemorrhage: the different factors related to the growth of single and multiple aneurysms

Object

This study was performed to investigate the risk factors related to the growth of small, asymptomatic, unruptured aneurysms in patients with no history of subarachnoid hemorrhage (SAH).

Methods

Between January 2005 and December 2010, a total of 508 patients in whom unruptured intracranial aneurysms were diagnosed at the University of California, Los Angeles medical center did not receive treatment to prevent rupture. Of these, 235 patients with no history of SAH who had asymptomatic, small, unruptured aneurysms (< 7 mm) were monitored with 3D CT angiography images. Follow-up images of the lesions were used to measure aneurysm size changes. Patient medical history, family history of SAH, aneurysm size, and location were studied to find the risk factors associated with small aneurysm growth.

Results

A total of 319 small aneurysms were included, with follow-up durations of 29.2 ± 20.6 months. Forty-two aneurysms increased in size during the follow-up; 5 aneurysms grew to become ≥ 7 mm within 38.2 ± 18.3 months. A trend of higher growth rates was found in single aneurysms than in multiple aneurysms (p = 0.07). A history of stroke was the only factor associated with single aneurysm growth (p = 0.03). The number of aneurysms (p = 0.011), number of aneurysms located within the posterior circulation (p = 0.030), and patient history of transient ischemic attack (p = 0.044) were related to multiple aneurysm growth.

Conclusions

Multiple small aneurysms are more likely to grow, and multiple aneurysms located in the posterior circulation may require additional attention. Although single aneurysms have a lower risk of growth, a trend of higher growth rates in single aneurysms was found.

An infundibulum of thalamoperforator arteries: Importance of angiographic images for appropriate diagnosis

Background:

The identification of infundibula on noninvasive imaging modalities may be challenging. Because these lesions have generally been viewed as nonpathological, distinguishing them from small or micro-aneurysms is important.

Case Description:

A 39-year-old male was diagnosed with recurrence of typical orgasmic headache. An outpoutching arising from the distal part of the right P1 at the take-off of thalamoperforator arteries was visualized on noninvasive investigations. The patient was referred to neurosurgery for surgical management of a right P1 aneurysm. Its unusual location and morphology led to be suspicious of an infundibular dilatation. Catheter angiography with 2D projections and 3D rotational reconstruction revealed an infundibulum at the common origin of two thalamoperforators, giving rise to a double-peaked shape, mimicking a true aneurysm, rather than the more characteristic conical shape of an infundibulum.

Conclusion:

Although noninvasive modalities may identify typical infundibula, the catheter angiogram with 2D projections was critical to establishing the diagnosis. The 3D rotational reconstruction enabled a straightforward understanding of the 3D vascular anatomy. This pyramidal variant of infundibular dilatation should be included in the differential diagnosis of a wide-based nonsaccular arterial contour deformities located in an area of multiple perforators.

Exploring the age of intracranial aneurysms using carbon birth dating: preliminary results

BACKGROUND AND PURPOSE

There is a controversy about the time span over which cerebral aneurysms develop. In particular, it is unknown whether collagen in ruptured aneurysms undergoes more rapid turnover than in unruptured aneurysms.(14)C birth dating of collagen could be used to address this question.

METHODS

Aneurysmal domes from patients undergoing surgical treatment for ruptured or unruptured aneurysms were excised. Aneurysmal collagen was isolated and purified after pepsin digestion. Collagen from mouse tendons served as controls. F(14)C levels in collagen were analyzed by accelerator mass spectrometry and correlated with patient age and aneurysm size.

RESULTS

Analysis of 10 aneurysms from 9 patients (6 ruptured, 3 unruptured) revealed an average aneurysm collagen age of <5 years, generally irrespective of patient age and aneurysm size or rupture status. Interestingly, F(14)C levels correlated with patient age as well as aneurysm size in ruptured aneurysm collagen samples.

CONCLUSIONS

Our preliminary data suggest that collagen extracted from intracranial aneurysms generally has a high turnover, associated with aneurysm size and patient age. The correlation of patient age and aneurysm F(14)C levels could explain models of aneurysm development. Although preliminary, our findings may have implications for the biological and structural stability of ruptured and unruptured intracranial aneurysms.

[Spontaneous subarachnoid hemorrhage]

The diagnosis, management and long-term implications of non-traumatic subarachnoid hemorrhage continue to be a multidisciplinary challenge. Often, the patients present to emergency or primary care physicians not particularly experienced in the differential diagnosis of headache. In most cases of a proven hemorrhage (aneurysm rupture in 85%), further treatment will require the discussion between experienced neurosurgeons and neuroradiologists whether to "clip or coil". Thus, subarachnoid hemorrhage is the first cerebrovascular disorder where a multidisciplinary approach has become the evidence-based standard of care. Patients with this condition are relatively young, and the survivors have a good life expectancy. Their neurologic, cognitive and psychiatric morbidity, risk of recurrent bleeding and elevated risk of other vascular diseases remain underestimated tasks for long-term care.

De novo basilar artery aneurysm formation after placement of a Wingspan stent

Report the de novo formation of an aneurysm after wingspan placement and describe the treatment modality. We report a patient with symptomatic basilar stenosis who underwent placement of a wingspan stent. On 9-month follow-up, the patient was found to have a new 5-mm aneurysm adjacent to the proximal tines of the stent. The patient subsequently underwent placement of an enterprise stent and coils for aneurysm occlusion. We reviewed the literature and discussed possible etiologies for the development of this unique de novo aneurysm.

[Unruptured intracranial aneurysms]

The incidental discovery of an asymptomatic intracranial arterial aneurysm is no longer uncommon. It can change a person's life. Decision-making should be guided by a thorough comparison of the risks associated with the natural course and with microsurgical or endovascular intervention. At present this comparison will favor a conservative approach in the majority of patients, especially in those with small aneurysms or who are over 50 years old.