Blister aneurysm

Blister aneurysms primarily involve small, fragile outpouchings in cerebral arteries and are associated with the brain. In contrast, dissecting aneurysms, or aortic dissections, are typically located in the aorta and result from a tear in the aortic wall. While both conditions are related to vascular abnormalities, they affect different parts of the circulatory system and require different approaches to diagnosis and treatment.

Blister aneurysm, or dissecting pseudoaneurysm, is a specific type of aneurysm that occurs in the intracranial blood vessels, typically in the arteries at the base of the brain. Blister aneurysms are characterized by small, fragile outpouchings or bulges on the arterial wall that have a blister-like appearance.

Unlike traditional saccular or berry-shaped aneurysms, blister aneurysms have distinct characteristics. They are often very small, measuring only a few millimeters in size, and have a thin and delicate wall. Blister aneurysms are typically located in the non-branching segments of arteries, such as the supraclinoid internal carotid artery or the posterior communicating artery.

Blister aneurysms are more prone to rupture compared to other types of aneurysms due to their fragility. The wall of a blister aneurysm is formed by a tear or separation within the layers of the arterial wall, creating a weakened area that is susceptible to bleeding. Rupture of a blister aneurysm can lead to subarachnoid hemorrhage, a type of bleeding in the space around the brain.

The exact cause of blister aneurysms is not fully understood, but they are believed to result from a combination of factors such as arterial wall weakness, hemodynamic stress, and underlying connective tissue disorders. Risk factors for blister aneurysms may include smoking, high blood pressure, and certain genetic conditions that affect blood vessel integrity.

Diagnosing blister aneurysms can be challenging due to their small size and unique characteristics. Imaging techniques such as magnetic resonance angiography (MRA) and computed tomography angiography (CTA) are commonly used to visualize the blood vessels and identify the presence of an aneurysm.

Treatment of blister aneurysms can be complex due to their location and fragile nature. The treatment approach may involve a combination of surgical clipping, endovascular coiling, or flow diversion techniques, depending on the specific characteristics of the aneurysm and the patient's overall health.

see Internal carotid artery blister aneurysm.

Endovascular treatment of blister aneurysms is a promising approach, even though they are vascular lesions challenging to treat due to their angioarchitectural characteristics.

Purpose: Our aim was to investigate clinical and radiologic outcomes after endovascular treatment of ruptured blister aneurysms.

Data sources: PubMed, Ovid MEDLINE, Ovid EMBASE, Scopus, and the Web of Science were screened.

Study selection: We performed a comprehensive review of the literature from 2010 to 2019 reporting series of patients with blister aneurysms treated with an endovascular approach.

Data analysis: Event rates were pooled across studies using a random effects meta-analysis.

Data synthesis: A total of 32 studies reporting on 684 patients (707 aneurysms) were included. Stent placement, stent-assisted coiling, and flow diversion were the most commonly described treatments (282, 256, and 155 patients, respectively). The long-term complete occlusion rate was 76.9% (95% CI, 69.2%-83.9%). The perioperative complication rate was 8.9%, and clinical outcome at final follow-up was mRS <2 in 76.6% (95% CI, 68.2%-84.2%) of patients. The mortality rate was 4.7% (95% CI, 2.30%-7.80%). Among the different techniques, stent-assisted coiling is the one that had the higher rate of immediate occlusion (63.4%); however, the occlusion rate at the final follow-up was comparable among the different techniques.

Limitations: Different techniques were described and data were reported in a nonhomogeneous way, possibly representing a bias in the present study.

Conclusions: This study suggests that endovascular treatment of blister aneurysms is associated with good long-term occlusion rates and reasonable complication and mortality rates. There is no consensus on the best endovascular techniques in blister aneurysm management ¹⁾.