A berry aneurysm is the most common intracranial aneurysm and usually, develops in the circle of Willis. Alterations in blood pressure and blood flow seem to be the probable causes, while risk factors include smoking, advanced age and hypertension. The main complication is the rupture and subsequent development of subarachnoid hemorrhage, which manifests as an excruciating headache. The diagnosis is made by imaging studies and surgery is the main form of treatment.
Unruptured berry aneurysms are usually asymptomatic until they rupture when patients report a headache that is often described as "the worst one ever experienced." This headache develops within seconds after aneurysmal rupture and may be followed by loss of consciousness and neurological deficits. In rare cases, seizures may be observed . Additional symptoms may include nausea, vomiting, altered mental status and drowsiness, depending on the severity of rupture.
To establish the presence of a berry aneurysm, imaging studies such as MRI and MR angiography should be performed, as they can identify the exact location and the size of an aneurysm . Catheter angiography, however, is the gold standard procedure in these patients. Insertion of a catheter, usually from the femoral artery that reaches the circle of Willis, is proven to be superior to the standard MR studies. Moreover, a 3D rotational angiography, now more frequently used in general practice, is the optimal diagnostic method. CT scan can be performed in patients with suspected subarachnoid hemorrhage, and larger aneurysms can be identified using CT .
Treatment of a berry aneurysm is mainly described in the case of rupture, where substantial efforts have to be made in order to preserve the neurological state. The goal of treatment is to prevent further blood loss and reduce the risk of rebleeding from a ruptured aneurysm. Two main approaches exist:
In addition to these approaches, the use of stents and bypass surgery are used as alternative procedures. In addition to surgical treatment, symptomatic measures such as maintenance of blood pressure, tissue oxygenation, and prevention of vasospasm through the administration of vasodilating agents such as nimodipine are necessary .
The prognosis of patients with a berry aneurysm may significantly vary, the most important factor being the presence of complications, but the overall prognosis is poor in case of rupture . Subarachnoid hemorrhage is the most important and most feared complication, as it is fatal in approximately 35% of patients. In fact, the ruptured intracranial aneurysm is established as the most common cause of non-trauma related subarachnoid hemorrhage. Larger aneurysms are shown to result in poorer outcomes . Additionally, rebleeding from the same aneurysm may develop and a further rise in overall mortality rates, up to 50%, is observed . Because of the intense buildup of pressure in the cranium, another potential complication may be the development of vasospasm after approximately 2-3 weeks, which can also be fatal. For these reasons, a high dose of clinical suspicion in patients who report typical symptoms may be life-saving.
Various theories have been made regarding the etiology of a berry aneurysm, but the exact cause and pathogenic mechanisms remain to be elucidated. Initial studies implicated congenital blood vessel malformation as the main mechanism, but current belief is that a combination of prolonged hemodynamic stress and alterations in blood flow causes vessel injury and thus create favorable conditions for the development of an aneurysm . Connective tissue diseases, such as Ehlers-Danlos syndrome and Marfan syndrome, are characterized by defective synthesis of collagen and elastin fibers, consequently leading to increased arterial fragility and susceptibility to aneurysm development . Further studies are required to determine the role of other factors, such as atherosclerosis, trauma, and infections.
Prevalence rates have been estimated to range between 1.5-6%, depending on the presence of comorbidities and risk factors . A 3.2% prevalence rate was established for patients without any identifiable comorbidities. On the other hand, a 6.4% prevalence rate was observed among ADPKD patients, 3.6% in patients who have brain tumors, 3.4% for patients with a positive family history and 1.7% in patients suffering from atherosclerosis. Factors that have shown to increase the risk of Berry aneurysm rupture include heavy alcohol intake, cigarette smoking, systemic arterial hypertension and advanced age . For reasons that remain to be disclosed, Finland and Japan are two countries that report significantly higher risks of aneurysm rupture . Once the diagnosis of a berry aneurysm is made, an estimated cumulative risk of rupture is 1% per year .
Although the exact events that lead to aneurysm formation are not clear, the pathogenesis presumably starts with increased shear stress, most likely due to systemic hypertension and other conditions that exert pressure on the arterial vessel walls. Alterations in flow patterns, described to be equally important in the pathogenesis, leads to formation sac-like pouch that contains all layers of the arterial vessel . Berry aneurysms most frequently develop on the arterial bifurcation in the circle of Willis, which is why their rupture is often fatal and may result in permanent neurological deficits.
Screening of at-risk patients may be one of the most important steps in reducing the burden of a berry aneurysm and its very high mortality rates in case of rupture. Individuals with ADPKD, family history of subarachnoid hemorrhage, and elderly patients in whom significant risk factors exist such as smoking and alcohol abuse, may be evaluated for this condition through the use of non-invasive procedures, including MRI or MR angiography. Having in mind the fact that environmental and behavioral factors are shown to increase the risk of a berry aneurysm, avoiding cigarette smoking and heavy alcohol consumption is recommended.
A berry aneurysm is an anatomic abnormality that implies abnormal dilation of the blood vessel wall and formation of a sac-like structure (also known as a saccular aneurysm) that is more prone to rupture. This type belongs to the group of "true" aneurysms, distinguished by the presence of all three blood vessel layers in its walls - tunica intima, media, and adventitia . The circle of Willis is the most common site of berry aneurysms, usually developing on the arterial bifurcations of posterior and anterior communicating arteries, but they can form in any part of the circulation. Although the exact cause remains unknown, the principal factors that are thought to be involved are hemodynamic stress due to increased flow and changes in flow patterns . These events can be seen in patients with systemic hypertension and autosomal dominant polycystic kidney disease (ADPKD), diseases that significantly increase the risk of developing a berry aneurysm. Additional risk factors include smoking, heavy alcohol consumption, and advanced age. Aneurysm rupture and consequent subarachnoid hemorrhage are the main complications, which are manifested by a severe headache, often described as the "worst headache ever experienced" . Patients may also lose consciousness and develop neurological deficits that may become permanent within hours if appropriate treatment is not initiated. To make the diagnosis of subarachnoid hemorrhage, computed tomography (CT) is performed, while the diagnosis of a berry aneurysm necessitates magnetic resonance (MR) angiography and catheter angiography . Because of the fact that about 35% of patients die of subarachnoid hemorrhage as a result of aneurysmal rupture, another 15% of patients develop fatal complications if rebleeding occurs and because vasospasm may occur within the next few weeks that further increase mortality rates from this disorder , treatment should be initiated immediately. Endovascular management of ruptured aneurysms is performed in most cases, either through clipping the aneurysmal neck or coil embolization, a procedure that is comprised of insertion of a platinum-based mesh in an aneurysm that promotes coagulation. Administration of vasodilating agents to prevent vasospasm, management of blood pressure and other supportive measures are equally important in managing patients.
A berry aneurysm is one of the most common types of aneurysm that develop in the arterial blood vessels of the brain. It is described as a pouch-like sac that is formed at the bifurcation of two blood vessels and can range from a few to up to 10 centimeters in diameter. The cause still remains unknown, but it is postulated that a combination of increased pressures on the blood vessel wall, as well as changes in blood flow pattern, lead to its formation. Crude estimates suggest that approximately 3% of the population develop an aneurysm in the brain, but these rates are established to be higher in patients who have certain risk factors. Hypertension, smoking, heavy alcohol consumption are shown to be factors that increase the risk of developing a berry aneurysm, while patients who have autosomal dominant polycystic kidney disease (ADPKD) are also shown to be at a higher risk. Berry aneurysms are usually asymptomatic, but they can be very dangerous and are commonly life-threatening when they rupture. In a matter of seconds, an intense headache is reported by patients, who can develop loss of consciousness, drowsiness, and seizures within minutes or hours. Various other symptoms may be present, but when a headache is described as "the most painful ever", it is one of the hallmarks of subarachnoid hemorrhage, the most dangerous complication of a berry aneurysm. It is fatal in about one-third of patients, which is why immediate diagnostic and therapeutic procedures must be performed. The diagnosis of subarachnoid hemorrhage can be made by computed tomography (CT scan), but the exact site of an aneurysm requires the use of more advanced imaging techniques such as magnetic resonance imaging (MRI), magnetic resonance angiography, or catheter angiography, the gold standard of berry aneurysm diagnosis. Once the aneurysm is located, surgical treatment can be performed. The goal of surgery is to stop the bleeding from the aneurysm and prevent rebleeding, which may occur within a few days after initial rupture and cause even higher mortality rates. The aneurysm is either clipped in its base and removed from circulation, or it may be filled with metal-based wires that promote coagulation and cease further blood loss. Management of blood pressure and prevention of vasospasm, another life-threatening complication that occurs 2 to 3 weeks after subarachnoid hemorrhage, are vital. Early and aggressive surgery can be life-saving for many patients, but despite these measures, ruptured berry aneurysms can still be fatal. For these reasons, it may be useful to do a screening of individuals who are known to be at risk for this condition, in order to reduce the burden of complications that arise from berry aneurysms.