Intracranial berry aneurysm
Encyclopedia
An intracranial berry aneurysm, also known as a saccular aneurysm
, is a sac-like outpouching in a cerebral blood vessel, which can seem berry-shaped, hence the name. Once a berry aneurysm has formed it is likely to rupture, causing a stroke
. Thus they are serious medical emergencies, and should be treated as soon as possible.
Intracranial berry aneurysms are the most common kind of aneurysm in the brain. Their incidence is 1 in 10000 people per year (around 27,000 cases per year in the United States). They have a mortality rate of 70–90%.
Berry aneurysms are usually found in the region of the Circle of Willis
.
, where small communicating vessels link the main cerebral vessels. These areas are particularly susceptible to berry aneurysms. These aneurysms can form in both the anterior circulation and the posterior circulation in the brain. Typical sites include the junctures or bifurcation of the major cerebral blood vessels: the internal (anterior circulation), and the vertebral artery
and basilar artery
(posterior circulation).
, vasospasm
, and subarachnoid hemorrhage. Subarachnoid hemorrhage (bleeding in the space between the layers of meninges covering the brain called arachnoid and pia mater) can lead to hydrocephalus
.
Most intracranial berry aneurysms do not show any symptoms unless they have ruptured, which causes bleeding in the brain. Small aneurysms that maintain their size generally will not show symptoms. But larger aneurysms that are steadily growing can put pressure on nerves and tissues. Signs of an aneurysm that has not ruptured include (but are not limited to):
Symptoms of a ruptured aneurysm are:
, CT scans, and Cerebrospinal fluid
analysis.
Most cerebral aneurysms are unobserved until they have already ruptured. Diagnostic tests can be used to detect if an aneurysm has or will rupture. Tests are usually acquired after a subarachnoid hemorrhage
, to confirm the presence of an aneurysm.
If an unruptured aneurysm has been discovered in the brain of a patient, there are surgical procedures that can treat the aneurysm. One of them is Micro-Vascular Clipping, where the surgeon goes into the brain and cuts off blood flow to the aneurysm. Once this surgery is performed, the clip remains in the patient and prevents any future bleeding. It has been proven to be highly effective, because most aneurysms that are clipped do not return.
Another, related procedure is called Occlusion. In this surgical procedure, the entire artery involved with an aneurysm is clamped off (occluded). After this is done, a small blood vessel is used to reroute the blood away from the afflicted artery. There are also other forms of treatment for berry aneurysms.
People who have been diagnosed with a berry aneurysm, or any kind of aneurysm, should take steps to control high blood pressure, including smoking cessation and avoidance of cocaine and other drugs that elevate blood pressure.
Cerebral aneurysm
A cerebral or brain aneurysm is a cerebrovascular disorder in which weakness in the wall of a cerebral artery or vein causes a localized dilation or ballooning of the blood vessel.- Signs and symptoms :...
, is a sac-like outpouching in a cerebral blood vessel, which can seem berry-shaped, hence the name. Once a berry aneurysm has formed it is likely to rupture, causing a stroke
Stroke
A stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...
. Thus they are serious medical emergencies, and should be treated as soon as possible.
Intracranial berry aneurysms are the most common kind of aneurysm in the brain. Their incidence is 1 in 10000 people per year (around 27,000 cases per year in the United States). They have a mortality rate of 70–90%.
Berry aneurysms are usually found in the region of the Circle of Willis
Circle of Willis
The Circle of Willis is a circle of arteries that supply blood to the brain...
.
Pathophysiology
Berry aneurysms are congenital in nature and result in a weakness of the blood vessel wall. Weak or thinned parts of the cerebral vasculature are vulnerable to the increased hydrostatic pressure caused by hypertension, and will bulge out. Berry aneurysms tend to have a lack of tunica media and elastic lamina around its dilated location (congenital). In addition, some parts of the brain vasculature are inherently weak: particularly areas along the Circle of WillisCircle of Willis
The Circle of Willis is a circle of arteries that supply blood to the brain...
, where small communicating vessels link the main cerebral vessels. These areas are particularly susceptible to berry aneurysms. These aneurysms can form in both the anterior circulation and the posterior circulation in the brain. Typical sites include the junctures or bifurcation of the major cerebral blood vessels: the internal (anterior circulation), and the vertebral artery
Vertebral artery
The vertebral arteries are major arteries of the neck. They branch from the subclavian arteries and merge to form the single midline basilar artery in a complex called the vertebrobasilar system, which supplies blood to the posterior part of the circle of Willis and thus significant portions of the...
and basilar artery
Basilar artery
In human anatomy, the basilar artery is one of the arteries that supplies the brain with oxygen-rich blood.The two vertebral arteries and the basilar artery are sometimes together called the vertebrobasilar system, which supplies blood to the posterior part of circle of Willis and anastomoses with...
(posterior circulation).
Risk factors
The risk factors for developing berry aneurysms include any condition that causes hypertension, or any condition that causes weakening of blood vessel walls. Conditions causing hypertension include atherosclerosis, renal disease, vasculitis, or drugs that induce hypertension (such as cocaine). Conditions that cause weakening of blood vessel walls include genetic or acquired malformation of a blood vessel, genetic disorders of connective tissue, head trauma, and infections. Between 10 and 30% of patients with autosomal dominant polycystic kidney disease will develop berry aneurysms.Complications
Complications of a ruptured aneurysm include strokeStroke
A stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...
, vasospasm
Vasospasm
Vasospasm refers to a condition in which blood vessels spasm, leading to vasoconstriction. This can lead to tissue ischemia and death . Cerebral vasospasm may arise in the context of subarachnoid hemorrhage. Symptomatic vasospasm or delayed cerebral ischemia is a major contributor to...
, and subarachnoid hemorrhage. Subarachnoid hemorrhage (bleeding in the space between the layers of meninges covering the brain called arachnoid and pia mater) can lead to hydrocephalus
Hydrocephalus
Hydrocephalus , also known as "water in the brain," is a medical condition in which there is an abnormal accumulation of cerebrospinal fluid in the ventricles, or cavities, of the brain. This may cause increased intracranial pressure inside the skull and progressive enlargement of the head,...
.
Signs and symptoms
The typical symptom of a ruptured berry aneurysm is the development of a headache so bad that the patient says "it is the worst headache I have ever had."Most intracranial berry aneurysms do not show any symptoms unless they have ruptured, which causes bleeding in the brain. Small aneurysms that maintain their size generally will not show symptoms. But larger aneurysms that are steadily growing can put pressure on nerves and tissues. Signs of an aneurysm that has not ruptured include (but are not limited to):
- Headaches
- Double vision (DiplopiaDiplopiaDiplopia, commonly known as double vision, is the simultaneous perception of two images of a single object that may be displaced horizontally, vertically, or diagonally in relation to each other...
) - Loss of vision
- Eye and neck pain
- Sentinel or warning headaches. These are headaches that are caused by leakage of blood into the brain for days up to weeks prior to the aneurysm's rupture (only a small percentage of patients experience a sentinel headache before rupture).
Symptoms of a ruptured aneurysm are:
- Sudden, severe headache
- Lethargy
- Confusion and/or stupor
- Seizures
- Sudden mood swings (Impulsivity, Irritability, Poor temper control)
- Speech impediment (dysarthriaDysarthriaDysarthria is a motor speech disorder resulting from neurological injury of the motor component of the motor-speech system and is characterized by poor articulation of phonemes...
) - Eyelids dropping, especially unilaterally (PtosisPtosis (eyelid)Ptosis is a drooping of the upper or lower eyelid. The drooping may be worse after being awake longer, when the individual's muscles are tired. This condition is sometimes called "lazy eye", but that term normally refers to amblyopia...
) - Movement disorders (ataxiaAtaxiaAtaxia is a neurological sign and symptom that consists of gross lack of coordination of muscle movements. Ataxia is a non-specific clinical manifestation implying dysfunction of the parts of the nervous system that coordinate movement, such as the cerebellum...
), especially unilaterally. - Death
Diagnosis and treatment
Once suspected, berry aneurysms can be diagnosed using angiography, Magnetic Resonance ImagingMagnetic resonance imaging
Magnetic resonance imaging , nuclear magnetic resonance imaging , or magnetic resonance tomography is a medical imaging technique used in radiology to visualize detailed internal structures...
, CT scans, and Cerebrospinal fluid
Cerebrospinal fluid
Cerebrospinal fluid , Liquor cerebrospinalis, is a clear, colorless, bodily fluid, that occupies the subarachnoid space and the ventricular system around and inside the brain and spinal cord...
analysis.
Most cerebral aneurysms are unobserved until they have already ruptured. Diagnostic tests can be used to detect if an aneurysm has or will rupture. Tests are usually acquired after a subarachnoid hemorrhage
Subarachnoid hemorrhage
A subarachnoid hemorrhage , or subarachnoid haemorrhage in British English, is bleeding into the subarachnoid space—the area between the arachnoid membrane and the pia mater surrounding the brain...
, to confirm the presence of an aneurysm.
If an unruptured aneurysm has been discovered in the brain of a patient, there are surgical procedures that can treat the aneurysm. One of them is Micro-Vascular Clipping, where the surgeon goes into the brain and cuts off blood flow to the aneurysm. Once this surgery is performed, the clip remains in the patient and prevents any future bleeding. It has been proven to be highly effective, because most aneurysms that are clipped do not return.
Another, related procedure is called Occlusion. In this surgical procedure, the entire artery involved with an aneurysm is clamped off (occluded). After this is done, a small blood vessel is used to reroute the blood away from the afflicted artery. There are also other forms of treatment for berry aneurysms.
People who have been diagnosed with a berry aneurysm, or any kind of aneurysm, should take steps to control high blood pressure, including smoking cessation and avoidance of cocaine and other drugs that elevate blood pressure.