Brain aneurysm is also known as cerebral or intracranial aneurysm. Aneurysm is a medical condition characterized by balloon like swelling of the walls of the blood vessels of the body. In brain aneurysm the blood vessel in the brain (artery or vein) becomes swollen giving the impression of berry hanging from the stem.
Like other aneurysms in the body the most dreaded complication of brain aneurysm is rupture and huge blood loss leading to hemorrhagic stroke. In most of the cases blood loss due to ruptured brain aneurysm usually occurs in the space between the brain tissue and the protective cover surrounding the brain, known as subarachnoid hemorrhage.
In many cases brain aneurysm as such do not produce any symptom and symptom producing aneurysms lead to the symptoms usually depending upon the status of the aneurysm like whether it is ruptured, leaking or yet to be ruptured.
Ruptured aneurysm should be treated urgently. Surgery is the mainstay of treatment and the options are surgical clipping and endovascular coiling. Even in unruptured aneurysm to prevent rupture in the future surgery is usually recommended.
It is estimated that about 1 out of 10,000 people are affected with brain aneurysm in the US alone, the incidence is highest between 30 and 60 years and rare among children.
Symptoms
In many cases brain aneurysm does not produce any symptom and detected only after brain scan done to investigate other health conditions.
If present, the natures of symptoms depend upon the status of the aneurysm. Like, in case of
1. Ruptured aneurysm: the most common presenting symptom of ruptured aneurysm is sudden onset splitting headache often described as “the worst headache of life”.  Other common presenting symptoms include nausea, vomiting, stiffness of the neck, visual problems like double vision, blurring of vision, intolerability to light (photosensitivity), convulsion, confusion even complete loss of consciousness etc.
2. Leaking aneurysm: sometimes just before frank rupture of an aneurysm blood may ooze from the aneurysm (sentinel bleeding). it presents as sudden onset headache and in most of the cases progresses to complete rupture of the aneurysm and its symptoms.
3. Unruptured aneurysm: These type of brain aneurysm may not produce any symptom especially if it is very small; however large aneurysms tend to produce symptoms due to pressure on the adjacent structures. These pressure symptoms include pain in the eye and also in the back of the eyes; visual problems like blurred vision, double vision, drooping of eyelids, numbness, weakness which may progress to complete paralysis of one side of the face etc.
There are several complications following rupture of brain aneurysm. Bleeding following rupture usually lasts for few seconds but lasting damage to the brain tissue may occur directly by the influence of the blood on the brain cells and indirectly due to the increased pressure on the brain structures in the enclosed space of the skull. Increased pressure in the skull may lead to compromised blood and therefore oxygen supply to the brain tissue leading to brain stroke.
Other complications are
1. Re-bleeding: especially in case of leaking aneurysm this complication is more common but a previously ruptured aneurysm may also rupture in the future
2. Vasospasm: following rupture of a brain aneurysm, the other blood vessels of the brain may also contract erratically leading to stoppage of blood supply to the brain tissue and ischemic stroke
3. Hydrocephalus: usually ruptured brain aneurysm leads to accumulation of blood in the subarachnoid space, a closed space hence the pressure on the brain tissue is elevated blocking the circulation (drainage) of the circulating cerebrospinal fluid (CSF) out of the brain. Hence the already increased pressure in the skull may increase further leading to damage to the different brain structures.
4. Hyponatremia: sometimes bleeding from the ruptured brain aneurysm may damage the hypothalamus either directly or indirectly by increasing pressure and thus by cutting off the blood supply to the hypothalamus. Hypothalamus is the one of the important structures of the body which maintains the normal sodium balance in the body. Thus there is a chance that hyponatremia may precipitate.