Aneurysms are rare pediatric lesions that can affect blood vessels throughout the body. They represent a “blistering” or “bubble-like” protrusion off of an artery. In the brain these “bubbles” tend to occur at very predictable locations. Usually they are at points where a major artery is branching into smaller arteries. These sites are not in the brain substance per se, but rather in the deep crevices between the various lobes of the brain. Most aneurysms that are found are in older individuals, in the 4th and 5th decades of life, but on rare occasions they can be found in children. Some causes of aneurysms are hereditary, but most are found in the general population without any specific cause.
Most aneurysms are found due to a sudden burst of blood into or around the brain because of a temporary rupture of the “bubble”. This “bubble ” will usually then seal itself off spontaneously. Usually some if not all of the blood will be found in and around these crevices in the brain, what are called the subarachnoid spaces. Hence the bleeding that occurs with ruptured aneurysms tends to be described as subarachnoid hemorrhages. The chief symptom of a ruptured aneurysm is usually a complaint of “the worst headache of my life” in adults or children old enough to give a good description. It is often associated with vomiting, a stiff neck, and light bothering the eye. Depending on such factors as the location of the aneurysm and the amount of blood in and around the brain, you can also see neurologic symptoms. These include almost the entire range of possible problems such as weakness, eye movement problems, stupor, seizures and even coma or death. There is upwards of a fifty percent mortality rate in those people with ruptured aneurysms. If a person survives the initial rupture, the greatest likelihood of the same site rebleeding is in the first two weeks from that point. Clearly it is essential to quickly establish the correct diagnosis as soon as possible.
The most common diagnosis that a ruptured aneurysm mimics in pediatrics is meningitis. Both conditions can cause fevers, headaches, stiff neck and photophobia (light bothering the eyes). In general there should be significant fevers in meningitis and less so with aneurysms though there is certainly overlap. The job of the physician is to determine if either of these conditions is present so that urgent treatment can be started. Certainly in pediatrics, meningitis is more common then a ruptured aneurysm so you do not want to delay in starting potentially life saving antibiotics while you try to establish the diagnosis.
The definitive diagnosis of meningitis is found on sampling the spinal fluid and looking for organisms of some sort. The diagnosis of a ruptured aneurysm usually requires several tests which ultimately lead to a arteriogram. Usually if an acute event has occurred with symptoms that were as described above, a CT or MRI will be emergently performed to look for a cause such as bleeding. Of course there are many other things that can cause some of the same symptoms such as: hydrocephalus, tumor, abscess, cysts, seizures, arteriovenous malformations and stroke. If the pattern of blood seen on a CT or MRI suggests that an aneurysm may be the cause then the child will usually have at some point an angiogram to get the best definition of the problem. The angiogram is essentially a “roadmap” of the vessels of the brain and demonstrate the anatomy of the aneurysm.
Once found, almost all aneurysms need to be treated. By and large they are fixed by placing very delicate clips at the base of the aneurysm where it arises from the artery. Care is taken not to injure or compromise the blood vessels in the area to prevent a stroke from occurring. While most aneurysms are “clipped” by neurosurgeons, there are some early attempts to try to treat some of these lesions from within the vessel proper. This is done by the interventional radiologists or neurosurgeons via a catheter that is fed up the arterial tree to the abnormal vessel in the brain. From here, various materials have been used to “plug” the aneurysm.
Once successfully treated, most people should be cured for life in regards to the aneurysm. However, as with many problems in neurosurgery, what ultimately may determine their prognosis is how the initial bleeding event affected their level of function and consciousness. For completeness sake it is important to mention vasospasm. In people who have a ruptured aneurysm, some will develop a “clamping down” of the blood vessels around the site of the aneurysm. Much like standing on a garden hose, this clamping down (vasospasm) will lead to a decrease in the blood supply to part of the brain. This can lead to temporary or permanent loss of function in part of the brain (stroke). This will almost always occur in the first 3-10 days after the bleeding event if it is to occur at all. The treatment is usually supportive care to maintain as best one can good blood supply to the brain until the condition resolves.
While this has been a very broad overview many important features of aneurysms have been touched upon. This includes the presentation, diagnosis, management and prognosis of these very tiny but potentially lethal lesions.