Peripheral Nerve |
Functional |
Paediatric Neurosurgery |
Cerebral aneurysms are abnormal dilatations in the walls of brain blood vessels. They are weak points that are at risk of rupturing into the subarachnoid space (subarachnoid haemorrhage or SAH); this being the space where brain blood vessels run. Patients with brain aneurysms usually have no symptoms. When bleeding occurs, the patient typically describes it as the "worse headache of his life". However, 20-30% of patients never reach the hospital alive while another third reach it either in a state of coma or are severely paralysed.
Management of patients with ruptured aneurysms is primarily aimed at preventing a second haemorrhage / bleed. The risk of a re-bleed is approximately 4% in the 1st day, 2.5% in the 2nd day, 1.5% in the 3rd day, reaching a cumulative risk of 20% in the first 2 weeks and >60-70% after 6 months. When re-bleeding occurs, mortality and severe morbidity (including being in coma, with paralysis and a poor quality of life) is in the region of >60-80%. Hence the need to secure the aneurysm and prevent a second bleed .
The second cause of death and severe morbidity is that of cerebral vasospasm, where the blood vessels constrict in response to exposure to the subarachnoid blood. For this reasons, patients today are given Nimodipine, to prevent life-threatening vasospasm.
Aneurysms typically arise at branch points of blood vessels, where the wall is weakened by haemodynamic stresses and degeneration. They were previously thought to be congenital defects in the vessel wall but there is little evidence for such inherited weakness.
There are medical conditions that are associated with an increased risk of cerebral aneurysms. These include:
| 1. | Polycystic kidney disease | |
| 2. | Fibromuscular dysplasia | |
| 3. | Connective tissure disorders (eg, Ehler's Danlos Syndrome, Marfan's Syndrome) | |
| 4. | High flow states (eg, arteriovenous malformations) | |
| 5. | Co-arctation of the aorta | |
| 6. | Anomalous vessels |
| Grade | Description |
| 0 | Unruptured |
| 1 | Asymptomatic, mild headache |
| 2 | Severe headache, neck stiffness |
| 3 | Mild focal neurological deficit (excluding cranial nerve deficits) |
| 4 | Mod/severe hemiparesis, stupor |
| 5 | Decerebrate rigidity, moribund appearance |
SAH
Women have a higher incidence of brain aneurysms while the peak age of a ruptured aneurysm is between 50-60 years. The risk factors of an aneurysm and its rupture are:
| 1. | Age. There is a higher incidence with increasing age. | |
| 2. | Smoking. This is a strong risk factor. | |
| 3. | Atherosclerosis. Asian's have a higher incidence of intracranial atherosclerosis which weakens the vessels wall. | |
| 4. | Hypertension. Not a strong risk factor. Many patients with aneuryms have a normal blood pressure. | |
| 5. | Excessive alchohol consumption. | |
| 6. | Recreational druge use (eg, cocaine). | |
| 7. | Pregnancy. |
| 1. | Trauma. Pseudoaneurysms. | |
| 2. | Infection. Mycotic Aneurysms. | |
| 3. | Vasculitis. Eg, SLE , Takayasu's arteritis. |
Patient's with a SAH typically describe the sudden onset of the worst headache of their lives. Some patients present acutely with a 'collapse' and sudden drowsiness. Other symptoms include nausea, vomiting, dizziness which is often associated with headache and an altered conscious level. A painful stiff neck, fever and photophobia (inability to withstand light) is often found while some patients present with a painful 3rd nerve palsy (pain associated with a dilated pupil and drooping of the eyelid).
A large majority of patients do not experience any symptoms prior to the onset of the rupture. The rupture occurs suddenly. Up to 40% of patient's experience 'sentinel headaches' days to weeks before the rupture and these are thought to be 'warning leak symptoms'.
Today, the vast majority of cases are diagnosed through a CT scan of the brain. Occasionally, a lumbar puncture may aid in the diagnosis.
Patients diagnosed to have spontaneous SAH must have a cerebral angiogram to map out the arteries in the brain, thereby localising the site and outlining the shape of the aneurysm. MR angiography may be employed but conventional digital subtraction angiography remains the gold standard as the former can miss 2-3 mm aneurysms. With multi-slice CT scanners, CT angiography is 'gaining popularity' and is increasingly used by some units to locate aneuryms.
Surgical Management
The time-tested treatment is surgical clipping of the aneurysm where a titanium clip is used to secure the aneuryms at its neck, thereby preventing a re-rupture. Today, intra-luminal coiling of aneurysms is increasingly used with excellent results. The jury is still out as to which treatment modality is better. Such debate is certainly out of the scope of this website. Suffice to say, the best treatment option depends on the exact configuration of the aneurysm (its site and shape) and the patient profile including his age and medical status. Many units in the world use a multi-disciplinary approach where the best option is recommended based on the views of both the neurosurgeon and endovascular surgeon.
It is however crucial to realize that that there are a whole host of problems that can arise, often requiring intensive treatment and care. As mentioned, cerebral vasospasm is the 2nd killer after a re-rupture and nimodipine is used to prevent such smooth muscle contraction. Other complications of a SAH include hydrocephalus (dilatation of the ventricles / drainage system within the brain, which may require a temporary drain or a permanent shunt), cerebral oedema / brain swelling, cerebral salt wasting, Syndrome of Inappropriate ADH secretion (SIADH) and other medical problems like neurogenic pulmonary (lung) oedema.
After definitive treatment with either surgery or coiling, the patient is still at risk of such problems. Medical and surgical support / treatment post-procedure are of paramount importance.