Subarachnoid hemorrhage (SAH) is a deadly condition that is often fatal despite the most professional care. Bleeding of this type is not so common, but it is very insidious and unpredictable. Before we say something more about the subarachnoid hemorrhage, we should describe the anatomy of brain meninges.
The brain is covered by three layers known as the meninges. Cerebral tissue is in direct contact with the lowest meninx known as pia mater. The middle meninx is called arachnoid mater and the most external meninx just below the skull bone is the dura mater.
If there is bleeding into the space between the skull and the dura mater, we speak about the so-called epidural hemorrhage. Subdural hemorrhage occurs when there is bleeding between the arachnoid mater and dura mater.
The space between the arachnoid and pia mater is also referred to as the subarachnoid space. It contains many small blood vessels that are in a close contact with cerebrospinal fluid. The cerebrospinal fluid is produced in the brain ventricles, surrounds the brain and protects it from mechanical damage. Subarachnoid hemorrhage means bleeding right into this subarachnoid space.
There are more causes of bleeding into the subarachnoid space. The most common are aneurysms of the cerebral vessels. These sac-like dilations of the blood vessels are usually present since birth in many people and cause no troubles during the whole life. However, in these aneurysms can rupture in some people allowing the blood to flow out into the subarachnoid space. Other possible causes of bleeding include arteriovenous malformations that are also inherited abnormal tangles of arteries and veins. Brain bleeding including the subarachnoid hemorrhage is more common in people with untreated hypertension.
The subarachnoid hemorrhage manifests with an extremely severe sudden headache and it may be associated with nausea, vomiting and unconsciousness. The bleeding is accompanied with high blood pressure. The hypertension is usually a secondary defensive mechanism of the body, which tries to keep the sufficient blood flow through the brain. The overall condition of the patient quickly deteriorates and it is followed by death. If the bleeding spontaneously stops, there may last an asymptomatic period, but the bleeding tends to repeat. The prognosis is extremely bad, some patients die during the initial bleeding and other due to the repeated hemorrhage. Patients, who survive, often suffer from lifelong consequences.
Any patient with a sudden headache of unknown origin should be immediately examined by a neurologist and computed tomography of the brain should be performed. If a lumbar puncture is performed, it will confirm presence of blood within the cerebrospinal fluid. However, the spinal tap can be done only when the patient does not suffer from intracranial hypertension.
If the subarachnoid hemorrhage is confirmed, it is necessary to transport the patient to a specialized center where the physicians may perform angiography of the cerebral arteries. This examination allows visualizing the brain arteries with a contrast agent, which can locate ruptured aneurysm or other sites of bleeding.
Effective therapy of a ruptured aneurysm usually requires an endovascular or neurosurgical procedure aimed to close the bleeding aneurysm.
The most commonly used neurosurgical intervention is the so-called clipping, when the aneurysm is clipped and closed by a special device.
The endovascular approach allows the doctors to get to the aneurysm directly through the local blood vessels. Very simply put, a tube-shaped device is inserted to a nearby artery and through the artery towards the aneurysm. The therapeutic method itself is called coiling. The doctor uses the created endovascular approach to insert many small metal wires (coils) into the aneurysm. The coils cause a local formation of a thrombus, which closes the aneurysm.
Both procedures are described in an extremely simplified way. In reality, both procedures are very difficult and require medical department with modern equipment and skilled staff.