A subarachnoid hemorrhage (SAH) is usually experienced as a sudden severe headache often described by patients as the worst headache of their life. This is often associated with neck pain, neck stiffness as well as sensitivity to light (photophobia), nausea, and vomiting. If the hemorrhage is severe enough, patients may immediately lose consciousness as the first sign of a problem. Other symptoms can include seizures, back pain, and leg pain.
What is a subarachnoid hemorrhage?
A subarachnoid hemorrhage (SAH) is bleeding within the fluid that surrounds the outside of the brain (cerebrospinal fluid). The majority of such bleeds are due to rupture of a cerebral aneurysm. A cerebral aneurysm is an outpouching of an artery. It has thinner walls than the other portions of the artery and therefore can easily burst open.
Sometimes a SAH occurs after significant head trauma, not in relation to an aneurysm. Other possible causes are an arterial venous malformation, a brain tumor, or in relation to a blood clot within a vein of the brain.
How is it diagnosed?
SAH is initially suspected based on the symptoms. A head CT scan will identify them 95-99% of the time. If the head CT scan does not reveal the hemorrhage, but suspicion on the part of physicians is still high, then patients will be asked to undergo a lumbar puncture (spinal tap) during which a needle is passed between the bones of the back in order to obtain a sample of cerebrospinal fluid. Blood in the cerebrospinal fluid is suggestive of SAH.
How is it treated?
A SAH is a medical emergency that requires the rapid evaluation and intervention of specialists such as radiologists, neurologists, neurosurgeons, and sometimes intensivists. Treatment is too complicated to discuss in detail. Once a SAH is diagnosed, assuming there has not been significant head trauma, then an immediate investigation for an intracranial aneurysm is undertaken. The test chosen is almost always a 4-vessel cerebral angiogram. In this test, a tiny catheter is inserted into an artery of the leg and threaded up to the arteries that supply the brain. Contrast dye is released so that x-ray pictures of the brain's arteries can be taken and an aneurysm identified.
Both radiologists and neurosurgeons can treat aneurysms and the approach taken will depend on the clinical circumstances.
Who gets these hemorrhages?
As discussed, head trauma (such as may occur in a motor vehicle accident or a fall from a large height) can lead to a SAH. Patients who have a family history of cerebral aneurysms are at higher risk of having aneurysms, and thus, of suffering from a SAH. Multiple other risk factors for the development of these hemorrhages can be found