The subarachnoid space is the area between two of the meninges (Arachnoid and pia mater) that covers the brain. This space normally contains a fluid called the cerebo spinal fluid. In addition, bleeding from a subarachnoid hemorrhage interrupts the vital blood supply to an area of the brain that normally is fed by the ruptured blood vessel. Where the swelling is most severe, the blood vessel wall become weak and prone to rupture. The sudden buildup of pressure outside the brain may also cause rapid loss of consciousness or death. Treatment focuses on stopping the bleeding, restoring normal blood flow, and relieving the pressure on the brain.
Subarachnoid hemorrhage (SAH) implies the presence of blood within the subarachnoid space from some pathologic process. One third of the patients who suffer a SAH will survive with good recovery; one third will survive with a disability or stroke; and one third will die. This has lead to the common practice of repeating angiography in patients whose initial imaging studies reveal no vascular malformations. Blood from a subarachnoid hemorrhage fills a portion of the space between the brain and the skull, and it mixes with the cerebrospinal fluid that cushions the brain and spinal cord. Most often, a subarachnoid hemorrhage happens because of a burst saccular aneurysm (a sac-like bulge in the wall of an artery), but it also can occur because of leakage from an AVM. Magnetic resonance imaging of the entire neuraxis is often performed to rule out other sources of subarachnoid bleeding including tumors and occult vascular malformations of the brain or spine. If the pattern of blood on computed tomography is consistent with a spinal source, myelography and spinal angiography are performed in an effort to detect a treatable source of future hemorrhage.
Subarachnoid hemorrhage occurs when a blood vessel just outside the brain ruptures. ) Aneurysms may be congenital (present at birth), or may develop later in life due to such factors as hypertension or atherosclerosis.Specifically it occurs within the cerebrospinal fluid-filled spaces surrounding the brain (also known as the subarachnoid space) At the M.G.H. Aneurysm/AVM Center a second angiogram is usually obtained approximately two weeks after subarachnoid hemorrhage in patients whose initial studies do not reveal a source of bleeding. An aneurysm is a weakened, ballooned area on an artery wall and has a risk for rupturing These are small areas of rounded or irregular swellings in the arteries.
Causes of Subarachnoid Hemorrhage
The common Causes of Subarachnoid Hemorrhage :
- This is a weakness in the wall of an artery causing a pouch or a swelling in the blood vessel. The thin walls of an aneurysm can burst and cause a hemorrhage.
- SAH may reflect a secondary dissection of blood from an intraparenchymal hematoma (eg, bleeding from hypertension or neoplasm).
- An infection
- This may occur from a ruptured cerebral aneurysm or arteriovenous malformation , but some result from unidentified causes.
- Cortical thrombosis
- Two thirds of nontraumatic SAH are caused by rupture of saccular aneurysms.
- This is the most common cause of an intracranial hemorrhage in people younger than 50.
- The most common cause of subarachnoid hemorrhage in young adults is a ruptured cerebral aneurysm.
Symptoms of Subarachnoid Hemorrhage
Some common Symptoms of Subarachnoid Hemorrhage :
- Nausea and vomiting may accompany the headache.
- Sudden onset of a severe headache (often described as "worst headache of their life").
- Difficulty seeing or changes in vision.
- Popping or snapping sensation in head.
- Muscle aches (especially neck pain and shoulder pain ).
- Paralysis on one side of the body or neurologic problems (this usually occurs in about 25% of the people who have subarachnoid hemorrhages).
- Seizure or spell .
- Frequent fluctuations in the heart beat and breathing rate often occur .
- Confusion .
Treatment of Subarachnoid Hemorrhage
Here is the list of the methods for treating Subarachnoid Hemorrhage :
- Triage and transport patients with altered level of consciousness or an abnormal neurologic examination to the closest medical center with a CT scan and neurosurgical backup.
- Ideally, avoid sedating these patients en route.
- Treatment for coma or decreased mental status may be required, including positioning, airway protection, and life support, and placement of a drain (small plastic tube into the fluid-filled spaces within the brain ventricles to relieve intracranial pressure).
- Surgical removal of large collections of blood may also be needed.
- Phenytoin or other medications may be used to prevent or treat seizures.
- Treatment is usually required, which may be either via a craniotomy (opening a hole in the skull) and clipping of the aneurysm (placing a metal clip across the base of the aneurysm so as to separate it from the circulation), or endovascular coiling (placing platinum coils within the aneurysm from the inside of the blood vessel itself).
- Ventriculostomy, when done correctly, is a relatively low-risk procedure that can result in dramatic and immediate clinical improvement in about two thirds of patients if the patient's grade improves enough as a result of ventriculostomy, the patient may become a candidate for early surgery.