What is Subarachnoid Hemorrhage (SAH)?
The brain is surrounded by three layers of coverings. All the important arteries supplying blood to the brain and veins draining impure blood from the brain run between these three layers. Bleeding into the subarachnoid space is known as Subarachnoid Hemorrhage (SAH).
What causes SAH?
The most common cause of SAH is head injury. However, the most devastating cause of SAH is due to rupture of a brain aneurysm. Often the bleeding stops, and the person survives. In more serious cases, the bleeding may cause brain damage with paralysis or coma. In the most severe cases, the bleeding leads to death. Bleeding into the cerebrospinal fluid may lead to acute increase in the intracranial pressure. Other conditions that can cause SAH are vascular malformation of the brain and venous stroke
What are the symptoms of SAH?
The main symptom is a sudden severe headache and neck pain. Other symptoms include
- Sensitivity to light
- Decreased vision
- Loss of consciousness
What to do when someone is diagnosed with SAH?
Immediate referral to a center with neurosurgery and neurointerventional facilities is paramount to appropriate diagnosis and management of the patient with SAH and prevent brain damage. If your aneurysm is being clipped, a craniotomy is performed and the aneurysm is closed. A craniotomy involves opening the skull to expose the area of involvement. Alternatively, endovascular coiling involves introducing a long catheter through one of the arteries in the groin, navigating it all the way into the aneurysm in the brain and closing the aneurysm using coils (thin threads made of platinum alloy).
If SAH causes a coma, treatment will include appropriate life support with artificial ventilation, protection of the airways, and placement of a draining tube in the brain to relieve pressure.
What are the complications of SAH?
- Remleiding from the aneurysm is a serious concern in a patient with aneurysm rupture. Hence, the aneurysm needs to be closed as soon as possible by either open surgery or endovascular therapy
- Bleeding into the CSF (cerebrospinal fluid) and in the space around the brain (subarachnoid space). The pool of blood forms a clot. Blood can irritate, damage, or destroy nearby brain cells. This may cause problems with body functions or mental skills.
- Blood from an aneurysm rupture can block CSF circulation. This can lead to fluid buildup and increased pressure on the brain. Because blood is spread around the base of the brain, the possibility of fluid buildup exists, causing hydrocephalus. The CSF containing spaces in the brain, called ventricles, may enlarge. It can make a patient lethargic, confused, or comatose. To stop fluid buildup, a drain may be placed in the ventricles. The tube is called a ventriculostomy, and often drains into a bag at the patient's bedside. This removes leaked blood and trapped CSF. If the hydrocephalus persists, the patient may require a ventriculoperitoneal shunt surgery to drain the CSF permanently.
- The blood around the base of the brain can also produce a problem called vasospasm. Vasospasm typically develops 5-8 days after the initial hemorrhage. Narrowing of the blood vessels can occur and at times not enough blood is supplied to the brain and a stroke may result. To treat vasospasm, blood pressure is often elevated with medicines. Certain medications are also given to try to reduce vasospasm. Finally, catheters can be introduced inside the artery in an attempt to use balloons or medications delivered to the vessel directly to open up these narrowed vessels. Vasospasm does subside over several days.
What is the outcome of SAH?
SAH survivors usually have a much longer recovery time than unruptured aneurysm patients, as well as more serious deficits. Symptoms are proportional to the degree of hemorrhage and the initial clinical condition. Patients who are comatose or semi-comatose after a hemorrhage have longer recoveries and have more significant neurocognitive problems as compared to patients with smaller hemorrhages or unruptured aneurysms.