Subarachnoid hemorrhage (SAH)

The brain is covered by three layers of membranes. From outside in they are: dura, arachnoid, and pia. The spaces between these layers and brain contain fluid and blood vessels. SAH means bleeding (or hemorrhage in medical terms) in the area/space between the brain and the arachnoid membrane. This area is called the subarachnoid space.

Causes of Subarachnoid hemorrhage

Ø      Bleeding from an aneurysm

Ø      Bleeding from an arteriovenous malformation (AVM)

Ø      Bleeding disorder

Ø      Use of blood thinning medicines

Ø      Injury-related subarachnoid hemorrhage

Ø      Unknown cause (idiopathic)

SAH caused by an aneurysm that breaks open (ruptures) occurs in about 40 - 50 out of 100,000 people over age 30. SAH due to rupture of aneurysm is most common in persons ages 20 to 60. It is slightly more common in women than men.

Risks include:

Ø      Smoking

Ø      High blood pressure

Ø      Aneurysm in other blood vessels

Ø      Fibromuscular dysplasia (FMD) and other connective tissue disorders

Ø      History of polycystic kidney disease

Ø      A strong family history of aneurysms

Symptoms

The main symptom is a severe headache that starts suddenly and is often worse near the back of the head. Patients often describe it as the "worst headache ever" (called Thunderclap headache) and unlike any other type of headache pain. The headache may start after a popping or snapping feeling in the head.

Other symptoms:

Ø      Nausea and vomiting

Ø      Eye discomfort in bright light (photophobia)

Ø      Stiff neck

Ø      Decreased consciousness and alertness

Ø      Mood and personality changes, including confusion and irritability

Ø      Muscle aches (especially neck pain and shoulder pain)

Ø      Numbness in part of the body

Ø      Weakness of one or more limbs

Ø      Seizure

Ø      Vision problems, including double vision, blind spots, or temporary vision loss in one eye; Eyelid drooping; Pupil size difference

Investigations:

If your doctor thinks you may have a subarachnoid hemorrhage, a CT scan of head (without contrast) should be done right away. In 5-10% of cases, the scan may be normal, especially if there has only been a small bleed. If the CT scan is normal, a lumbar puncture (spinal tap) may be performed. In this, a thin needle is inserted in the spine and small amount of fluid is aspirated and sent for laboratory exam to look for evidence of bleeding.

Following confirmation of bleeding (based upon clinical findings, CT scan or lumbar puncture) other tests will be done to look for the disease causing the bleeding.

Ø      Angiography of blood vessels of the brain. Angiography means ‘study of the blood vessels’. It can be done with CT (CT angiography), MRI (MR Angiography) or DSA (Digital subtraction angiography). Of these, DSA is the best and preferred test but more invasive. DSA is done by doctors trained in subject called ‘neurointervention’ and have traditionally been performed by interventional neuro-radiologists (now neurosurgeons and neurologists also have are doing it).

Treatment

The goals of treatment are to:

Ø      Save your life

Ø      Prevent complications such as permanent brain damage (stroke)

Ø      Repair the cause of bleeding

Ø      Relieve symptoms

A person who is conscious may need to be on strict bed rest. The person will be told to avoid activities that can increase pressure inside the head, including:

Ø      Bending over

Ø      Straining

Ø      Suddenly changing position

Ø      Coughing

Treatment for coma or decreased alertness includes:

Ø      Life support

Ø      Methods to protect the airway

Ø      Special positioning

Ø      External ventricular drainage to decrease the rising pressure inside the skull (hydrocephalus)*

Treatment will also include:

Ø      Medicines given through an intravenous line to control blood pressure

Ø      Nimodipine to prevent artery spasm**

Ø      Painkillers and anti-anxiety medications to relieve headache and reduce pressure in the skull

Ø      Phenytoin or other medications to prevent or treat seizures

Ø      Stool softeners or laxatives to prevent straining during bowel movements

Surgery may be done to:

Ø      Remove large collections of blood***

Ø      Relieve pressure on the brain****

Ø      Repair the aneurysm if the hemorrhage is due to an aneurysm rupture*****

Ø      If the patient is critically ill, surgery may have to wait until the person is more stable.

*External ventricular drainage for hydrocephalus: Inside the skull and surrounding the brain is fluid (Cerebrospinal fluid or CSF) which is being constantly produced, circulating and going out of the skull. With bleeding, the fluid is not able to go out. This increases the pressure inside the skull and compresses the brain. The brain has hollow cavities inside called as ventricles. The fluid starts accumulating inside the ventricles which start to balloon out. The condition is called as ‘hydrocephalus’. It develops on one fourth of the patients. To treat it a thin tube in inserted in the ventricle though the skull via a minor surgery and connected to a drainage bag outside. The duration required is usually a week to 10 days. Rarely the patients may need permanent drainage. In such situations, internal drainage procedure is done. In this, a tube is connected from the ventricles to the abdominal cavity and left behind.

** Artery spasm (vasospasm): In about one fourth of patients, the blood vessels of the brain undergo spasm (spontaneous and prolonged narrowing). This can cause decrease in the blood flow to some areas of brain and cause permanent damage. To prevent and treat this condition certain treatment options are available: medications like nimodipine which can be given intravenously of intra arterially, Triple H therapy, and balloon angioplasty (in this we take a small balloon via the artery and inflate at the site of narrowing so as to dilate it).

*** Craniotomy (cutting a hole in the skull): may be required if large blood clots have formed in the brain so as to decrease the pressure over the brain.

**** To relieve pressure over the brain, craniotomy may be done; intravenous medications are also given and control the pressure to a large extent.

*****Aneurysm repair

Aneurysm is a local abnormal swelling of the artery like a balloon. With time this balloon keeps increasing in size and weakens, eventually the wall of the aneurysm becomes very thin and friable and gives way causing leakage of the blood. The blood leakage is stopped by the spontaneous vasospasm and by the pressure of the blood clot surrounding the aneurysm. However the aneurysm can give way again and again. To prevent this, the aneurysm has to be repaired. This can be done by two means: 1) Open surgery – in this, after opening up the skull, small titanium clip is applied at the base (neck) of the aneurysm so as to stop any blood from entering the aneurysm; 2) Endovascular coiling – via the same route as the angiography procedure, a very thin tube (microcatheter) is navigated into the aneurysm and through it one or more spring like coils made of platinum are deposited inside the aneurysm to completely fill it.

Whatever method is chosen, it is imperative to secure the aneurysm as early as possible because repeat bleed form the aneurysm has extremely high chances of death (as high as 75%). Also, during the course of the disease, doctors will increase the blood pressure of the patient, doing which can re-rupture the aneurysm.

 Management in non- aneurismal causes of SAH:

 Expectations (prognosis):

How well a patient with SAH does will depend on many different factors: