Subarachnoid hemorrhage is bleeding in the area between the brain and the thin tissues that cover the brain. This area is called the subarachnoid space.
Hemorrhage - subarachnoid
Subarachnoid hemorrhage can be caused by:
- Bleeding from a tangle of blood vessels called an arteriovenous malformation (AVM)
- Bleeding disorder
- Bleeding from a cerebral aneurysm
- Head injury
- Unknown cause (idiopathic)
- Use of blood thinners
Subarachnoid hemorrhage caused by injury is often seen in the elderly who have fallen and hit their head. Among the young, the most common injury leading to subarachnoid hemorrhage is motor vehicle crashes.
- Aneurysm in other blood vessels
- Fibromuscular dysplasia (FMD) and other connective tissue disorders
- High blood pressure
- History of polycystic kidney disease
A strong family history of aneurysms may also increase your risk.
The main symptom is a severe headache that starts suddenly (often called thunderclap headache). It is often worse near the back of the head. Many people often describe it as the "worst headache ever" and unlike any other type of headache pain. The headache may start after a popping or snapping feeling in the head.
- Decreased consciousness and alertness
- Eye discomfort in bright light (photophobia)
- Mood and personality changes, including confusion and irritability
- Muscle aches (especially neck pain and shoulder pain)
- Nausea and vomiting
- Numbness in part of the body
- Stiff neck
- Vision problems, including double vision, blind spots, or temporary vision loss in one eye
Other symptoms that may occur with this disease:
- Eyelid drooping
- Pupil size difference
- Sudden stiffening of back and neck, with arching of the back (opisthotonos; not very common)
Exams and Tests
- A physical exam may show a stiff neck
- A brain and nervous system exam may show signs of decreased nerve and brain function (focal neurologic deficit)
- An eye exam may show decreased eye movements. A sign of damage to the cranial nerves (in milder cases, no problems may be seen on an eye exam)
If your doctor thinks you have a subarachnoid hemorrhage, a head CT scan (without contrast dye) will be done right away. In some cases, the scan is normal, especially if there has only been a small bleed. If the CT scan is normal, a lumbar puncture (spinal tap) may be done.
Other tests that may be done include:
- Cerebral angiography of blood vessels of the brain
- CT scan angiography (using contrast dye)
- Transcranial Doppler ultrasound, to look at blood flow in the arteries of the brain
- Magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) (occasionally)
The goals of treatment are to:
- Save your life
- Repair the cause of bleeding
- Relieve symptoms
- Prevent complications such as permanent brain damage (stroke)
Surgery may be done to:
- Remove large collections of blood or relieve pressure on the brain if the hemorrhage is due to an injury
- Repair the aneurysm if the hemorrhage is due to an aneurysm rupture
If the person is critically ill, surgery may have to wait until the person is more stable.
Surgery may involve:
- Craniotomy (cutting a hole in the skull) and aneurysm clipping, to close the aneurysm
- Endovascular coiling, placing coils in the aneurysm and stents in the blood vessel to cage the coils reduces the risk of further bleeding
If no aneurysm is found, the person should be closely watched by a health care team and may need more imaging tests.
Treatment for coma or decreased alertness includes:
- Draining tube placed in the brain to relieve pressure
- Life support
- Methods to protect the airway
- Special positioning
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:
- Bending over
- Suddenly changing position
Treatment may also include:
- Medicines given through an IV line to control blood pressure
- Nimodipine to prevent artery spasms
- Painkillers and anti-anxiety medicines to relieve headache and reduce pressure in the skull
- Phenytoin or other medications to prevent or treat seizures
- Stool softeners or laxatives to prevent straining during bowel movements
How well a person with subarachnoid hemorrhage does depends on a number of different factors, including:
- Location and amount of bleeding
Older age and more severe symptoms can lead to a poorer outcome.
People can recover completely after treatment. But some people die even with treatment.
Repeated bleeding is the most serious complication. If a cerebral aneurysm bleeds for a second time, the outlook is much worse.
Changes in consciousness and alertness due to a subarachnoid hemorrhage may become worse and lead to coma or death.
Other complications include:
- Complications of surgery
- Medicine side effects
When to Contact a Medical Professional
Go to the emergency room or call the local emergency number (such as 911) if you have symptoms of a subarachnoid hemorrhage.
Identifying and successfully treating an aneurysm can prevent subarachnoid hemorrhage.
Mayer SA. Hemorrhagic cerebrovascular disease. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 408.
Reinhardt MR. Subarachnoid hemorrhage. J Emerg Nurs. 2010;36:327-329. PMID: 20624566 www.ncbi.nlm.nih.gov/pubmed/20624566.
Tateshima S, Duckwiler G. Vascular diseases of the nervous system: intracranial aneurysms and subarachnoid hemorrhage. In: Daroff RB, Fenichel GM, Jankovic J, Mazziotta JC. Bradley's Neurology in Clinical Practice. 6th ed. Philadelphia, PA: Elsevier Saunders; 2012:chap 51C.
Reviewed By: Amit M. Shelat, DO, FACP, Attending Neurologist and Assistant Professor of Clinical Neurology, SUNY Stony Brook, School of Medicine, Stony Brook, NY. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.