Subarachnoid Hemorrhage


A subarachnoid hemorrhage is a condition where there is bleeding into the subarachnoid space between the pia mater (inner layer) and arachnoid mater (middle layer) of the tissue covering the brain. A subarachnoid hemorrhage is life-threatening and can rapidly result in serious and permanent disabilities. This is the only type of stroke that is more common among women than it is among men.

Causes and risk factors

The area between the brain and the thin tissues that cover the brain is known as the subarachnoid space. Subarachnoid hemorrhage is bleeding in this part of the brain and, up to 80 percent of the time, is caused by a cerebral aneurysm. Other causes for spontaneous subarachnoid hemorrhage include an arteriovenous malformation, a bleeding disorder, or use of blood thinners. In a very small percentage of cases, subarachnoid hemorrhage can be attributed to genetic factors.


The main symptom of a subarachnoid hemorrhage is a sudden, severe headache that is often called a “thunderclap” a headache. The pain is often worse near the back of the head. Many people describe it as the most extreme headache they have ever experienced. A headache may follow a popping or snap feeling in the head. Subarachnoid hemorrhage symptoms may include:

  • Decreased alertness
  • Eye discomfort in bright light
  • 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
  • Seizure
  • Stiff neck
  • Vision problems, including double vision, blind spots, or temporary vision loss in one eye

Additional subarachnoid hemorrhage symptoms that may occur are:

  • Eyelid drooping
  • Pupil size difference
  • Sudden stiffening of back and neck, with arching of the back

Diagnosis and testing

Our team of specialists will provide you with a thorough neurological evaluation, using the latest diagnostic technology including an MRI, CT angiography and 3D angiography. Other tests may be employed, such as a lumbar puncture to sample the cerebrospinal fluid or the use of a Doppler ultrasound to monitor blood flow in the brain.


A subarachnoid hemorrhage is a life-threatening emergency and requires immediate medical attention. Treatment may include drug therapy for blood pressure control, a drain may need to be inserted into the brain to relieve pressure within the skull or a surgical intervention such as neurosurgical clipping or endovascular coiling. Your doctor will consult with experts from the Neurocritical Care Center and the Stroke Center and work collaboratively with the departments of neurology, neurosurgery, interventional neuroradiology and radiation oncology to ensure the appropriate treatment for the best possible outcome.


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The Neuroscience Institute

We are dedicated to the world-class diagnosis and treatment of neurological diseases and disorders.