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Medical Advances

Breaking Down Brain Aneurysms (Infographic)

Difference Between Strokes and Aneurysms

Every 40 seconds in the United States, someone has a stroke.

Strokes occur when blood flow to the brain is disrupted. This can occur when blood vessels, the body’s “pipes” that carry blood, become plugged or leak. When blood — and the oxygen and nutrients it carries — can’t get to the brain, brain cells die, which can cause neurological complications and even death.

Some strokes (ischemic) are caused by blockage of brain blood vessels. They account for 87% of strokes.

The other 13% of strokes are hemorrhagic, caused by leakage of blood into or around the brain tissue. This may be due to a ruptured cerebral (brain) aneurysm. Commonly confused with stroke, cerebral aneurysms are “blisters” that form when a weak spot in a blood vessel of the brain bulges or balloons out. If an aneurysm ruptures, it causes a stroke, but not all strokes are caused by aneurysms.

Hemorrhagic strokes are further broken down into subarachnoid hemorrhages (SAH) and intracerebral hemorrhages (ICH).


  • Account for approximately 3% of strokes
  • Cause bleeding in the space around the brain and blood vessels
  • Result in significant injury or death
  • One-third of people will have a good outcome
  • One-third will have a disability
  • One-third will die immediately


  • Account for approximately 10% of strokes
  • Cause bleeding into the brain tissue

“Hemorrhagic strokes are by far the most fatal,” says Babak S. Jahromi, MD, PhD, vice chair, Regional Neurosurgery, Northwestern Medicine. “While aneurysm rupture is rare, once an aneurysm bursts, the odds of brain damage and death drastically increase. Fortunately, there are advanced treatment options for stopping unruptured aneurysms in their tracks.”

Let’s take a closer look at brain aneurysms.


Northwestern Medicine Stroke and Cerebrovascular Care

Babak S. Jahromi, MD, PhD
Babak S. Jahromi, MD, PhD
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Professor, Feinberg School of Medicine
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