Ischemic stroke occurs when a blood clot blocks an artery and prevents the blood flow to part of the brain. Without a continuous supply of blood, brain cells become damaged and die.

Blood clots can develop in the brain or travel to the brain from other locations in the body. The types of blood clots that cause ischemic stroke include: /p>

• Cerebral thrombosis: This is a blood clot that forms in an artery in the brain. It is usually the result of the buildup of plaque inside the arteries (atherosclerosis). Over time, the plaque can completely block the artery.
• Cerebral embolism: This type of blood clot usually breaks off from plaque in the heart or large arteries in the chest and neck. The blood clot travels through the bloodstream to the brain. Eventually, the arteries become too narrow for the blood clot to pass and the clot gets stuck.

A hemorrhagic stroke occurs when a blood vessel in the brain bursts and blood leaks into the surrounding area. The pooling blood creates pressure and injures the brain tissue.

Types of hemorrhagic stroke include:

• Intracerebral hemorrhage: The rupture happens within the brain.
• Subarachnoid hemorrhage: The hemorrhage occurs in the space between the brain and the membrane that covers the brain.

• A transient ischemic attack (TIA), also known as a "mini-stroke," is a temporary blockage. Though symptoms last less than five minutes, a TIA is a warning that you may have a major stroke in the future.

The main causes of ischemic stroke are:

• Atherosclerosis, the buildup of fatty plaque inside your arteries. When atherosclerosis occurs in the carotid arteries (the main arteries in your neck) it is called carotid artery disease.
• Atrial fibrillation, an irregular heartbeat which increase your risk of blood clots.

Hemorrhagic stroke occurs when there are defects in the blood vessels in your brain. These abnormalities make it more likely the artery will rupture and bleed, especially if you have high blood pressure.

The most common causes of hemorrhagic stroke are:

• Arteriovenous malformations, tangles of arteries and veins that usually form before birth
• Brain aneurysm, a weakened area in a blood vessel that expands like a balloon
• Cerebral amyloid angiopathy, a buildup of protein in the blood vessels of the brain that makes them fragile

The goal of ischemic stroke treatment is to open up the blocked blood vessel. If you arrive at the hospital within about four hours of the start of symptoms you may receive a medication that dissolves blood clots.

Endovascular thrombectomy is another option if medication is not effective or you arrive to the hospital too late. This is a minimally invasive catheter-based treatment. Your doctor inserts the catheter into an artery in your groin or wrist and advances the catheter to the blood clot in your brain. Techniques for removing the blood clot include:

• Opening the clogged area by inflating a balloon in the artery and installing a metal mesh tube called a stent to keep it open
• Suctioning out the clot through the catheter
• Trapping the clot in wire mesh and pulling it out

Typically, endovascular procedures are only effective within six hours of the start of symptoms. But Penn Medicine doctors are able to offer this procedure to some patients up to 24 hours after a stroke.

In some cases, people do not receive treatment within the 24-hour window. Generally, removal of the clot at this point is not effective and patients receive supportive care to relieve symptoms. Penn researchers are investigating whether endovascular thrombectomy can help improve outcomes after 24 hours.

Rehabilitation helps you regain lost function from the damage to your brain. This might include problems with movement, touch, speech, memory, thinking and emotions.

You will begin rehabilitation in the hospital and continue after you go home. Some people recover from a stroke completely, while others have permanent disabilities. The Penn neurorehabilitation team offers specialized, compassionate care throughout your recovery.

Treatment for hemorrhagic stroke includes strategies to stop the bleeding, including:

• Medications: You may receive medications to lower blood pressure, reduce inflammation in the brain and prevent brain damage. If you take a blood thinner such as warfarin, your doctor will stop the medication.
• Endovascular procedures: Minimally invasive endovascular neurosurgery procedures can repair a damaged blood vessel without a need for surgery.
• Radiation treatment: This treatment uses advanced technology, such as Gamma Knife®, to remove or shrink arteriovenous malformations.
• Surgery: This may be the best option to reduce swelling or remove pooled blood. Aneurysm clipping is a type of surgery that can repair an aneurysm permanently.

If you have a transient ischemic attack, a neurologist will evaluate your condition and take steps to reduce your risk of a major stroke. This might include lifestyle changes, medications and minimally invasive or surgical treatment. At Penn, you have access to every available option to help you manage your condition.

After stroke treatment, patients transfer to a neurocritical care unit. Here, you receive close monitoring to quickly identify and treat and problems that may arise. Penn Medicine has one of the largest neurocritical care units in the nation.