Diagnostic tests examine how the brain looks, works and gets its blood supply. They can outline the injured brain area. Most of them are safe and painless. Diagnostic tests fall into three categories:

Imaging tests give a picture of the brain similar to X-rays. A CT scan (computed tomography) or CAT scan uses radiation to create a picture of the brain. It's usually one of the first tests given to patients suspected of stroke. CT test results give valuable information about the cause of stroke and the location and extent of brain injury. MRI (magnetic resonance imaging) uses a large magnetic field to produce an image of the brain. Like the CT scan, it shows the location and extent of brain injury. The image produced by MRI is sharper and more detailed than a CT scan so it's often used to diagnose small, deep injuries.

Electrical tests record the electrical impulses of the brain. Two basic tests, EEG and Evoked Response, show the brain's electrical activity. In an EEG (electroencephalogram), small metal discs (electrodes) are placed on a person's scalp to pick up electrical impulses. These electrical signals are printed out as brain waves. An Evoked Response test measures how the brain handles different sensory information. Electrodes record electrical impulses related to hearing, body sensation or vision.

Blood flow tests show any problem that may cause changes in blood flow to the brain. Several blood flow tests exist; most use ultrasound technology. A probe is placed over the suspect artery — especially arteries in the neck (carotid) or at the base of the skull (vertebral) — and the amount of blood flow is determined. Examples of blood flow tests are B-mode imaging, Doppler testing and duplex scanning. These tests give detailed information about the condition of arteries. Another blood flow test is a medical procedure called angiography (arteriography or arteriogram). This test is like a cardiac catheterization, only the catheter is placed in the arteries of the brain rather than in the arteries of the heart. In this test, a special dye is injected into the blood vessels and an X-ray is taken. Angiography gives a picture of the blood flow through the vessels. This allows the size and location of blockages to be evaluated. This test can be especially valuable in diagnosing aneurysms and malformed blood vessels and providing information before surgery.

Early treatment can help minimize damage to brain tissue and improve the outcome (prognosis). Treatment depends on whether the stroke is ischemic or hemorrhagic and on the underlying cause of the condition. The long-term goals of treatment include rehabilitation and prevention of additional strokes.
Initial treatment for ischemic stroke involves removing the blockage and restoring blood flow. Tissue plasminogen activator (t-PA) is a medication that can break up blood clots and restore blood flow when administered within 3 hours of the event. This medication carries a risk for increased intracranial hemorrhage and is not used for hemorrhagic stroke. Mannitol, a diuretic, may be administered intravenously (through an IV) to reduce intracranial pressure during an ischemic stroke.
Hemorrhagic stroke usually requires surgery to relieve intracranial (within the skull) pressure caused by bleeding. Most of the damage caused by this type of stroke results from the physical disruption of brain tissue. Surgical treatment for hemorrhagic stroke caused by an aneurysm or defective blood vessel can prevent additional strokes. Surgery may be performed to seal off the defective blood vessel and redirect blood flow to other vessels that supply blood to the same region of the brain. Endovascular treatment involves inserting a long, thin, flexible tube (catheter) into a major artery, usually in the thigh, guiding it to the aneurysm or the defective blood vessel, and inserting tiny platinum coils (called stents) into the blood vessel through the catheter. Stents support the blood vessel to prevent further damage and additional strokes.

Recovery and rehabilitation are import aspects of stroke treatment. In some cases, undamaged areas of the brain may be able to perform functions that were lost when the stroke occurred. Physical rehabilitation involves using exercise and other physical means to help patients regain the use of their arms and legs and prevent muscle stiffness in patients with permanent paralysis. Speech and occupational therapies also help patients regain independent function and relearn basic skills.
Prognosis depends on the type of stroke, the degree and duration of obstruction or hemorrhage, and the extent of brain tissue death. Most stroke patients experience some permanent disability that may interfere with walking, speech, vision, understanding, reasoning, or memory. Approximately 70% of ischemic stroke patients are able to regain their independence and 10% recover almost completely. Approximately 25% of patients die as a result of the stroke. The location of a hemorrhagic stroke is an important factor in the outcome, and this type generally has a worse prognosis than ischemic stroke.