• First, the blood supply to the brain may be blocked -- tiny clots (emboli or thrombi) may plug the vessels that bring blood to parts of the brain, or the vessels themselves may be narrowed, reducing the amount of blood to the brain (as is seen in Moyamoya Syndrome, for example).

• Second, the blood may not have enough oxygen in it to begin with (as in cases when someone can't breathe for long periods of time or in the setting of carbon monoxide poisoning) or the blood may not be circulating fast enough to bring fresh oxygen to the brain (as might occur if the heart is not beating appropriately).

• Lastly, the brain itself might be under pressure (as occurs in brain swelling after trauma or when there is bleeding around the brain) or there may be bleeding within the substance of the brain itself, which directly injures the brain tissue and also makes it harder for blood with oxygen to be delivered to it. In these cases of increased pressure, the blood with oxygen from the heart cannot enter the confines of the skull if the pressure is too high.

Some parts of the brain can suffer strokes with little or no recognizable symptoms, even if injury can be seen on MRIs or CT scans (so-called 'silent' strokes). Other strokes, even very small ones, can cause devastating symptoms, such as paralysis, blindness or even death, if they occur in sensitive areas of the brain.

• Deficiencies of protein C and S
• antithrombin-III deficiency
• prothrombin G20210A mutant genotype
• sickle cell disease
• activated protein C resistance
• dyslipoproteinemias
• homocystinuria
• mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS)
• Fabry disease
• Menkes disease
• Tangier disease

• congenital heart disease
• bacterial endocarditis

Sickle cell disease and other prothrombotic processes, which can be genetic, such as:

• factor V Leiden mutation
• antiphospholipid antibodies
• hyperhomocysteinemia
• elevated lipoprotein (a)
  

• infection
• medications
• hepatic or renal disease.

Neonatal stroke

Vasculitis

Vasculitis may be infectious or noninfectious. Infectious cases include:

• sepsis of any type (particularly meningitis)
• varicella
• human immunodeficiency virus (HIV)
• mycoplasma

• Behcet disease
• sarcoidosis
• Sjögren syndrome
• ulcerative colitis
• Kawasaki disease
• Henoch-Schonlein Purpura (HSP)

Fibromuscular dysplasia

Arteriovenous Malformations (AVMs) and Arteriovenous Fistulas (including dural arteriovenous fistulas) (AVFs, DAVs, DAVFs, DAVMs)

Vein of Galen Malformations (VOGMs)

Aneurysms

Moyamoya Syndrome

Venous thrombosis

Arterial ischemic stroke

Arterial dissection (vertebral dissection, carotid dissection)

• First, the underlying cause of the stroke (such as high brain pressure, narrowed blood vessels or an increased tendency of the blood to clot inappropriately) should be diagnosed and corrected, if possible.

• Second, regardless of the cause of the stroke, the problems that result from the stroke (weakness, numbness, etc.) can sometimes be improved with therapy over time. Identifying which patients may benefit from specialized therapy might require evaluation by specific health care professionals, such as neurologists, rehabilitation medicine physicians, or physical, occupational or speech therapists.

Arteriovenous Malformations (AVMs) and Arteriovenous Fistulas (including dural arteriovenous fistulas) (AVFs, DAVs, DAVFs, DAVMs)
Vein of Galen Malformations (VOGMs)
Aneurysms
Moyamoya Syndrome
Venous thrombosis
Arterial ischemic stroke
Arterial dissection (vertebral dissection, carotid dissection)

Contact Edward Smith, MD, or R. Michael Scott, MD, for more information.