School of Medicine

Wayne State University School of Medicine

Stroke

Stroke is an emergency that result from cutting off vital blood flow and oxygen to the brain. The statistics below give a perspective on stroke and its devastating impact:

  • In the United States, stroke is the fourth leading cause of death, killing over 133,000 people each year, and a leading cause of serious, long-term adult disability.
  • There are an estimated 7,000,000 stroke survivors in the U.S. over age 20.
  • Approximately 795,000 strokes will occur this year, one occurring every 40 seconds, and taking a life approximately every four minutes.
  • Stroke can happen to anyone at any time, regardless of race, sex or age.
  • From 1998 to 2008, the annual stroke death rate fell approximately 35 percent, and the actual number of deaths fell by 19 percent.
  • Approximately 55,000 more women than men have a stroke each year.
  • African Americans have almost twice the risk of first-ever stroke compared with whites.
  • Two million brain cells die every minute during stroke, increasing risk of permanent brain damage, disability or death. Recognizing symptoms and acting FAST to get medical attention can save a life and limit disabilities.
  • Women are twice more likely to die from stroke than breast cancer annually.
  • The estimated direct and indirect cost of stroke in the United States in 2010 is $73.7 billion.

During an acute ischemic event, cellular adenosine triphosphate is depleted, leading to failure of cell membrane sodium-potassium pumps. This (along with other chemical effects) leads to an acute influx of water into cells with swelling of the affected cells (cytotoxic edema). The end result is that the increased intracellular water (which shows less overall diffusion than does extracellular interstitial water) demonstrates a decrease in the amount of net diffusion of water present in brain parenchyma experiencing cytotoxic edema. There are alternative explanations for what is occurring at the cellular level, but the end result is the same with respect to imaging.

Our Laboratory Investigates:

Quantification of tissue injury and repair following stroke. This can be done in various ways but understating water diffusion is key to acute stroke biology. Net diffusion of water on a DWI MR scan. Areas of decreased water diffusion will be seen as areas of increased signal on d MR and can be seen as early as 22 minutes after an ischemic insult. Scans or ADC maps are usually considered evidence of irreversible ischemic damage, though there are reports of reversal of DWI MR findings after successful recanalization of a blood vessel with intra-arterial thrombolysis. Similarly, although DWI MR is considered a sensitive method for ruling out infarction, there have also been case reports of patients with initially (within 4 hours) negative DWI MR scans who went on to cerebral infarction.

Our interest is in quantifying tissue injury and repair occurring after stroke and how it may affect clinical outcomes. Despite several advances in the field of stroke including the clot busting drug “tPA”, it is not clear why repair following acute stroke varies from person to person after adjusting for all variables such as hypertension, high cholesterol, diabetes, weight, smoking, and etc.

Newer imaging techniques such as DTI, MTR, and MRS will provide quantitative information regarding tissue injury and repair potential after stroke.

It is also well known that stroke occurs more commonly in African-Americans than Caucasians. and that African-Americans tend to experience a worse outcome after stroke. The reasons for these are not entirely clear, especially relating to repair in the brain in African-Americans with stroke. These investigations could help design strategies to improve outcomes and recovery from stroke.

CT perfusion maps of cerebral blood volume; white oval shows a region of decresed blood volume
CT perfusion maps of cerebral blood flow; black oval shows a region of decresed blood flow
DWI showing acute infarct in the left MCA region
DWI showing acute infarct in the left MCA region