Focal ischemia usually involves the cessation of blood flow, oxygen, and nutrients to a particular region of an organ when a blood clot blocks an arterial vessel. The condition can occur anywhere on the body. When blockages occur in the brain, doctors commonly refer to the condition as an ischemic stroke. Physical symptoms associated with strokes occur due to immediate blockage and possible extensive damage. The sooner people seek a diagnosis and doctors locate the focal ischemic lesion, the better the chance of preventing further damage or reversing symptoms.
Plaque formation may contribute to the likelihood of focal ischemia, as the condition typically narrows blood vessels. When blood flows through these narrow passageways, circulation slows and can cause blood cells to build up and clots to form. Over time, the clot becomes large enough to cause complete blockage of the blood vessels, leading to an ischemic stroke. Blood clots can also form in other parts of the body, including the heart. The clots then travel through the bloodstream to the brain.
Once totally blocked or occluded, chemical reactions take place that cause cell damage and deterioration. Electrical impulses and cellular communications cease. Focal ischemia also disrupts the regulation of the sodium/potassium pump, leading to extracellular spaces being filled with potassium and causing inflammation. The intracellular spaces are filled with calcium and sodium. The intracellular endoplasmic reticulum and mitochondria release more calcium into the cell.
The cell rapidly consumes existing glucose and oxygen-producing lactic acid wastes, which damaged cells cannot remove. The waste products can cause the breakdown of lipids and the subsequent destruction of the cell membrane. Within 24 hours after the occurrence, the cells die. The cumulative pressure and possible bleeding in the brain extend the amount of cell damage. When the focal ischemic event occurs, people may experience a severe headache, dizziness, or loss of consciousness.
Victims of focal ischemia usually show drooping on one side of the face. The paralysis can spread to the entire side of the body, inhibiting balance and immobility. Visual fields can be partially blocked or result in total blindness. Although cognitive ability may remain the same, speech may be slurred or incoherent. Although patients cognitively know what they want to say, the damaged speech center can no longer associate the thought with the appropriate words.
Statistics indicate that 80 to 85 percent of strokes are caused by ischemic conditions. When symptoms occur, doctors advise people to seek medical intervention as quickly as possible. Doctors generally use vascular imaging studies to locate the area affected by focal ischemia. Treatment may include the use of drugs to dissolve the clot or surgical removal of the clot. Follow-up treatment may include continued anticoagulation and physical therapy.