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Focal ischemia generally involves cessation of blood circulation, oxygen and nutrients in a particular region of an organ when an arterial vessel becomes blocked by a blood clot. The condition may occur anywhere in the body. When blockages happen in the brain, physicians commonly refer to the condition as an ischemic stroke. Physical symptoms associated with strokes occur because of immediate blockage and possible extensive damage. The sooner individuals seek diagnosis and physicians locate the focal ischemic lesion, the greater the possibility 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 narrowed passageways, circulation slows and may cause blood cell clumping and clot formation. In time, the clot becomes large enough that it causes complete blood vessel blockage, producing an ischemic stroke. Blood clots might also form in other parts of the body, including the heart. Clots then travel through the bloodstream to the brain.
Once totally blocked, or occluded, chemical reactions occur, causing cellular damage and deterioration. Electrical impulses and cell communications cease. Focal ischemia also interrupts regulation of the sodium/potassium pump, leading to extracellular spaces filling with potassium, producing swelling. Intracellular spaces fill with calcium and sodium. Intracellular endoplasmic reticulum and mitochondria release more calcium into the cell.
The cell quickly consumes existing glucose and oxygen-producing lactic acid wastes, which damaged cells cannot eliminate. Waste products may lead to lipid breakdown and subsequent cell membrane destruction. Within 24 hours of the occurrence, cells die. Accumulative pressure and possible bleeding into the brain extends the amount of cellular damage. When the focal ischemic event occurs, individuals may experience a severe headache, dizziness or loss of consciousness.
Victims of focal ischemia typically display drooping on one side of the face. Paralysis may extend to the entire side of the body, inhibiting balance and immobility. Visual fields may become partially blocked or produce total blindness. Though cognitive ability might remain the same, speech may be slurred or incoherent. Though patients cognitively know what they want to say, the damaged speech center can no longer associate thought with the appropriate words.
Statistics indicate 80 to 85 percent of strokes are caused by ischemic conditions. When symptoms occur, physicians advise individuals to seek medical intervention as quickly as possible. Physicians generally use vascular imaging studies to locate the area affected by focal ischemia. Treatment may involve the use of clot dissolving medications or surgical removal of the clot. Follow up treatment may involve continued anticoagulation and physical therapy.