Stroke 2.0 - Transient Ischemia, General Effects of Ischemic Stroke

Transient Ischemia

= Transient interruptions of cerebral blood supply = Small strokes

Tempo­rary disruptions of cerebral circulation, accompanied by rapidly developing:

sensory disturbance

limb weakness

slurred speech

visual anomalies

dizziness

confusion

mild aphasia

 

  • About 1/3 of patients who have TIAs/RINDs/PRINDs will have a stroke that leaves them with permanent neurologic deficits within 5 years of the transient ischemic event

I

Transient ischemic attacks (TIAs)

 

Causes

Prognosis


Most common: By small emboli that temporarily occlude an artery, then break up or dissolve.

Resolve completely within few minutes to 24 hours.

Further Classification

II

Reversible ischemic neurologic deficits (RINDs). 

 

last > 24 hours; completely resolve within a few days

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III

Partially reversible ischemic neuro­logic deficits (PRINDs). 

 

last > 24 hours; leave minor deficits after a few days 

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Physiologic changes following major ischemic strokes:


E.g:

  1. Neurons deprived of blood supply die
  2. Damaged brain tissue swells → raise intracranial pressure and cause displacement of brain tissues
  3. Blood flow to both hemispheres diminishes.
  4. Transneural degeneration - Neurons in undamaged parts of the brain that connect with destroyed neurons degenerate because of the lost of con­nections
  5. Diaschisis – phenomenon in which brain function is disrupted in regions away from the site of injury but connected to it by neuronal pathways.
References:
Brookshire, R.H. (2007). Introduction to neurogenic communication disorders (7th Ed). St. Louis: Mosby. (page 36- 50)

Next: Stroke 3.0 -  General Prognosis of Major Stroke