on 21-Aug-2021 (Sat)

Cerebral ischemia is caused by a reduction in blood flow that lasts longer than several seconds. Neurologic symptoms are manifest within seconds because neurons lack glycogen, so energy failure is rapid. If the cessation of flow lasts for more than a few minutes, infarction or death of brain tissue results. When blood flow is quickly restored, brain tissue can recover fully and the patient’s symptoms are only transient: this is called a transient ischemic attack (TIA).

A gen- eralized reduction in cerebral blood flow due to systemic hypotension (e.g., cardiac arrhythmia, myocardial infarction, or hemorrhagic shock) usually produces syncope

Focal ischemia or infarction, con- versely, is usually caused by thrombosis of the cerebral vessels themselves or by emboli from a proximal arterial source or the heart . Intracranial hemorrhage is caused by bleeding directly into or around the brain; it produces neurologic symptoms by producing a mass effect on neural structures, from the toxic effects of blood itself, or by increasing intracranial pressure

patients and their family members should be counseled to call emergency medical services immediately if they experience or witness the sudden onset of any of the following: loss of sensory and/or motor function
on one side of the body (nearly 85% of ischemic stroke patients have hemiparesis); change in vision, gait, or ability to speak or understand; or a sudden, severe headache. The acronym FAST (Facial weakness, Arm weakness, Speech abnormality, and Time) is simple and helpful to teach the lay public about the common physical symptoms of stroke and to underscore that treatments are highly time-sensitive