Stroke is a very sudden onset (acute) disorder of central nervous system function, which is due to the disruption or cessation of the blood supply to a larger or smaller part of the brain or spinal cord .

The cause is either a clog of (clot in) an artery, which is the most common cause, or that an artery has ruptured (brain/spinal cord hemorrhage).

In both cases, swelling and tissue death occur in the affected area. In the latter case, there is the mechanical pressure damage caused by the bleeding itself (hematoma).

The resulting disease picture is extraordinarily varied and naturally depends on which blood vessel is affected (and thus which part of the central nervous system has been damaged/rendered inoperative).

Common signs of illness are:
- sensory disturbance
- visual disturbance;
- speech disorder;
- loss of consciousness;