Doctors classify hypoxia of the brain into four distinct categories, ranging from least to most severe:

Diffuse cerebral hypoxia causes mild to moderate impairment in brain function due to low blood oxygen levels. This sort of hypoxia is common among people who hold their breaths for too long, or who participate in sports that involve choking one's opponent, such as jujitsu.

Focal cerebral ischemia occurs when there is oxygen deprivation in a specific area of the brain. This is usually the result of a hemorrhage, stroke, or blockage in a single blood vessel.

Global cerebral ischemia is a complete cessation of blood flow to the brain. It quickly leads to cerebral anoxia. Severe strokes, traumatic injuries such as gunshot wounds, choking, and suffocation can cause global cerebral ischemia.

Cerebral infarction is a cessation of blood flow to multiple areas of the brain and often causes extensive brain damage. A stroke is the most common cause.