ANOXIA   [ back to Glossary Index ]
Anoxia is damage to the nerve cells (neurons) of the brain as a result of temporary, total oxygen deprivation. Such deprivation can result from near drowNing, cardiac arrest, blockage of the airway in the throat from any cause, blood loss through open wounds, pulmonary embolism, carbon monoxide poisoning, and other mechanisms. Following head trauma the brain can swell until it reaches the maximum volume of open space in the skullcase, and from that point on, further swelling will crush closed the arterial supply of blood and oxygen to the brain, causing the death of brain cells. If the brain swelling is not very rapidly reversed by a cooling helmet, administration of manitol, or in other ways, the patient is likely to die or suffer severe, irreversible brain damage. The is true of a blood clot from an epidural or subdural hemorrhage, which can crush the brain tissue and shut the arteries if it becomes large enough. The treatment for a blood clot (hematoma) is mechanical removal of the clot by a neurosurgeon. Ischemic brain damage, which is less severe than anoxia, results from the partial shut off of oxygen to the brain.
The prognosis for good recovery is generally worse for persons having anoxic brain damage vs. those with traumatic brain damage.  However, a TBI can evolve into an anoxic brain insult if cerebral edema (brain swelling) or the unchecked growth of a large hematoma occurs as a consequence of the TBI. Closed head injury checklists handed out at Emergency Rooms set out the obvious signs and symptoms of a large epidural or subdural blood clot pressing against the brain, such as tunnel vision, double vision, vomiting or extreme lethargy. Persons who suffer a concussion with "mild" TBI are mistakenly told they are "fine" by physicians who wrongly regard the absence of those life-threatening symptoms as proof the brain was not injured by head trauma.