Lack of Oxygen (Anoxia and Hypoxia)
It is vital that the brain gets enough oxygen. Brain cells start to die if their oxygen supply is significantly reduced for four minutes or longer. After five minutes, this can cause a permanent brain injury. The greater the loss of oxygen, the more widespread and serious the injury is likely to be.
Factors that may cause a lack of oxygen include:
severe irregular heartbeat, a heart attack, poisoning, suffocation, choking, carbon monoxide poisoning, electrocution, a drug overdose and near-drowning.
Anoxia means a total lack of oxygen to the brain.
Hypoxia means a partial lack of oxygen to the brain.
A tumour is an abnormal growth of cells. The exact cause of brain tumours is not clear. Brain tumours come in many forms. Their effects depend on factors such as their location, how quickly they grow and the amount of pressure on the brain they cause.
As a tumour grows, it takes up more space in the skull and pushes on the brain. This results in swelling which can affect the supply of blood and oxygen to healthy brain cells.
Common symptoms of a brain tumour include headaches, numbness or tingling in the arms or legs, seizures, memory problems, mood and personality changes, balance problems and changes in speech, sight or hearing.
A brain injury can result, not just from the effects of the tumour, but also from the chemotherapy, radiation or surgery used to treat it.
Encephalopathy is a general term used for a condition that affects the function or structure of the brain. There are many types of encephalopathy – some are permanent and cause a brain injury, while others are temporary. Encephalopathy can often be a complication of another medical condition – liver failure or kidney failure, for example. Changes in the body due to a poison, illegal drugs or alcohol (known as Alcohol-Related Brain Injury) can also cause encephalopathy.