Injury, other health problems, infections, tumors, and even high altitudes -- any of these problems can cause brain swelling to occur. The following list explains different ways the brain can swell:
Traumatic brain injury (TBI): A TBI is also called a head injury, brain injury, or acquired brain injury. In TBI, a sudden event damages the brain. Both the physical contact itself and the quick acceleration and deceleration of the head can cause the injury. The most common causes of TBI include falls, vehicle crashes, being hit with or crashing into an object, and assaults. The initial injury can cause brain tissue to swell. In addition, broken pieces of bone can rupture blood vessels in any part of the head. The body's response to the injury may also increase swelling. Too much swelling may prevent fluids from leaving the brain.
Ischemic strokes: Ischemic stroke is the most common type of stroke and is caused by a blood clot or blockage in or near the brain. The brain is unable to receive the blood -- and oxygen -- it needs to function. As a result, brain cells start to die. As the brain responds, swelling can occur.
Brain (intracerebral) hemorrhages and strokes: Hemorrhage refers to blood leaking from a blood vessel. Hemorrhagic strokes are the most common type of brain hemorrhage. They occur when blood vessels anywhere in the brain rupture. As blood leaks and the body responds, pressure builds inside the brain. High blood pressure is thought to be the most frequent cause of this kind of stroke. Hemorrhages in the brain can also be due to head injury, certain medications, and unknown malformations present from birth.
Infections: Illness caused by an infectious organism such as a virus or bacterium can lead to brain swelling.
Tumors: Growths in the brain can cause swelling in several ways. As a tumor develops, it can press against other areas of the brain. Tumors in some parts of the brain may block cerebrospinal fluid from flowing out of the brain. New blood vessels growing in and near the tumor can also lead to swelling.
High altitudes: Although researchers don't know the exact causes, brain swelling is more likely to occur at altitudes above 4,900 feet. This type of brain edema is usually associated with severe acute mountain sickness (AMS) or high-altitude cerebral edema (HACE).
Symptoms of brain swelling vary, depending on the severity and the cause. Usually they begin suddenly. You may notice any of these symptoms:
Neck pain or stiffness
Nausea or vomiting
Vision loss or changes
Inability to walk
Loss of consciousness
The steps used by your doctor to diagnose brain swelling depend on the symptoms and the suspected cause. Common exams and tests used in the diagnosis include: Head and neck exam, Neurologic exam, CT scan of the head to identify the extent and location of the swelling, MRI of the head to identify the extent and location of the swelling, Blood tests to check for causes of the swelling.