Brain swelling (brain edema) is a quite specific example of a swollen body part. Other organs and tissues may get swollen as well, but they have usually one space to enlarge. The brain dose not. It is located within the skull and the skull bones are tightly connected (in adults). Therefore, brain swelling is related with a dangerous increase of the intracranial pressure. Swollen brain is just not the same as the swollen leg.
There are many possible causes as the brain may react by swelling to virtually any damage. Brain edema may occur in brain injuries, brain infections (encephalitis, meningitis), acute strokes, brain tumors and brain metastases. Swelling accompanies even obstructive hydrocephalus, when there is disrupted the drainage of cerebrospinal fluid. Swelling of the brain may also result from severe epilepsy with a series of recurring seizures (so-called status epilepticus).
In addition, brain edema may be caused by diseases that are not based primarily in the brain. It accompanies conditions associated with severe increase of the blood pressure and disorders of the internal environment like changes of blood concentrations of ions such as sodium and chloride, too aggressive and rapid treatment of high blood sugar in diabetics, etc.
Small edema may not cause any visible symptoms. Large edema usually causes signs of intracranial hypertension including headache, nausea, vomiting, dizziness and various neurological disorders. The greatest risk is a situation, when the brainstem and upper part of the spinal cord are forced into a hole in the skull’s basis. The pressure damages both structures as it compresses them against adjacent bone having fatal consequences.
A person with the above symptoms should be examined by a neurologist and computed tomography of the brain is performed. This imaging method may not only confirm the edema, but often also show its cause. Signs of intracranial hypertension may be shown by an ocular examination. It should be emphasized that a presence of cerebral edema together with increased intracranial pressure is a clear contraindication of the lumbar puncture. Specialized neurological departments have special methods to directly monitor the intracranial pressure by using a special electrode, which is inserted through the skull just next to the brain.
The patient should be hospitalized, ideally in an intensive care unit. He should lie with slightly elevated head and the doctors may administer some substances that reduce the pressure within the skull (mannitol, corticosteroids). In addition, it is necessary to treat the underlying cause of the edema, if it is possible. When the conservative treatment is not effective enough, surgical intervention may be performed, in which a part of the skull is removed to reduce the intracranial hypertension and prevent a brain damage.