The main cause of fluid on the brain is partial blockage that limits the flow of cerebrospinal fluid, according to Mayo Clinic. The problem occurs due to lack of balance between the production and absorption of the fluid within and from the brain respectively.
Cerebrospinal fluid protects the brain from damage, helps keep a normal pressure within the brain and eliminates waste products from the brain, explains Mayo Clinic. Blockage of the normal flow of the fluid occurs when the flow of fluid from one ventricle to another or from ventricles to spaces within the brain is incorrect. Rarely, the problem may be as a result of inability of the blood vessels to absorb the fluid. This is normally due to inflammation within the brain as a result of injury or disease.
In some cases, too much cerebrospinal fluid may occur when production of the fluid exceeds the amount the bloodstream absorbs, according to Mayo Clinic. In infants and children, the problem may be as a result of inflammation in fetal brain tissues due to infections, including syphilis and rubella, that affect the uterus when women are pregnant. The fluid may also build up when ventricles bleed.
Risk factors for excess fluid on the brain include bleeding in the brain as a result of injury or stroke as well as brain or spinal cord tumors, states Mayo Clinic. People who suffer from central nervous system infections, including mumps and bacterial meningitis, are at a higher risk of experiencing the problem.