Hydrocephalus (Pathophysiology of NS)

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• The fluid surrounding the brain (cerebrospinal fluid, CSF) is produced in spaces within the brain called ventricles. The fluid must be drain to a different area, where it is absorbed into the blood. When the fluid cannot drain, hydrocephalus (water in the brain) develops.
• Hydrocephalus often increases the pressure in the ventricles, which compresses the brain. 
• Many conditions, such as a birth defect, bleeding within the brain, or brain tumours can block drainage and cause hydrocephalus.
• An abnormally large head my be a symptom of hydrocephalus. The infant usually fails to develop normally.
• CT scan, ultrasound, or MRI scan of the head reveals the diagnosis as well as the degree of brain compression.
• The goal of treatment is to keep pressure normal within the brain. A permanent alternate drainage path (shunt) for CSF decrease the pressure and volume of the fluid inside the brain.
• A doctor places the shunt in the ventricles in the brain and runs it under the skin from the head to another site, usually the abdomen (ventriculoperitoneal shunt). The shunt contains a valve that allows fluid to leave the brain if the pressure  becomes too high.
• Although a few children can eventually do without the shunt as they get older, shunts are rarely removed.
• If needed, pressure within the brain can often be temporarily reduced with drugs (such as acetazolamide or furosemide) or repeated lumbar puncture until a shunt is placed.
• Some children with hydrocephalus develop normal intelligence. Others are mentally retarded or have learning disabilities.