An excessive accumulation of fluid in the brain is known as hydrocephalus or hydrocephaly, from the Greek words hydro (meaning “water”) and cephalus (meaning “head”). The term is something of a misnomer, however, since the fluid in question is not actually water, as was once believed, but a combination of brain chemicals called cerebrospinal fluid. The brain needs cerebrospinal fluid, but too much of it can cause brain swelling, illness, blurred vision, and disorientation.

Normally, the fluid in the skull keeps the brain buoyant, serves as a shock-absorbing cushion, delivers nutrients, and carries away wastes. The fluid is produced continuously, so any condition that blocks absorption back into the bloodstream will result in overaccumulation in the ventricles. Babies can be born with a congenital form of hydrocephalus, of which the most telling sign is a rapidly expanding head circumference. Other types of hydrocephalus can be acquired at any age as a result of head trauma, infection, a complication of surgery, and other, unknown reasons. When a person’s skull cannot expand to accommodate the fluid buildup, symptoms such as nausea, vomiting, drowsiness, irritability, or coordination problems occur.

Hydrocephalus is diagnosed through ultrasonography, CT scans, or MRIs. The most common treatment involves inserting a shunt with an adjustable valve into the brain’s ventricles, which diverts the flow of fluid down into the abdomen or chest, where it can be absorbed into the bloodstream. These shunts aren’t perfect; they typically require regular monitoring to correct over-or underdrainage. Proper treatment, however, can often help patients recover completely and lead normal lives with few limitations.

ADDITIONAL FACTS

  1. Normal pressure hydrocephalus, a condition most common in elderly people, is sometimes misdiagnosed as untreatable Alzheimer’s disease or dementia. Symptoms include disorientation and clumsiness, memory loss, urinary incontinence, and a shuffling gait.
  2. One of the most common causes of hydrocephalus is aqueductal stenosis, a narrowing of the aqueduct of Sylvius—a small passage between the third and fourth ventricles, in the middle of the brain.
  3. In 2007, French scientists discussed the remarkable case of a 44-year-old man with hydrocephalus whose brain had been reduced to little more than a thin sheet of tissue due to the buildup of fluid in his skull. Doctors were amazed that the married father of two, who was examined after reporting weakness in his left leg, still had an IQ of 75 and led a normal life, despite having so little brain tissue left.
  4. One or 2 of every 1,000 babies is born with hydrocephalus, making the condition as common as Down syndrome and more common than spina bifida or brain tumors.