Hydrocephalus – or “water on the brain” – is a general term used to describe a range of medical conditions caused by excessive cerebrospinal fluid in the brain. Some babies are born with “congenital” forms of hydrocephalus. Other children develop the condition – often due to physical trauma at the time of birth. Predicting the effects of hydrocephalus is extremely difficult, but some infants with acquired cases will develop developmental disabilities and nervous system disorders.

What Is Hydrocephalus?

The medical condition that researchers call hydrocephalus is often known as “water on the brain.” While this title is evocative, and an adequate translation of the Greek word hydrocephalus, it’s not quite accurate. People with hydrocephalus don’t have too much water in their brains; they have too much cerebrospinal fluid in their brains.

In babies, this buildup of cerebrospinal fluid in the brain puts significant pressure on brain tissue. Over time, this increased pressure can injure the brain’s white matter, while constricting the development of the cerebral cortex. Some hydrocephalic babies, especially those who do not receive proper treatment, will be left with permanent mental and physical disabilities.

Cerebrospinal Fluid

Cerebrospinal fluid (CSF) is a clear liquid that surrounds the brain and spinal cord.

Produced deep inside the brain by channels called “ventricles,” CSF acts as a cushion, absorbing external shocks to the central nervous system. CSF also filters out waste products produced by the brain and transports nutrients and chemicals.

Healthy human brains are constantly producing cerebrospinal fluid. Likewise, the liquid is always being reabsorbed by the bloodstream. Notwithstanding normal fluctuations, the average brain produces about 500 millimeters of CSF every day, the Hydrocephalus Association reports. At any one time, the central nervous system is bathed in between 100 and 160 mL of cerebrospinal fluid.

In patients with hydrocephalus, including newborns, this process has been impaired for some reason. As a result, the cerebrospinal fluid builds up, swelling the ventricles to a dangerous extent.

Causes Of Hydrocephalus

Hydrocephalus comes in several different forms, depending on what kind of problem is causing the condition. In general, there are three issues that can lead to “water on the brain”:

  • the brain ventricles produce too much cerebrospinal fluid
  • the flow of cerebrospinal fluid is blocked by an obstruction
  • the bloodstream is unable to reabsorb enough cerebrospinal fluid

In many cases, it can be hard to figure out why an infant’s cerebrospinal fluid system has been impaired. Some genetic abnormalities, including spina bifida, seem to increase the risk that a child will develop hydrocephalus. Other cases of the condition are caused by fetal infections – which can be transmitted from mother to child inside the womb – and brain tumors. Bleeding in the brain, and more general cardiovascular problems, can also lead to hydrocephalus in babies.

Traumatic Head Injuries In Delivery

Traumatic head injuries are another potential cause of hydrocephalus.

While some babies will sustain head trauma during difficult labors, these injuries are relatively rare. More commonly, children delivered with birth-assistive devices, like forceps and vacuum extractors, can sustain head injuries due to the pressure exerted by these tools. The use of birth-assistive devices has also been seen to increase the risk for intracranial bleeding, which can interrupt the proper flow of cerebrospinal fluid.

Symptoms Of Fluid In The Brain

Infants may actually be able to withstand the effects of hydrocephalus better than adults. A baby’s head, after all, is still growing, and this continued development applies to the skull as well. Rather than meeting a hard, bony barrier that acts as an absolute limit, the cerebrospinal fluid is able to push an infant’s skull outward. In short, the skull of a newborn may be able to accommodate minor increases in the amount of cerebrospinal fluid without causing permanent damage.

This odd benefit of youth isn’t a solution to hydrocephalus, though. The skull can only expand so much, and there may also be other problems blocking the drainage of CSF.

No matter the cause, most infants will be diagnosed with hydrocephalus after parents or a doctor notice that the child has an abnormally large head. Other symptoms of the condition include:

  • increase in head size over the first days, weeks or months of life
  • down-turned gaze (“sun setting”)
  • lethargy and sleepiness
  • irritability
  • shrill crying
  • vomiting
  • seizures

In some children, hydrocephalus will cause “failure to thrive,” or inadequate weight gain. Other infants will miss developmental milestones. Doctors confirm the diagnosis by taking ultrasound images of a newborn’s brain. In children over the age of 2, diagnosis is usually made using MRI or CT scans, since the bones of the skull have fused together after this age.

Treatment For Hydrocephalus

Hydrocephalus is a progressive condition; it will get worse. Without proper treatment, a child’s symptoms will intensify and permanent brain damage is likely. Thankfully, hydrocephalus can be effectively treated in most children, but surgical intervention is almost always the only viable option, Columbia University Medical Center reports.

Shunt Systems

In the most common procedure used to treat hydrocephalus, surgeons insert a catheter, called a “shunt,” into a child’s brain. This shunt, equipped with a one-way valve, diverts cerebrospinal fluid from the ventricles to another place in the body where it can be absorbed properly.

These systems usually balance out the adverse effects of hydrocephalus, but as with any surgical procedure, shunts come with their own serious risks. Infections are fairly common, often caused by bacteria already present in a child’s body. Shunt failure is even more common. As a child’s head continues to develop, shunts wear out or get clogged with CSF. In other cases, the devices can break apart. Shunt failure occurs in an estimated 50% of patients within two years of implantation.

Ventriculostomy

An alternative procedure involves making a tiny hole in the floor of a ventricle, which allows the cerebrospinal fluid to drain from the brain cavity. This surgery, called a ventriculostomy, is performed using tiny cameras and a tiny drill.

Long-Term Consequences Of Hydrocephalus

While these procedures, carefully performed at an appropriate time, can relieve cerebrospinal fluid on the brain, they can’t solve the underlying cause of an infant’s hydrocephalus. Thus ongoing medical issues will have to be diagnosed and managed effectively to avoid subsequent injuries.

Hydrocephalus can cause permanent neurological damage, and some children will develop intellectual or physical disabilities as a result. Cerebral palsy and seizure disorders are a possibility, as are significant developmental disabilities. When left untreated, the condition can even be fatal.

Proper and timely diagnosis is essential in managing hydrocephalus. As we’ve seen, the condition is serious, and can have severe results, but is perfectly treatable in the vast majority of cases.