Hydrocephalus (without Spina Bifida)

 

Condition Description

Hydrocephalus (HY-dro-SEF-ah-lus) is not a specific disease but a congenital or acquired condition with multiple causes resulting in impaired cerebral spinal fluid (CSF) circulation, absorption or (rarely), production. This causes a build-up of spinal fluid within the brain. The body produces spinal fluid constantly, about 1 pint per day in an adult. The CSF contains sugars and salts and protects the brain. The fluid acts as a shock absorber cushion for the brain. CSF also delivers nutrients to the brain tissue and removes waste, and it keeps a steady pressure in the brain to ensure proper blood flow. When the flow of CSF is blocked, the increased pressure causes symptoms that can damage delicate brain tissue. The two main kinds of hydrocephalus in children are:

  1. Non-communicating: the blockage is located within the brain's ventricles (open spaces in the center of the brain where CSF is produced and reabsorbed). The most common place where the blockage occurs (in about 1/3 of all cases) is between the brain's third and fourth ventricles (called the aqueduct of Sylvius).
  2. Communicating: The CSF flows freely in the brain but is blocked elsewhere outside ventricular system (for example, in the spine because of a myelomeningocele). Some of the causes of communicating hydrocephalus are bleeding into the brain, infection, trauma, tumors, and structural malformations. Babies can be born with hydrocephalus acquired from intrauterine infections (i.e., rubella, syphilis, cytomegalovirus, toxoplasmosis). They might have an infection after birth such as bacterial meningitis. Whether the infection is before or after birth, the result is the same: the CSF will not be reabsorbed properly by the arachnoid villi in the brain's ventricles due to scarring from the inflammatory process. Aneurysms or tumors in the brain can also cause hydrocephalus.

Prematurely born babies can develop hydrocephalus after they have bleeding into the brain's ventricles (called intraventricular hemorrhage); the blood causes scarring of the chorionic villa and the CSF cannot be properly reabsorbed, so it accumulates in the brain.

Prevalence

Hydrocephalus occurs in about 1 of every 500 children, though the rate is hard to calculate because it occurs as a complication of so many different conditions.

Common Associated Conditions

If diagnosed prenatally on ultrasound, hydrocephalus is typically more severe and associated with other brain abnormalities. Dandy-Walker malformation, an enlargement of the 4 th ventricle with a cyst that extends into the brain's posterior fossa, is a cause of 5-10% of hydrocephalus. Chiari malformation, a complication of myelomeningocele, is a condition where the cerebellum of the brain extends into the spinal canal, blocking CSF flow and causing neurological symptoms; surgery to correct Chiari malformation is necessary to prevent permanent damage.

Babies with hydrocephalus typically have a rapidly increasing head size, with open spaces between the bones of the skull (the cranial sutures and fontanelles) and a prominent forehead. Because of the increased pressure in the brain they will show signs of increasing intracranial pressure: irritability, nausea, vomiting, headache, feeding difficulties, and even spasticity or clonus (tremor of the foot when suddenly flexed). Older children and adults will show serious signs sooner than infants because the bones of the skull are fused and cannot expand as they do in infants. Headache will be a common early sign of increasing intracranial pressure after infancy, as well as vomiting, irritability or personality changes. Other symptoms can occur, depending on the underlying cause of the hydrocephalus. Papilledema (enlarged blood vessel in the retina at the back of the eye), drowsiness, and altered breathing and heart rate are late-appearing signs of increased intracranial pressure. Symptom severity is determined by the rate of CSF absorption and production.

Short-term Treatment and Outcomes

Imaging techniques such as computed tomography (CT) or magnetic resonance imaging (MRI) have made diagnosis of hydrocephalus and its treatment much more precise. Treatment depends on causation but will typically require surgical placement of a shunt system between brain's ventricles and the abdominal cavity to divert the CSF to harmlessly drain there where it is readily absorbed. A shunt is a thin plastic tube that has a valve to regulate the flow as well as a reservoir (bubble-like enlargement of tubing) that can be felt through the skin and used to take samples of the CSF to test for infection, if this is suspected. Shunting is not a cure, and complications of with shunts may occur (infection, malfunction). Infected or malfunctioning shunts need to be quickly replaced.

Long-term Treatment and Outcomes

As child grows, shunts will need to be replaced. The child requires lifetime monitoring by neurosurgeons and neurologists, and regular assessment of neurologic and developmental function. Parents need to be educated about the subtle signs of progressive intracranial pressure and infection.

Common Complications

Seizures are unusual in children with hydrocephalus. However, pressure on the hypothalamus from dilatation of the third ventricle can cause accelerated sexual development as well as fluid and electrolyte imbalances. Other complications due to prolonged increased intracranial pressure include strabismus (crossing or out-turning of the eyes) and optic atrophy (loss of vision). New shunt technology and surgical techniques has reduced infections and complications to less that 5%.

Implications for Children's Development

Developmental effects depend on the underlying cause of the hydrocephalus, the extent and duration of increased intracranial pressure, and number of complications. Children are at risk for cognitive deficits that can affect learning (such as memory and information processing) and typically require rehabilitation therapies and special education. Visual and motor deficits are less common than in the past due to prompt surgery and improved techniques. Children with communicating hydrocephalus are more likely to have normal intelligence than those with non-communicating types.

Clearly, regular assessment and planning of care and educational options will be important to maximize the child's abilities and strengths. Parents, health care providers and teachers must always be aware of the shunt and be alert for subtle signs of infection or increased intracranial pressure. Children whose hydrocephalus results in many surgeries and disabilities will require frequent psychological and social evaluations to be sure that they are coping with their condition and receiving maximum help to live full and independent lives. Parents, school and health professional staff all must work together to be sure that systems and support are in place to allow children with disabilities to be independent, healthy and well-educated. Within the limits of safety they can participate in activities with their non-disabled peers and be responsible for their own health needs. If there are learning problems, educational evaluation with careful consideration of class placement and special services is essential, and it is very important to remember that each child's effects of hydrocephalus are unique, from very mild to complex.

Typically, children's health will stabilize years go by, particularly once they are finished growing and the shunt is well-healed in place. Transition planning to encourage independent decision-making within safe limits must begin in the childhood years, including finding adult health care providers when pediatric services are no longer appropriate.

Information and support for parents is essential to help in learning about hydrocephalus and anticipatory guidance and can be accessed via several online support organizations.