Hydrocephalus occurs when the fluid in the normal spaces in the brain (ventricles) cannot drain.
The fluid may accumulate for many reasons, such as a birth defect, bleeding within the brain, or brain tumors.
Typical symptoms include an abnormally large head and abnormal development.
The diagnosis is based on computed tomography (CT), ultrasonography, or magnetic resonance imaging (MRI).
Surgery is needed to insert a drain (shunt) into the brain or to create an opening that allows fluid to drain.
(See also Overview of Brain and Spinal Cord Birth Defects Overview of Brain and Spinal Cord Birth Defects Birth defects of the brain and spinal cord can occur in early or late fetal development. Typical symptoms include intellectual disability, paralysis, incontinence, or loss of sensation in some... read more .)
The fluid surrounding the brain (cerebrospinal fluid) is produced in spaces within the brain called ventricles. The fluid is constantly being produced and must drain to a different area, where it is absorbed into the blood. When the fluid cannot drain, it accumulates in the ventricles and/or subarachnoid space, causing hydrocephalus (water on the brain). Often, the pressure in the ventricles and within the brain increases, compressing brain tissue.
Many conditions, such as a birth defect, bleeding within the brain Bleeding in and around the brain Birth injury is damage that occurs as a result of physical pressure during the birthing process, usually during transit through the birth canal. Many newborns have minor injuries during birth... read more (often associated with prematurity Preterm (Premature) Newborns A preterm newborn is a baby delivered before 37 weeks of gestation. Depending on when they are born, preterm newborns have underdeveloped organs, which may not be ready to function outside of... read more ), or brain tumors Overview of Brain Tumors in Children Brain tumors (also see brain tumors in adults) are the second most common cancer in children younger than 15 years of age (after leukemia) and the second leading cause of death from cancer.... read more , can block drainage and cause hydrocephalus. Hydrocephalus may also be caused by certain gene defects.
Infants can be born with hydrocephalus or it can occur during or after birth.
Symptoms of Hydrocephalus
An abnormally large head may be a symptom of untreated hydrocephalus. When pressure within the brain is increased, infants are irritable and listless, have a high-pitched cry, and vomit, and they may have seizures. Also, the soft spots between the skull bones (called the fontanelles) may bulge, causing a soft bump on the head. The eyes may not move together, sometimes making the child look cross-eyed (called strabismus Strabismus Strabismus is an intermittent or constant misalignment of an eye so that its line of vision is not pointed at the same object as the other eye. If untreated, strabismus can cause amblyopia ... read more ).
Older children may have a headache, problems with vision, or both.
If hydrocephalus is not treated, infants do not develop normally. Some children with hydrocephalus, especially those who develop hydrocephalus early in the pregnancy, are intellectually disabled Intellectual Disability Intellectual disability is significantly below average intellectual functioning present from birth or early infancy, causing limitations in the ability to conduct normal activities of daily... read more or have learning disabilities Learning Disorders Learning disorders involve an inability to acquire, retain, or broadly use specific skills or information, resulting from deficiencies in attention, memory, or reasoning and affecting academic... read more . Some children have vision loss. Other children develop normal intelligence.
Diagnosis of Hydrocephalus
Before birth, prenatal ultrasonography
After birth, computed tomography, magnetic resonance imaging, or ultrasonography of the head
Before birth, hydrocephalus is often detected when routine prenatal ultrasonography Ultrasonography Prenatal diagnostic testing involves testing the fetus before birth (prenatally) to determine whether the fetus has certain abnormalities, including certain hereditary or spontaneous genetic... read more is done.
After birth, doctors suspect the diagnosis in newborns based on symptoms noted during a routine physical examination. Doctors then do ultrasonography Ultrasonography Ultrasonography uses high-frequency sound (ultrasound) waves to produce images of internal organs and other tissues. A device called a transducer converts electrical current into sound waves... read more of the head to confirm the diagnosis of hydrocephalus.
In older infants and children, doctors do computed tomography Computed Tomography (CT) In computed tomography (CT), which used to be called computed axial tomography (CAT), an x-ray source and x-ray detector rotate around a person. In modern scanners, the x-ray detector usually... read more (CT), magnetic resonance imaging Magnetic Resonance Imaging (MRI) In magnetic resonance imaging (MRI), a strong magnetic field and very high frequency radio waves are used to produce highly detailed images. MRI does not use x-rays and is usually very safe... read more (MRI), or ultrasonography of the head to confirm the diagnosis.
Once the diagnosis has been made, all children undergo CT or ultrasonography to monitor the hydrocephalus and determine whether it is worsening.
Treatment of Hydrocephalus
Sometimes spinal taps
Usually a permanent alternate drainage path (a shunt or opening in the ventricles)
The goal of treatment is
To keep pressure within the brain normal
Treatment of hydrocephalus depends on what is causing the disorder, how severe it is, and whether it is worsening.
If needed, pressure within the brain can often be temporarily reduced by removing spinal fluid with repeated spinal taps Spinal Tap Diagnostic procedures may be needed to confirm a diagnosis suggested by the medical history and neurologic examination. Electroencephalography (EEG) is a simple, painless procedure in which... read more (lumbar punctures) until a shunt is placed.
If hydrocephalus is worsening, doctors place a ventricular shunt. The shunt is a plastic tube that creates a permanent alternate drainage path for cerebrospinal fluid. Draining the cerebrospinal fluid decreases the pressure and volume of the fluid inside the brain. Doctors place the shunt in the ventricles in the brain and run it under the skin from the head to another site, usually the abdomen (called a ventriculoperitoneal shunt, or VP 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 because of the risk of bleeding and injury.
In some children, doctors do a ventriculostomy. In this procedure, doctors create an opening between a ventricle and the subarachnoid space in the brain to treat the hydrocephalus. This opening allows excess fluid to drain and be absorbed as usual.
After placing a shunt, doctors measure head circumference Head Circumference Physical growth refers to an increase in body size (length or height and weight) and in the size of organs. From birth to about age 1 or 2 years, children grow rapidly. After this rapid infant... read more and determine how the child is developing. Imaging tests (such as computed tomography or magnetic resonance imaging) are done periodically.
Complications of shunts
Shunts can become infected. Children who develop an infection are given antibiotics. Typically the shunt is then removed and replaced.
Shunts can break or become blocked and stop functioning correctly. To determine how a shunt is functioning, doctors take x-rays of the shunt and do imaging tests of the brain. A shunt that is not working correctly is typically removed and replaced.