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Hydrocephalus

Hydrocephalus

Definition

The word hydrocephalus derives from the Greek words hydro, meaning water, and cephalus, meaning head. Hydrocephalus is the result of the excessive accumulation of fluid in the brain. Traditionally, hydrocephalus has been described as a disease characterized by increased intracranial pressure (ICP), increased cerebrospinal fluid (CSF) volume, and dilatation of the CSF spaces known as cerebral ventricles.

Description

Hydrocephalus is the result of an imbalance between the formation and drainage of cerebrospinal fluid. This imbalance appears when an injury or illness alters the circulation of CSF; one or more of the ventricles of the brain become enlarged as CSF accumulates. However, hydrocephalus is not a single disease entity, as a wide number of underlying diseases are responsible for causing retention of CSF, resulting in ventricular dilatation and increased intracranial pressure (ICP). In infants and children, for example, hydrocephalus usually results from a birth defect, viral infection, head injury, hemorrhage, meningitis, or tumor.

In adults, the causes of hydrocephalus include brain damage due to stroke or injury, Alzheimer's disease, or obstruction of the ventricles. Often, the cause is unknown. Conditions responsible for hydrocephalus in a fetus include infantile congenital (present at birth) hydrocephalus, hydrocephalus associated with encephalocele or myelomeningocele, posthemorrhagic hydrocephalus in newborns, and postmeningitic hydrocephalus. Conditions responsible for hydrocephalus in adults include hydrocephalus following subarachnoid hemorrhage, idiopathic adult hydrocephalus, and posttraumatic hydrocephalus. Tumors can also result in hydrocephalus in both children and adults. Based on the different kind of CSF circulation in the brain, hydrocephalus can be divided into two types: communicating and non-communicating. In communicating hydrocephalus, the CSF circulation pathways are competent from the ventricles inside of the brain to the fluid spaces just below the third ventricle. Non-communicating (obstructive) hydrocephalus refers to hydrocephalus that

develops from a blockage of the normal circulation of CSF within the brain. In most cases, it refers to a blockage between the third and fourth ventricles.

Demographics

Overall incidence of infantile hydrocephalus is approximately one to two per 1,000 live births. The overall prevalence of hydrocephalus in the United States is about 0.5%. When cases of spina bifida are included, congenital hydrocephalus occurs in two to five births per 1,000 births. The incidence of acquired hydrocephalus in adults is not known because it occurs as a result of injury, illness, or environmental factors. Normal pressure hydrocephalus was found to be significantly more prevalent in males, and can occur in adults of any age group. The age distribution in children and teenagers is disputed.

Causes and symptoms

Approximately 16 oz (500 ml) of CSF are formed within the brain each day, by cells located on the wall of the four ventricles in the brain. Once formed, CSF circulates among all the ventricles before it is absorbed. The normal adult volume of circulating CSF is about 2 oz (150 ml). The CSF turnover rate is more than three times per day. Because production is independent of absorption, reduced absorption causes CSF to accumulate within the ventricles.

Hydrocephalus can be subdivided into three forms, involving the following:

  • Disorders of cerebrospinal fluid circulation. Tumors, hemorrhages, congenital malformations, and infections can cause such obstructions in the circulation of cerebrospinal fluid.
  • Disorders of cerebrospinal fluid absorption, resulting from diseases such as the superior vena cava syndrome and sinus thrombosis.
  • Disorders of cerebrospinal fluid production: This is the less common form of hydrocephalus resulting from tumors that secrete cerebrospinal fluid in excess of its absorption.

Congenital hydrocephalus is thought to be caused by a complex interaction of genetic and environmental factors. The origin of hydrocephalus in congenital cases is unknown. Very few cases (less than 2%) are inherited (X-linked hydrocephalus). The most common causes of hydrocephalus in acquired cases are tumor obstruction, trauma, intracranial hemorrhage, and infection.

The two most common adult forms of hydrocephalus are hydrocephalus ex-vacuo and normal pressure hydrocephalus. Hydrocephalus ex-vacuo occurs when a stroke or injury damages the brain, yielding a brain substance. Although there is more CSF than usual, the CSF pressure may or may not be elevated. Normal pressure hydrocephalus is an abnormal increase of CSF in the brain's ventricles due to the gradual blockage of the CSF-draining pathways. This may result from a subarachnoid hemorrhage, head trauma, infection, tumor, or complications of surgery. The ventricles enlarge to handle the increased volume of the CSF, and the compression of the brain from within by the fluid-filled ventricles destroys or damages brain tissue. Fluctuation of CSF pressure from high to normal to low can also be present.

For congenital-onset hydrocephalus, early symptoms include enlargement of the head (increased head circumference), bulging fontanelles (soft spots) with or without enlargement of the head size, separation of sutures (the flexible and fibrous joints between the skull bones of an infant), and vomiting. Symptoms of continued hydrocephalus include irritability and muscle spasticity . Late symptoms of congenital-onset hydrocephalus seen in children up to five years of age include decreased mental function, delayed development, slow or restricted movement, difficulty feeding, lethargy, and delayed growth.

In children, symptoms depend on the amount of damage caused by ICP. Symptoms may be similar to many of those in infants or may include headache , vomiting, vision changes such as crossed eyes, uncontrolled eye movements, loss of coordination, poor gait (walking pattern), mental confusion, or psychosis. For adult-onset hydrocephalus, headaches and nausea are the most common symptoms. Other signs of the condition include difficulty focusing the eyes, unsteady gait, weakness of the legs, sudden falls, and a distinctive inability to walk forward. As hydrocephalus progresses, decreased mental activity appears, including lethargy, apathy, impaired memory, and speech problems. Urinary and bowel incontinence can also occur. During the final stage, dementia involving loss of movement, sensory functions, and cognitive abilities may result.

Diagnosis

Ultrasound can be used to diagnose prenatal hydrocephalus. Although fetal hydrocephalus may be an isolated finding, it is more frequently found along with other cerebral anomalies, including neural tube defects. Diagnosis after birth may be suggested by symptoms; however, imaging studies of the brain are the mainstay of diagnosis. Computed tomography (CT ) and magnetic resonance imaging (MRI) reveal enlarged ventricles and may indicate a specific cause of hydrocephalus, such as a tumor or hemorrhage. The presence of papilledema (elevation or swelling of the optic disc) also indicates that hydrocephalus that is well developed. In rare cases, long-standing hydrocephalus causes blindness.

Small abnormalities that may not be seen with CT scanning, such as cysts and abscesses, are often seen with MRI . These studies can also help the neurosurgeon differentiate between communicating and non-communicating hydrocephalus. In cases of suspected normal pressure hydrocephalus, a lumbar puncture (spinal tap) may help determine CSF pressure. Also, a cisternagram can be useful to evaluate the dynamics of CSF flow in the brain and spinal chord. Cisternography can reveal CSF concentration, obstruction, leakage, and pressure. Also, certain biochemical markers in the blood have been described in the disease. They include increased neurofilament light protein (NFL) and tau protein, both markers of neuronal degeneration; increased myeline basic protein (a marker of demyelination; and albumin); and a marker of the blood-brain barrier function.

Treatment team

Treatment of hydrocephalus for children or adults will likely involve a neurologist , neurosurgeon, obstetrician, pediatrician, and specialty nurses and physical therapists.

Treatment

Medical treatment is first aimed at reducing intracranial pressure, while the need for a more permanent solution is determined. Reduction of fluid intake and administration of drugs such as mannitol, glycerol, urea (drugs with an osmotic effect), or furosemide (a diuretic) are able to reduce ICP and CSF production.

External drainage of the CSF is useful for urgent reduction of intracranial pressure, as well as of ventricular or subarachnoid hemorrhage. Complications include overdrainage, blocked tube, or bacterial contamination. The placement of a permanent ventricular shunt (internal shunting) is a common procedure. Around 33,000 shunts are placed in the United States each year; almost half of them to replace previous shunt devices. CSF from the ventricles in the brain is usually shunted to the peritoneum, pleura, ureter, bladder, or vascular spaces such as the jugular or subclavian veins. Most shunts are connected to the peritoneum. Some shunts operate according to intracranial pressure by using a valve system able to regulate the flow at a pressure close to the normal values of ICP. Others are programmable and can be adjusted to open at a given ICP. Complications include overdrainage that may cause intracranial hypotension, subdural hematoma , shunt occlusion, and infection. The risk of shunt failure is greater within the first year (between 2540% of shunts must be replaced). The subsequent failure rate is around 5% for each year.

Other surgical procedures include, in some cases, choroid plexectomy, third ventriculostomy, and ventricular reservoir. Ventricular reservoir is basically a catheter inserted into a ventricle of the brain to draw CSF. This procedure is much simpler than placing a full shunt system and is used to provide temporary control of ICP until a full shunt can be placed.

Recovery and rehabilitation

Hydrocephalus is a chronic condition, and clinical symptoms are based on the time of insurgence of the disease. With appropriate, early treatment, a normal lifespan with few limitations can be reached. After surgery, specially trained medical professionals carefully monitor the patient. Some symptoms such as headaches may disappear immediately due to the release of excess pressure. The symptoms associated with normal pressure hydrocephalus (walking difficulties, mild dementia, poor bladder control) may improve quickly, or may take weeks to months to improve. In some patients, little or no improvement is also possible.

The length of the patient's hospital stay will be determined by the rate of recovery. If neurological problems persist, rehabilitation may be required to further the patient's improvement. However, recovery may be limited by the extent of the damage already caused by the hydrocephalus. Because hydrocephalus is an ongoing condition, patients do require long-term follow up. Follow-up diagnostic tests, including CT scans, MRI, and x rays, may be performed to determine if the shunt is working correctly.

Clinical trials

Ventricular shunts are the most common surgical treatment for hydrocephalus and appear to be the safest. It is possible that choroid plexectomy and third ventriculostomy may become more feasible in the future if better procedures and equipment are developed.

As of mid-2004, several clinical trials to study hydrocephalus were underway, including a trial to evaluate the efficacy and safety of endoscopic choroid plexus coagulation with third ventriculostomy in the treatment of idiopathic normal pressure hydrocephalus, sponsored by the Frenchay Hydrocephalus Research Fund. The National Institute of Neurological Disorders and Stroke is sponsoring a study to establish the physiology of syringomyelia . Updated information on these and other ongoing clinical trials may be found at the National Institutes of Health website for clinical trials at <http://www.clinicaltrials.gov>.

Prognosis

Untreated hydrocephalus has a survival rate of 4050%, with the survivors having varying degrees of intellectual, physical, and neurological disabilities. Prognosis for treated hydrocephalus varies, depending on the cause. If the child survives for one year, more than 80% will have a fairly normal lifespan. Approximately one-third will have normal intellectual function, but neurological difficulties may persist. Hydrocephalus not associated with infection has the best prognosis, and hydrocephalus caused by tumors has a very poor prognosis. About 50% of all children who receive appropriate treatment and follow up will develop IQs in the near-normal or normal range.

Resources

BOOKS

Matsumoto, Satoshi. Hydrocephalus: Pathogenesis and Treatment. New York: Springer-Verlag, 1991.

The Official Parent's Sourcebook on Hydrocephalus: A Revised and Updated Directory for the Internet Age. San Diego: Icon Group International, 2002.

Toporek, Chuck, and Kellie Robinson. Hydrocephalus: A Guide for Patients, Families and Friends. Sebastopol, CA: Patient-Centered Guides, 1999.

PERIODICALS

Arriada, N., and J. Sotelo. "Review: Treatment of Hydrocephalus in Adults." Surg Neurol. (2002) Dec 58 (6): 37784.

Davis, G. H. "Fetal Hydrocephalus." Clin Perinatol. (2003) Sep 30 (3): 5319.

Meier, U., and C. Miethke. "Predictors of Outcome in Patients with Normal-Pressure Hydrocephalus." J Clin Neurosci. (2003) Jul 10 (4): 4539.

OTHER

"NINDS Hydrocephalus Information Page." National Institute of Neurological Disorders and Stroke. May 15, 2004 (May 22, 2004). <http://www.ninds.nih.gov/health_and_medical/disorders/hydrocephalus.htm>.

"What is Hydrocephalus?" Hydrocephalus Foundation, Inc. May 15, 2004 (May 22, 2004). <http://www.hydrocephalus.org/>.

ORGANIZATIONS

Hydrocephalus Association. 870 Market Street, Suite 705, San Francisco, CA 94102. (415) 732-7040 or (888) 598-3789; Fax: (415) 732-7044. info@hydroassoc.org. <http://www.hydroassoc.org>.

National Hydrocephalus Foundation. 12413 Centralia Road, Lakewood, CA 90715-1623. (562) 402-3523 or (888) 857-3434; Fax: (562) 924-6666. hydrobrat@earthlink.net. <http://nhfonline.org>.

Antonio Farina, MD, PhD

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Hydrocephalus

Hydrocephalus

Definition

Hydrocephalus is an abnormal expansion of cavities (ventricles) within the brain that is caused by the accumulation of cerebrospinal fluid. Hydrocephalus comes from two Greek words: hydros means water and cephalus means head.

There are two main varieties of hydrocephalus: congenital and acquired. An obstruction of the cerebral aqueduct (aqueductal stenosis) is the most frequent cause of congenital hydrocephalus. Acquired hydrocephalus may result from spina bifida, intraventricular hemorrhage, meningitis, head trauma, tumors, and cysts.

Description

Hydrocephalus is the result of an imbalance between the formation and drainage of cerebrospinal fluid (CSF). Approximately 500 milliliters (about a pint) of CSF is formed within the brain each day, by epidermal cells in structures collectively called the choroid plexus. These cells line chambers called ventricles that are located within the brain. There are four ventricles in a human brain. Once formed, CSF usually circulates among all the ventricles before it is absorbed and returned to the circulatory system. The normal adult volume of circulating CSF is 150 ml. The CSF turn-over rate is more than three times per day. Because production is independent of absorption, reduced absorption causes CSF to accumulate within the ventricles.

There are three different types of hydrocephalus. In the most common variety, reduced absorption occurs when one or more passages connecting the ventricles become blocked. This prevents the movement of CSF to its drainage sites in the subarachnoid space just inside the skull. This type of hydrocephalus is called "noncommunicating." In a second type, a reduction in the absorption rate is caused by damage to the absorptive tissue. This variety is called "communicating hydrocephalus."

Both of these types lead to an elevation of the CSF pressure within the brain. This increased pressure pushes aside the soft tissues of the brain. This squeezes and distorts them. This process also results in damage to these tissues. In infants whose skull bones have not yet fused, the intracranial pressure is partly relieved by expansion of the skull, so that symptoms may not be as dramatic. Both types of elevated-pressure hydrocephalus may occur from infancy to adulthood.

A third type of hydrocephalus, called "normal pressure hydrocephalus," is marked by ventricle enlargement without an apparent increase in CSF pressure. This type affects mainly the elderly.

Hydrocephalus has a variety of causes including:

  • congenital brain defects
  • hemorrhage, either into the ventricles or the subarachnoid space
  • infection of the central nervous system (syphilis, herpes, meningitis, encephalitis, or mumps)
  • tumor

Hydrocephalus is believed to occur in approximately one to two of every 1,000 live births. The incidence of adult onset hydrocephalus is not known. There is no known way to prevent hydrocephalus.

Causes and symptoms

Hydrocephalus that is congenital (present at birth) is thought to be caused by a complex interaction of genetic and environmental factors. Aqueductal stenosis, an obstruction of the cerebral aqueduct, is the most frequent cause of congenital hydrocephalus. As of 2001, the genetic factors are not well understood. According to the British Association for Spina Bifida and Hydrocephalus, in very rare circumstances, hydrocephalus is due to hereditary factors, which might affect future generations.

Signs and symptoms of elevated-pressure hydrocephalus include:

  • headache
  • nausea and vomiting, especially in the morning
  • lethargy
  • disturbances in walking (gait)
  • double vision
  • subtle difficulties in learning and memory
  • delay in children achieving developmental milestones

Irritability is the most common sign of hydrocephalus in infants. If this is not treated, it may lead to lethargy. Bulging of the fontanelles, or the soft spots between the skull bones, may also be an early sign. When hydrocephalus occurs in infants, fusion of the skull bones is prevented. This leads to abnormal expansion of the skull.

Symptoms of normal pressure hydrocephalus include dementia, gait abnormalities, and incontinence (involuntary urination or bowel movements).

Diagnosis

Imaging studiesx ray, computed tomography scan (CT scan), ultrasound, and especially magnetic resonance imaging (MRI)are used to assess the presence and location of obstructions, as well as changes in brain tissue that have occurred as a result of the hydrocephalus. Lumbar puncture (spinal tap) may be performed to aid in determining the cause when infection is suspected.

Treatment

The primary method of treatment for both elevated and normal pressure hydrocephalus is surgical installation of a shunt. A shunt is a tube connecting the ventricles of the brain to an alternative drainage site, usually the abdominal cavity. A shunt contains a one-way valve to prevent reverse flow of fluid. In some cases of non-communicating hydrocephalus, a direct connection can be made between one of the ventricles and the subarachnoid space, allowing drainage without a shunt.

Installation of a shunt requires lifelong monitoring by the recipient or family members for signs of recurring hydrocephalus due to obstruction or failure of the shunt. Other than monitoring, no other management activity is usually required.

Some drugs may postpone the need for surgery by inhibiting the production of CSF. These include acetazolamide and furosemide. Other drugs that are used to delay surgery include glycerol, digoxin, and isosorbide.

Some cases of elevated pressure hydrocephalus may be avoided by preventing or treating the infectious diseases which precede them. Prenatal diagnosis of congenital brain malformation is often possible, offering the option of family planning.

Prognosis

The prognosis for elevated-pressure hydrocephalus depends on a wide variety of factors, including the cause, age of onset, and the timing of surgery. Studies indicate that about half of all children who receive appropriate treatment and follow-up will develop IQs greater than 85. Those with hydrocephalus at birth do better than those with later onset due to meningitis. For individuals with normal pressure hydrocephalus, approximately half will benefit by the installation of a shunt.

Resources

BOOKS

Toporek, Chuck, and Kellie Robinson. Hydrocephalus: A Guide for Patients, Families & Friends. Cambridge, Mass.: O'Reilly & Associates, 1999.

PERIODICALS

"Hydrocephalus." Review of Optometry 137, no. 8 (August 15, 2000): 56A.

ORGANIZATIONS

Association for Spina Bifida and Hydrocephalus. 42 Park Rd., Peterborough, PE1 2UQ. UK 0173 355 5988. Fax: 017 3355 5985. postmaster@asbah.org. http://www.asbah.demon.co.uk.

Hydrocephalus Foundation, Inc., (HyFI). 910 Rear Broadway, Saugus, MA 01906. (781) 942-1161. HyFI1@netscape.net. http://www.hydrocephalus.org.

OTHER

"Hydrocephalus." American Association of Neurological Surgeons/Congress of Neurological Surgeons. http://www.neurosurgery.org/pubpages/patres/hydrobroch.html.

"Hydrocephalus." Institute for Neurology and Neurosurgery. Beth Israel Medical Center, New York, NY. http://nyneurosurgery.org/child/hydrocephalus/hydrocephalus.htm.

"Hydrocephalus." National Library of Medicine. MEDLINEplus. http://www.nlm.nih.gov/medlineplus/hydrocephalus.html.

KEY TERMS

Cerebral ventricles Spaces in the brain that are located between portions of the brain and filled with cerebrospinal fluid.

Cerebrospinal fluid Fluid that circulates throughout the cerebral ventricles and around the spinal cord within the spinal canal.

Choroid plexus Specialized cells located in the ventricles of the brain that produce cerebrospinal fluid.

Fontanelle One of several "soft spots" on the skull where the developing bones of the skull have yet to fuse.

Shunt A small tube placed in a ventricle of the brain to direct cerebrospinal fluid away from the blockage into another part of the body.

Stenosis The constricting or narrowing of an opening or passageway.

Subarachnoid space The space between two membranes surrounding the brain, the arachnoid and pia mater.

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Hydrocephalus

Hydrocephalus

Definition

Hydrocephalus is an abnormal expansion of cavities, called ventricles, within the brain, which is caused by an abnormally large accumulation of cerebrospinal fluid (CSF ).

Description

Hydrocephalus is the result of an imbalance between the formation and drainage of CSF. There are four ventricles in the human brain. CSF is formed by structures within these ventricles. Once formed, CSF circulates among all the ventricles before it is absorbed and returned to the circulatory system. When the ventricles are obstructed, the CSF cannot circulate and be absorbed. An elevated level of CSF in the brain leads to pressure within the ventricles. This pressure pushes against the soft tissues of the brain, resulting in damage to these tissues.

There are three different types of hydrocephalus: communicating hydrocephalus, noncommunicating hydrocephalus, and normal pressure hydrocephalus. Communicating hydrocephalus is the most common type and exists when one or more passages connecting the ventricles become blocked. This blockage prevents the movement of CSF to its drainage sites in the subarachnoid space just inside the skull. In noncommunicating hydrocephalus, the tissue within the brain responsible for absorption of CSF is damaged. Normal pressure hydrocephalus is marked by ventricle enlargement without an apparent increase in CSF pressure. This type affects mainly the elderly and will not be discussed in this entry.

Hydrocephalus may be either congenital (present at birth) or acquired. An obstruction within the brain is the most frequent cause of congenital hydrocephalus. Acquired hydrocephalus may result from other birth defects such as spina bifida , conditions related to prematurity such as intraventricular hemorrhage (bleeding within the brain), infections such as meningitis , or other causes such as head trauma, tumors, and cysts.

Demographics

Hydrocephalus is believed to occur in approximately one to two of every 1,000 live births. It is not more prevalent in males or females, nor in any individual racial group.

Causes and symptoms

Hydrocephalus has a variety of causes including the following:

  • congenital brain defects
  • hemorrhage, either into the ventricles or the subarachnoid space
  • infection of the central nervous system (syphilis, herpes, meningitis, encephalitis , or mumps)
  • tumor

Signs and symptoms of elevated-pressure hydrocephalus include the following:

  • headache
  • nausea and vomiting , especially in the morning
  • lethargy
  • disturbances in walking (gait)
  • double vision
  • subtle difficulties in learning and memory
  • delay in achieving childhood developmental milestones

Irritability is the most common sign of hydrocephalus in infants. If this is not treated, it may lead to lethargy. Bulging of the fontanelles, or the soft spots between the skull bones, may also be an early sign. When hydrocephalus occurs in infants, fusion of the skull bones is prevented, which leads to abnormal expansion of the skull.

Diagnosis

Imaging studies such as x ray, computed tomography scan (CT scan), ultrasound, and especially magnetic resonance imaging (MRI) are used to assess the presence and location of obstructions, as well as changes in brain tissue that have occurred as a result of the hydrocephalus. Lumbar puncture (spinal tap) may be performed to aid in determining the cause when infection is suspected.

Treatment

The primary method of treatment for hydrocephalus is surgical installation of a shunt. A shunt is a tube connecting the ventricles of the brain to an alternative drainage site, usually the abdominal cavity. A shunt contains a one-way valve to prevent reverse flow of fluid. In some cases of non-communicating hydrocephalus, a direct connection can be made between one of the ventricles and the subarachnoid space, allowing drainage without a shunt.

Installation of a shunt requires lifelong monitoring by the recipient or family members for signs of recurring hydrocephalus due to obstruction or failure of the shunt. Other than monitoring, no other management activity is usually required.

Some drugs may postpone the need for surgery by inhibiting the production of CSF. These include acetazolamide and furosemide. Other drugs that are used to delay surgery are glycerol, digoxin, and isosorbide.

Prognosis

The prognosis for elevated-pressure hydrocephalus depends on a wide variety of factors, including the cause, age of onset, and the timing of surgery. Studies indicate that about half of all children who receive appropriate treatment and follow-up will develop IQs greater than 85. Those with hydrocephalus at birth do better than those with later onset due to meningitis. For individuals with normal pressure hydrocephalus, approximately half will benefit by the installation of a shunt.

Prevention

There is no known prevention of congenital hydrocephalus. Some cases of elevated pressure hydrocephalus may be avoided by preventing or treating the infectious diseases that precede them. Prenatal diagnosis of congenital brain malformation is often possible, offering the option of family planning.

Parental concerns

Parents may be concerned about the intellectual development of a child with hydrocephalus. While nearly 50 percent of all children with hydrocephalus have average intelligence , many do not. Early intervention programs are important to the development of children with special needs and are available in most communities. In addition to developmental issues, many children with hydrocephalus require medical care. It is important for parents to prepare children for medical treatment and surgery. A healthcare team including a pediatrician, surgeon, and social worker is a valuable asset for parents and most children's hospitals can assist parents in finding the support and resources they need.

When to call the doctor

The most common treatment for hydrocephalus is the surgical installation of a shunt. If a child with a shunt has any of the following symptoms, parents should contact the child's doctor because the shunt may not be functioning properly. According to the Spina Bifida Association of America, nearly 40 percent of shunts malfunction and may need to be replaced within one year, 60 percent will require revision within five years, and 80 to 90 percent within ten years.

For this reason, parents need to be aware of the symptoms of shunt malfunction and contact their physician if they notice any of the following symptoms:

  • headaches
  • nausea
  • vomiting
  • seizures
  • change in intellect or personality
  • swallowing problems
  • impaired muscle function, balance, or coordination

KEY TERMS

Cerebrospinal fluid The clear, normally colorless fluid that fills the brain cavities (ventricles), the subarachnoid space around the brain, and the spinal cord and acts as a shock absorber.

Choroid plexus Specialized cells located in the ventricles of the brain that produce cerebrospinal fluid.

Fontanelle One of several "soft spots" on the skull where the developing bones of the skull have yet to fuse.

Shunt A passageway (or an artificially created passageway) that diverts blood flow from one main route to another. Also refers to a small tube placed in a ventricle of the brain to direct cerebrospinal fluid away from a blockage into another part of the body.

Ventricles Four cavities within the brain that produce and maintain the cerebrospinal fluid that cushions and protects the brain and spinal cord.

Resources

BOOKS

Cinalli, G., et al. Hydrocephalus. New York: Springer, 2004.

PERIODICALS

"Hydrocephalus." Review of Optometry 137, no. 8 (August 15, 2000): 56A.

ORGANIZATIONS

Hydrocephalus Foundation Inc. (HyFI). 910 Rear Broadway, Saugus, MA 01906. Web site: <www.hydrocephalus>.

WEB SITES

"Hydrocephalus." American Association of Neurological Surgeons/Congress of Neurological Surgeons. Available online at <www.neurosurgery.org/pubpages/patres/hydrobroch.html> (accessed October 22, 2004).

"Hydrocephalus." Hyman-Newman Institute of Neurology and Neurosurgery. Available online at <http://nyneurosurgery.org> (accessed October 22, 2004).

L. Fleming Fallon, MD, PhD, DrPH Deborah L. Nurmi, MS

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"Hydrocephalus." Gale Encyclopedia of Children's Health: Infancy through Adolescence. . Encyclopedia.com. 11 Dec. 2017 <http://www.encyclopedia.com>.

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"Hydrocephalus." Gale Encyclopedia of Children's Health: Infancy through Adolescence. . Retrieved December 11, 2017 from Encyclopedia.com: http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/hydrocephalus-1

hydrocephalus

hydrocephalus Derived from the Greek for ‘water’ and ‘head’, hydrocephalus was recognized by Greek and Roman philosophers, including Hippocrates and Galen. Arabic medical scholars, like Albucasis, preserved and built upon the knowledge of the ancients, combining it with Arabic surgical expertise. One of the earliest illustrations of the condition, and a method of treating it, which involved opening the head and evacuating fluid, appeared in the fifteenth-century surgical manuscript by Sharaf ad Din. Nearly 200 years later, the Italian surgeon Marco Aurelio Severino depicted and described a case of infantile hydrocephalus in De Recondita Abscessuum Natura Libri VII (Seven Books on the Obscure Nature of Abscesses).

Hydrocephalus is sometimes called ‘water on the brain’, but the excess of fluid is in fact ‘in’ rather than ‘on’. There is normally cerebrospinal fluid filling the cerebral ventricles — the cavities deep inside the brain — and hydrocephalus describes an increase in its volume, and therefore of the size of the ventricles. Cerebrospinal fluid (CSF) is continually produced by transfer of a watery solution from the blood into the ventricles, flowing slowly through these cavities, and into the subarachnoid space, to bathe the outside of the brain and spinal cord; thence it is continually reabsorbed into the bloodstream. Hydrocephalus occurs if the rate of absorption does not keep pace with production.

Most often the problem is a mechanical obstruction. This may occur before birth, due to a malformation in the brain, resulting in an enlarged head which can pose problems during delivery. In other cases, although caused by a congenital defect — often associated with spina bifida — hydrocephalus may develop only later during infancy. Up to the age of two, when the bones of the skull begin to fuse, hydrocephalus results in overall enlargement in the size of the baby's head.

Later in life, at any age, a tumour may block a narrow part of the ventricular system, so that the system above this block expands; or there can be blockage in the surface spaces due to adhesions following meningitis or haemorrhage.

Obstructive forms of hydrocephalus occurring after fusion of the skull bones result in increasing intracranial pressure, with headache, vomiting, and danger to sight, with eventual death if unrelieved. The block can be located by imaging techniques (CT scan or MRI), which clearly show the shape and size of the ventricles. If it is not possible to remove the obstruction, the block may be bypassed by inserting a tube, with a one-way valve, leading from the ventricles either to the venous side of the heart or into the peritoneal cavity.

Hydrocephalus may result also from wasting away of the brain substance due to progressive disease such as Alzheimer's, or to sudden and massive insults such as those which lead to the vegetative state. There is no rise in pressure because the excess of ‘water’ simply takes up the space in and around the wasted brain.

Karol K. Weaver, and Bryan Jennett

Bibliography

Lyons, A. E. (1995). Hydrocephalus first illustrated. Neurosurgery, 37, 511–3.
Montagnani, C. A. (1986). Pediatric surgery in Islamic medicine from the Middle Ages to the Renaissance. Progress in Pediatric Surgery, 20, 39–51.

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hydrocephalus

hydrocephalus (hī´drəsĕf´ələs), also known as water on the brain, developmental (congenital) or acquired condition in which there is an abnormal accumulation of body fluids within the skull. The congenital form may be associated with other abnormalities. The acquired form may follow meningitis or another cerebral inflammation or tumor. The accumulation of fluid causes compression of the brain and enlargement of the skull, sometimes with separation of bone structures. Paralysis and death may result or, at the least, mental retardation. Many forms of therapy, including surgery, have been attempted, but usually without much success in extreme cases.

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"hydrocephalus." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. 11 Dec. 2017 <http://www.encyclopedia.com>.

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Hydrocephalus

Hydrocephalus

Why Is the Babys Head So Big?

What Is Hydrocephalus?

What Causes Hydrocephalus?

How Is Hydrocephalus Treated?

Resources

Hydrocephalus (hy-dro-SEF-a-lus) is a condition that occurs when there is too much fluid inside the skull. The excess fluid inside the skull often creates pressure on the brain and may result in mental and physical handicaps.

KEYWORDS

for searching the Internet and other reference sources

Cerebrospinal fluid

Neurology

Ventricular system

Why Is the Babys Head So Big?

When Liz saw her baby brother in the hospital nursery, she was upset by his appearance. His head seemed huge. The doctor explained that John had hydrocephalus, or too much fluid within his skull. Because he was a newborn, the bones in his head had not yet grown together, allowing his head to expand with the pressure caused by the extra fluid. The doctor warned Lizs family that Johns brain might have been squeezed and damaged by the excess fluid, but that it was too soon to tell for sure.

What Is Hydrocephalus?

Hydrocephalus refers to fluid buildup in and around the brain. The term comes from two Greek words: hydro meaning water, and cephalie meaning brain. Hydrocephalus often is called water on the brain, but the brain and spinal cord are actually bathed in cerebrospinal fluid (CSF). CSF is a mixture of water, protein, sugar, and minerals that is made by the tissues lining the inside of the brain to cushion and protect it.

The brain contains four cavities, or spaces, called ventricles (VENtri-kuls). CSF normally flows through the ventricles, through tiny openings at the base of the brain, over the brains surface, and around the spinal cord. Normally, the pressure exerted on the brain by CSF is kept fairly constant because excess CSF is reabsorbed into the bloodstream.

People develop hydrocephalus when the flow of CSF is blocked (obstructive hydrocephalus) or when it cannot be reabsorbed (communicating hydrocephalus). In both cases, CSF accumulates and the extra pressure squeezes the brain and disrupts blood flow to the brain. Without the oxygen and sugar that blood carries, the brain cannot function properly. Over time, blood vessels and nerve cells are damaged, resulting in problems with learning, thinking, and moving. The severity of hydrocephalus varies from person to person.

What Causes Hydrocephalus?

The cause of hydrocephalus often is unknown, but in many cases a cause can be found. Congenital hydrocephalus means that a person is born with the condition, and it affects about 1 in 1,000 babies. It may occur because the brain did not develop properly or because the fetus developed a viral or protozoan infection, such as rubella (German measles), herpes, cytomegalovirus, or toxoplasmosis. Spina bifida is a congenital disorder in which there is an opening in the spinal cord and spinal column, and at least 80 percent of babies with spina bifida also develop some degree of hydrocephalus.

In infants, children, and adults, brain tumors can cause hydrocephalus by blocking the flow of CSF. Hydrocephalus also can be caused by meningitis, an infection of the linings of the brain and spinal cord, and by bleeding in the brain because of a stroke* or a head injury. Infants born very prematurely frequently experience bleeding in the ventricles of the brain, which often leads to hydrocephalus. Hydrocephalus is less common in adults.

* stroke
may occur when a blood vessel bringing oxygen and nutrients to the brain bursts or becomes clogged by a blood clot or other particle. As a result, nerve cells in the affected area and the specific body parts they control do not properly function.

How Is Hydrocephalus Treated?

Babies suspected of having hydrocephalus are watched closely. Johns head kept getting bigger and ultimately his doctor used a CT scan* and an MRI* to examine his brain.

* CT scans
or CAT scans are the short names for computerized axial tomography, which uses computers and x-rays to view cross sections inside the body.
* MRI
means magnetic resonance imaging, which uses magnets to view inside the body.

Some forms of hydrocephalus require no treatment, but most, like Johns, require surgery. The surgeon placed a device called a shunt in Johns brain to drain the excess CSF. Shunts are thin flexible tubes that are placed through the skull and drain some of the excess CSF into the bloodstream or the abdomen to be reabsorbed by the body. This procedure relieves pressure on the brain, but it does not cure the brain damage that has occurred already.

Most babies born with hydrocephalus live if they receive treatment, but 60 percent of those babies have mental and physical handicaps. Lizs baby brother John was lucky. He was among the 40 percent of children born with hydrocephalus whose mental and physical abilities are unaffected.

See also

Brain Tumor

German Measles (Rubella)

Meningitis

Spina Bifida

Stroke

Toxoplasmosis

Resources

Book

Toporek, Chuck, and Kellie Robinson. Hydrocephalus: A Guide for Parents, Families, and Friends. OReilly and Associates, 1999.

Organizations

The U.S. National Institute of Neurological Disorders and Stroke posts a fact sheet about childhood hydrocephalus at its website. http://www.ninds.nih.gov/patients/Disorder/hydrochd/HYDROCHD. HTM

Hydrocephalus Association, 870 Market Street, Suite 955, San Francisco, CA 94102. Telephone 415-732-7040 http://neurosurgery.mgh.harvard.edu/ha/default.html

Association for Spina Bifida and Hydrocephalus, 42 Park Road, Peterborough, PE1 2UQ, England. Telephone 01733-555988 http://www.asbah.demon.co.uk

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hydrocephalus

hydrocephalus (hy-droh-sef-ă-lŭs) n. an abnormal increase in the amount of cerebrospinal fluid within the ventricles of the brain. In childhood, before the sutures of the skull have fused, hydrocephalus makes the head enlarge. In adults, hydrocephalus raises the intracranial pressure, with consequent drowsiness and vomiting. Spina bifida may be associated with hydrocephalus in childhood.
www.asbah.org Website of the Association for Spina Bifida and Hydrocephalus

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"hydrocephalus." A Dictionary of Nursing. . Encyclopedia.com. 11 Dec. 2017 <http://www.encyclopedia.com>.

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"hydrocephalus." A Dictionary of Nursing. . Retrieved December 11, 2017 from Encyclopedia.com: http://www.encyclopedia.com/caregiving/dictionaries-thesauruses-pictures-and-press-releases/hydrocephalus

hydrocephalus

hy·dro·ceph·a·lus / ˌhīdrōˈsefələs/ • n. Med. a condition in which fluid accumulates in the brain, typically in young children, enlarging the head and sometimes causing brain damage. DERIVATIVES: hy·dro·ce·phal·ic / ˌhīdrōsəˈfalik/ adj. hy·dro·ceph·a·ly / -ˈsefəlē/ n.

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hydrocephalus

hydrocephalus Increased volume of cerebrospinal fluid (CSF) in the brain. A condition that exerts dangerous pressure on brain tissue, it can be due to obstruction or a failure of natural reabsorption. In babies, it is congenital; in adults, it may arise from injury or disease. It is treated by insertion of a shunting system to drain the CSF into the abdominal cavity.

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