A Glossary of Hydrocephalus Related Words
amblyopic: also called lazy eye. Undeveloped central vision in one eye that leads to the use of the other eye as the dominant eye. Strabismus is the leading cause, followed by anisometropia. There are no symptoms. The patient may be found squinting and closing one eye to see; there may be unrecognized blurred vision in one eye and vision loss.
arachnoid cysts: cysts filled with cerebrospinal fluid that may occur anywhere in the brain. Some arachnoid cysts are self-contained, while others may be connected by a passageway with the ventricles or the subarachnoid space. The entrapped fluid may block the CSF pathways, producing hydrocephalus.
arachnoid granulations: arachnoid villi.
arachnoid membrane: the middle of the three meninges, lying between the dura mater and the pia mater. The arachnoid membrane covers the brain and spinal cord smoothly without conforming to the irregularities of their surfaces.
arachnoid villi (arachnoid granulations): small projections in the dura mater that protrude into the dural venous (blood) sinuses. Cerebrospinal fluid is reabsorbed from the arachnoid space by passing through the arachnoid villi and entering the venous system.
astigmatism: a condition when the cornea, and sometimes the lens, curves differently in different directions. This causes light to bend differently when it focuses on the retina. The image is thus blurred or ghosted unless corrected by contact lenses or spectacles.
ataxis: ataxia is the shaky and unsteady movements that result from the brain’s failure to regulate the body’s posture and the strength and direction of movements. Ataxia is most often caused by disease activity in the cerebellum.
brain tumor: an abnormal growth of tissue in the brain that can be benign or malignant. The tissue, which results from rapid cell growth, serves no physiological purpose. Brain tumors can cause acquired hydrocephalus.
cerebral aqueduct: aqueduct of Sylvius.
cerebral cortex: the surface layer of gray matter of the cerebrum. The cerebral cortex functions chiefly to coordinate sensory and motor information.
cerebral hemispheres: the two hollow lateral halves of the cerebrum.
cerebrospinal fluid (CSF): a clear, colorless liquid secreted primarily by the choroid plexus and contained within the ventricles and the subarachnoid space. CSF functions primarily to nourish and protect the brain and spinal cord.
cerebrum: the upper part of the brain, which overlies the rest of the brain and includes the cerebral hemispheres and their connecting structures. The cerebrum is thought to control conscious mental processes.
Chiari II malformation: a cause of congenital hydrocephalus in which part of the cerebellum and the fourth ventricle push downward through the opening at the base of the skull, blocking CSF’s flow out of the fourth ventricle and thus producing hydrocephalus. This condition is often referred to as spina bifida.
cocktail party syndrome: a hyperverbal condition, found in some children with hydrocephalus, in which a childseems to never stop talking, while content is usually superficial or inappropriate. It can mask learning difficulties such as an inability to listen or to understand the relevant aspects of a situation.
congenital hydrocephalus: hydrocephalus caused by a problem that is present at birth. Hydrocephalus that develops later in life, even in adults, but is caused by a condition that existed at birth, is still considered a form of congenital hydrocephalus. Congenital hydrocephalus can be caused by aqueductal stenosis, a neural tube defect, arachnoid cysts, or Dandy-Walker syndrome.
CSF: cerebrospinal fluid.
CSF shunt: a tube surgically placed in the body that channels cerebrospinal fluid away from the brain or spinal cord into another part of the body, where it can be absorbed and transported to the bloodstream.
CT scan: computerized tomography scan.
Dandy-Walker syndrome: a cause of congenital hydrocephalus in which the fourth ventricle becomes enlarged because its outlets are partly or completely closed, and part of the cerebellum fails to develop. Dandy-Walker syndrome sometimes leads to aqueductal stenosis.
decompensated congenital hydrocephalus: hydrocephalus that may have been present at birth, and perhaps even treated in early childhood, but remained largely compensated and asymptomatic for many years.
distal (outflow) catheter: outflow (distal) catheter.
dura mater (dura): one of the three meninges.The dura mater, the outermost and heaviest layer of the meninges, lies closest to the skull.
echolalia: a learning disability sometimes manifested by children with hydrocephalus in which the child repeats what someone else has said, rather than responding appropriately.
endoscopic third ventriculostomy (ETV): a surgical operation that creates an opening through the membranous floor of the third ventricle, permitting cerebrospinal fluid to exit the third ventricle and flow directly into the subarachnoid space at the base of the brain.
fourth ventricle: a cavity within the brain that is situated between the brain stem and the cerebellum. Cerebrospinal fluid enters the fourth ventricle from the cerebral aqueduct; it exits via the foramina of Luschka and Magendie, flowing into the subarachnoid space.
hydrocephalus: an abnormal condition that occurs when there is an imbalance between the rate of cerebrospinal fluid production and the rate of absorption, leading to gradual accumulation of CSF.
hydrostatic: relating to fluids, such as cerebrospinal fluid, when they’re at rest or to the pressures they exert or transmit.
individualized education plan (IEP): a personalized program that takes into account a child’s strengths and weaknesses, targeted educational goals, and approaches to help him or her reach these goals. An IEP, designed to maximize a child’s academic and personal potential, is created by a team including child care workers, neuropsychologists, teachers, other appropriate professionals, and parents.
interventricular foramen: foramen of Monro.
intraventricular hemorrhage: bleeding into the ventricles.
lateral ventricle: one of two normal cavities within the cerebral hemispheres that contains cerebrospinal fluid. CSF flows from the lateral ventricles into the third ventricle via the foramen of Monro.
magnetic resonance imaging (MRI) scan: a type of brain scan that uses radio signals and a powerful magnet to create a picture of brain. It is the most widely used test in diagnosing hydrocephalus because it provides more specific details about the size of the ventricles than a computerized tomography (CT) scan does. It takes approximately 30 minutes to perform.
meningitis: inflammation of the meninges. Meningitis can result from a bacterial or a viral infection. Scarring of the arachnoid membrane resulting from meningitis can restrict or block cerebrospinal fluidflow and absorption.
neural tube defect (NTD): birth defect of the brain or spinal cord. A neural tube defect can cause hydrocephalus.
noncommunicating hydrocephalus: hydrocephalus in which the ventricular pathways are blocked. Noncommunicating hydrocephalus is caused by the obstructed flow of cerebrospinal fluid through the cerebral aqueduct or from the fourth ventricle to the subarachnoid space.
nonverbal learning disorder (NLD): a specific type of learning disability that has been identified in children with hydrocephalus. It affects both academic progress and social and emotional development.
normal pressure hydrocephalus (NPH): type of adult-onset hydrocephalus whose symptoms usually include difficulty walking, mild dementia, and impaired bladder control. This form of hydrocephalus occurs most often in people over age 60.
opisthotonos: opisthotonos is a condition of abnormal posturing that involves rigidity and severe arching of the back, with the head thrown backward. If a person with opisthotonos were laid on his or her back, only the back of the head and the heels would touch the supporting surface. Opisthotonos may occur in infants with meningitis, where it is a sign of irritation of the membranes surrounding the brain and spinal cord (meninges). It may also occur as a sign of depressed brain function or injury to the nervous system.
papilledema: swelling around the optic nerve, usually due to pressure on the nerve by a tumor. Papilledema is optic disc swelling that is caused by increased intracranial pressure. The swelling is usually bilateral and can occur over a period of hours to weeks. Papilledema occurs in approximately 50% of those with a brain tumor.
peritoneum: thin membrane that lines the abdominal cavity. Cerebrospinal fluid is sometimes shunted to the peritoneum, which can act as a suitable drainage site.
pia mater: one of the three meninges. The pia mater is the layer closest to the brain.
porencephaly: congenitally deficient development of the cerebral cortex and gray matter so that cystic cavities communicate with the brain surface.
prenatal hydrocephalus: hydrocephalus that is diagnosed before birth.
preservation: a learning disability sometimes manifested by children with hydrocephalus in which the child repeats the same thing over and over again.
prominent: unusually full. Prominent scalp veins may be a sign of hydrocephalus in infants.
proximal (inflow) catheter: inflow catheter.
sac: bodily pouch that often contains fluid (such as cerebrospinal fluid).
sacrum: the part of the vertebral column that is connected with the pelvis.
sagittal sinus: a large vein close to the suture between the parietal bones of the skull.
shunt: a hallow plastic tube (catheter) that is placed in the ventricle of the brain. The tube is attached to a valve and is then threaded under the skin from the brain to either the abdomen (Ventricular-Peritoneal shunt) or heart (Ventricular-Atrial shunt).
spina bifida: a condition caused by the Chiari II malformation in which part of the cerebellum and the fourth ventricle push downward through the opening at the base of the skull, blocking the flow of cerebrospinal fluid out of the fourth ventricle and thus producing hydrocephalus.
Staphylococcus Epidermidis: member of the bacterial genus Staphylococcus mainly found on the skin and mucous membrane of humans and animals. They are a common cause of medical device-associated infections.
subarachnoid space: the space under the arachnoid membrane.
sunsetting sign: downward turning of the eyes. The sunsetting sign can be a symptom of hydrocephalus in infants.
syncope: fainting, loss of consciousness. In some cases of adult-onset hydrocephalus, syncope can result from insufficient blood flow to the brain.
symptom of hydrocephalus in young and middle-aged adults (SHYMA): type of adult-onset hydrocephalus whose symptoms usually include difficulty walking, mild dementia, and impaired bladder control, along with chronic headaches, visual problems, and fainting ( syncope). This form of hydrocephalus occurs most often in younger adults.
thalamus: a part of the brain that lies deep in the forebrain. There is one thalamus on either side of the brain. The thalamus chiefly relays impulses, especially sensory impulses, to and from the cerebral cortex.
third ventricle: a midline cavity within the brain that is situated between the right and left thalamus. Cerebrospinal fluid enters the third ventricle from each lateral ventricle via the foramen of Monro; it exits the third ventricle via the aqueduct of Sylvius.
ultrasonography: a noninvasive diagnostic technique that uses sound waves to image internal body structures. Ultrasonography can be used to diagnose hydrocephalus prenatally or after birth, before the skull’s suture lines have closed.
ventricle: a cavity within the brain that contains cerebrospinal fluid.
ventricular lining: the lining of the ventricles.