hydrocephalic
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Hydrocephalus is a condition in which an accumulation of
cerebrospinal fluid Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates. CSF is produced by specialised ependymal cells in the choroid plexus of the ventricles of the ...
(CSF) occurs within the
brain A brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as Visual perception, vision. I ...
. This typically causes increased pressure inside the skull. Older people may have
headache Headache is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of depression in those with severe headaches. Headaches can occur as a result ...
s,
double vision Diplopia is the simultaneous perception of two images of a single object that may be displaced horizontally or vertically in relation to each other. Also called double vision, it is a loss of visual focus under regular conditions, and is often v ...
, poor balance,
urinary incontinence Urinary incontinence (UI), also known as involuntary urination, is any uncontrolled leakage of urine. It is a common and distressing problem, which may have a large impact on quality of life. It has been identified as an important issue in geri ...
, personality changes, or
mental impairment Intellectual disability (ID), also known as general learning disability in the United Kingdom and formerly mental retardation, Rosa's Law, Pub. L. 111-256124 Stat. 2643(2010). is a generalized neurodevelopmental disorder characterized by signifi ...
. In babies, it may be seen as a rapid increase in head size. Other symptoms may include
vomiting Vomiting (also known as emesis and throwing up) is the involuntary, forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose. Vomiting can be the result of ailments like food poisoning, gastroenter ...
, sleepiness,
seizures An epileptic seizure, informally known as a seizure, is a period of symptoms due to abnormally excessive or synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much of the body with lo ...
, and downward pointing of the eyes. Hydrocephalus can occur due to
birth defect A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities ca ...
s or be acquired later in life. Associated birth defects include neural tube defects and those that result in
aqueductal stenosis Aqueductal stenosis is a narrowing of the aqueduct of Sylvius which blocks the flow of cerebrospinal fluid (CSF) in the ventricular system. Blockage of the aqueduct can lead to hydrocephalus, specifically as a common cause of congenital and/or ob ...
. Other causes include meningitis, brain tumors,
traumatic brain injury A traumatic brain injury (TBI), also known as an intracranial injury, is an injury to the brain caused by an external force. TBI can be classified based on severity (ranging from mild traumatic brain injury TBI/concussionto severe traumatic br ...
,
intraventricular hemorrhage Intraventricular hemorrhage (IVH), also known as intraventricular bleeding, is a bleeding into the brain's ventricular system, where the cerebrospinal fluid is produced and circulates through towards the subarachnoid space. It can result from phys ...
, and subarachnoid hemorrhage. The four types of hydrocephalus are communicating, noncommunicating, ''ex vacuo'', and normal pressure. Diagnosis is typically made by physical examination and medical imaging. Hydrocephalus is typically treated by the surgical placement of a
shunt system A cerebral shunt is a device permanently implanted inside the head and body to drain excess fluid away from the brain. They are commonly used to treat hydrocephalus, the swelling of the brain due to excess buildup of cerebrospinal fluid (CSF). If ...
. A procedure called a
third ventriculostomy Endoscopic third ventriculostomy (ETV) is a surgical procedure for treatment of hydrocephalus in which an opening is created in the floor of the third ventricle using an endoscope placed within the ventricular system through a burr hole. This all ...
is an option in some people. Complications from shunts may include overdrainage, underdrainage, mechanical failure,
infection An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dis ...
, or obstruction. This may require replacement. Outcomes are variable, but many people with shunts live normal lives. Without treatment, death or permanent disability may occur. About one to two per 1,000 newborns have hydrocephalus. Rates in the developing world may be higher. Normal pressure hydrocephalus is estimated to affect about 5 per 100,000 people, with rates increasing with age. Description of hydrocephalus by
Hippocrates Hippocrates of Kos (; grc-gre, Ἱπποκράτης ὁ Κῷος, Hippokrátēs ho Kôios; ), also known as Hippocrates II, was a Greek physician of the classical period who is considered one of the most outstanding figures in the history o ...
dates back more than 2,000 years. The word ''hydrocephalus'' is from the Greek grc, text=ὕδωρ, label=none, translit=hydōr, meaning 'water' and grc, text=κεφαλή, label=none, translit=kephalē, meaning 'head'.


Signs and symptoms

The clinical presentation of hydrocephalus varies with chronicity. Acute dilatation of the
ventricular system The ventricular system is a set of four interconnected cavities known as cerebral ventricles in the brain. Within each ventricle is a region of choroid plexus which produces the circulating cerebrospinal fluid (CSF). The ventricular system is co ...
is more likely to manifest with the nonspecific signs and symptoms of increased intracranial pressure (ICP). By contrast, chronic dilatation (especially in the elderly population) may have a more insidious onset presenting, for instance, with Hakim's triad (Adams' triad). Symptoms of increased ICP may include
headache Headache is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of depression in those with severe headaches. Headaches can occur as a result ...
s,
vomiting Vomiting (also known as emesis and throwing up) is the involuntary, forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose. Vomiting can be the result of ailments like food poisoning, gastroenter ...
,
nausea Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. While not painful, it can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the ...
,
papilledema Papilledema or papilloedema is optic disc swelling that is caused by increased intracranial pressure due to any cause. The swelling is usually bilateral and can occur over a period of hours to weeks. Unilateral presentation is extremely rare. In ...
,
sleepiness Somnolence (alternatively sleepiness or drowsiness) is a state of strong desire for sleep, or sleeping for unusually long periods (compare hypersomnia). It has distinct meanings and causes. It can refer to the usual state preceding falling asleep ...
, or coma. With increased levels of CSF, there have been cases of hearing loss due to CSF creating pressure on the auditory pathways or disrupting the communication of inner ear fluid. Elevated ICP of different etiologies have been linked to sensorineural hearing loss (SNHL). Transient SNHL has been reported after the loss of CSF with shunt surgeries. Hearing loss is a rare but well-known sequela of procedures resulting in CSF loss. Elevated ICP may result in uncal or tonsillar herniation, with resulting life-threatening
brain stem The brainstem (or brain stem) is the posterior stalk-like part of the brain that connects the cerebrum with the spinal cord. In the human brain the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The midbrain is co ...
compression. Hakim's triad of gait instability,
urinary incontinence Urinary incontinence (UI), also known as involuntary urination, is any uncontrolled leakage of urine. It is a common and distressing problem, which may have a large impact on quality of life. It has been identified as an important issue in geri ...
, and
dementia Dementia is a disorder which manifests as a set of related symptoms, which usually surfaces when the brain is damaged by injury or disease. The symptoms involve progressive impairments in memory, thinking, and behavior, which negatively affe ...
is a relatively typical manifestation of the distinct entity normal-pressure hydrocephalus. Focal neurological deficits may also occur, such as
abducens nerve The abducens nerve or abducent nerve, also known as the sixth cranial nerve, cranial nerve VI, or simply CN VI, is a cranial nerve in humans and various other animals that controls the movement of the lateral rectus muscle, one of the extraocul ...
palsy and vertical gaze palsy ( Parinaud syndrome due to compression of the quadrigeminal plate, where the neural centers coordinating the conjugated vertical eye movement are located). The symptoms depend on the cause of the blockage, the person's age, and how much
brain tissue The human brain is the central organ of the human nervous system, and with the spinal cord makes up the central nervous system. The brain consists of the cerebrum, the brainstem and the cerebellum. It controls most of the activities of th ...
has been damaged by the swelling. In infants with hydrocephalus, CSF builds up in the central nervous system (CNS), causing the fontanelle (soft spot) to bulge and the head to be larger than expected. Early symptoms may also include: * Eyes that appear to gaze downward * Irritability * Seizures * Separated sutures * Sleepiness * Vomiting Symptoms that may occur in older children can include: * Brief, shrill, high-pitched cry * Changes in personality, memory, or the ability to reason or think * Changes in facial appearance and eye spacing (craniofacial disproportion) * Crossed eyes or uncontrolled eye movements * Difficulty feeding * Excessive sleepiness * Headaches * Irritability, poor temper control * Loss of bladder control (
urinary incontinence Urinary incontinence (UI), also known as involuntary urination, is any uncontrolled leakage of urine. It is a common and distressing problem, which may have a large impact on quality of life. It has been identified as an important issue in geri ...
) * Loss of coordination and trouble walking * Muscle spasticity (
spasm A spasm is a sudden involuntary contraction of a muscle, a group of muscles, or a hollow organ such as the bladder. A spasmodic muscle contraction may be caused by many medical conditions, including dystonia. Most commonly, it is a muscle c ...
) * Slow growth (child 0–5 years) * Delayed milestones *
Failure to thrive Failure to thrive (FTT), also known as weight faltering or faltering growth, indicates insufficient weight gain or absence of appropriate physical growth in children. FTT is usually defined in terms of weight, and can be evaluated either by a low ...
* Slow or restricted movement * Vomiting Because hydrocephalus can injure the brain, thought and behavior may be adversely affected.
Learning disabilities Learning disability, learning disorder, or learning difficulty (British English) is a condition in the brain that causes difficulties comprehending or processing information and can be caused by several different factors. Given the "difficult ...
, including
short-term memory loss Amnesia is a deficit in memory caused by brain damage or disease,Gazzaniga, M., Ivry, R., & Mangun, G. (2009) Cognitive Neuroscience: The biology of the mind. New York: W.W. Norton & Company. but it can also be caused temporarily by the use o ...
, are common among those with hydrocephalus, who tend to score better on verbal IQ than on performance IQ, which is thought to reflect the distribution of nerve damage to the brain. Hydrocephalus that is present from birth can cause long-term complications with speech and language. Children can have issues such as nonverbal learning disorder, difficulty understanding complex and abstract concepts, difficulty retrieving stored information, and spatial/perceptual disorders. Children with hydrocephalus are often known in having the difficulty in understanding the concepts within conversation and tend to use words they know or have heard. However, the severity of hydrocephalus can differ considerably between individuals, and some are of average or above-average intelligence. Someone with hydrocephalus may have coordination and visual problems, or clumsiness. They may reach puberty earlier than the average child (this is called
precocious puberty In medicine, precocious puberty is puberty occurring at an unusually early age. In most cases, the process is normal in every aspect except the unusually early age and simply represents a variation of normal development. In a minority of childr ...
). About one in four develops
epilepsy Epilepsy is a group of non-communicable neurological disorders characterized by recurrent epileptic seizures. Epileptic seizures can vary from brief and nearly undetectable periods to long periods of vigorous shaking due to abnormal electrica ...
.


Cause


Congenital

Congenital hydrocephalus is present in the infant prior to birth, meaning the fetus developed hydrocephalus ''
in utero ''In Utero'' is the third and final studio album by American rock band Nirvana. It was released on September 21, 1993, by DGC Records. After breaking into the mainstream with their second album, ''Nevermind'' (1991), Nirvana hired Steve Albin ...
'' during
fetal development Prenatal development () includes the development of the embryo and of the fetus during a viviparous animal's gestation. Prenatal development starts with fertilization, in the germinal stage of embryonic development, and continues in fetal devel ...
. The most common cause of congenital hydrocephalus is aqueductal stenosis, which occurs when the narrow passage between the third and fourth ventricles in the brain is blocked or too narrow to allow sufficient cerebral spinal fluid to drain. Fluid accumulates in the upper ventricles, causing hydrocephalus. Other causes of congenital hydrocephalus include neural-tube defects, arachnoid cysts, Dandy–Walker syndrome, and
Arnold–Chiari malformation Chiari malformation (CM) is a structural defect in the cerebellum, characterized by a downward displacement of one or both cerebellar tonsils through the foramen magnum (the opening at the base of the skull). CMs can cause headaches, difficu ...
. The
cranial bone The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...
s fuse by the end of the third year of life. For head enlargement to occur, hydrocephalus must occur before then. The causes are usually genetic, but can also be acquired and usually occur within the first few months of life, which include intraventricular matrix hemorrhages in premature infants, infections, type II Arnold-Chiari malformation, aqueduct atresia and stenosis, and Dandy-Walker malformation. Hydrocephalus has also been seen in cases of
congenital syphilis Congenital syphilis is syphilis present ''in utero'' and at birth, and occurs when a child is born to a mother with syphilis. Untreated early syphilis infections results in a high risk of poor pregnancy outcomes, including saddle nose, lower extr ...
. In newborns and toddlers with hydrocephalus, the head circumference is enlarged rapidly and soon surpasses the 97th percentile. Since the skull bones have not yet firmly joined, bulging, firm anterior and
posterior fontanelle The posterior fontanelle (lambdoid fontanelle, occipital fontanelle) is a gap between bones in the human skull (known as fontanelle), triangular in form and situated at the junction of the sagittal suture and lambdoidal suture. It generally closes ...
s may be present even when the person is in an upright position. The infant exhibits fretfulness, poor feeding, and frequent vomiting. As the hydrocephalus progresses,
torpor Torpor is a state of decreased physiological activity in an animal, usually marked by a reduced body temperature and metabolic rate. Torpor enables animals to survive periods of reduced food availability. The term "torpor" can refer to the time ...
sets in, and infants show lack of interest in their surroundings. Later on, their upper eyelids become retracted and their eyes are turned downwards ("sunset eyes") (due to hydrocephalic pressure on the mesencephalic tegmentum and paralysis of upward gaze). Movements become weak and the arms may become tremulous. Papilledema is absent, but vision may be reduced. The head becomes so enlarged that they eventually may be bedridden. About 80–90% of fetuses or newborn infants with
spina bifida Spina bifida (Latin for 'split spine'; SB) is a birth defect in which there is incomplete closing of the spine and the membranes around the spinal cord during early development in pregnancy. There are three main types: spina bifida occulta, men ...
—often associated with
meningocele Spina bifida (Latin for 'split spine'; SB) is a birth defect in which there is incomplete closing of the spine and the membranes around the spinal cord during early development in pregnancy. There are three main types: spina bifida occulta, men ...
or
myelomeningocele Spina bifida (Latin for 'split spine'; SB) is a birth defect in which there is incomplete closing of the spine and the membranes around the spinal cord during early development in pregnancy. There are three main types: spina bifida occulta, men ...
—develop hydrocephalus.


Acquired

This condition is acquired as a consequence of CNS
infections An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable di ...
, meningitis, brain tumors,
head trauma A head injury is any injury that results in trauma to the skull or brain. The terms ''traumatic brain injury'' and ''head injury'' are often used interchangeably in the medical literature. Because head injuries cover such a broad scope of inju ...
,
toxoplasmosis Toxoplasmosis is a parasitic disease caused by '' Toxoplasma gondii'', an apicomplexan. Infections with toxoplasmosis are associated with a variety of neuropsychiatric and behavioral conditions. Occasionally, people may have a few weeks or mont ...
, or
intracranial hemorrhage Intracranial hemorrhage (ICH), also known as intracranial bleed, is hemorrhage, bleeding internal bleeding, within the Human skull, skull. Subtypes are intracerebral bleeds (intraventricular bleeds and intraparenchymal bleeds), subarachnoid bleed ...
(subarachnoid or intraparenchymal), and is usually painful.


Type

The cause of hydrocephalus is not known with certainty and is probably multifactorial. It may be caused by impaired CSF flow, reabsorption, or excessive CSF production. * Obstruction to CSF flow hinders its free passage through the ventricular system and subarachnoid space (e.g., stenosis of the
cerebral aqueduct The cerebral aqueduct (aqueductus mesencephali, mesencephalic duct, sylvian aqueduct or aqueduct of Sylvius) is a conduit for cerebrospinal fluid (CSF) that connects the third ventricle to the fourth ventricle of the ventricular system of the br ...
or obstruction of the interventricular foramina secondary to
tumor A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...
s,
hemorrhage Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, v ...
s,
infection An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dis ...
s or congenital malformations) and can cause increases in ICP. * Hydrocephalus can also be caused by overproduction of CSF (relative obstruction) (e.g., choroid plexus papilloma, villous
hypertrophy Hypertrophy is the increase in the volume of an organ or tissue due to the enlargement of its component cells. It is distinguished from hyperplasia, in which the cells remain approximately the same size but increase in number.Updated by Linda J. ...
). * Bilateral
ureter The ureters are tubes made of smooth muscle that propel urine from the kidneys to the urinary bladder. In a human adult, the ureters are usually long and around in diameter. The ureter is lined by urothelial cells, a type of transitional epit ...
ic obstruction is a rare, but reported, cause of hydrocephalus. Hydrocephalus can be classified into communicating and noncommunicating (obstructive). Both forms can be either congenital or acquired.


Communicating

Communicating hydrocephalus, also known as nonobstructive hydrocephalus, is caused by impaired CSF reabsorption in the absence of any obstruction of CSF flow between the ventricles and subarachnoid space. This may be due to functional impairment of the arachnoidal granulations (also called arachnoid granulations or Pacchioni's granulations), which are located along the superior sagittal sinus, and is the site of CSF reabsorption back into the venous system. Various neurologic conditions may result in communicating hydrocephalus, including subarachnoid/intraventricular hemorrhage, meningitis, and congenital absence of arachnoid villi. Scarring and fibrosis of the subarachnoid space following infectious, inflammatory, or hemorrhagic events can also prevent reabsorption of CSF, causing diffuse ventricular dilatation.


Noncommunicating

Noncommunicating hydrocephalus, or obstructive hydrocephalus, is caused by an obstruction to the flow of CSF. * Foramen of Monro obstruction may lead to dilation of one, or if large enough (e.g., in
colloid cyst A colloid cyst is a non-malignant tumor in the brain. It consists of a gelatinous material contained within a membrane of epithelial tissue. It is almost always found just posterior to the foramen of Monro in the anterior aspect of the third ve ...
), both lateral ventricles. * The aqueduct of Sylvius, normally narrow, may be obstructed by a number of genetic or acquired lesions (e.g., atresia, ependymitis, hemorrhage, or tumor) and lead to dilation of both lateral ventricles, as well as the
third ventricle The third ventricle is one of the four connected ventricles of the ventricular system within the mammalian brain. It is a slit-like cavity formed in the diencephalon between the two thalami, in the midline between the right and left lateral ...
. *
Fourth ventricle The fourth ventricle is one of the four connected fluid-filled cavities within the human brain. These cavities, known collectively as the ventricular system, consist of the left and right lateral ventricles, the third ventricle, and the fourth ve ...
obstruction leads to dilatation of the aqueduct, as well as the lateral and third ventricles (e.g., Chiari malformation). * The foramina of Luschka and foramen of Magendie may be obstructed due to congenital malformation (e.g.,
Dandy–Walker malformation Dandy–Walker malformation (DWM), also known as Dandy–Walker syndrome (DWS), is a rare congenital brain malformation in which the part joining the two hemispheres of the cerebellum (the cerebellar vermis) does not fully form, and the fourth ...
).


Other

*
Normal pressure hydrocephalus Normal-pressure hydrocephalus (NPH), also called malresorptive hydrocephalus, is a form of communicating hydrocephalus in which excess cerebrospinal fluid (CSF) occurs in the ventricles, and with normal or slightly elevated cerebrospinal fluid p ...
(NPH) is a particular form of chronic communicating hydrocephalus, characterized by enlarged cerebral ventricles, with only intermittently elevated cerebrospinal fluid pressure. Characteristic triad of symptoms are; dementia, apraxic gait and urinary incontinence. The diagnosis of NPH can be established only with the help of continuous intraventricular pressure recordings (over 24 hours or even longer), since more often than not instant measurements yield normal pressure values. Dynamic compliance studies may be also helpful. Altered compliance ( elasticity) of the ventricular walls, as well as increased
viscosity The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water. Viscosity quantifies the inte ...
of the cerebrospinal fluid, may play a role in the pathogenesis. * ''Hydrocephalus ex vacuo'' also refers to an enlargement of cerebral ventricles and subarachnoid spaces, and is usually due to brain atrophy (as it occurs in
dementia Dementia is a disorder which manifests as a set of related symptoms, which usually surfaces when the brain is damaged by injury or disease. The symptoms involve progressive impairments in memory, thinking, and behavior, which negatively affe ...
s), post- traumatic brain injuries, and even in some psychiatric disorders, such as
schizophrenia Schizophrenia is a mental disorder characterized by continuous or relapsing episodes of psychosis. Major symptoms include hallucinations (typically hearing voices), delusions, and disorganized thinking. Other symptoms include social wit ...
. As opposed to hydrocephalus, this is a compensatory enlargement of the CSF-spaces in response to brain parenchyma loss; it is not the result of increased CSF pressure.


Mechanism

Hydrocephalus is usually due to blockage of CSF outflow in the ventricles or in the subarachnoid space over the brain. In a person without hydrocephalus, CSF continuously circulates through the brain, its ventricles and the
spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the sp ...
and is continuously drained away into the circulatory system. Alternatively, the condition may result from an overproduction of the CSF, from a congenital malformation blocking normal drainage of the fluid, or from complications of head injuries or infections. Compression of the brain by the accumulating fluid eventually may cause neurological symptoms such as
convulsions A convulsion is a medical condition where the body muscles contract and relax rapidly and repeatedly, resulting in uncontrolled shaking. Because epileptic seizures typically include convulsions, the term ''convulsion'' is sometimes used as a s ...
,
intellectual disability Intellectual disability (ID), also known as general learning disability in the United Kingdom and formerly mental retardation, Rosa's Law, Pub. L. 111-256124 Stat. 2643(2010). is a generalized neurodevelopmental disorder characterized by signif ...
, and
epileptic seizure An epileptic seizure, informally known as a seizure, is a period of symptoms due to abnormally excessive or synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much of the body with los ...
s. These signs occur sooner in adults, whose skulls are no longer able to expand to accommodate the increasing fluid volume within. Fetuses, infants, and young children with hydrocephalus typically have an abnormally large head, excluding the face, because the pressure of the fluid causes the individual skull bones—which have yet to fuse—to bulge outward at their juncture points. Another
medical sign Signs and symptoms are the observed or detectable signs, and experienced symptoms of an illness, injury, or condition. A sign for example may be a higher or lower temperature than normal, raised or lowered blood pressure or an abnormality showi ...
, in infants, is a characteristic fixed downward gaze with whites of the eyes showing above the iris, as though the infant were trying to examine its own lower eyelids. The elevated ICP may cause compression of the brain, leading to brain damage and other complications. A complication often overlooked is the possibility of hearing loss due to ICP. The mechanism of ICP on hearing loss is presumed that the transmission of CSF pressure to and from the Perilymphatic space through a patent cochlear aqueduct. The cochlear aqueduct connects the Perilymphatic space of the inner ear with the subarachnoid space of the posterior cranial fossa. A loss of CSF pressure can induce Perilymphatic loss or endolymphatic hydrops resembling the clinical presentation of
Ménière's disease Ménière's disease (MD) is a disease of the inner ear that is characterized by potentially severe and incapacitating episodes of vertigo, tinnitus, hearing loss, and a feeling of fullness in the ear. Typically, only one ear is affected initi ...
associated hearing loss in the low frequencies. CSF can accumulate within the ventricles, this condition is called internal hydrocephalus and may result in increased CSF pressure. The production of CSF continues, even when the passages that normally allow it to exit the brain are blocked. Consequently, fluid builds inside the brain, causing pressure that dilates the ventricles and compresses the
nervous tissue Nervous tissue, also called neural tissue, is the main tissue component of the nervous system. The nervous system regulates and controls body functions and activity. It consists of two parts: the central nervous system (CNS) comprising the brain ...
. Compression of the nervous tissue usually results in irreversible brain damage. If the
skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...
bones are not completely
ossified Ossification (also called osteogenesis or bone mineralization) in bone remodeling is the process of laying down new bone material by cells named osteoblasts. It is synonymous with bone tissue formation. There are two processes resulting in t ...
when the hydrocephalus occurs, the pressure may also severely enlarge the head. The
cerebral aqueduct The cerebral aqueduct (aqueductus mesencephali, mesencephalic duct, sylvian aqueduct or aqueduct of Sylvius) is a conduit for cerebrospinal fluid (CSF) that connects the third ventricle to the fourth ventricle of the ventricular system of the br ...
may be blocked at the time of
birth Birth is the act or process of bearing or bringing forth offspring, also referred to in technical contexts as parturition. In mammals, the process is initiated by hormones which cause the muscular walls of the uterus to contract, expelling the f ...
or may become blocked later in life because of a tumor growing in the brainstem.


Treatments


Procedures

Hydrocephalus treatment is surgical, creating a way for the excess fluid to drain away. In the short term, an external ventricular drain (EVD), also known as an extraventricular drain or ventriculostomy, provides relief. In the long term, some people will need any of various types of
cerebral shunt A cerebral shunt is a device permanently implanted inside the head and body to drain excess fluid away from the brain. They are commonly used to treat hydrocephalus, the swelling of the brain due to excess buildup of cerebrospinal fluid (CSF). If ...
. It involves the placement of a ventricular
catheter In medicine, a catheter (/ˈkæθətər/) is a thin tubing (material), tube made from medical grade materials serving a broad range of functions. Catheters are medical devices that can be inserted in the body to treat diseases or perform a surgi ...
(a tube made of
silastic Silastic (a portmanteau of 'silicone' and 'plastic') is a trademark registered in 1948 by Dow Corning Corporation for flexible, inert silicone elastomer. Composition The Silastic trademark refers to silicone elastomers, silicone tubing and some cr ...
) into the cerebral ventricles to bypass the flow obstruction/malfunctioning arachnoidal granulations and drain the excess fluid into other body cavities, from where it can be resorbed. Most shunts drain the fluid into the
peritoneal cavity The peritoneal cavity is a potential space between the parietal peritoneum (the peritoneum that surrounds the abdominal wall) and visceral peritoneum (the peritoneum that surrounds the internal organs). The parietal and visceral peritonea are la ...
( ventriculoperitoneal shunt), but alternative sites include the
right atrium The atrium ( la, ātrium, , entry hall) is one of two upper chambers in the heart that receives blood from the circulatory system. The blood in the atria is pumped into the heart ventricles through the atrioventricular valves. There are two at ...
( ventriculoatrial shunt),
pleural cavity The pleural cavity, pleural space, or interpleural space is the potential space between the pleurae of the pleural sac that surrounds each lung. A small amount of serous pleural fluid is maintained in the pleural cavity to enable lubrication b ...
( ventriculopleural shunt), and
gallbladder In vertebrates, the gallbladder, also known as the cholecyst, is a small hollow organ where bile is stored and concentrated before it is released into the small intestine. In humans, the pear-shaped gallbladder lies beneath the liver, although ...
. A shunt system can also be placed in the lumbar space of the spine and have the CSF redirected to the peritoneal cavity ( lumbar-peritoneal shunt). An alternative treatment for obstructive hydrocephalus in selected people is the endoscopic third ventriculostomy (ETV), whereby a surgically created opening in the floor of the third ventricle allows the CSF to flow directly to the basal cisterns, thereby shortcutting any obstruction, as in aqueductal stenosis. This may or may not be appropriate based on individual anatomy. For infants, ETV is sometimes combined with choroid plexus cauterization, which reduces the amount of cerebrospinal fluid produced by the brain. The technique, known as ETV/CPC, was pioneered in
Uganda }), is a landlocked country in East Africa. The country is bordered to the east by Kenya, to the north by South Sudan, to the west by the Democratic Republic of the Congo, to the south-west by Rwanda, and to the south by Tanzania. The sou ...
by neurosurgeon Benjamin Warf and is now in use in several U.S. hospitals. Hydrocephalus can be successfully treated by placing a drainage tube (shunt) between the brain ventricles and abdominal cavity. Some risk exists of
infection An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dis ...
being introduced into the brain through these shunts, however, and the shunts must be replaced as the person grows.


External hydrocephalus

External hydrocephalus is a condition generally seen in infants which involves enlarged fluid spaces or subarachnoid spaces around the outside of the brain. This condition is generally
benign Malignancy () is the tendency of a medical condition to become progressively worse. Malignancy is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous ''benign'' tumor in that a malignancy is not s ...
, and resolves spontaneously by two years of age and therefore usually does not require insertion of a shunt. Imaging studies and a good medical history can help to differentiate external hydrocephalus from subdural hemorrhages or symptomatic chronic extra-axial fluid collections which are accompanied by vomiting, headaches, and seizures.


Shunt complications

Examples of possible complications include shunt malfunction, shunt failure, and shunt infection, along with infection of the shunt tract following surgery (the most common reason for shunt failure is infection of the shunt tract). Although a shunt generally works well, it may stop working if it disconnects, becomes blocked (clogged) or infected, or it is outgrown. If this happens, the CSF begins to accumulate again and a number of physical symptoms develop (headaches, nausea, vomiting,
photophobia Photophobia is a medical symptom of abnormal intolerance to visual perception of light. As a medical symptom photophobia is not a morbid fear or phobia, but an experience of discomfort or pain to the eyes due to light exposure or by presence of ...
/light sensitivity), some extremely serious, such as
seizure An epileptic seizure, informally known as a seizure, is a period of symptoms due to abnormally excessive or synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much of the body with l ...
s. The shunt failure rate is also relatively high (of the 40,000 surgeries performed annually to treat hydrocephalus, only 30% are a person's first surgery) and people not uncommonly have multiple shunt revisions within their lifetimes. Another complication can occur when CSF drains more rapidly than it is produced by the
choroid plexus The choroid plexus, or plica choroidea, is a plexus of cells that arises from the tela choroidea in each of the ventricles of the brain. Regions of the choroid plexus produce and secrete most of the cerebrospinal fluid (CSF) of the central nerv ...
, causing symptoms of listlessness, severe headaches, irritability, light sensitivity, auditory hyperesthesia (sound sensitivity), hearing loss, nausea, vomiting,
dizziness Dizziness is an imprecise term that can refer to a sense of disorientation in space, vertigo, or lightheadedness. It can also refer to disequilibrium or a non-specific feeling, such as giddiness or foolishness. Dizziness is a common medical c ...
,
vertigo Vertigo is a condition where a person has the sensation of movement or of surrounding objects moving when they are not. Often it feels like a spinning or swaying movement. This may be associated with nausea, vomiting, sweating, or difficulties w ...
, migraines, seizures, a change in personality,
weakness Weakness is a symptom of a number of different conditions. The causes are many and can be divided into conditions that have true or perceived muscle weakness. True muscle weakness is a primary symptom of a variety of skeletal muscle diseases, i ...
in the arms or legs,
strabismus Strabismus is a vision disorder in which the eyes do not properly align with each other when looking at an object. The eye that is focused on an object can alternate. The condition may be present occasionally or constantly. If present during a ...
, and
double vision Diplopia is the simultaneous perception of two images of a single object that may be displaced horizontally or vertically in relation to each other. Also called double vision, it is a loss of visual focus under regular conditions, and is often v ...
to appear when the person is vertical. If the person lies down, the symptoms usually vanish quickly. A CT scan may or may not show any change in ventricle size, particularly if the person has a history of slit-like ventricles. Difficulty in diagnosing over-drainage can make treatment of this complication particularly frustrating for people and their families. Resistance to traditional analgesic pharmacological therapy may also be a sign of shunt overdrainage or failure. Following placement of a ventriculoperitoneal shunt there have been cases of a decrease in post-surgery hearing. It is presumed that the cochlea aqueduct is responsible for the decrease in hearing thresholds. The cochlea aqueduct has been considered as a probable channel where CSF pressure can be transmitted. Therefore, the reduced CSF pressure could cause a decrease in Perilymphatic pressure and cause secondary endolymphatic hydrops. In addition to the increased hearing loss, there have also been findings of resolved hearing loss after ventriculoperitoneal shunt placement, where there is a release of CSF pressure on the auditory pathways. The diagnosis of CSF buildup is complex and requires specialist expertise. Diagnosis of the particular complication usually depends on when the symptoms appear, that is, whether symptoms occur when the person is upright or in a prone position, with the head at roughly the same level as the feet. Standardized protocols for inserting cerebral shunts have been shown to reduce shunt infections. There is tentative evidence that preventative antibiotics may decrease the risk of shunt infections.


Epidemiology

The hydrocephalus disease burden are concentrated in the developing world while North America and Canada has the least number of cases. A systematic review in 2019 estimated that there are 180,000 childhood hydrocephalus cases from African continent alone per year, followed by 90,000 cases from Southeast Asia and Western Pacific. Latin America also has high prevalence of hydrocephalus. However, data on hydrocephalus disease burden in adults are lacking.


History

In the pre-historic area, there were various paintings or artifacts depicting children or adults with
macrocephaly Macrocephaly is a condition in which circumference of the human head is abnormally large. It may be pathological or harmless, and can be a familial genetic characteristic. People diagnosed with macrocephaly will receive further medical tests to ...
(large head) or clinical findings of hydrocephalus. However, due to lack of writing, it was unknown how the people thought of the disorder at that time and the ways to treat the disease. References to hydrocephalic skulls can be found in ancient Egyptian medical literature from 2,500 BC to 500 AD. Hydrocephalus was described more clearly by the ancient Greek physician Hippocrates in the fourth century BC, while a more accurate description was later given by the
Roman Roman or Romans most often refers to: *Rome, the capital city of Italy *Ancient Rome, Roman civilization from 8th century BC to 5th century AD *Roman people, the people of ancient Rome *'' Epistle to the Romans'', shortened to ''Romans'', a lette ...
physician
Galen Aelius Galenus or Claudius Galenus ( el, Κλαύδιος Γαληνός; September 129 – c. AD 216), often Anglicized as Galen () or Galen of Pergamon, was a Greek physician, surgeon and philosopher in the Roman Empire. Considered to be one ...
in the second century AD. The first clinical description of an operative procedure for hydrocephalus appears in the '' Al-Tasrif'' (1,000 AD) by the
Arab The Arabs (singular: Arab; singular ar, عَرَبِيٌّ, DIN 31635: , , plural ar, عَرَب, DIN 31635: , Arabic pronunciation: ), also known as the Arab people, are an ethnic group mainly inhabiting the Arab world in Western Asia, ...
surgeon
Abulcasis Abū al-Qāsim Khalaf ibn al-'Abbās al-Zahrāwī al-Ansari ( ar, أبو القاسم خلف بن العباس الزهراوي;‎ 936–1013), popularly known as al-Zahrawi (), Latinised as Albucasis (from Arabic ''Abū al-Qāsim''), was ...
, who clearly described the evacuation of superficial intracranial fluid in hydrocephalic children. He described it in his chapter on
neurosurgical Neurosurgery or neurological surgery, known in common parlance as brain surgery, is the medical specialty concerned with the surgical treatment of disorders which affect any portion of the nervous system including the brain, spinal cord and peri ...
disease, describing infantile hydrocephalus as being caused by mechanical compression. He wrote: In 1881, a few years after the landmark study of Retzius and Key,
Carl Wernicke Carl (or Karl) Wernicke (; ; 15 May 1848 – 15 June 1905) was a German physician, anatomist, psychiatrist and neuropathologist. He is known for his influential research into the pathological effects of specific forms of encephalopathy and also ...
pioneered sterile ventricular puncture and external drainage of CSF for the treatment of hydrocephalus. It remained an intractable condition until the 20th century, when
cerebral shunt A cerebral shunt is a device permanently implanted inside the head and body to drain excess fluid away from the brain. They are commonly used to treat hydrocephalus, the swelling of the brain due to excess buildup of cerebrospinal fluid (CSF). If ...
and other neurosurgical treatment modalities were developed. It is a lesser-known medical condition; relatively little research is conducted to improve treatment, and still no cure has been found. In developing countries, the condition often goes untreated at birth. Before birth, the condition is difficult to diagnose, and access to medical treatment is limited. However, when head swelling is prominent, children are taken at great expense for treatment. By then, brain tissue is undeveloped and neurosurgery is rare and difficult. Children more commonly live with undeveloped brain tissue and consequential intellectual disabilities and restrictions.


Society and culture


Name

The word ''hydrocephalus'' is from the Greek meaning 'water' and meaning 'head'. Other names for hydrocephalus include "water on the brain", a historical name, and "water baby syndrome".


Awareness campaign

September was designated National Hydrocephalus Awareness Month in July 2009 by the
U.S. Congress The United States Congress is the legislature of the federal government of the United States. It is bicameral, composed of a lower body, the House of Representatives, and an upper body, the Senate. It meets in the U.S. Capitol in Washin ...
in . The resolution campaign is due in part to the advocacy work of the Pediatric Hydrocephalus Foundation. Prior to July 2009, no awareness month for this condition had been designated. Many hydrocephalus organizations, such as the One Small Voice Foundation, promote awareness and fundraising activities.


Exceptional case

One case of hydrocephalus was a man whose brain shrank to a thin sheet of tissue, due to a buildup of cerebrospinal fluid in his skull. As a child, the man had a shunt, but it was removed when he was 14. In July 2007, at age 44, he went to a hospital due to mild weakness in his left leg. When doctors learned of the man's medical history, they performed a CT and MRI scan, and were astonished to see "massive enlargement" of the lateral ventricles in the skull. Dr. Lionel Feuillet of Hôpital de la Timone in
Marseille Marseille ( , , ; also spelled in English as Marseilles; oc, Marselha ) is the prefecture of the French department of Bouches-du-Rhône and capital of the Provence-Alpes-Côte d'Azur region. Situated in the camargue region of southern Fra ...
said, "The images were most unusual... the brain was virtually absent." Intelligence tests showed the person had an IQ of 75, considered "
Borderline intellectual functioning Borderline intellectual functioning, also called borderline mental retardation (in the International Statistical Classification of Diseases and Related Health Problems#ICD-8a, ICD-8), is a categorization of intelligence wherein a person has below ...
", just above what would be officially classified as intectually disabled. The person was a married father of two children, and worked as a civil servant, leading an at least superficially normal life, despite having enlarged ventricles with a decreased volume of brain tissue. "What I find amazing to this day is how the brain can deal with something which you think should not be compatible with life", commented Dr. Max Muenke, a pediatric brain-defect specialist at the
National Human Genome Research Institute The National Human Genome Research Institute (NHGRI) is an institute of the National Institutes of Health, located in Bethesda, Maryland. NHGRI began as the Office of Human Genome Research in The Office of the Director in 1988. This Office transi ...
. "If something happens very slowly over quite some time, maybe over decades, the different parts of the brain take up functions that would normally be done by the part that is pushed to the side."


Notable cases

* Ice hockey player Colby Cave had acute obstructive hydrocephalus due to a colloid cyst. * Author
Sherman Alexie Sherman Joseph Alexie Jr. (born October 7, 1966) is a Spokane- Coeur d'Alene-Native American novelist, short story writer, poet, screenwriter, and filmmaker. His writings draw on his experiences as an Indigenous American with ancestry from se ...
, born with the condition, wrote about it in his semi-autobiographical junior fiction novel '' The Absolutely True Diary of a Part-Time Indian''. *
Prince William, Duke of Gloucester Prince William, Duke of Gloucester (24 July 1689 – 30 July 1700), was the son of Princess Anne (later Queen of England, Ireland and Scotland from 1702) and her husband, Prince George of Denmark. He was their only child to survive infanc ...
(1689–1700), probably contracted meningitis at birth, which resulted in this condition.Somerset, p. 116 * Emperor
Ferdinand I of Austria en, Ferdinand Charles Leopold Joseph Francis Marcelin , image = Kaiser Ferdinand I.jpg , caption = Portrait by Eduard Edlinger (1843) , succession = Emperor of AustriaKing of Hungary , moretext = ( more...) , cor-type = ...
(1793–1875) became emperor in 1835 despite various health issues including hydrocephalus and epilepsy. * In the
American folklore American folklore encompasses the folklores that have evolved in the present-day United States since Europeans arrived in the 16th century. While it contains much in the way of Native American tradition, it is not wholly identical to the tribal ...
of the states of Ohio, Michigan, and Connecticut, an urban legend exists about the melon heads, the inbred descendants of families of people born with hydrocephaly. * Masato Kudo, a professional soccer player, died of hydrocephalus on October 21, 2022.


References


External links

*
Guidelines for pediatric hydrocephalus
{{Authority control Congenital disorders of nervous system Disorders causing seizures Pediatrics Ventricular system Wikipedia medicine articles ready to translate Wikipedia neurology articles ready to translate