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Hydrocephalus
Official reprint from UpToDate®
www.uptodate.com ©2014 UpToDate®
Hydrocephalus
Authors
Abilash Haridas, MD
Tadanori Tomita, MD
Section Editors
Marc C Patterson, MD, FRACP
Leonard E Weisman, MD
Deputy Editor
Alison G Hoppin, MD
Disclosures
All topics are updated as new evidence becomes available and our peer review process is complete.
Literature review current through: Feb 2014. | This topic last updated: May 20, 2013.
INTRODUCTION — Hydrocephalus is a disorder in which an excessive amount of cerebrospinal fluid (CSF)
accumulates within the cerebral ventricles and/or subarachnoid spaces, which are dilated [1,2].
In children, hydrocephalus is almost always associated with increased intracranial pressure (ICP). In most cases,
this is caused by excess CSF accumulating in the cerebral ventricles due to disturbances of CSF circulation
(known as obstructive or non-communicating hydrocephalus). Less often, the CSF accumulates because of
impaired absorption (known as communicating hydrocephalus). These types of hydrocephalus will be the focus of
this topic review.
By contrast, in normal pressure hydrocephalus, the cerebral ventricles are pathologically enlarged, but the ICP is
within the normal range. This condition is usually caused by impaired CSF absorption. This type of hydrocephalus
is more often seen in adults and is discussed separately. (See "Normal pressure hydrocephalus".)
These forms of hydrocephalus are distinct from two radiographic findings that include the same word. The term
“hydrocephalus ex-vacuo” refers to dilatation of the ventricles secondary to brain atrophy or loss of brain tissue
secondary to an insult; hydrocephalus ex-vacuo is not accompanied by increased ICP. The term “external
hydrocephalus” or “benign enlargement of the extra-axial spaces” refers to excessive fluid, usually CSF, in the
subarachnoid spaces and is associated with familial macrocephaly [3,4].
EPIDEMIOLOGY — The prevalence of congenital and infantile hydrocephalus in the United States and Europe has
been estimated as 0.5 to 0.8 per 1000 live and still births [5-7]. Approximately half of these cases are associated
with myelomeningocele (spina bifida), but that proportion varies substantially across different populations. There is
substantial familial aggregation for congenital hydrocephalus. In a population-based study of congenital
hydrocephalus (not including cases associated with neural tube defects), the recurrence risk ratios for same-sex
twins, first-degree relatives, and second-degree relatives were 34.8, 6.2, and 2.2, respectively [8].
PHYSIOLOGY — Cerebrospinal fluid (CSF) is produced primarily by the choroid plexus. It circulates through the
ventricular system and then through subarachnoid space, in which it is absorbed into the systemic blood
circulation. The flow of CSF is primarily cephalad.
CSF production — CSF is produced primarily by the choroid plexus, which is responsible for 60 to 80 percent of
CSF production. The choroid plexus tissue is located in each cerebral ventricle and consists of villous folds lined by
epithelium with a central core of highly vascularized connective tissue. The choroidal epithelial cells produce CSF
using active transport dependent upon carbonic anhydrase, which can be blocked by acetazolamide (Diamox®), a
carbonic anhydrase inhibitor. In addition to the active secretion, there is a diffusion component that is not blocked
by acetazolamide.
The remainder of the CSF is produced by cerebral tissue, which secretes CSF directly into the extracellular space
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(there are no lymphatic channels in the central nervous system). This fluid flows through the ependymal layer into
the cerebral ventricles or the spinal central canal.
CSF production rates are constant in physiological conditions unless extremely high levels of intracranial pressure
are reached. Thus, absorption of CSF generally matches the rate of production to accommodate the volume of CSF
being formed each day. In adults, the production rate of CSF is approximately 20 mL/hour, which results in
complete turnover of the CSF three or four times per day. In newborns and young children, the CSF production rate
is proportional to the size of the brain. Estimates of CSF production rates in infants and children are derived from
measurements of the hourly output of the CSF from external ventricular drains. These studies suggest that CSF
output increases logarithmically with age and body weight, ranging from 0.1 to 26.5 mL/hour [9]. Output increases
rapidly in infancy; by the age of two years, output is 64 percent of that at 15 years.
The total volume of CSF in infants is approximately 50 mL, compared with 125 to 150 mL in normal adults. In
adults, approximately 25 percent of the CSF is within the ventricular system. (See "Cerebrospinal fluid: Physiology
and utility of an examination in disease states", section on 'Physiology of CSF formation and flow'.)
CSF circulation — The CSF originating in the choroid plexus and in cerebral tissue circulates through the
ventricular system into the subarachnoid space. The ventricular system is comprised of a pair of lateral ventricles,
each of which connects to the midline third ventricle through an interventricular foramen (of Monro) (figure 1). There
are no direct connections between two lateral ventricles because they are separated by a membrane (the septum
pellucidum). The third ventricle is connected to a midline fourth ventricle by the cerebral aqueduct (of Sylvius). The
CSF exits from the fourth ventricle into the subarachnoid space via three foramen: the paired lateral foramina of
Luschka and a midline foramen of Magendie. Focally enlarged areas of subarachnoid spaces known as cisterns are
present at the base of the brain. The cisterns in the posterior fossa connect to the subarachnoid spaces over the
cerebral convexities through pathways that cross the tentorium. The basal cisterns connect the spinal and
intracranial subarachnoid spaces.
CSF absorption — CSF is absorbed into the systemic venous circulation primarily across the arachnoid villi into
the venous channels of the major sinuses. The arachnoid villi consist of a cluster of cells that project from the
subarachnoid space to the sinus lumen; these are covered by a layer of endothelium with tight junctions that are
continuous with the inner layer of the sinuses. This assembly acts as a one-way valve, allowing passive absorption
of CSF down a pressure gradient; if the CSF pressure is less than the venous pressure, the arachnoid villi close
and do not allow blood to pass into the ventricular system. The rate of absorption is relatively linear over the
physiological range. Some CSF absorption also occurs across the ependymal lining of the ventricles and the
choroid plexus, as well as from the spinal subarachnoid space to the perineural spaces. Although the CSF
absorption via a lymphatic system has been noted in animals, this mechanism has not been established in
humans.
PATHOGENESIS — Hydrocephalus results from an imbalance between the intracranial cerebrospinal fluid (CSF)
inflow and outflow. It is caused by obstruction of CSF circulation, by inadequate absorption of CSF, or (rarely) by
overproduction of the CSF. Regardless of the cause, the excessive volume of CSF causes increased ventricular
pressure and leads to ventricular dilatation.
It is increasingly recognized that many cases of hydrocephalus have both obstructive and absorptive components
[10]. This accounts for the variable response to third ventriculostomy for cases of hydrocephalus previously
presumed to be purely obstructive, as discussed below. Moreover, the absorptive component of the hydrocephalus
and the response to treatment may change over time. (See 'Third ventriculostomy' below.)
Obstruction — The most common mechanism of hydrocephalus is anatomic or functional obstruction to CSF flow
(known as obstructive or non-communicating hydrocephalus). The obstruction occurs at the foramen of Monro, at
the aqueduct of Sylvius, or at the fourth ventricle and its outlets. Dilatation of the ventricular system occurs proximal
to the obstruction. The ventricle just proximal to the obstruction usually dilates most prominently. As examples:
Obstruction of the aqueduct of Sylvius (aqueductal stenosis) causes dilation of the lateral and third
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ventricles, while the size of the fourth ventricle remains relatively normal. This is a very common cause of
hydrocephalus in infants and children.
Obstruction at the body of the lateral ventricle causes dilation of the distal temporal horn and atrium.
Obstruction of one foramen of Monro causes dilatation of the lateral ventricle on that side.
Impaired absorption — Less commonly, hydrocephalus is caused by impaired absorption of CSF, known as
communicating hydrocephalus. This is typically due to inflammation of the subarachnoid villi but also may be
caused by impaired CSF absorption. The radiographic hallmark of communicating hydrocephalus is dilation of the
entire ventricular system, including the fourth ventricle. Impaired CSF absorption also can occur when cranial
venous sinus pressure is elevated.
Excessive production — Excessive production of CSF is a rare cause of hydrocephalus. This condition may
occur with a functional choroid plexus papilloma. It leads to enlargement of the entire ventricular system and of the
subarachnoid spaces, with a radiographic appearance that is similar to communicating hydrocephalus from other
causes. (See 'Choroid plexus papilloma or carcinoma' below.)
PATHOPHYSIOLOGY — The pathophysiology of hydrocephalus depends upon the underlying cause, upon how
quickly the condition develops, and upon the presence of compensatory mechanisms:
Hydrocephalus that begins in infancy before fusion of the cranial sutures, if untreated, typically results in
marked enlargement of the head and in less destruction of brain tissue, compared with hydrocephalus that
develops acutely. This is because the skull expands, partially relieving the intracranial pressure. In addition,
the force of the intracranial pressure is distributed over the greater surface area of an enlarged ventricular
system, so there is less pressure on the brain parenchyma compared with hydrocephalus that develops in a
ventricular system that is not previously enlarged.
If hydrocephalus occurs acutely or occurs after fusion of the cranial sutures, the head does not enlarge. This
results in significantly increased intracranial pressure and in more rapid destruction of brain tissue.
The progression of ventricular dilatation is usually uneven. The frontal and occipital horns typically enlarge first and
to the greatest extent. Their progressive enlargement disrupts the ependymal lining of the ventricles, allowing the
cerebrospinal fluid (CSF) to move directly into the brain tissue. This reduces CSF pressure but also leads to edema
of the subependymal areas and to progressive involvement of the white matter.
As the hydrocephalus progresses, edema and ischemia develop in the periventricular brain tissue, leading to
atrophy of the white matter. The gyri become flattened, and the sulci become compressed against the cranium,
obliterating the subarachnoid space over the hemispheres. The width of the cerebral mantle may be substantially
reduced; gray matter is better preserved than white matter, even in advanced stages. The vascular system is
compressed, and the venous pressure in the dural sinuses increases.
ETIOLOGY — Hydrocephalus can be congenital or acquired. Both categories include a diverse group of conditions.
Congenital — Congenital hydrocephalus can result from central nervous system (CNS) malformations (which
include nonsyndromic and syndromic disorders), infection, intraventricular hemorrhage, genetic defects, trauma,
and teratogens [11]. A rare cause of hydrocephalus is obstruction caused by a congenital CNS tumor, especially if
located near the midline. The disorders can be grouped according to the primary pathogenic mechanism
(obstructive versus absorptive) (table 1).
Neural tube defects — The majority of patients with myelomeningocele have hydrocephalus. The etiology is
obstruction of fourth ventricular outflow or flow of CSF through the posterior fossa due to the Chiari II malformation or
to an associated aqueductal stenosis. This type of hydrocephalus tends to have both an obstructive component and
a communicating component [10]. (See "Pathophysiology and clinical manifestations of myelomeningocele (spina
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bifida)".)
Encephalocele is another relatively common neural tube defect, in which the brain and/or meninges herniate
through a defect in the skull. Up to 50 percent of individuals with occipital encephalocele have associated
hydrocephalus. (See "Primary (congenital) encephalocele".)
Isolated hydrocephalus — Isolated hydrocephalus is frequently caused by aqueductal stenosis (image 1).
This can be due to congenital narrowing of the aqueduct or can result from inflammation due to intrauterine
infection. (See 'Intrauterine infection' below.)
X-linked hydrocephalus — The most common genetic form of congenital hydrocephalus is X-linked
hydrocephalus with stenosis of the aqueduct of Sylvius (aqueductal stenosis), which accounts for about 5 percent
of cases of congenital hydrocephalus [11]. Approximately 50 percent of affected boys have adducted thumbs, which
is helpful in making the diagnosis. Some have other CNS abnormalities such as agenesis (or dysgenesis) of the
corpus callosum, small brainstem, pachygyria, polymicrogyria, or absence of the pyramidal tract [12].
This disorder is due to mutations in the gene encoding L1, a neuronal cell adhesion molecule that belongs to the
immunoglobulin superfamily and that is essential in neurodevelopment [13]. The gene for L1 has been mapped to
Xq28. Mutations in L1 also result in other conditions, known as the L1 spectrum, that are characterized by
neurologic abnormalities and by mental retardation. These include MASA spectrum (Mental retardation, Aphasia,
Shuffling gait, Adducted thumbs), X-linked spastic paraplegia type 1, and X-linked agenesis of the corpus callosum.
CNS malformations — CNS malformations are frequently associated with hydrocephalus.
In the Chiari malformations, which often accompany a neural tube defect, portions of the brainstem and
cerebellum are displaced caudally into the cervical spinal canal. This obstructs the flow of CSF in the
posterior fossa, leading to hydrocephalus. (See "Chiari malformations".) The Chiari II malformation seen in
spina bifida is acquired and is accompanied by other features on a magnetic resonance imaging (MRI), such
as agenesis of corpus callosum low lying torcular herophili, tectal breaking, medullary kinking, and
heterotopias (image 2 and image 3).
The Dandy-Walker malformation consists of a large posterior fossa cyst that is continuous with the fourth
ventricle and defective development of the cerebellum, including partial or complete absence of the vermis
(image 4). Hydrocephalus develops in 70 to 90 percent of patients with Dandy-Walker malformation and is
caused by atresia of the foramina of Luschka and Magendie. Dandy-Walker malformation is a heterogeneous
disorder. Some patients have a syndromic form with associated congenital anomalies including dysgenesis
of the corpus callosum, orofacial deformities, and congenital abnormalities of the heart, genitourinary, and
gastrointestinal systems [14]. There is a wide range in neurodevelopmental outcomes, which depend upon
the effectiveness of management of hydrocephalus as well as the associated central nervous system
abnormalities. (See "Prenatal diagnosis of CNS anomalies other than neural tube defects and
ventriculomegaly", section on 'Dandy-Walker malformation'.)
A vein of Galen malformation is a rare cause of hydrocephalus. Obstruction results from compression of the
aqueduct of Sylvius by the markedly dilated and distorted vein of Galen (image 5). The hydrocephalus in
these patients is primarily caused by arterial pressure in the venous system rather than by compression of
the aqueduct. Presentation in the neonatal period typically includes intractable heart failure [15]. (See
"Prenatal diagnosis of CNS anomalies other than neural tube defects and ventriculomegaly", section on
'Aneurysm of the vein of Galen'.)
Syndromic forms — Hydrocephalus can be part of syndromes associated with dysmorphic features and with
other congenital abnormalities [11]. The most frequent cytogenetic disorders associated with hydrocephalus are
trisomies 13, 18, 9, and 9p, as well as triploidy [11]. Rare autosomal recessive disorders include Walker-Warburg
syndrome, which is also characterized by ocular anomalies, and hydrolethalus syndrome, in which micrognathia
and postaxial polydactyly of the hands and preaxial polydactyly of the feet are associated. (See "Oculopharyngeal,
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distal, and congenital muscular dystrophies", section on 'Walker-Warburg syndrome'.)
Intrauterine infection — Intrauterine infections such as rubella, cytomegalovirus, toxoplasmosis, lymphocytic
choriomeningitis (LCM), and syphilis can result in congenital hydrocephalus. The mechanism is inflammation of the
ependymal lining of the ventricular system and the meninges in the subarachnoid space [11]. This may lead to
impaired absorption of CSF and/or to obstruction of CSF flow through the aqueduct or basal cisterns [10].
Choroid plexus papilloma or carcinoma — A papilloma or carcinoma of the chorioid plexus causes
communicating hydrocephalus because of increased CSF secretion. This disorder usually can be identified by MRI
(image 6).
Acquired hydrocephalus
Infections and tumors — Common causes of acquired hydrocephalus are CNS infections, such as bacterial
meningitis or viral infections including mumps, and tumors, especially posterior fossa medulloblastomas,
astrocytomas, and ependymomas. These conditions are associated with obstructed flow of CSF through the
ventricular system and with impaired CSF absorption [10].
Posthemorrhagic hydrocephalus — Another important cause is hemorrhage into the subarachnoid space or,
less commonly, into the ventricular system, by ruptured aneurysms, arteriovenous malformations, trauma, or
systemic bleeding disorders. The hemorrhage induces an inflammatory response followed by fibrosis (image 7A-B).
The main mechanism for hydrocephalus is impaired absorption of CSF (communicating hydrocephalus), although
some obstruction to CSF flow also may occur. (See "Management and complications of intraventricular hemorrhage
in the newborn", section on 'Posthemorrhagic hydrocephalus (PHH)'.)
Posthemorrhagic hydrocephalus occurs in approximately 35 percent of preterm infants with intraventricular
hemorrhage (IVH). It can be obstructive, communicating, or both and can be transient or sustained, with slow or
rapid progression. (See "Management and complications of intraventricular hemorrhage in the newborn".)
Low pressure hydrocephalus — This is an uncommon entity and is extremely challenging to manage. It is
diagnosed when neurological improvement is attained by external ventricular drainage. Patients usually have
symptomatic ventriculomegaly and surprisingly low intracranial pressure. This condition may result from tumors,
chronic hydrocephalus, subarachnoid hemorrhage, and infections. Management is with low pressure shunts [16].
CLINICAL FEATURES — The signs and symptoms of hydrocephalus result from increased intracranial pressure
(ICP) and dilatation of the ventricles. The time of presentation depends upon the acuity of the process. If
accumulation of excessive cerebrospinal fluid (CSF) is slow, allowing adjustments to occur, the patient may have a
long period without symptoms. Rapid progression of ventricular dilatation typically results in early development of
symptoms. (See 'Pathophysiology' above.)
Symptoms of hydrocephalus are nonspecific and independent of the etiology [17]. Headache is a prominent
symptom. It is caused by distortion of the meninges and blood vessels. The pain often varies in intensity and
location and may be intermittent or persistent. Headaches due to increased ICP tend to occur in the early morning
and may be associated with nausea and vomiting. They tend to occur in the morning because venous pressure is
higher in the recumbent position; this reduces CSF absorption and increases ICP. (See "Approach to the child with
headache", section on 'Worrisome findings'.)
Affected patients often have changes in their personality and behavior. These include irritability, obstreperousness,
indifference, and loss of interest. The mechanism of the behavior changes is uncertain but is related, in part, to
increased ICP. As the hydrocephalus worsens, midbrain and brainstem dysfunction may result in lethargy and
drowsiness. Increased ICP in the posterior fossa often leads to nausea, vomiting, and decreased appetite.
Physical examination — Physical findings are due to the effects of increased ICP. The following signs are often
present:
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Vital signs — Distortion of the brainstem may result in changes in vital signs such as bradycardia, systemic
hypertension, and altered respiratory rate.
Head — Effects of hydrocephalus on the head are most obvious in infants who develop hydrocephalus while
the cranial sutures are still open.
Hydrocephalus is an important cause of macrocephaly in infants. Excessive head growth may be noted
on serial measurements of head circumference plotted on growth curves. However, significant dilatation
of the ventricles can occur before head growth becomes abnormal. The anterior fontanelle may become
full or distended. The sutures feel more widely split due to an enlarging head circumference. There is an
abnormal percussion note to the head when the sutures are spread (the “cracked pot” sound or
Macewen’s sign) [18]. (See "Macrocephaly in infants and children: Etiology and evaluation".)
Young infants may develop frontal bossing, an abnormal skull contour in which the forehead becomes
prominent.
The scalp veins may appear dilated and prominent. This is sometimes noted by the parents and is
mentioned in the history.
Cranial nerves
Compression of the third or sixth cranial nerve may result in extraocular muscle pareses leading to
diplopia.
Pressure on the midbrain may result in impairment of upward gaze. This is known as the setting-sun
sign because of the appearance of the sclera visible above the iris (picture 1), and it may be part of a
larger constellation of neuro-ophthalmologic signs known as Parinaud syndrome (table 2). (See
"Supranuclear disorders of gaze in children", section on 'Parinaud syndrome'.)
Fundus — Funduscopic examination may reveal papilledema.
Spine — The spine of children should be carefully examined for stigmata suggestive of an acquired Chiari II
malformation associated with spinal dysraphism, such as a pit located above the gluteal crease, a palpable
lumbar mass (suggestive of lipoma), or skin stigmata of spinal dysraphism (table 3). However, if the pit is
located between the upper buttocks in the intergluteal cleft and if the coccyx is palpable, the lesion usually
is benign and does not require imaging unless neurological or urinary symptoms develop. (See
"Pathogenesis and types of occult spinal dysraphism".)
Motor function — Stretching of the fibers from the motor cortex around the dilated ventricles may result in
spasticity of the extremities, especially the legs.
Growth and pubertal development — Accelerated pubertal development and disturbed growth, ans well as
fluid and electrolyte homeostasis, may result from pressure of the dilated third ventricle on the hypothalamus
[19].
The neurological examination of infants and children is described in detail in separate topic reviews. (See "Detailed
neurologic assessment of infants and children" and "Neurological examination of the newborn".)
Infants and children with suspected hydrocephalus should also be examined for associated congenital anomalies,
including bilateral adducted thumbs (suggestive of X-linked hydrocephalus), ocular anomalies (suggestive of WalkerWarburg syndrome), and other syndromic features. (See 'Syndromic forms' above.)
DIAGNOSIS — Hydrocephalus should be suspected in an infant whose head circumference is enlarged at birth or
in whom serial measurements cross percentiles in standard growth curves, indicating excessive head growth [20].
(See "The pediatric physical examination: General principles and standard measurements", section on 'Growth
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parameters'.) In some cases, the diagnosis is made by antenatal ultrasonography. (See "Ultrasound diagnosis of
neural tube defects".) Hydrocephalus should be considered in children with severe headache and other features
suggesting increased intracranial pressure (ICP). (See "Approach to the child with headache", section on
'Worrisome findings'.)
Imaging — The diagnosis of hydrocephalus is confirmed by neuroimaging. In a newborn, ultrasonography is the
preferred technique for the initial examination because it is portable and avoids ionizing radiation. Ultrasound is
good for imaging the lateral ventricles but does not assess the posterior fossa well; the diagnostic accuracy of
ultrasound also depends upon the expertise of the user. As the anterior fontanelle closes, the ultrasound is no
longer a useful diagnostic modality. In older infants and children with suspected hydrocephalus, computerized
tomography (CT) or magnetic resonance imaging (MRI) should be performed. These imaging studies will also detect
associated central nervous system (CNS) malformations or tumors.
CT is fast, is reliable, and does not interfere with implanted medical devices. Head CT scanning usually can be
accomplished without sedation. Disadvantages of CT scanning include radiation exposure [21]. (See "Approach to
neuroimaging in children", section on 'Computed tomography'.)
MRI is generally the imaging modality of choice in patients with unexplained hydrocephalus, if it is readily available.
MRI provides superior visualization of pathological processes in the cerebrospinal fluid (CSF) pathway, including
CSF flow dynamics. There are numerous sequences, but few will provide useful information regarding
hydrocephalus. T2-weighted imaging provides information regarding the CSF spaces and cisterns. Specific
sequences such as Turbo-spin echo (TSE), three-dimensional constructive interference in the steady state (3DCISS), and cine phase contrast (cine PC) have gained wide acceptance in evaluating CSF flow and anatomy [22].
(See "Approach to neuroimaging in children", section on 'Magnetic resonance imaging'.)
Obstructive versus communicating hydrocephalus — Brain imaging can help to distinguish obstructive
(non-communicating) from absorptive (communicating) hydrocephalus. This distinction informs treatment decisions
about shunting versus third ventriculostomy. (See 'Management' below.)
The site of obstructed CSF flow may be suggested by the pattern of ventricular dilatation. Stenosis of the aqueduct
(a common type of obstructive hydrocephalus) typically results in dilated lateral and third ventricles and in a fourth
ventricle of normal size. In contrast, communicating hydrocephalus (eg, caused by either extraventricular
obstruction or by impaired CSF absorption) in neonates and infants usually results in symmetric dilatation of all four
ventricles. If extraventricular obstruction or impaired CSF absorption occurs in children and adults, it may cause
benign intracranial hypertension (pseudotumor cerebri) without ventricular dilatation, because of reduced
compliance of the brain tissue.
Hydrocephalus versus atrophy — It may be difficult to differentiate hydrocephalus from ventriculomegaly due
to cerebral atrophy (“hydrocephalus ex-vacuo”). The following characteristics are suggestive of hydrocephalus,
rather than ventriculomegaly secondary to atrophic brain:
Enlargement of the recesses of the third ventricle
Dilation of the temporal horns of the lateral ventricle
Interstitial edema of the periventricular tissues (seen on T2-weighted or FLAIR [fluid-attenuated inversion
recovery] MRI sequences)
Effacement of the cortical sulci
Antenatal MRI — Antenatal MRI of the fetus is becoming a more common practice and is often used to further
evaluate ventricular abnormalities detected by fetal ultrasonography. Ventriculomegaly is diagnosed if the ventricular
atrium exceeds 10 mm at any gestational age [23]. The posterior portion of the lateral ventricles is normally larger
than the anterior portion in the fetus, and the discrepancy becomes less marked as the fetus approaches term.
This configuration is called colpocephaly and is often misinterpreted as hydrocephalus by clinicians lacking
experience in fetal imaging.
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Lumbar puncture — If an infection causing adhesive arachnoiditis or ependymitis is suspected, a lumbar puncture
(LP) should be performed, and the CSF should be examined. However, LP is contraindicated if the patient has
evidence of a space-occupying lesion such as an intracranial tumor or a brain abscess, because of the risk of
cerebral herniation. Thus, neuroimaging should be performed prior to LP in an infant or child with hydrocephalus.
(See "Lumbar puncture: Indications, contraindications, technique, and complications in children".)
MANAGEMENT — Most cases of hydrocephalus are progressive, meaning that neurological deterioration will occur
if the hydrocephalus is not effectively and continuously treated. The most effective treatment is surgical drainage,
using a shunt or third ventriculostomy. In cases of hydrocephalus caused by a vein of Galen malformation,
embolization of the malformation may be more appropriate than surgical drainage [24,25].
Shunting can be effective for hydrocephalus caused either by obstruction or by impaired cerebrospinal fluid (CSF)
absorption (communicating hydrocephalus). By contrast, third ventriculostomy is only effective for obstructive
hydrocephalus; it may be the optimal procedure for obstructive hydrocephalus including aqueductal stenosis [26].
However, many types of hydrocephalus have both obstructive and absorptive components, so the selection of
procedure is not always clear [10].
Rarely, hydrocephalus is not progressive because alternate pathways of CSF absorption develop or because normal
mechanisms for CSF handling become reestablished. This is known as “arrested hydrocephalus.” In this case,
shunt revision is unnecessary.
Shunt — A mechanical shunt system is placed to prevent the excessive accumulation of CSF. The shunt allows
CSF to flow from the ventricles into the systemic circulation or to the peritoneum where it is absorbed, bypassing
the site of mechanical or functional obstruction to absorption. Shunts consist of the following components:
A catheter is placed into one of the lateral ventricles (usually the right).
The catheter is connected to a one-way valve system (usually placed beneath the scalp of the postauricular
area) that opens when the pressure in the ventricle exceeds a certain value. The ventricular pressure
decreases as fluid drains, resulting in closure of the valve until the pressure increases again.
The distal end of the system is connected to a catheter that is placed in the right atrium of the heart
(ventriculoatrial [VA]) or into the peritoneal cavity (ventriculoperitoneal [VP]).
Complications — In general, complications of treated hydrocephalus are due to malfunction of the shunt. If the
shunt malfunctions and if the mechanism causing the hydrocephalus is still active, symptoms of hydrocephalus
recur, and a shunt revision or other drainage procedure is required.
Malfunction may be caused by infection or mechanical failure. Approximately 40 percent of standard shunts
malfunction within the first year after placement, and 5 percent per year malfunction in subsequent years [27-29].
Infection — Shunt infection is a common complication, occurring in approximately 5 to 15 percent of
procedures [27,28,30]. This may lead to ventriculitis [31], may promote the development of loculated
compartments of CSF, and may contribute to impaired cognitive outcome and death [27]. The risk of shunt
infections may be higher in newborns compared with shunts placed in older infants and children [32].
Most shunt infections occur in the first six months after shunt placement. This is important in the algorithm
of deciding when to tap shunts to evaluate a fever, especially when there is no clinical or radiographic
evidence of mechanical shunt failure. Infection must be considered in a child with a shunt who develops
persistent fever. Antibiotics should be started, but this treatment alone is usually not effective. In most
cases, an infected shunt must be removed, and an external ventricular drain must temporarily be placed.
Perioperative antibiotic prophylaxis may reduce the risk of infection. In a meta-analysis of 17 trials in 2134
participants, prophylactic antibiotics in the perioperative period and antibiotic-impregnated catheters reduced
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the risk of shunt infection by approximately 50 percent [33]. Whether prophylactic antibiotics are beneficial
after the perioperative period remains uncertain.
Mechanical failure — Mechanical shunt failure is another important cause of shunt failure. Like shunt
infection, it is most common during the first year after shunt placement [27]. More than half of first shunt
failures result from obstruction at the ventricular catheter [27]. One mechanism is excessive drainage of CSF
(overdrainage), which greatly reduces the size of the ventricles. This causes the catheter to lie against the
ependyma and choroid plexus, and these tissues block the holes at the end of the catheter. Fractured
tubing is the cause of shunt failure in approximately 15 percent of cases. Other causes include migration of
part or all of the shunt (7.5 percent).
Overdrainage — In addition to obstruction, overdrainage can cause functional shunt failure, which causes
subnormal intracranial pressure (particularly in the upright position) and which is associated with
characteristic neurological symptoms such as postural headache and nausea [27]. Overdrainage can also
lead to slit-ventricle syndrome, which is characterized by small or slit-like ventricles, coupled with transient
episodes of symptoms of raised ICP [34]. Changes in shunt design to address the problem of overdrainage
include valves designed to open at different pressures and selected based upon the patient’s characteristics;
anti-siphoning devices to minimize the siphon effect caused by changes in posture; and valves that regulate
by flow rather than by pressure differences.
Third ventriculostomy — Endoscopic third ventriculostomy (ETV) is a procedure in which a perforation is made to
connect the third ventricle to the subarachnoid space. This has been used in the initial treatment of selected cases
of obstructive hydrocephalus and as an alternative to shunt revision. Some experts consider it the treatment of
choice for aqueductal stenosis, although about 20 percent of patients still require shunting [26]. ETV is not useful
for patients with communicating hydrocephalus (due to impaired CSF absorption). The success of the procedure
depends upon the cause of hydrocephalus and upon previous complications [35-37]. When successful, ETV
provides a treatment for hydrocephalus that is relatively low-cost and durable. In an observational study, the quality
of life one year after the procedure was similar for patients treated with ETV compared with those treated with VP
shunting [38].
In an analysis of 618 ETV procedures performed at 12 international institutions, the overall success of ETV was 66
percent six months after the procedure [39]. Older age at the time of the procedure (eg, greater than one year of
age) was by far the strongest predictor of success, and noninfectious etiologies (eg, myelomeningocele,
intraventricular hemorrhage, aqueductal stenosis, or tectal tumor) and lack of previous shunt were also important
predictors. Based upon these data, the investigators retrospectively developed and validated an ETV success score
that predicts the likelihood of early success. For the patients with successful ETV at six months, more than 80
percent are still successful five years later. In a follow-up study, the same investigators found that the best ETV
candidates (high ETV success score) had substantially better outcomes after ETV compared with shunt. By
contrast, for those with a low ETV success score, the risk of ETV failure is initially higher than the risk of shunt
failure but becomes lower than the risk of shunt failure six months after the intervention [40].
Criteria for selection of patients for ETV versus shunting are not fully established. In our practice, we use the
following approach:
We generally perform ETV for patients with fourth ventricular outlet obstruction or with clear aqueductal
stenosis and for those with pineal region tumors and tectal tumors, because these respond well to ETV.
We generally do not perform ETV in patients with a history of intraventricular hemorrhage, meningitis, or
previous shunting, because the likelihood of success is low. However, if patients with these disorders also
have acquired aqueductal stenosis, we generally attempt ETV prior to pursuing shunting, because we have
had moderate success with this approach.
We generally do not perform ETV in infants with obstructive hydrocephalus who are younger than three
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months of age, because the likelihood of success is around 25 percent in this age group, as compared with
a 45 percent success rate in infants between three and six months of age [41] and with a success rate of 64
percent in those between 6 and 12 months of age [39].
Complications of third ventriculostomy are mainly perioperative and include inability to complete the procedure,
hemorrhage, hypothalamic dysfunction (diabetes insipidus, syndrome of inappropriate antidiuretic hormone
secretion, or precocious puberty), meningitis, and cerebral infarction. In a systematic review, permanent morbidity
after the procedure was 2.1 percent, and mortality was 0.22 percent [42].
If ETV is performed, it is important to monitor the patient postoperatively with serial clinical examinations and
imaging to determine if the procedure was successful. If the hydrocephalus progresses, a shunting procedure
generally is performed, because repeating the ETV acutely is not likely to be successful [10].
Medical therapy — Nonsurgical treatment for hydrocephalus includes the use of diuretics, fibrinolysis, and serial
lumbar punctures. These procedures have significant complications and are less effective than surgical treatment.
Diuretics and fibrinolytics — The diuretics furosemide and acetazolamide decrease CSF production. They
have been used for short periods in slowly progressive hydrocephalus in patients too unstable for surgery.
In newborn infants with posthemorrhagic hydrocephalus, treatment with diuretics is generally not effective and is
associated with complications. Treatment with fibrinolytic agents has had mixed results in this group of patients
and also is associated with significant complications. These issues are discussed in a separate topic review. (See
"Management and complications of intraventricular hemorrhage in the newborn", section on 'Management of PHH'.)
Serial lumbar punctures — Repeated lumbar punctures have been used as a temporizing measure in preterm
infants with post-hemorrhagic hydrocephalus, although they do not appear to be effective. In a systematic review of
four trials, the relative risks for shunt placement, death, disability, and multiple disability were similar for repeated
lumbar puncture and for supportive measures alone [43]. However, drainage of CSF was considered a reasonable
treatment when evidence of increased intracranial pressure exists. In cases of rapidly progressive hydrocephalus, a
temporary ventricular drainage device (ventriculostomy) may be needed until a permanent shunt can be placed or
until the hydrocephalus resolves spontaneously [44,45]. (See "Management and complications of intraventricular
hemorrhage in the newborn", section on 'Management of PHH'.)
OUTCOME — The outcome of hydrocephalus depends upon the etiology, the associated abnormalities, and the
complications such as infection.
Survival — Survival in untreated hydrocephalus is poor. Approximately 50 percent of affected patients die before
three years of age, and 77 to 80 percent die before reaching adulthood [27]. Treatment markedly improves the
outcome for hydrocephalus not associated with tumor, with 89 and 95 percent survival in two reports [32,46].
Epilepsy — Seizures occur frequently in children with shunted hydrocephalus [46-48]. In one report from France of
802 children treated with VP shunt and followed for a mean of eight years, 32 percent had epilepsy [48]. Seizures
often started approximately at the time at which the diagnosis of hydrocephalus was made. However, shunt
placement and complications also predisposed to epilepsy.
The incidence of seizures varied according to the etiology of hydrocephalus. The risks in patients with infection,
with cerebral malformations or intraventricular hemorrhage (IVH), and with spina bifida were approximately 50, 30,
and 7 percent, respectively [48].
Seizures are associated with poor cognitive outcome. In the large French series, fewer children with seizures had
normal cognition (intelligence quotient [IQ] >90) compared with those without seizures (24 versus 66 percent) [48].
Seizures in this setting can be subclinical or can occur exclusively at night [49]. Electroencephalogram (EEG)
monitoring should be considered in patients with neurologic deterioration who do not appear to have shunt failure or
infection.
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Functional outcome — Functional outcome depends upon factors including degree of prematurity, central nervous
system (CNS) malformations, other congenital abnormalities, and epilepsy, as well as sensory and motor
impairments [27]. A Hydrocephalus Outcome Questionnaire has proven to be a useful tool to measure the physical,
emotional, cognitive, and social function of hydrocephalic children, aspects of health that are often overlooked
[50,51]. Few studies of long-term outcome are available.
In a report from France, outcome at 10 years was evaluated in 129 consecutive children with hydrocephalus
without tumor who had shunt placement before two years of age [46]. Motor deficits, visual or auditory
deficits, and epilepsy occurred in 60, 25, and 30 percent of patients, respectively. IQ was >90 in 32 percent
and was <50 in 21 percent. Attendance at a normal school was possible for 60 percent, although one-half
were one to two years behind for their age or were having difficulties. Of the remainder, 31 percent were in
special classes or were institutionalized, and 9 percent were not considered educable.
In a series from the United Kingdom, 155 children with shunted hydrocephalus were followed for 10 years or
until death (which occurred in 11 percent) [32]. For survivors, until school age, 59 percent attended a normal
school. Children with hydrocephalus caused by infection or by IVH were more likely to need special school
than were those with congenital hydrocephalus (52 and 60 percent versus 29 percent).
Cognitive outcome at 5 to 10 years of age was assessed in 73 children with hydrocephalus born in Sweden
between 1989 and 1993 [52]. IQ was ≥85 in 33 percent, 70 to 84 in 30 percent, 50 to 69 in 21 percent, and
<50 in 16 percent. Median IQ was decreased among those who were born preterm compared with term
(median IQ score 68 versus 76); among those with isolated hydrocephalus at birth compared with those with
hydrocephalus and myelomeningocele or with acquired hydrocephalus (median IQ score 60 versus 77); and
among those with cerebral palsy and/or epilepsy compared with those without (median IQ score 66 versus
78). There was a discrepancy between median verbal and performance IQ (90 and 76, respectively), which
has been noted in other studies [53].
In extremely low-birthweight infants, hydrocephalus associated with intraventricular hemorrhage and a shunt
correlated with adverse neurodevelopmental outcomes at 18 to 22 months follow-up, compared with children
with and without severe intraventricular hemorrhage and with no shunt [54].
INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, “The Basics” and
“Beyond the Basics.” The Basics patient education pieces are written in plain language, at the 5th to 6th grade
reading level, and they answer the four or five key questions a patient might have about a given condition. These
articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the
Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the
10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with
some medical jargon.
Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these
topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on
“patient info” and the keyword(s) of interest.)
Basics topics (see "Patient information: Hydrocephalus (The Basics)")
SUMMARY AND RECOMMENDATIONS
Most cases of hydrocephalus in children are caused by excess CSF accumulating in the cerebral ventricles
due to disturbances of CSF circulation (known as obstructive or non-communicating hydrocephalus). Less
often, the CSF accumulates because of impaired absorption (known as communicating hydrocephalus) or
because of excessive CSF production. (See 'Pathogenesis' above.)
Untreated hydrocephalus that begins in infancy before fusion of the cranial sutures typically results in
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marked enlargement of the head and in less destruction of brain tissue compared with hydrocephalus that
develops acutely. This is because the skull expands, partially relieving the intracranial pressure. As
hydrocephalus progresses, edema and ischemia develop in the periventricular brain tissue, leading to
atrophy of the white matter. (See 'Pathophysiology' above.)
Common causes of congenital hydrocephalus include intraventricular hemorrhage and neural tube defects
including myelomeningocele. Other causes include infection, genetic defects (X-linked hydrocephalus),
trauma, tumors, and teratogens. These disorders can be grouped according to the primary pathogenic
mechanism (obstructive versus absorptive) (table 1).
The signs and symptoms of hydrocephalus result from increased intracranial pressure (ICP) and dilatation of
the ventricles. The time of presentation depends upon the acuity of the process. Symptoms of
hydrocephalus are nonspecific and independent of the etiology. Headache is a prominent symptom; it tends
to occur in the early morning and may be associated with nausea and vomiting. Affected patients often have
changes in their personality and behavior. (See 'Clinical features' above.)
Hydrocephalus should be suspected in an infant whose head circumference is enlarged at birth or in whom
serial measurements cross percentiles in standard growth curves, indicating excessive head growth. The
diagnosis is confirmed by head ultrasonography in infants and by computerized tomography (CT) or
magnetic resonance imaging (MRI) in older infants or children. Brain imaging can help to distinguish
obstructive (non-communicating) from absorptive (communicating) hydrocephalus, and this information
informs treatment decisions. (See 'Imaging' above.)
Most cases of hydrocephalus are progressive, meaning that neurological deterioration will occur if the
hydrocephalus is not effectively and continuously treated, using shunting or endoscopic third ventriculostomy
(ETV). In general, ETV is the procedure of choice for pure obstructive hydrocephalus. Shunting is used for
patients with communicating hydrocephalus or for those in whom ETV is not successful. However, many
forms of hydrocephalus have both obstructive and absorptive components, so the outcome of ETV cannot be
consistently predicted. (See 'Management' above.)
Most complications of treated hydrocephalus are due to malfunction of the shunt. If the shunt malfunctions
and if the mechanism causing the hydrocephalus is still active, symptoms of hydrocephalus recur, and a
shunt revision or other drainage procedure is required. Shunt malfunction may be caused by infection or by
mechanical failure. Approximately 40 percent of standard shunts malfunction within the first year after
placement. (See 'Complications' above.)
Use of UpToDate is subject to the Subscription and License Agreement.
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47. Klepper J, Büsse M, Strassburg HM, Sörensen N. Epilepsy in shunt-treated hydrocephalus. Dev Med Child
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48. Bourgeois M, Sainte-Rose C, Cinalli G, et al. Epilepsy in children with shunted hydrocephalus. J Neurosurg
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49. Caraballo RH, Bongiorni L, Cersósimo R, et al. Epileptic encephalopathy with continuous spikes and waves
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50. Kulkarni AV, Donnelly R, Shams I. Comparison of Hydrocephalus Outcome Questionnaire scores to
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51. Kulkarni AV, Drake JM, Rabin D, et al. Measuring the health status of children with hydrocephalus by using a
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52. Lindquist B, Carlsson G, Persson EK, Uvebrant P. Learning disabilities in a population-based group of
children with hydrocephalus. Acta Paediatr 2005; 94:878.
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Topic 6174 Version 11.0
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GRAPHICS
Subarachnoid spaces and cisterns as seen in a median section
of the brain
The superior cistern (located dorsal to the midbrain) together with the subarachnoid
space at the sides of the midbrain are referred to clinically as the cisterna ambiens.
The superior cistern is important because it contains internal cerebral veins which
join caudally to form the great cerebral vein (of Galen). It also contains the
posterior cerebral and superior cerebellar arteries. The choroid plexuxes in the roof
of the third and fourth ventricles are shown in red.
Graphic 74410 Version 2.0
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Common causes of hydrocephalus in the infant and newborn:
Classification of obstructive versus absorptive hydrocephalus
Communicating hydrocephalus
Permanent impaired absorption:
Primary congenital hydrocephalus
Malformed brain
Developmental/genetic association
Secondary prenatal hydrocephalus
Posthemorrhagic
Postinfectious
Secondary postnatal hydrocephalus
Prematurity-related
Posthemorrhagic
Postinfectious
Venous congestion: craniosynostosis, achondroplasia
Venous thrombosis: superior vena cava obstruction after cardiac surgery
Increased secretion: Choroid plexus papilloma/carcinoma
Communicating hydrocephalus, with an obstructive component
Tumors
Intraventricular hemorrhage resulting in a clot at aqueduct or fibrosis of aqueduct (acute
phase)*
Intraventricular hemorrhage resulting in intracranial cysts (acute phase)*
Infection resulting in intracranial cysts
Meningitis/encephalitis resulting in secondary obstruction*
Chiari 2 malformation
Dandy Walker malformation
Holoprosencephaly: lobar, semilobar, alobar
Encephalocele
Lissencephaly
Hydranencephaly
Obstructive hydrocephalus, with a transient minor communicating
component
Same as group 2, subacute or late phase (at least several months from primary insult:
infection, bleed)*
Large arachnoid cysts
Chromosomal abnormalities, syndromic, genetic:
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X-linked hydrocephalus (mostly aqueductal stenosis)
Osteogenesis imperfecta
C raniofacial syndromic disorders
Part of metabolic inherited disease:
Hurler's disease (MPS T1)
Achondroplasia
Obstructive hydrocephalus (pure)
Intracranial cysts with no evidence of bleed at diagnosis
Triventricular hydrocephalus due to radiologically apparent aqueductal stenosis
Membranous obstruction of aqueduct
Asymmetrical hydrocephalus, due to atresia of the foramen of Monro
Obstruction of fourth ventricle outlets
* In these disorders, the communicating component is initially prominent, but tends to decrease
over time, so that the obstructive component predominates in the later phases.
Reproduced from: Beni-Adani L, Biani N, Ben-Sirah L, Constantini S. The occurrence of obstructive vs
absorptive hydrocephalus in newborns and infants: relevance to treatment choices. Childs Nerv Syst
2006; 22:1543; with kind permission from Springer Science + Business Media B.V.
Graphic 82965 Version 2.0
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Aqueductal stenosis due to a tectal lesion
Sagittal T1 weighted magnetic resonance imaging (MRI) showing
aqueductal stenosis. The hydrocephalus was treated with a third
ventriculostomy.
Courtesy of Drs. Abilash Haridas and Tadanori Tomita.
Graphic 78793 Version 2.0
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Hydrocephalus due to a Chiari II malformation
Sagittal T1 weighted magnetic resonance imaging (MRI) showing
acquired hydrocephalus due to a Chiari II malformation in a child with
spina bifida. Note the shallow posterior fossa and descent of
cerebellar tonsils past the foramen magnum. Other findings include
large massa intermedia, low lying torcula, and partial agenesis of the
corpus callosum.
Courtesy of Drs. Abilash Haridas and Tadanori Tomita.
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Hydrocephalus
Intracranial MRI findings of a child with a Chiari II
malformation
A sagittal T1-weighted MRI in a pediatric patient shows several
characteristic intracranial findings of the Chiari II malformation,
including downward displacement of cerebellar tissue through the
foramen magnum (white arrow), a small fourth ventricle (yellow
arrow), and tectal beaking (pink arrow).
Courtesy of Eric D Schwartz, MD.
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Hydrocephalus
Hydrocephalus associated with Dandy Walker malformation
Four-month-old child with a Dandy Walker malformation, showing agenesis of
the cerebellar vermis and a large posterior fossa cyst.
Courtesy of Drs. Abilash Haridas and Tadanori Tomita.
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Hydrocephalus
Hydrocephalus due to a vein of Galen malformation
Vein of Galen malformation, causing hydrocephalus.
(Panels A-D) Axial T2 weighted magnetic resonance imaging (MRI).
(Panels E, F) Cerebral angiogram.
Courtesy of Drs. Abilash Haridas and Tadanori Tomita.
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Hydrocephalus
Hydrocephalus due to a choroid plexus papilloma
Magnetic resonance imaging in a 10-month-old male infant, showing a
papilloma of the choroid plexus in the right lateral ventricle. There is
associated hydrocephalus, caused by overproduction of cerebrospinal
fluid (CSF).
Courtesy of Drs. Abilash Haridas and Tadanori Tomita.
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Hydrocephalus
Hydrocephalus due to germinal matrix intraventricular
hemorrhage (IVH) of prematurity
Ultrasound in an infant with grade IV intraventricular hemorrhage.
(Panel A) Coronal view.
(Panel B) Sagittal view.
Courtesy of Drs. Abilash Haridas and Tadanori Tomita.
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Hydrocephalus
Post hemorrhagic hydrocephalus sequelae
Coronal T2 weighted MRI in a child with communicating hydrocephalus.
Courtesy of Drs. Abilash Haridas and Tadanori Tomita.
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Hydrocephalus
Parinaud syndrome (dorsal midbrain syndrome)
The patient has (A) bilateral lid retraction, pupillary dilatation; (B) the
inability to look upward. The pupils do not react to light but do
constrict to near effort.
Reproduced with permission from: Tasman W, Jaeger E. The Wills Eye
Hospital Atlas of Clinical Ophthalmology, 2nd ed, Lippincott Williams & Wilkins,
2001. Copyright © 2001 Lippincott Williams & Wilkins.
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Hydrocephalus
Ophthalmic findings in the Parinaud syndrome
Vertical gaze abnormalities, especially upgaze
Downward gaze preference or tonic downward deviation of the eyes ("setting-sun sign")
Primary position upbeat or downbeat nystagmus
Impaired convergence and divergence
Excessive convergence tone
Convergence-retraction nystagmus
Skew deviation, often with the higher eye on the side of the lesion
Alternating adduction hypertropia or alternating adduction hypotropia
Bilateral upper eyelid retraction (Collier "tucked-lid" sign)
Bilateral ptosis
Pupillary abnormalities (large with light-near dissociation)
Modified with permission from: Lee AG, Brazis PW. Clinical Pathways in Neuro-ophthalmology: An
Evidence-based Approach, Thieme, New York 1998.
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The cutaneous syndrome in occult spinal dysraphism
Patch of hyperkeratosis
Patch of hypertrichosis
Patch of hyperpigmentation
Patch of epidermal atrophy (may be tender)
Subcutaneous mass (lipoma or neurofibroma)
Capillary hemangioma or cutaneous angioma
Dorsal dermal sinus
Sacrococcygeal pit
Sacrococcygeal dimple
Caudal cutaneous appendage (true tail or pseudotail)
Isolated deviation of the intergluteal fold
Courtesy of Chaouki Khoury, MD, MS.
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