Hydrocephalus

Question 1

Define hydrocephalus

Answer 1

Accumulation of CSF in or around ventricles, which usually results in ventricular expansion (dilation) and pressure on other parts of the brain

Question 2

Noncommunicating hydrocephalus

Answer 2

Obstructive form of hydrocephalus; associated with disorders that obstruct the outflow of CSF into the subarachnoid space; often associated with congenital disorders, cysts, etc.

Question 3

Communicating hydrocephalus

Answer 3

Abnormality in CSF absorption, which can occur in a variety of injuries affecting the subarachnoid space around the ventricles. Intracranial pressure is not always increased, such as in cases of ventricular enlargement secondary to loss of brain tissue

Question 4

Internal versus external hydrocephalus

Answer 4

Internal typically involves the foramen of Monro or aqueductal stenosis and is usually obstructive, such as in classic forms of congenital hydrocephalus with accumulation of CSF, ICP, ventricular expansion, compression of the brain.
External involves subarachnoid spaces and usually associated with CSF reabsorption disorders.

Question 5

Congenital versus acquired hydrocephalus

Answer 5

In congenital hydrocephalus, the origin is typically very early in development. Embryogenesis-related disorders include spina bifida, aqueductal stenosis, and Dandy-Walker syndrome, while intraventricular hemorrhage in premature infants is also a common congenital form.

Acquired hydrocephalus may occur across the lifespan due to various disorders, such as tumors, meningitis, cysts, hemorrhage, TBI, or be idiopathic

Question 6

Increased intracranial pressure versus NPH

Answer 6

ICP is often associated with internal hydrocephalus.
Normal pressure hydrocephalus can result in sporadic and fluctuating ICP, as well as accumulation of CSF in ventricles and ventriculomegaly

Question 7

What are the effects of ventricular dilation on the brain

Answer 7

Stretching and enlargement of periventricular white matter fibers, reduced blood flow, neurochemical changes involving glucose and oxygen utilization, toxic metabolic byproduct accumulation in the brain

Question 8

What are some of the key considerations in classifying hydrocephalus?

Answer 8

Age at origin, site of disruption, increased ICP, ventricular expansion

Question 9

What is spina bifida and when does it typically occur?

Answer 9

Spina bifida (split spine) is a neural tube defect in which the portion that eventually forms the vertebral columns fails to fuse during early embryogenesis. It occurs in the first 30 days of gestation. The degree of closure leads to different kinds of spinal lesions.

Question 10

What portion of congenital hydrocephalus is due to spina bifida?

Answer 10

About 70% of all childhood cases

Question 11

What is myelomeningocele?

Answer 11

A form of spina bifida consisting of an “open” neural tube defect in which CNS tissue is exposed and the spinal cord protrudes through the meninges. Typically associated with a Chiari II malformation of the hindbrain, which obstructs the 4th ventricle, and apparent at birth

Question 12

How prevalent is hydrocephalus in myelomeningocele?

Answer 12

About 90% of infants develop hydrocephalus

Question 13

What other features are associated with myelomeningocele?

Answer 13

Brain abnormalities, small posterior fossa in which the cerebellum is herniated and downwardly extends through the foramen of Monro, crowding effects on the medulla and tectum of the cerebellum, hypogenesis of the rostrum or splenium and hypoplasia of the corpus callosum

Question 14

How often are corpus callosum abnormalities found in myelomeningocele?

Answer 14

About 1/2 of those with myelomeningocele lack development of the rostrum or splenium, and most also have thinning of the corpus callosum secondary to hydrocephalus

Question 15

What specific brain abnormalities have been identified through imaging shunted myelomeningocele brains?

Answer 15

Reduction in gray and white matter with increased CSF; posterior regions more affected by thinning whereas frontal regions show little volume loss; gyrification is reduced frontally and enhanced posteriorly; hippocampus has reduced volume and integrity; basal ganglia appear normal but show abnormalities on DTI, particularly the caudate and palladium

Question 16

What is anencephaly?

Answer 16

A lethal neural tube defect at the cephalad end, resulting in little development of the cortex

Question 17

What factors influence severity and outcome in spina bifida?

Answer 17

Outcomes vary in part by severity of the Chiari malformation and direct effects on cerebellar functions (motor control and precision); having other features such as tectal beaking and hypogenesis of corpus callosum have worse outcomes.
Another factor is a higher level of spinal lesion, (lower thoracic worse than sacral levels) which can cause inability to ambulate (upper thoracic/cervical are usually fatal)

Question 18

What is the incidence of neural tube defects? What trends have occurred in the prevalence of spina bifida and why?

Answer 18

About 1-10 in 1,000 births worldwide, roughly equal for spina bifida and anencephaly. Spina bifida occurs in about 2 per 1,000 live births in the US.

Declining rates due to increased emphasis on folate acid supplementation among child-bearing women, dietary fortification of bread and other products; possibly also elective terminations due to advances in prenatal diagnosis

Question 19

What is aqueductal stenosis? How is it identified?

Answer 19

Congenital narrowing of the aqueduct of Sylvius, which causes hydrocephalus. It can occur in closed neural defects even without Chiari II malformation.
Usually detected in infancy due to problems with head size and control, and gaze problems. Can be detected with radiological studies in cases of headaches and unexpected vomiting.

Question 20

How common is partial callosal hypogenesis in aqueductal stenosis without spinal defect?

Answer 20

Partial callosal hypogenesis is seen in about 20% of cases

Question 21

How do outcomes differ for those with only aqueductal stenosis and hydrocephalus versus those with additional callosal and cerebellar abnormalities?

Answer 21

The former group has better cognitive and motor functions, and severity is more directly related to hydrocephalus. Conversely the latter group will have more severe outcomes.

Question 22

What portion of congenital hydrocephalus is due to aqueductal stenosis?

Answer 22

About 5-15%

Question 23

What portion of congenital hydrocephalus is due to Dandy Walker syndrome (DWS)?

Answer 23

5-10% of all cases

Question 24

What neuroanatomical abnormalities are seen in DWS?

Answer 24

Cystic malformation of the 4th ventricle with expansion; partial to complete agenesis of the cerebellar vermis; enlarged posterior fossa; partial agenesis of the corpus callosum

Question 25

What is the prognosis in DWS?

Answer 25

Fatal in about 1/2 of cases, but prognosis improves with early diagnosis (can be detected prenatally) and improved treatment. Severity of outcomes depends on severity of the cystic malformation and degree of vermis hypogenesis (particularly with gait and upper extremity control)

Question 26

What are some early signs of DWS in infancy?

Answer 26

Problems with head size, poor control, gaze problems; later they have difficulties with gait and upper extremity control

Question 27

What portion of children with DWS develop hydrocephalus?

Answer 27

70-80%, often requiring shunting around the blockage created by the cyst

Question 28

What is prematurity intraventricular hemorrhage (IVH) and how does it cause hydrocephalus?

Answer 28

Shortly after birth, a hemorrhage of the germinal matrix which bleeds into the ventricles, obstructing the flow of CSF. Only grades III and IV are associated with hydrocephalus.

Question 29

How is prematurity IVH graded?

Answer 29

I is germinal matrix hemorrhage not bleeding into ventricles
II is germinal matrix hemorrhage with bleeding into ventricle
III is bleeding with ventricular enlargement
IV is bleeding into the tissue around the ventricles with ventricular enlargement

Question 30

How is hydrocephalus in IVH typically classified?

Answer 30

Arrested and nonprogressive with severe cases occurring less frequently; unlike progressive hydrocephalus in myelomeningocele and aqueductal stenosis

Question 31

What factors correlate with risk and severity of prematurity IVH?

Answer 31

Main risk factor is birth weight- with increased risk as birth weight decreases, especially in extremely premature infants.
Outcomes are complicated by birth weight, lung disease, etc., independently of hydrocephalus. Thus, hydrocephalus is a manifestation of severity of prematurity rather than a determinant of outcome.

Question 32

What is the most common type of hydrocephalus in adults?

Answer 32

Normal pressure hydrocephalus (NPH)
Characterized by chronically dilated ventricles, presenting with clinical triad of gait, urinary incontinence, and mental decline (wobbly, wet, wacky). CSF pressure may occur intermittently or not at all

Question 33

What differences in congenital cases versus acquired hydrocephalus influence differences in severity?

Answer 33

In congenital cases the skull can expand to accommodate ventricular expansion, whereas in acquired forms there is no where for the brain to go when displaced by ventricular expansion.

Question 34

How prevalent is NPH?

Answer 34

Occurs in 5-6 per 100,000, most common in those over 65

Question 35

What key factors influence the severity and outcome of NPH?

Answer 35

Increased ICP and compression of ventricles on other parts of the brain;
Identification of the disorder that’s producing the hydrocephalus (and severity of the disorder);
Treating the hydrocephalus before irreversible damage occurs

Question 36

What are acute signs of hydrocephalus?

Answer 36

Urinary incontinence, gait abnormalities, mental decline, headaches are acute presentations in older children and adults.
Prenatal tests include alpha-fetal protein tests of the blood (though high false-positive rates), ultrasonography may detect early hydrocephalus.
IVH is identified and monitored based on routine ultrasonography.

Question 37

What are chronic aspects of hydrocephalus?

Answer 37

Long-term effects vary depending on the disorder and specific stage of development at onset, but can include ongoing attention and motor control problems. Risks from shunts can also impact chronic course and require lifetime monitoring. Longterm consequences of arrested hydrocephalus are not well understood.

Question 38

How is hydrocephalus typically treated?

Answer 38

Shunt placement to divert flow of CSF around the site of blockage

Question 39

Where are shunts placed in treating hydrocephalus?

Answer 39

Most commonly placed in right posterior ventricle with a valve that drains fluid into the peritoneal cavity.
Any ventricle could be used, and bilateral shunts are occasionally needed.

Question 40

What other surgical intervention is used in hydrocephalus?

Answer 40

Endoscopic third ventriculostomy - perforation made in floor of the third ventricle to drain CSF into an open CSF space (usually the subcistern)

Question 41

In what situations is endoscopic third ventriculostomy typically used? Why?

Answer 41

Aqueductal stenosis, or in developing countries without shunt technology. The success rate is low.

Question 42

What are some of the complications of shunts?

Answer 42

Blockage, infection, some require lengthening the tube or replacing the shunt

Question 43

What alternative treatments may be used in communicating hydrocephalus?

Answer 43

medications that absorb excessive fluid, large volume CSF removal by lumbar puncture in NPH

Question 44

What alternative treatments may be used in disorders associated with congenital hydrocephalus?

Answer 44

For premature infants, treatments for lung problems can prevent IVH.
Spinal defects can sometimes be corrected soon after birth or even with prenatal surgery.

Question 45

What outcomes were seen at 3 years of age after prenatal surgical correction of spinal defects?

Answer 45

At 3 years, they had reduced risk of a Chiari II malformation; reduced risk of shunting; better motor functions; cognitive functions were not improved

Question 46

Describe the benefits of shunting in adults with idiopathic NPH.

Answer 46

Neuropsychological deficits often improve with shunting, but more so in patients without severe gait problems or evidence of dementia or stroke.

Question 47

In general, what neuropsychological findings are expected in congenital hydrocephalus?

Answer 47

Fine motor skill and processing speed deficits (worse in myelomeningocele than aqueductal stenosis), attention problems, executive dysfunction.
Verbal comprehension better than perceptual reasoning.
Word reading and spelling better than reading comprehension, writing, and math.
Intact rote memory for associative material, but impairment in verbal and nonverbal learning and retrieval

Question 48

How do attention deficits in congenital hydrocephalus differ from developmental ADHD?

Answer 48

Rather than problems with self-regulation or signs of frontostriatal/anterior attention system dysfunction, they have more problems orienting and disengaging, stronger regulation when oriented and engaged, and appear under-aroused and lethargic

Question 49

According to Rourke, what pattern is typically seen in executive function deficits among children with congenital hydrocephalus?

Answer 49

Somewhat similar to nonverbal learning disability:
strengths in verbal skills (phonology, vocab, grammar, auditory attn); but weaknesses in motor, tactile, spatial, concept formation, problem solving, verbal comprehension, prosody, math, writing, and social skills.

Question 50

According to Dennis, what are the core deficits and strengths in prototypic congenital hydrocephalus?

Answer 50

attention, motor functions, and timing deficits that persist through development.
Strengths involve verbal learning, facial recognition, vocab, grammar, word decoding, and spelling.

Question 51

What factors make it less likely for a child to develop aforementioned areas of strength?

Answer 51

Lower SES, having additional complications of hydrocephalus, very severe Chiari malformation, callosal hypogenesis, an upper level spinal defect, or neurological problems like seizures.

Question 52

In general, what neuropsychological findings are expected in DWS?

Answer 52

No prototypical pattern except severe difficulties with upper motor coordination, likely due to cerebellar hypoplasia; intellectual disabilities are more common.

Question 53

In general, what neuropsychological findings are expected in prematurity IVH?

Answer 53

Clear progression according to grade of IVH. No particular pattern of strengths or weaknesses.

Question 54

What emotional and personality characteristics may be seen in congenital hydrocephalus?

Answer 54

High interest in people, strong interpersonal skills, can be hypersocial, overly talkative, and intrusive. May later develop depressive feelings related to disability and/or social isolation.

Question 55

What is the best predictor of level of independence in patients who grow up with congenital hydrocephalus?

Answer 55

Mathematics ability

Question 56

In general, what neuropsychological findings may be seen in NPH?

Answer 56

Deficits on motor-based tasks, variable deficits in attention, memory, spatial skills, and concept formation

Question 57

What is the treatment response of those with congenital hydrocephalus and ADHD to stimulant meds?

Answer 57

response is less positive than in developmental disorders; commonly overmedicated when stimulants are used

Question 58

What family problems can emerge when children have congenital hydrocephalus?

Answer 58

The relationship between over-parenting and teaching independence can be difficult, given that motoric deficits may prevent exploration in young children, bowel and bladder problems may require assistance, and reduced levels of physical activity are common. Parents tend to be protective.
Later in development, adolescents may have difficulty maintaining social supports, accepting appearance and disability.

Question 59

What considerations are important for children with congenital hydrocephalus starting school?

Answer 59

Many forms are inaccurately viewed primarily as an orthopedic disability rather than neurological condition, particularly myelomeningocele. Students may not receive necessary accommodations to compensate for difficulties in math, reading comprehension, writing, as well as behavioral challenges like hypersociality.

Question 60

In adults with undiagnosed NPH, what are the common misdiagnoses?

Answer 60

Parkinson’s disease, dementia

Question 61

What is spina bifida occulta?

Answer 61

A common disorder where outer part of the spinal vertebrae are not completely closed; it’s often asymptomatic except for back pain, identified only on imaging. Not obviously related to other forms of spina bifida.

Question 62

What is meningocele?

Answer 62

Rare spinal dysraphism, meninges protrude through the spinal cord causing a bulge in the skin. There is typically a sac with CSF but no CNS tissue inside. Brain is usually normal, although some develop hydrocephalus due to aqueductal stenosis. Symptoms include lower limb difficulties and urinary problems.

Question 63

What is spinal lipoma?

Answer 63

A fatty tumor with fibrous material interlaced with the spinal cord. Brain is usually normal, but orthopedic and urinary difficulties occur below the mass.

Question 64

What is diastomyelia?

Answer 64

Rare spinal dysraphism with congenital cleft or cavity in the spinal cord that gives the appearance of a split, or duplicated spinal cord. Rarely associated with hydrocephalus.

Question 65

What is Parinaud’s Syndrome?

Answer 65

In more severe or rapidly developing cases of hydrocephalus, dilation of the suprapineal recess of the posterior third ventricle pushes down on the collicular plate of the midbrain. Causes limited vertical gaze, especially upward. Termed “setting sun” in kids with acute hydrocephalus- bilateral deviation of eyes down and inward may be seen