Congenital and Acquired Hydrocephalus

Question 1

Hydrocephalus definition

Answer 1

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

Question 2

What happens when ventricular dilation occurs?

Answer 2

stretching and enlargement of the periventricular white matter fibers –> reductions in blood flow because of impairment to blood vessels serving the white matter.

In younger children particularly - disruption of the development of the cerebral white matter can result as well

Question 3

Common Types of Congenital Hydrocephalus

Answer 3

• Spina bifida myelomeningocele (70%)
• Aqueductal stenosis
• Dandy-Walker syndrome
• Prematurity intraventricular hemorrhage

All are typically obstructive, internal, and noncommunicating.

Question 4

Internal versus External Hydrocephalus

Answer 4

Internal hydrocephalus (“classic” hydrocephalus) usually refers to obstructive hydrocephalus involving the foramen of Monro or a narrowing of the aqueduct of Sylvius (aqueductal stenosis)

External hydrocephalus involves the subarachnoid spaces and is most often used to describe individuals with disorders of CSF absorption (e.g., meningitis)

Question 5

Spina Bifida Myelomeningocele

Answer 5

Spina bifida (“split spine”) is a typically nonlethal neural tube defect that occurs in the first 30 days of gestation.

Most common form of spina bifida and the most common cause of congenital hydrocephalus (70% of all childhood cases)

myelomeningocele - “open” neural tube defect because spinal cord protrudes through the meninges

Question 6

Neurological feature of Spina Bifida Myelomeningocele

Answer 6

hydrocephalus develops in about 90% of infants because of the Chiari II malformation (small posterior fossa) of the hindbrain, which causes obstruction at the fourth ventricle.

Question 7

Chiari II malformation

Answer 7

congenital (Chiari I develops as the skull and brain are growing and may not occur until late childhood or adulthood)

almost always associated with myelomeningocele, involving a small posterior fossa in which the cerebellum is herniated and downwardly extends through the foramen magnum.

• cerebellum itself is abnormal, with additional crowding effects on the medulla (kinking) and tectum (beaking).

corpus callosum is also usually abnormal because of under-development (hypogenesis) and thinning (hypoplasia)

Question 8

Chiari II acronym

Answer 8

“MAD”

M - Myelomeningocele
A - aqueduct and medulla compression
D - dangerous symptom (hydrocephalus, paralysis…)

Question 9

Aqueductal Stenosis

Answer 9

congenital narrowing of the Sylvian/cerebral aqueduct and usually without a spinal defect

brain and cerebellum are generally normal

expansion in head circumference and abnormalities of head control and gaze

Question 10

Dandy-Walker Syndrome (DWS)

Answer 10

70–80% of children with DWS develop hydrocephalus because of a cystic fourth ventricle with partial to complete agenesis of the cerebellar vermis (pictured).
- posterior fossa is enlarged with expansion of the fourth ventricle (compared to myelomeningocele that is caused by small posterior fossa)
- expansion in head circumference and abnormalities of head control and gaze, and gait abnormalities are common at birth

very rare, often fatal

Question 11

Prematurity Intraventricular Hemorrhage (IVH)

Answer 11

Children with prematurity IVH develop hydrocephalus because of a hemorrhage involving the germinal matrix shortly after birth.

Hydrocephalus is caused by bleeding into the ventricles from a germinal matrix hemorrhage in very-low-birth-weight infants

Grades III and IV are associated with hydrocephalus.

hydrocephalus is more often arrested and nonprogressive (compared to myelomeningocele and aqueductal stenosis)

arrested = balance between production and absorption is restored

Question 12

Neural tube defects

Answer 12

Detected at birth and sometimes with ultrasound
reduced by folate acid supplements
some genetic component

anencephaly - without brain
hydranencephaly - missing hemispheres

Question 13

Normal Pressure Hydrocephalus (NPH)

Answer 13

most common in people over 65, incidence increases with age

It is usually diagnosed by radiological study in people presenting with headaches, urinary incontinence, gait abnormalities, and mental decline (wet, wobbly, and weird)

Question 14

Neuropsychological outcomes

Answer 14

Children with spina bifida have more significant difficulties on fine motor skills because of the Chiari malformation

ADHD, predominantly inattentive presentation is common

Poor processing speed

Impaired verbal and nonverbal learning

EF difficulties are common

verbal > visual

word reading/spelling > comprehension and math

Question 15

ADHD presentation in developmental ADHD vs. hydrocephalus

Answer 15

Children with developmental forms of ADHD most commonly have difficulties with self-regulation, reflecting problems with “top-down” control associated with frontostriatal function and other aspects of an anterior attention system.

Children with congenital hydrocephalus have difficulties with orienting and disengaging, but stronger regulation when oriented and engaged, which may be consistent with a disorder of the posterior attention system. Children and adults with any form of hydrocephalus often appear under-aroused and lethargic.

Question 16

Meningocele

Answer 16

rare spinal malformation in which the meninges protrude through the spinal cord, causing a bulge in the skin. There is a sac with CSF, but usually no CNS tissue (which is a myelomeningocele). The brain of children with meningocele is often normal, although some develop hydrocephalus because of aqueductal stenosis. Problems with lower limb control and urinary problems occur below the level of the spinal lesion.

Question 17

Shunt treatment for children with early hydrocephalus is…?

Answer 17

Essential in children with elevated ICP and progressive ventricular expansion. Progressive hydrocephalus can be fatal.

Question 18

Acute hydrocephalus…?

Answer 18

requires monitoring and may require intervention, usually through a new shunt or shunt revision

Question 19

Prenatal surgery for myelomeningocele…?

Answer 19

improves motor but not cognitive functions

Question 20

Social skills in early hydrocephalus

Answer 20

Can be a relative strength. People with early hydrocephalus, especially spina bifida, are often amiable and extraverted. Some children are hypersocial to the point of being overly friendly and not safe.

Question 21

Intraventricular hemorrhage in low birth weight infants…

Answer 21

is decreasing because of interventions that prevent germinal matrix hemorrhage

Question 22

On neuropsychological tests, children with hydrocephalus secondary to spina bifida myelomeningocele and aqueductal stenosis:

Answer 22

show similar patterns of performance except in the motor domain, where children with spina bifida have more fine motor difficulties because of the Chiari malformation.

Question 23

Which brain region is most often affected by hydrocephalus

Answer 23

Posterior d/t ventricle expansion damaging posterior white matter tracts (ventricles expand in a posterior to anterior direction)

This may partially explain the greater visual deficits - however, there is substantial variability between cases with shunted hydrocephalus

Question 24

What type of syndrome is hydrocephalus generally considered?

Answer 24

Subcortical disconnection syndrome –> due to injury of long periventricular pathways (e.g., corpus callosum, projection pathway).

Question 25

Difference between internal vs. external hydrocephalus

Answer 25

Internal hydrocephalus –> usually refers to
obstructive hydrocephalus involving the foramen of Monro or a narrowing of the aqueduct of Sylvius
(aqueductal stenosis). These are classic forms of
congenital hydrocephalus that result in accumulation of CSF, increased intracranial
pressure, ventricular expansion, and compression of
the brain.

External hydrocephalus –> involves the
subarachnoid spaces and is most often used to
describe individuals with disorders of CSF
absorption (e.g., meningitis), but is also used to
describe other forms of hydrocephalus external to
the ventricles that do not necessarily involve
increased intracranial pressure.

Question 26

Communicating Hydrocephalus

Answer 26

No obstructive, but due to abnormalities of CSF production.

Occurs after injuries affecting the subarachnoid space around the ventricles that are involved in absorption of CSF.

ICP is NOT always involved.

Question 27

Noncommunicating Hydrocephalus

Answer 27

Obstructive

Associated with congential disorders, but can be associated with other dx as well.

Question 28

What are the 4 types of congenital (“early”) hydrocephalus?

Answer 28

Embryogenesis –> spina bifida, aqueductal stenosis, and Dandy Walker Syndrome)

Acquired and associated with prematurity and IVH –> prematurity intraventricular hemorrhage

Question 29

What are the main causes of congenital and acquired hydrocephalus?

Answer 29

Neural tube defect –> spina bifida myelomeningocele, hydrocephalus results from
the obstruction caused by the Chiari II malformation of the
hindbrain

Aqueductal stenosis –> caused by congenital narrowing of the aqueduct of Sylvius

Dandy-Walker Syndrome –> cystic 4th ventricle with partial to complete agenesis of the cerebellar vermis.

Prematurity IVH –> hydrocephalus is caused by bleeding into the ventricles from a germinal matric hemorrhage in very low birth weight infants.

NPH –> older adults, idiopathic hydrocephalus occurs as a
communicating disorder with impaired reabsorption of CSF; may
be secondary to obstructive process

Question 30

What is the worldwide incidence of neural tube defect?

Answer 30

1-10 per 1000 births.

Roughly equal for spina bifida and anencephaly.

Question 31

Anencephaly

Answer 31

lethal

failure of the neural tube to close at the cephalad end, so there is little development of the cortex.

Question 32

Why was the prevalence of neural tube defects declining in North America?

Answer 32

Folic acid supplementation for women in childbearing years

dietary fortification of bread and other products.

Question 33

Prevalence and incident rates of Aqueductal stenosis

Answer 33

5-10 per 100,000 live births

accounts for 5-15% of cases with congenital hydrocephalus.

Figures include –> x-linked hydrocephalus (e.g., affects males and is associated with ID).

Usually identified on radiological findings due to complaints of headaches and unexpected vomiting.

Question 34

Prevalence and incidence of Dandy-Walker Syndrome

Answer 34

3-5 per 100,000 live births

Accounts for 5-10% of congenital hydrocephalus

Detected prenatally.

First year of life –> head size, poor control, gaze problems.

Question 35

Prevalence and incidence of Prematurity IVH

Answer 35

Determined by grade, not by incidence.

Occurs with the highest incidence and severity at LOWEST level of gestational age and birthweight.

Question 36

Prevalence and incidence of NPH

Answer 36

5-6 per 100,000 people

Most common over age 65

Prevalence rate of 0.65%

Question 37

Treatment of hydrocephalus

Answer 37

Shunt – diverts flow of CSF around the site of blockage

Endoscopic Third Ventriculostomy (ETV) –> floor of the 3rd ventricle is perforated to drain CSF into an open CSF space, usually the subcistern. Its used more often in congenital hydrocephalus.

Question 38

Where is the most common place for shunt placement?

Answer 38

Right posterior ventricle with a valve that drains fluid into the peritoneal cavity.

Question 39

Treatment considerations for individuals with congenital hydrocephalus

Answer 39

Level of supervision

Driving

Employment

School/Vocational training

Capacity

Emotional/Psychological issues –> hyper sociality, issues with disability identification, social relations, and isolation emerge in adolescents and adults.

Psychiatric implications

Medications –> response to stimulants is generally LESS positive

Interpersonal relationships

Functional issues

Rehabilitation considerations.

Question 40

Common reasons why Shunts do not work

Answer 40

Fail to work – need to be revised or replaced.

Blockage

Infection at the shunt site.

Question 41

Diastomyelia

Answer 41

Rare spinal dysraphisms represented by congenital cleft or
cavity in the spinal cord that gives the appearance of a split (tethered) or
duplicated spinal cord.

Question 42

Endoscopic third ventriculostomy

Answer 42

An alternative to shunt implantation in
which the floor of the third ventricle is perforated to permit the flow of CSF
into an open CSF space (usually the subcistern). Only patients with specific
characteristics are candidates for this procedure, which is more typically
used with aqueductal stenosis and in developing countries where shunt
technology is not widely available.

Question 43

Spina bifida occulta

Answer 43

A common condition in otherwise healthy people in
which the outer part of the spinal vertebrae are not completely closed. This
form of spina bifida is often not identified except through radiological study
and, in many cases, represents a normal variation that is asymptomatic.

Question 44

Spinal Lipoma

Answer 44

A fatty tumor with fibrous material interlaced with the spinal
cord. People with lipomas typically have normal brains, but orthopedic and
urinary difficulties occur below the mass.