Congenital and Acquired Hydrocephalus Flashcards
Hydrocephalus definition
accumulation of cerebrospinal fluid (CSF) in or around the ventricles, which usually results in ventricular expansion and pressure on other parts of the brain
What happens when ventricular dilation occurs?
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
Common Types of Congenital Hydrocephalus
- Spina bifida myelomeningocele (70%)
- Aqueductal stenosis
- Dandy-Walker syndrome
- Prematurity intraventricular hemorrhage
All are typically obstructive, internal, and noncommunicating.
Internal versus External Hydrocephalus
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)
Spina Bifida Myelomeningocele
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
Neurological feature of Spina Bifida Myelomeningocele
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.
Chiari II malformation
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)
Chiari II acronym
“MAD”
M - Myelomeningocele
A - aqueduct and medulla compression
D - dangerous symptom (hydrocephalus, paralysis…)
Aqueductal Stenosis
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
Dandy-Walker Syndrome (DWS)
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
Prematurity Intraventricular Hemorrhage (IVH)
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
Neural tube defects
Detected at birth and sometimes with ultrasound
reduced by folate acid supplements
some genetic component
anencephaly - without brain
hydranencephaly - missing hemispheres
Normal Pressure Hydrocephalus (NPH)
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)
Neuropsychological outcomes
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
ADHD presentation in developmental ADHD vs. hydrocephalus
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.
Meningocele
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.
Shunt treatment for children with early hydrocephalus is…?
Essential in children with elevated ICP and progressive ventricular expansion. Progressive hydrocephalus can be fatal.
Acute hydrocephalus…?
requires monitoring and may require intervention, usually through a new shunt or shunt revision
Prenatal surgery for myelomeningocele…?
improves motor but not cognitive functions
Social skills in early hydrocephalus
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.
Intraventricular hemorrhage in low birth weight infants…
is decreasing because of interventions that prevent germinal matrix hemorrhage
On neuropsychological tests, children with hydrocephalus secondary to spina bifida myelomeningocele and aqueductal stenosis:
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.
Which brain region is most often affected by hydrocephalus
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
