CSF & Hydrocephalus Flashcards
CSF is produced primarily by?
Choroid Plexus
Choroid plexus is found in?
- Lateral ventricle (majority- 65%) *
- Third ventricle
- Fourth ventricle
– Consists of villous folds lined by epithelium with a central core of highly vascularized connective tissue
– Specialized layer of ? cells = choroidal epithelium overlies these
villi
Choroid Plexus
- ependymal
BBB
1. Continuous ? junctions
- ? provides structural support
- ? necessary for BBB development
- Transport carriers for ? and essential amino acids
- ? ion transporters
- Metabolic processes within the ? cells control entry of neurotransmitters
- Tight **
- Basement membrane
- Astrocytic foot processes
- Glucose
- Sodium
- Endothelial
Blood-CSF Barrier
- Separates the CSF and blood
- Restricts the passage of substances
- More or less permeable than the blood-brain barrier?
- Impairment in the blood-CSF barrier leads
to an increase in ? concentration in
the CSF
- More
- Protein
Blood-CSF Barrier
- ? cells are interconnected by tight junctions
Choroid cells **
CSF takes 2 steps to form
Filtration and active transport
How do plasma and CSF compare?
It differs in quantity not quality
Ex. Plasma protein is 7000 and CSF is 20
Test for CSF composition by lumbar puncture between ? and ?
L4 and L5
Functions of CSF
- Protection: “shock absorber”
– Protects brain from damage by “buffering”
the brain
– Protects from sudden pressure or
temperature changes
- Buoyancy
– Brain is immersed in fluid, the net weight is reduced from 1,400 gm to about 50 gm
– Pressure at the base of the brain is reduced *** - Metabolic
– One-way flow of CSF to the blood takes
potentially harmful metabolites, drugs, and
other substances away from the brain - Endocrine Medium for the Brain
– CSF serves to transport hormones to other
areas of the brain
What are the cavities inside the brain?
- Paired lateral ventricles
- 3rd ventricle
- Cerebral aqueduct
- 4th ventricle
What leaves the 4th ventricle?
- 2 lateral foramina (Luschka)
- 1 medial foramen (Magendie)
Flow of CSF
- Lateral Ventricle
- Through interventricular foramen of Monroe
- Third ventricle
- Cerebral aqueduct
- Down to the Fourth Ventricle between pons and cerebellum
- Goes to subarachnoid space via the 2 lateral and 1 medial aperture besides going to the central canal
- Through the arachnoid villi, absorbed from subarachnoid space to sagittal sinus
When ? is higher than ?, it will flow to the sagittal sinus
- CSF
- Venous pressure
(it will never flow backwards!)
Disorder in which an excessive amount of cerebrospinal fluid (CSF) accumulates
within the cerebral ventricles and/or subarachnoid spaces, resulting in ventricular
dilation and increased intracranial pressure (ICP)
- can be congenital or aquired
Hydrocephalus
Hydrocephalus:
- May be due to: ?
■ Overproduction of CSF (rare)
■ Under-absorption of CSF (at the level of the arachnoid villi)
■ Obstruction of the outflow of CSF from the ventricles
2 types of Hydrocephalus
- Communicating (or non-obstructive)
2. Non-communicating (or obstructive)
Communicating Hydrocephalus:
- Flow of CSF is blocked (before or after?) it exits the ventricles
- Due to abnormalities that inhibit the resorption of CSF, most often at the level of the ?
- Typically associated with (increased or decreased?) ICP
- AFTER
- arachnoid villi
- increased
- Condition of pathologically enlarged ventricular size
- Characterized by: enlarged cerebral ventricles with intermittent elevated CSF pressure on lumbar puncture
- Most common in adults over 60
Normal Pressure Hydrocephalus
- Chronic Communicating Hydrocephalus
Normal Pressure Hydrocephalus
(Chronic Communicating Hydrocephalus) :
- Triad of symptoms?
- Dementia (memory loss)
- Apraxic gait
- Urinary incontinence
Normal Pressure Hydrocephalus
(Chronic Communicating Hydrocephalus) :
- Could be due to?
– Increased viscosity of CSF
– Altered elasticity of ventricular walls
– Impaired absorption due to prior meningitis or subarachnoid hemorrhage
- Compensatory enlargement of cerebral ventricles and subarachnoid spaces
- Not accompanied by increased ICP
Communicating Hydrocephalus:
Hydrocephalus Ex-Vacuo
Hydrocephalus Ex-Vacuo
- Due to?
■ Brain atrophy (in dementias)
■ Post-traumatic brain injuries
■ Some psychiatric disorders (schizophrenia)
■ Excess accumulation of cerebrospinal fluid
(CSF) due to structural blockage of CSF flow
within the ventricular system
■ Obstruction can be congenital or acquired
■ Depending on location of the obstruction
there is selective dilation of ventricles
- Lateral and third ventricle are enlarged and the 4th ventricle is normal
- So there is blockage at the cerebral aqueduct
Non-Communicating = Obstructive Hydrocephalus
- Can pinpoint where ventricles are dilated! ** (versus communicating)
■ Narrowing of the cerebral aqueduct blocking
the flow of CSF
■ Most likely place for blockage
Aqueductal Stenosis (obstructive)
Signs/symptoms of Aqueductal Stenosis?
- “Thunderclap headache”
- Papilledema (increased pressure causing optic nerve to swell so vision issues and headaches or vomitting)
- Enlarged head (in infants)
- Cognitive/developmental delays
- Decreased level of consciousness
- Upward gaze palsy—difficulty looking up
- Tremors have been reported
Causes of Aqueductal Stenosis ?
– Tumor compression
– Narrow aqueduct
– Gliosis (reactive change in glial cells)
■ Obstruction at the outlet of the 4th ventricle + cerebellar hypoplasia
■ Congenital brain malformation (chromosomal abnormalities)
■ Involves a complete or partial agenesis of the cerebellar vermis
Dandy-Walker Malformation
obstructive
Symptoms of Dandy-Walker Malformation?
Slow motor development, breathing difficulties, irritability, and vomitting
Characteristic of Dandy-Walker Cysts?
Enlarged fourth ventricles
What is key to know about Dandy-Walker Malformation?
- Can have underdevelopment or missing Vernis **
- Cystic enlargement of 4th ventricle **
- Can have enlarged base of skull (usually in infants) and posterior fossa **
Characterized by:
– Downward displacement of inferior cerebellar vermis and cerebellar tonsils and medulla through the foramen magnum into the upper cervical canal
Chiari II Malformation
What is displaced through foramen magnum in Chiari II Malformation?
- Medulla
- 4th ventricle
- Cerebellar vermis
Chiari II Malformation Causes?
– Structural defects in the brain and SC during fetal development
– Result of genetic mutations
– Lack of certain vitamins in maternal diet
What disorder is usually accompanied by lumbosacral
myelomeningocele?
Chiari II Malformation
What is seen in 90% of cases of Chiari II Malformation?
Hydrocephalus
What is the cause of obstruction for Chiari II Malformation?
Narrowing of the cerebral aqueduct
Symptoms of Chiari II Malformation in an infant?
– Swallowing problems
– Slow and noisy breathing
– Feeding problems :
■ Gagging
■ Drooling
■ Vomiting
– Difficulty moving lower extremities
– Poor bladder control
– Clubfoot
(from case study)
What part of the brain is associated with clumsiness and ataxia?
Cerebellum
What disease? ■ 3 year old male presents with: – Headaches – Morning N/V that gradually gets worse – Clumsiness or ataxia – Decreased activity
Acquired Hydrocephalus
MRI for Acquired Hydrocephalus
- Lateral and third ventricle are enlarged
- Tumor compressing on cerebral aqueduct (ex. Medulla Blastoma)
■ Develops later in life
■ Occurs when something happens to prevent the CSF in the brain from draining
properly
Acquired Hydrocephalus
Causes of Acquired Hydrocephalus
– Brain tumor or cyst
– Blocked CSF flow
– Bleeding inside the brain (subarachnoid hemorrhage)
– Head trauma
– Infection (such as meningitis)
MRI for Chiari II Malformation
- Significance in lateral ventricle, Third ventricle, and a normal Fourth ventricle
- Vermis, medulla, and part of the 4th ventricle protrude through the foramen magnum
- Also in most cases see protrusion of lumbar-sacral spine (spina bifida)
MRI of Dandy-Walker Malformation
- Large lateral ventricle
- A big cyst on the back of the head
- Cerebellar vermis being pushed up and the cerebellum being compressed
MRI of Aqueductal Stenosis
- Lateral and third ventricle are enlarged
- Fourth ventricle is enlarged
- Blockage in cerebral aqueduct
Hydrocephalus Ex-Vacuo CT (communicating)
- Ventricles are enlarged
- On the sides of the brain there is cortical atrophy (filled with CSF)
Chronic Communicating Hydrocephalus CT
- enlarged lateral ventricles
- Third and Fourth ventricles are enlarged
- Black inside the brain = extra fluid in there
- Ballooning of corpus callosum
