Cerebrospinal Fluid Flashcards
Is the CSF-brain barrier and BBB the same thing?
No
What does the CSF-brain barrier relate to>?
The extracerebral fluid that is found within the ventricles and around the brain
What are the two main categories of function of the CSF-brain barrier?
- Physical
- Biochemical
What are the physical functions of the CSF-brain barrier?
- Cushions and protects the brain from shear forces and impact
- Plays a role in regulating intracerebral blood pressure, thus prevents ischaemia
What are the biochemical functions of the CSF-brain barrier?
- Removes waste and toxins from the CNS
- Helps regulate levels of hormones and neurologically active substances
What is CSF produced by?
A type of glial cell called an ependymal cell
Where is CSF produced?
Mainly in the choroid plexi in the lateral ventricles of the brain
Where does CSF exit after it’s produced in the choroid plexus?
Through the intraventricular foramen of Munro, into the third ventricle
Where does CSF go after the third ventricle?
Through the aqueduct of Sylvius, into the fourth ventricle
Where does CSF go after the fourth ventricle?
Down the spinal cord and over the cerebral hemispheres
How is CSF reabsorbed into the circulation?
Via the arachnoid villi
At what rate is CSF produced?
Around 30ml/hour
What is the volume of CSF after age of 2 years?
150ml
What volume of CSF is found in the ventricular system after the age of 2?
35ml
What might abnormalities of CSF circulation result in?
Hydrocephalus
What are the types of hydrocephalus?
- Communicating
- Non-communicating
What is the difference between communicating and non-communicating hydrocephalus?
In communicating, there is no obstruction between the ventricles and the subarachnoid space.
In non-communicating, there is a physical obstruction between the ventricles and subarachnoid space
What can communicating hydrocephalus be caused by?
- Excessive CSF production
- Impaired CSF reabsorption
Is excessive CSF production common?
No, it is rare
What can cause excessive CSF production?
Choroid plexus tumour
What can cause impaired CSF reabsorption?
Blockage of arachnoid granulations by debris after meningitis or haemorrhage
What can non-communicating hydrocephalus be caused by?
- Congenital malformations
- Acquired obstruction
Give 2 examples of congenital malformations causing non-communicating hydrocephalus?
- Aqueduct stenosis
- Arnold-Chiari malformations
Give an example of an acquired obstruction causing non-communicating hydrocephalus?
Brain tumour
What is idiopathic intracranial hypertension?
A special case where the CSF is elevated in the absence of hydrocephalus or intracranial mass lesion
What does the treatment of hydrocephalus depend on?
Cause
What might the treatment of hydrocephalus include?
- Resection of intracranial obstruction
- Placing of stent in stenosed aqueduct
- Removal of excess CSF
How can excess CSF be removed in hydrocephalus?
Insertion of a one-way valved ventriculoperitoneal shunt
What does the insertion of a ventriculoperitoneal shunt form?
A direct drainage route for CSF from the cranial vault to the low pressure of the peritoneal cavity
What do the clinical features of hydrocephalus depend on?
- Site of the obstruction
- Capacity of the cranial vault to expand
Why might the cranial vault be able to expand?
If the sutures are not yet fused
Are the symptoms of hydrocephalus acute or chronic?
Can be either
What are the acute symptoms of hydrocephalus?
- Vomiting
- Irritability
- Headaches
- Change in consciousness
What are the chronic symptoms of hydrocephalus?
- Visual disturbance
- ‘Sunsetting eyes’
- Deterioration in school performance
Give an example of a cause of acute hydrocephalus?
Blocked ventriculoperitoneal shunt
What can acute hydrocephalus lead to if untreated?
Brainstem herniation and death
In what disorders might CSF analysis be of value?
- Meningitis
- Metabolic disorders
- Leukaemia
- Neurodegenerative conditions
- Autoimmune disorders
What is the limitation of CSF analysis in meningitis?
It may initially be normal, so clinical impression is of prime importance
What is the normal CSF neutrophil count in a term neonate?
<5
What is the normal CSF lymphocyte count in a term neonate?
<20
What is the normal CSF protein count in a term neonate?
<1.0
What is the normal CSF glucose in a term neonate?
≥2.5mmol/L
What is the normal CSF neutrophil count in a child >1 month?
0
What is the normal CSF lymphocyte count in a child >1 month of age?
≤5
What is the normal CSF protein count in a child >1 month of age?
<0.4
What is the normal CSF glucose in a child >1 month of age?
≥2.5mmol/L
What is the CSF neutrophils in bacterial meningitis?
100-10,000 (but may be normal)
What is the CSF neutrophils in bacterial meningitis?
Usually <100
What is the CSF protein in bacterial meningitis?
> 1.0 (but may be normal)
What is the CSF glucose in bacterial meningitis?
<0.4 (but may be normal)
What is the CSF neutrophils in viral meningitis?
Usually <100
What is the CSF lymphocytes in viral meningitis?
10-1000 (but may be normal)
What is the CSF protein in viral meningitis?
0.4-1 (but may be normal
What is the CSF glucose in viral meningitis?
Usually normal
What is the CSF neutrophils in TB meningitis?
<100
What is the CSF lymphocyte count in TB meningitis?
50-1000 (but may be normal)
What is the CSF protein in TB meningitis?
1-5 (but may be normal)
What is the CSF glucose in TB meningitis?
<0.3 (but may be normal)
What is the significance of finding neutrophils in the CSF?
It is unusual to find neutrophils in the CSF beyond the neonatal period, and so finding them should raise suspicion of a bacterial infection
How does CSF white cell count and protein level differ at birth from in later infancy?
It is higher
What kind of white cells are found in viral meningitis?
Lymphocytes are more characteristic, but neutrophils may predominate
Do antibiotics significantly change CSF cell count or§ biochemistry?
Not if taken within 24 hours of initial dose
When is meningococcal PCR testing on CSF samples particularly useful?
In patients with a clinical picture consistent with meningococcal meningitis, but who have received prior antibiotics
What might be found in CSF in patients with central nervous inflammatory diseases?
CSF IgG
Give 2 examples of CNS inflammatory diseases?
- Multiple sclerosis
- Sub-acute sclerosing panencephalitis
What is the most commonly used diagnostic test for MS?
- CSF index
- Oligoclonal band detection
What is CSF index?
The ratio of CSF IgG to CSF albumin, compared to serum IgG to serum albumin
What happens to the CSF index in MS?
It is raised
What are monoamine neurotransmitter disorders caused by?
Defects in the synthesis, degradation, or transport of dopamine, noradrenaline, adrenaline, or serotonin
What are monoamine neurotransmitter disorders implicated in?
A varied group of conditions, including;
- Mitochondrial disorders
- Rett’s syndrome
- Leukodystrophies
How do monoamine neurotransmitter disorders usually present?
With abnormal neurological features, e.g. encephalopathy, epilepsy, and pyramidal and extrapyramidal motor disorders
What might the diagnosis of monoamine neurotransmitter disorders include?
Analysis of neurotransmitters in CSF
What does the analysis of neurotransmitters in CSF involve?
A precise protocol for collection and rapid freezing of samples, and specialised laboratory analysis
