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content:cerebrospinal_fluid [2020/02/01 20:05] – [Indications for CSF examination] icna | content:cerebrospinal_fluid [2020/02/17 12:39] – [References] icna | ||
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====== Cerebrospinal fluid (CSF) ====== | ====== Cerebrospinal fluid (CSF) ====== | ||
+ | {{tag> | ||
The cerebrospinal fluid (CSF) is formed by the choroid plexuses within the ventricles, passes into the subarachnoid space around the spinal cord and finally over the surface of the brain, to be absorbed in the arachnoid villi in the sagittal sinus. The composition of the CSF changes during circulation from its creation to its final absorption. The CSF protein is lowest in the lateral ventricles, intermediate in the lumbar subarachnoid space, and highest in the subarachnoid spaces over the surface of the cerebral hemispheres where it is sometimes sampled in mistake for subdural fluid. Except when there is obstruction to the flow of CSF from the ventricular system or potential downward herniation of the brain, CSF is obtained by a lumbar puncture. A blood sample | The cerebrospinal fluid (CSF) is formed by the choroid plexuses within the ventricles, passes into the subarachnoid space around the spinal cord and finally over the surface of the brain, to be absorbed in the arachnoid villi in the sagittal sinus. The composition of the CSF changes during circulation from its creation to its final absorption. The CSF protein is lowest in the lateral ventricles, intermediate in the lumbar subarachnoid space, and highest in the subarachnoid spaces over the surface of the cerebral hemispheres where it is sometimes sampled in mistake for subdural fluid. Except when there is obstruction to the flow of CSF from the ventricular system or potential downward herniation of the brain, CSF is obtained by a lumbar puncture. A blood sample | ||
===== Appearance ===== | ===== Appearance ===== | ||
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The opening pressure should always be measured using a manometer attached to the needle. | The opening pressure should always be measured using a manometer attached to the needle. | ||
- | Pressure measurements obtained by the usual manometric method will be in centimetres of water (cmH2O), but those obtained with the aid of a transducer will be in milimetres of mercury (mmHg). [1mmHg = 1.3cmH< | + | Pressure measurements obtained by the usual manometric method will be in centimetres of water (cmH< |
<table Normal CSF Pressures in Neonates> | <table Normal CSF Pressures in Neonates> | ||
< | < | ||
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Although immunoglobulins may be increased because of disruption of the blood-brain barrier an important cause is intrathecal synthesis of immunoglobulin. Various formulae or indices are used to give a quantitative measure of intrathecal synthesis of IgG, the most important of the immunoglobulins. | Although immunoglobulins may be increased because of disruption of the blood-brain barrier an important cause is intrathecal synthesis of immunoglobulin. Various formulae or indices are used to give a quantitative measure of intrathecal synthesis of IgG, the most important of the immunoglobulins. | ||
- | {{ investigations: | + | {{ content: |
The upper limit of normal for children under 18 months is 0.17, and for children over 18 months 0.22. Values above these figures suggest intrathecal IgG synthesis. | The upper limit of normal for children under 18 months is 0.17, and for children over 18 months 0.22. Values above these figures suggest intrathecal IgG synthesis. | ||
- | {{ investigations: | + | {{ content: |
The ' | The ' | ||
- | {{ investigations: | + | {{ content: |
In the above calculations the degree of intrathecal IgG synthesis may be falsely elevated when measurements are made after a traumatic lumbar puncture. | In the above calculations the degree of intrathecal IgG synthesis may be falsely elevated when measurements are made after a traumatic lumbar puncture. | ||
- | Immunoglobulin - qualitative: | + | |
+ | **Immunoglobulin - qualitative: | ||
The presence of two or more bands of immunoglobulin on isoelectric focusing (IEF) of CSF is referred to as ' | The presence of two or more bands of immunoglobulin on isoelectric focusing (IEF) of CSF is referred to as ' | ||
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Although it has been suggested that in adults - where multiple sclerosis is a predominant condition - it is only necessary to request IEF for OCB, in children it is wise to request both quantitative (CSF:serum IgG index) and qualitative (isoelectric focusing for OCB) measures to determine whether there is local CSF IgG synthesis. | Although it has been suggested that in adults - where multiple sclerosis is a predominant condition - it is only necessary to request IEF for OCB, in children it is wise to request both quantitative (CSF:serum IgG index) and qualitative (isoelectric focusing for OCB) measures to determine whether there is local CSF IgG synthesis. | ||
===== Asialotransferrin ===== | ===== Asialotransferrin ===== | ||
- | The proportion of asialotransferrin ([[: | + | The proportion of asialotransferrin ([[: |
===== Myelin basic protein ===== | ===== Myelin basic protein ===== | ||
- | This component of myelin may be found in increased quantities at the time of acute demyelination (as in [[: | + | This component of myelin may be found in increased quantities at the time of acute demyelination (as in [[: |
===== Cytokines ===== | ===== Cytokines ===== | ||
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* acute neurological systemic lupus erythematosus. | * acute neurological systemic lupus erythematosus. | ||
===== Indications for CSF examination ===== | ===== Indications for CSF examination ===== | ||
- | Lumbar puncture is indicated in all cases of suspect meningitis or encephalitis, | + | Lumbar puncture is indicated in all cases of suspect meningitis or encephalitis, |
- | The remaining indications may be summarized as follows (with findings in parentheses). | ||
* Acute polyneuropathy or Guillain-Barre syndrome ⇒ increased total protein without increased cells. | * Acute polyneuropathy or Guillain-Barre syndrome ⇒ increased total protein without increased cells. | ||
* Suspect poliomyelitis ⇒ increased cells - lymphocytes and/or polymorphs. | * Suspect poliomyelitis ⇒ increased cells - lymphocytes and/or polymorphs. |