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content:cerebrospinal_fluid [2020/02/01 20:17] – [Pressure] icna | content:cerebrospinal_fluid [2022/04/30 11:31] (current) – administrator@icnapedia.org | ||
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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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In the neonatal period and later, a white blood cell (WBC) count up to 5/ | In the neonatal period and later, a white blood cell (WBC) count up to 5/ | ||
- | Adjustment of CSF white blood cell counts in traumatic taps has been shown to be of little diagnostic utility[(: | + | Adjustment of CSF white blood cell counts in traumatic taps has been shown to be of little diagnostic utility[(: |
===== Protein ===== | ===== Protein ===== | ||
The protein in the CSF consists mostly of albumin, synthesized entirely extrathecally, | The protein in the CSF consists mostly of albumin, synthesized entirely extrathecally, | ||
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Increase in CSF protein (albumin) occurs when there is disruption of the blood-brain barrier (and notably in polyneuropathy). | Increase in CSF protein (albumin) occurs when there is disruption of the blood-brain barrier (and notably in polyneuropathy). | ||
- | Traumatic blood contamination may be expected to increase the CSF protein by around 1.1 mg/dL for every 1000 cell increase in CSF red blood cells per mm(3)[(: | + | Traumatic blood contamination may be expected to increase the CSF protein by around 1.1 mg/dL for every 1000 cell increase in CSF red blood cells per mm(3)[(: |
===== Albumin ===== | ===== Albumin ===== | ||
The concentration of Albumin in CSF is a reflection of the blood-CSF carrier since it comes entirely from outside the CSF. | The concentration of Albumin in CSF is a reflection of the blood-CSF carrier since it comes entirely from outside the CSF. | ||
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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 ===== |