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content:cerebrospinal_fluid [2020/02/02 11:41] – [Myelin basic protein] icnacontent:cerebrospinal_fluid [2022/04/30 11:31] (current) – administrator@icnapedia.org
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 ====== Cerebrospinal fluid (CSF) ====== ====== Cerebrospinal fluid (CSF) ======
 +{{tag>labtests}}
 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  must always be taken at the same time as lumbar puncture (preferably immediately before) to allow proper interpretation of CSF findings. 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  must always be taken at the same time as lumbar puncture (preferably immediately before) to allow proper interpretation of CSF findings.
 ===== Appearance ===== ===== Appearance =====
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 In the neonatal period and later, a white blood cell (WBC) count up to 5/mm<sup>3</sup> is normal. The distribution is skewed to smaller numbers, such that the median neonatal WBC count is 1/mm<sup>3</sup>. Even 1 neutrophil/mm<sup>3</sup> should be considered as abnormal. The recognition of CSF malignant cells requires specialist expertise, but eosinophils are detectable with standard staining. In the neonatal period and later, a white blood cell (WBC) count up to 5/mm<sup>3</sup> is normal. The distribution is skewed to smaller numbers, such that the median neonatal WBC count is 1/mm<sup>3</sup>. Even 1 neutrophil/mm<sup>3</sup> should be considered as abnormal. The recognition of CSF malignant cells requires specialist expertise, but eosinophils are detectable with standard staining.
  
-Adjustment of CSF white blood cell counts in traumatic taps has been shown to be of little diagnostic utility[(:cite:18989240>{{pubmed>long:18989240}})].+Adjustment of CSF white blood cell counts in traumatic taps has been shown to be of little diagnostic utility[(:cite:18989240>{{pmid>long:18989240}})].
 ===== Protein ===== ===== Protein =====
 The protein in the CSF consists mostly of albumin, synthesized entirely extrathecally, and immunoglobulins - IgG, etc. - synthesized both extrathecally and intrathecally. The protein in the CSF consists mostly of albumin, synthesized entirely extrathecally, and immunoglobulins - IgG, etc. - synthesized both extrathecally and intrathecally.
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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)[(:cite:21492866>{{pubmed>long:21492866}})] but, as with similar calculations on cell counts, caution is indicated.+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)[(:cite:21492866>{{pmid>long:21492866}})] but, as with similar calculations on cell counts, caution is indicated.
 ===== 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 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 ([[:desialotransferrin]], tau protein, t protein) to total transferrin may be measured simply, quickly and cheaply by 2D gel electrophoresis. Normally asialotransferrin forms more than 8% of CSF transferrin, but in [[:elf2b-relaled_disorders]] ([[:vanishing_white_matter_disease]] and several other phenotypes) it is below 8%. Although this test has not yet been validated in infancy, from toddlerhood onwards it has a high degree of sensitivity and specificity to predict mutations in the genes responsible for one of the five subunits of [[:elf2b]]. It may be a first-line investigation once a leukoencephalopathy has been detected on MRI/MRS.+The proportion of asialotransferrin ([[:desialotransferrin]], tau protein, t protein) to total transferrin may be measured simply, quickly and cheaply by 2D gel electrophoresis. Normally asialotransferrin forms more than 8% of CSF transferrin, but in [[:elf2b-relaled_disorders|elf2b related disorders]] ([[:vanishing_white_matter_disease|vanishing white matter disease]] and several other phenotypes) it is below 8%. Although this test has not yet been validated in infancy, from toddlerhood onwards it has a high degree of sensitivity and specificity to predict mutations in the genes responsible for one of the five subunits of [[:elf2b]]. It may be a first-line investigation once a leukoencephalopathy has been detected on MRI/MRS.
  
 ===== Myelin basic protein ===== ===== Myelin basic protein =====
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