Presentation on theme: "CEREBROSPINAL FLUID BY Hossam HASSAN"— Presentation transcript:
1 CEREBROSPINAL FLUID BY Hossam HASSAN Welcome to first session of Unit 4 - Cerebrospinal FluidPlease carefully follow your course objectives as you move through this unit.
2 Overview of Body Fluid Analysis Laboratory exam of body fluidsPhysical characteristicsChemical constituentsMorphologic elementsCulture for microorganismsAncillary studiesBody fluids, other than urine are not easily obtained – usually requiring the insertion of a needle deeply into a normally sterile cavity .There are inherit risks involved.The sample obtained is usually of a small volume and is very fragile.The results of the tests often have significant impact on the treatment and prognosis for the patient.Therefore Laboratories that offer tests on these body fluids must be able to provide Accurate & timely results as well as be a Source of information for , normal values, reliability of the results, and Proper specimen collection and handling.Depending on the physicians reason for drawing the body fluid, the examination involves evaluation of the Physical characteristics, Chemical analysis, microscopic review of the cells and other Morphologic elements as well as culturing for microorganisms. Ancillary or other special studies may be done in-house, or sent to a reference lab.
3 Cerebrospinal Fluid (CSF) Composition and formationCSF is the 3rd major fluid of the bodyAdult volume mLNeonate volume mLComposition and formationCSF is the 3rd major fluid of the body after blood and urine.Adult volume mLNeonate volume mL
4 Cerebrospinal Fluid (CSF) Produced at the Choroid plexus of the 4 ventricles by modified Ependymal cellsAt ml/day is producedCSF flows through the Subarachnoid spaceWhere a volume of 90 – 150 ml is maintained (adults)Reabsorbed at the Arachnoid villus / granulationto be eventually reabsorbed into the bloodCSF is Produced at the Choroid plexus of the 4 ventricles by modified Ependymal cells At ml / hr (adults)The CSF flows through the Subarachnoid space where the appropirate volume of the fluid is maintained (adults)The CSF is then Reabsorbed at the Arachnoid villus / granulation and is eventually reabsorbed into the bloodThis pattern of flow is shown in the drawing from the Strassinger reference textbookMed training 150 ml/day is produced.
5 Cerebrospinal Fluid (CSF) Blood Brain BarrierOccurs due to tight fitting endothelial cells that prevent filtration of larger molecules.Controls / restricts / filters blood componentsRestricts entry of large molecules, cells, etc.Therefore CSF composition is unlike blood’s** CSF is NOT an ultrafiltrateThere is a secure barrier between the blood and the csf fluids that surround the brain called the Blood Brain BarrierThis barrier is due to the tight fitting endothelial cells that prevent filtration of larger moleculesDue to the blood brain barrier, CSF composition is very different from that of plasma.And therefore CSF is NOT considered an ultrafiltrate of plasma.TjhereforControls / restricts / filters blood componentsRestricts entry of large molecules, cells, etc.Therefore CSF composition is unlike blood’s**
6 Cerebrospinal Fluid (CSF) Blood Brain BarrierEssential to protect the brainBlocks chemicals, harmful substancesAntibodies and medications also blockedTests for those substances normally blocked can indicate level of disruption by diseases: ie meningitis and multiple sclerosis.The purpose of the Blood Brain Barrier is to protect the brain from chemicals, and other harmful substances . In this process, Antibodies and medications also blockedTesting for those substances normally blocked - can indicate the level of disruption by diseases: ie meningitis and multiple sclerosis.
7 Cerebrospinal Fluid (CSF) CSF functionsSupplies nutrients to nervous tissuesRemoves metabolic wastesProtects / cushions against traumaThere are 3 major functions of CSF . ItSupplies nutrients to nervous tissuesRemoves metabolic wastesProtects / cushions against trauma
8 Cerebrospinal Fluid (CSF) Four major categories of diseaseMeningeal infectionsSubarachnoid hemorrhageCNS malignancyDemyelinating diseaseThere are Four major categories of diseaseMeningeal infections – such as bacterial or viral meningitisSubarachnoid hemorrhage – commonly refereed to as a stroke.Central Nervous System malignancyDemyelinating disease - such a multiple sclerosis.
9 Cerebrospinal Fluid (CSF) Indications for analysisTo confirm diagnosis of meningitisEvaluate for intracranial hemorrhageDiagnose malignancies, leukemiaInvestigate central nervous system disordersFour categories of disease lead to 4 Indications for analysisCSF us analyzed To confirm diagnosis of meningitis , Evaluate for intracranial hemorrhage, toDiagnose malignancies, and leukemia and toInvestigate central nervous system disorders
10 Cerebrospinal Fluid (CSF) Specimen collection and handlingRoutinely collected via lumbar puncture between 3rd & 4th, or 4th & 5th lumbar vertebrae under sterile conditionsIntracranial pressure measurement taken before fluid is withdrawn.Specimen collection and handlingCSF is Routinely collected via lumbar puncture between 3rd & 4th, or 4th & 5th lumbar vertebrae under sterile conditionsOnce the puncture has been made, the first step is to measure the Intracranial pressure . This must be done before the fluid is removed..A low opening pressure is seen in trauma where there has been a loss of the csf fluid. and an increased pressure is diagnostic of intracranial hypertension – which is present in many pathological states including tumors, intracranial bleeding and meningitis.
12 Cerebrospinal Fluid (CSF) This slide from the web Adam series included only as a pictorial representation of the spinal puncture process.
13 Cerebrospinal Fluid (CSF) Specimen collection and handlingTube 1 – chemistries and serologyTube 2 – microbiology culturesTube 3 – hematologyTesting considered STATSpecimen potentially infectiousAs the spinal fluid is removed it is collected into a series of tubes. The tubes are numbered to indicate how the fluid was removed. In other words, The first fluid that is removed will go into tube 1, the next amout of fluid will be in tube 2 and so forth.Usually 3 tubes are collected, but sometimes you will see four tubes.Tube 1 – chemistries and serologyTube 2 – microbiology culturesTube 3 – hematologyIf there was a 4 th tube, usually the first tube is set aside – tube number 2 then becomes tube 1, tube 3 becomes number 2. Sounds confusing, but every thing just slides down a number.Keep in mind that the goal is to have the hematology tube be the last sample removed, so any cells present can be definitely said to have come from the spinal cannal and not a result of a traumic stick.All csf Testing considered STAT and always keep in mind that csf samples are potentially infectious
14 Cerebrospinal Fluid (CSF) Specimen collection and handlingIf immediate processing not possibleTube 1 (chem-sero) frozenTube 2 (micro) room tempTube 3 (hemo) refrigeratedI am a firm believer that CSF testing must be performed Stat. However, if immediate processing and testing is not possibleTube 1 (chem-sero) frozenTube 2 (micro) room tempTube 3 (hemo) refrigerated
15 Cerebrospinal Fluid (CSF) AppearanceNormal - Crystal clear, colorlessDescriptive Terms – hazy, cloudy, turbid, milky, bloody, xanthrochromicOften are quantitated – slight, moderate, marked, or grossly.Unclear specimens may contain increased lipids, proteins, cells or bacteria. Use precautions.Clots indicate traumatic tapMilky – increased lipidsOily – contaminated with x-raymediaCSF is Normally - Crystal clear, colorlessWhen its transparency is not clear - Appropriate descriptive Terms include – hazy, cloudy, turbid, milky, bloody,When the non-clear terms are used, they are Often quantitated – so you may see a designation such as slightly hazy, moderately cloudy, or grossly bloody. Etc/.Unclear specimens CSF specimens may contain increased lipids, proteins, cells or bacteria. Use precautions.\xanthrochromic is a term used to describe a yellow / yellow-orangeish colored csf/The picture in the slide shows how putting a newspaper behind the CSF sample can be used as aid in evaluating its clarity. The sample on the right is normal and the one on the left is moderately cloudy. –The cloudy sample is often an indication that it contains WBCs as would be seen in meningitis.Other reasons that the csf is not clear and colorless are also indicated on the slide.
16 Cerebrospinal Fluid (CSF) AppearanceXanthrochromic – Yellowing discoloration of supernatent (may be pinkish, or orange).Most commonly due to presence of ‘old’ blood.Other causes include increased bilirubin, carotene, proteins, melanomaXanthrochromia is a – Yellowing discoloration of the csf supernatent (may be pinkish, or orange).This term is unique to CSF samples.Xanthrochromia is Most commonly due to presence of ‘old’ blood. However it may be the result of increased bilirubin, or carotene,Other reasons may include proteins, melanomaAgain, xanthrochromia – usually indicates old blood or bilirubin
17 Cerebrospinal Fluid (CSF) AppearanceClots – indicates increased fibrinogen & usually due to traumatic tap, but may indicate damage to blood- brain barrier. (see below)Pellicle formation in refrigerated specimen associated with tubercular meningitis.Pellicle formation - picture at right (pellicle in L. tube, R is normal)Milky – increased lipidsOily – contaminated with x-ray mediaClots – indicates increased fibrinogen & usually due to traumatic tap, but may indicate damage to blood-brain barrier. (see below)Pellicle formation in refrigerated specimen associated with tubercular meningitis.An example of Pellicle formation is seen in the lower right picture.The tube at the far right is normal and pellicle webbing that is associated with tubularcar meningitis is seen in the left tube.A Milky appearing CSF likely contains increased lipidsAn Oily appearing CSF is sometime seen in samples that are – contaminated with x-ray /dye or contrast media
18 Traumatic collection vs cerebral hemorrhage Even distribution of blood in the numbered tubesClot formation possibleXanthrochromic supernatent– RBCs must have been in 2+ hours- D-dimer, fibrin degradation product from hemorrhage siteMicroscopic presence of erythrophages, or siderophages, Hemosiderin granulesWhen blood is found in the csf sample there is need to determine whether the blood’s presence is due to A bleed or Trauma during the collection or due to a cerebral hemorrhageThe characteristics of the Cerebral hemorrhage includeEven distribution of blood in the numbered tubes – the picture below left represents two consecutive csf tubes. As you can see, They both appear to have a similar amount of blood in them- as would be seen in the cerebral bleed.If there is sufficient blood and fibrinogen present, clots may be seen.After spinning the csf sample in the centriguge, a Xanthrochromic / yellow supernatent will be seen in the patients with cerebral bleed, if enough time has gone by.– The authors note that the RBCs must have been in 2+ hours before this process results in the xanthrocromia.Serological test for - D-dimer, - which is a fibrin degradation product may also be helpful information from hemorrhage siteOn the The Microscopic differential you may find erythrophages, and siderophages, as well as Hemosiderin granules and hemotoidion bars
19 Cerebrospinal Fluid (CSF) Expected resultsNormally 0 RBCs/uL regardless of ageWBCsAdult – up to 5 mononuclear WBCs/uLNewborn – up to 30 mononuclear WBCs/uLChildren (1-4) - up to 20 mononuclear /uLChildren (5+) – up to 10 mononuclear / uLIncreased numbers = PleocytosisNormally there are no RBCs found in the CSF.The normal value and type of WBCs depend on the patients ageAdults – up to 5 mononuclear WBCs/uLNewborns– up to 30 mononuclear WBCs/uLAnd the values for children are provided on the slidsChildren (1-4) - up to 20 mononuclear /uLChildren (5+) – up to 10 mononuclear / uLPleocytosis is the term used to indicate an increased number of cells.You can have a neutrophilic pleocytosis, lymphocytic pleocytosis, mixed cell pleocytosis, etc.
20 Cerebrospinal Fluid (CSF) WBC counts3% acetic acid can be used to lyse RBCMethylene blue staining will improve visibilityIf there are too many rbcs present to get an accurate wbc count, you can lyse the RBCs with 3% acetic acid. Using methylene blue stain will also help improve the visibility. If using a stain or lysing the rbcs with the acid, be sure you keep track of the dilution you are making and account for it in your calculation.
21 Cerebrospinal Fluid (CSF) Correction of WBC count for traumatic tap contamination.Uses ratio of WBCs to RBCs in blood and compares it to same ratio (WBC/RBC) in CSFIf patient’s peripheral cell counts are normal, can subtract 1 WBC for each 700 RBCs counted in CSF.Great chance for considerable error, makes this of little value.On occasion, it may be necessary to Correct the WBC count for traumatic tap contamination.Although I include the needed information on the slide, be warned that there are too many variables and assumptions that have to be made that would result in the possibility for considerable error..Before doing such a correction, consult with the department head or pathologist. He or she may want to consult with the attending physician to make them aware of the error that is possible. As the more appropriate process would be to to have the sample recollectedUses ratio of WBCs to RBCs in blood and compares it to same ratio (WBC/RBC) in CSFIf patient’s peripheral cell counts are normal, can subtract 1 WBC for each 700 RBCs counted in CSF.Great chance for considerable error, makes this of little value.
22 Differential Diagnosis of Meningitis by Laboratory Results BacterialViralTubercularFungalIncreased WBC countNeutrophilsLymphsLymps & MonosLymphs & MonosMarked ↑ proteinMod. ↑ proteinMod-Marked ↑ proteinMarked ↓ glucose↔ normal glucose↓ glucoseNormal to ↓ glucoseLactate > 35 mg/dLLactate normalLactate > 25 mg/dL+ gram stainsPellicle formation+ India ink with Cryptococcus neoformans+ bacterial antigen tests+ immunological test for C. neo.I have consolatatedI strongly encourage you to spend some time evaluating this chart that compares the various lab results seen in bacterial, viral tubuarlular and fungal meningitis.