Cerebrospinal Fluid Analysis

Vocabulary flashcards covering the formation, anatomy, specimen collection, physical characteristics, microscopic analysis, and chemical testing of cerebrospinal fluid as presented in Chapter 10 of Graff’s Textbook of Urinalysis and Body Fluids.

Dura mater

The outer layer of the meninges lining the skull and vertebral canal; Latin for "Hard-mother."

Arachnoid

The filamentous inner layer of the meninges; Latin for "Spiderweb-like."

Pia Mater

The thin membrane lining the surface of the brain and spinal cord; Latin for "Gentle-mother."

Choroid plexus

Capillary networks in the two lumbar ventricles and the third and fourth ventricles that form CSF through selective filtration under hydrostatic pressure and active transport secretion.

Blood-brain barrier

Endothelial cells of the choroid plexus with tight-fitting junctures that prevent the passage of many molecules, including medications and antibiotics, into the CNS.

Arachnoid granulations

A series of one-way valves through which CSF is reabsorbed back into the blood capillaries at a rate equal to production.

Xanthochromia

A term describing CSF supernatant that is pink, orange, or yellow after centrifuging; most commonly caused by red blood cell degradation products from an old bleed.

Tube 1 (CSF Collection)

The first tube collected during lumbar puncture, designated for clinical chemistry and serological testing; it is least affected by blood or bacteria introduced by the tap.

Tube 2 (CSF Collection)

The second tube collected during lumbar puncture, designated for microbiology laboratory testing.

Tube 3 (CSF Collection)

The third tube collected during lumbar puncture, designated for hematology (cell count) because it is least likely to contain cells introduced by the spinal tap.

Pleocytosis

The increase of white blood cells ($WBCs$) in a body fluid such as CSF.

Neutrophilic pleocytosis

An increase in neutrophils in CSF, associated with bacterial meningitis, cerebral abscess, and the early stages of other forms of meningitis.

Lymphocytic pleocytosis

An increase in lymphocytes in CSF, associated with later stages of viral, tubercular, fungal, and syphilitic meningitis.

Siderophages

Macrophages containing stored iron (hemosiderin), typically appearing in the CSF $2-4$ days after a CNS hemorrhage.

Lipophage

A macrophage with ingested fat (fat inclusions) that may be seen in CSF following a brain infarct.

PAM cells

Pia arachnoid epithelial cells; lining cells that may be a normal finding in neonates or increased in children with hydrocephalus.

CSF/serum albumin index

A measurement used to determine the degree of permeability of the blood-brain barrier; index values between $9-14$ indicate slight impairment, while values $>30$ indicate severe impairment.

Oligoclonal bands

Bands located in the gamma region during CSF protein electrophoresis that are present in CSF but not serum; used to help establish a diagnosis of multiple sclerosis.

Myelin Basic Protein (MBP)

A protein residing in the myelin sheath; levels in CSF greater than $4\,ng/mL$ can indicate demyelinating diseases like multiple sclerosis.

tau transferrin

A carbohydrate-deficient "CSF-specific" transferrin ($\beta_2-transferrin$) made primarily by the CNS; discovery of this band confirms diagnoses of otorrhea and rhinorrhea.

CSF Lactate

A product of CNS anaerobic metabolism; levels greater than $35\,mg/dL$ often help differentiate bacterial, fungal, and tubercular meningitis from viral meningitis.

Pellicle

A clot formation in CSF specifically associated with tubercular meningitis.

India Ink

A stain used to identify Cryptococcus neoformans in CSF, often having a sensitivity of $25-50\%$.