Chapter 13: Diagnostic tests
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Related theory
Abnormalities of cerebrospinal fluid
Blood
Red discolouration of the CSF is indicative of the presence of blood. If the presence of blood is caused by a traumatic spinal tap, the blood will usually clot and the fluid will clear as the procedure continues. If the presence of blood is due to subarachnoid haemorrhage, no clotting will occur (Lindsay et al. [126], Pagana and Pagana [177]).
Colour
Hyperbilirubinaemia, hypercarotenaemia, melanoma and elevated protein levels can each cause a change in the colour of the CSF. A cloudy CSF is indicative of the presence of a large number of white cells or protein.
Cells
The presence of different types of blood cells in the CSF can be diagnostic of a variety of neurological disorders:
- Erythrocytes are indicative of haemorrhage.
- Neutrophils (polymorphonuclear leukocytes) are indicative of bacterial meningitis, a cerebral abscess.
- Neutrophils (mononuclear leukocytes) are indicative of viral or tubercular meningitis or encephalitis.
- Monocytes are indicative of a viral or tubercular meningitis or encephalitis.
- Lymphocytes present in larger numbers are indicative of viral, tubercular, fungal or syphilitic meningitis or infiltration of the meninges by malignant disease.
- The presence of leukaemic blast cells is indicative of infiltration of the meninges by leukaemia.
- Viral, bacterial and fungal cultures from the CSF sample are indicative of infection (Barker and Laia [10], Pagana and Pagana [177]).
