Cerebrospinal fluid analysis - significance, procedure and informative value of the examination of the cerebrospinal fluid

The liquor analysis is a diagnostic examination of the liquor cerebrospinalis (also known as cerebrospinal fluid): nervous fluid or cerebrospinal fluid). It is used to assess diseases of the central nervous system (CNS) such as inflammations, infections, haemorrhages, neurodegenerative or autoimmune diseases. The cerebrospinal fluid surrounds the brain and spinal cord and fulfils important functions such as protection, transport of substances and pressure regulation.

When is a CSF analysis useful?

Cerebrospinal fluid analysis is used for the following clinical questions:

• Suspicion of meningitis (inflammation of the meninges) or encephalitis

• Multiple sclerosis or other demyelinating diseases

• Neurodegenerative diseases (e.g. Alzheimer's, Parkinson's, Creutzfeldt-Jakob)

• Haemorrhages in the subarachnoid space

• Suspected tumour in the CNS or meningeosis carcinomatosa

• Clarification of unclear neurological symptoms (e.g. headache, dizziness, seizures, paralysis)

Cerebrospinal fluid analysis is also becoming increasingly important in research into biomarker-based early diagnoses, such as Alzheimer's or Parkinson's disease.

Procedure of the examination

The lumbar puncture is usually performed in the area of the lumbar spine (between L3/L4 or L4/L5):

• The patient is sitting or lying on their side

• A fine puncture needle is inserted into the cerebrospinal fluid space (subarachnoid space)

• In most cases, 5-15 ml of CSF is removed

The procedure is usually low-risk, but can lead to headaches or back pain in the short term.

What is analysed in the cerebrospinal fluid?

The laboratory analysis includes, depending on the question:

• Cell count and cell differentiation (e.g. increased in inflammation)

• Total protein and albumin quotient to assess the blood-cerebrospinal fluid barrier

• Glucose and lactate concentration (e.g. altered in bacterial infections)

• Specific antibodies (e.g. in multiple sclerosis: oligoclonal bands)

• Pathogen detection (PCR, culture, antigen tests) in case of suspected infection

• Biomarkers such as β-amyloid, tau protein, phosphorylated tau in Alzheimer's

Informative value

Cerebrospinal fluid analysis provides important indications of inflammatory, infectious or neurodegenerative processes in the brain or spinal cord. In many cases, it can contribute to early diagnosis or confirm differential diagnoses

Example: In Alzheimer's, the analysis typically shows:

• Low β-amyloid 1-42

• Increased total tau and phosphorylated tau
  The detection of multiple sclerosis can also be diagnostic in oligoclonal bands in the cerebrospinal fluid

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Literature references:

• Rauer, S. et al. (2018). "Guideline on cerebrospinal fluid diagnostics." German Society of Neurology (DGN)

• Tumani, H. et al. (2017). "The cerebrospinal fluid - a window to the brain." Deutsches Ärzteblatt

• Robert Koch Institute (2023). "Pathogen detection in cerebrospinal fluid - laboratory and reporting obligations."