CSF Analysis is The investigation of clinical disorders of the central nervous system (CNS) and brain and spinal cord and it is partly based on the examination of cerebrospinal fluid (CSF analysis). 

CSF Analysis | Cerebrospinal fluid (CSF) analysis 

CEREBROSPINAL FLUID (CSF)--The investigation of clinical disorder of the central nervous system (CNS) is partly based on the examination of cerebrospinal fluid (CSF analysis). The central nervous system consists of the brain, spinal cord, and peripheral nerves.

CSF Analysis  Cerebrospinal fluid (CSF) analysis

The brain is encased within the cranial cavity and weighs about one-fifth of the body weight. Structurally it is partitioned into the cerebrum (greater brain), the brain stem (midbrain, pons Varolii and medulla oblongata), and the cerebellum (lesser brain)

The brain is encased within the cranial cavity and weighs about one-fifth of the body weight. Structurally it is partitioned into the cerebrum (greater brain), the brain stem (midbrain, pons Varolii, and medulla oblongata), and the cerebellum (lesser brain)

Layers of meningitis

The brain is protected by the cranium, and the spinal cord by the vertebral column. The brain and the spinal cord are covered by three membranes collectively called the meninges. The meninges consist of

1. An outer protective membrane is called the dura mater.
2. A middle membrane is called the arachnoid mater.
3. An inner membrane called the pia mater

 

CSF Analysis | Cerebrospinal fluid (CSF) analysis 

The arachnoid mater and the pia mater are separated from each other by the subarachnoid space which is filled with the cerebrospinal fluid. There is a subdural space Between the dura mater and the arachnoid mater.

Formation of Cerebrospinal Fluid (CSF)

The lateral ventricle is a large irregularly shaped chamber that lies deep within each cerebral hemisphere. Within these lateral ventricles are vascular structures called choroid plexuses where the CSF is formed. The cells of the choroid plexus actively secrete CSF. The fluid passes into the third ventricle via the interventricular foramen of Monro before flowing down to the cerebral aqueduct into a fourth ventricle.

 

The fourth ventricle lies between the pons and cerebellum of the brain. The CSF then flows from the fourth ventricle down the small central canal of the spinal cord and through openings (foramina) into the subarachnoid space to completely surround the brain and the spinal cord. Small blood vessels in the arachnoid mater constantly reabsorb CSF in circulation so that the production is balanced by equal reabsorption of fluid.

 

Functions of CSF (Cerebrospinal Fluid)

1. Cerebrospinal Fluid provides a "fluid cushion" to support and protect the brain and the spinal cord.
2. It acts as a shock absorber for the brain and the spinal cord.
3. It carries nutrients to the brain and spinal cord and removes waste products.
4. It helps to maintain constant pressure inside the head and around the spinal cord.
5. It keeps the brain and spinal cord moist.

Collecting CSF (Lumbar Puncture)

 A specimen of CSF is collected by a lumbar puncture, using a long needle with a stylet inside. The needle is introduced between the third and fourth lumbar vertebrae into the spinal subarachnoid space with the patient's back well flexed for good separation of the vertebrae. It is a very critical operation and damage to the spinal cord can easily occur.

The cord stops at the level of the first lumbar vertebra and cannot be damaged by the needle entering the subarachnoid space a few centimeters lower.

The CSF is usually collected into 2 or 3 sterile containers, numbered according to the order of collection, each containing about 1-3ml of CSF.

Possible complications of lumbar puncture

1. Production of cerebellar pressure cone in patients with increased intracranial pressure.
2. In the case of a spinal cord tumor, paresis may progress to paralysis as a result of lumbar puncture.
3. During the whole process of lumbar puncture, an infection can inadvertently be introduced by

(a) The use of unsterile equipment

(b) bypassing the needle through a septic spot in the lumbar region,(c) by not observing aseptic precautions.

4. After-puncture headache as a result of leakage of CSF. This condition can be minimized by using a small-bore needle. 

Indications for CSF examination

1. Diagnosis and detection of suspected meningitis, subarachnoid hemorrhage, encephalitis, central nervous system syphilis, spinal cord tumor, or multiple sclerosis.
2. Differential diagnosis of cerebral infarction from intracerebral hemorrhage (about 80 % of the latter show xanthochromia or bloody appearance of CSF).

Composition of CSF (Cerebrospinal Fluid)

 The CSF is mainly composed of water, dissolved oxygen, and solids. The average volume is between 100 ml and 150 ml which is produced at the rate of 430 ml/day. It is similar to plasma in composition, but the concentrations of sodium, chloride, magnesium, and glutamine are greater in CSF than in plasma; while concentrations of glucose, potassium, calcium, cholesterol, uric acid, and iron are higher in plasma. The table shows the composition of normal CSF.

 

 

Composition of normal  Cerebrospinal Fluid (CSF)
Volume	100-150ml
Total protein	0.15-0.45g/dl
Glucose	3-4.5 mmol/l (50-80mg%)
chloride	118-134 mmol/l
Sodium	144-154 mmol/l
PH	7.3-7.4
CELLS	0-5 Lymphocytes/cu.mm

 

Routine Laboratory Examination Of  CSF Analysis (Cerebrospinal Fluid)