CEREBROSPINAL FLUIDCSF

DR. U. RATHNA KUMARIMD – Post Graduate

IPEM

Liquor cerebrospinalis

• A clear, colorless fluid that surrounds and permeates the CNS.

• Offers support, protection and nourishment.

• In essence, the brain "floats" in it.

• Cerebrospinal fluid (CSF) is a clear fluid present in the ventricles of the brain, the central canal of the spinal cord, and the subarachnoid space.

• CSF is produced in the brain by modified ependymal cells in the choroid plexus (approx. 50-70%), and the remainder is formed around blood vessels and along ventricular walls. 

Functions of CSF

• Protects, lubricates the brain• Provides nutrients, removes waste 90-150 ml adult 10-60 ml in newborn• Modulates pressure changes (Buoyancy) • Serves as a chemical buffer to maintain

constant ionic environment• Serves as a transport medium for

nutrients and metabolites, endocrine substances and even neurotransmitters

Location of CSF

• Two lateral ventricles

• Third ventricle

• Fourth ventricle

• Spinal cord central canal

• Subarachnoid space

• Continuous with extracellular fluid of brain parenchyma

• CSF flows through the subarachnoid space between the arachnoid and pia mater

• 20 ml of fluid produced every hr in choroids plexus and reabsorbed by arachnoid villi

Formation of CSF

• Choroid plexuses of lateral, third and fourth ventricles

• Ependymal lining of ventricular system• Pia-glial membrane• Blood vessels• Cells are believed to actively secrete Na+ into the

ventricular system in exchange for K+. Sodium ions electrically attract Cl- and osmotically draw water from the blood vascular system to constitute the CSF.

Circulation of CSFLateral ventricles

interventricular foramen of Monroe

third ventricle

mesencephalic aqueduct (aqueduct of Sylvius)

fourth ventricle

spinal cord central canal; also, out the lateral apertures to the subarachnoid space

to the venous system

• foramina of Magendie (Median aperture) and foramina of Luschka(Lateral apertures);

Circulates,

• Due to pulsation of blood in choroid plexus

• Due to pulsation of ependymal cells

Circulation of CSF

Absorption of CSF

1. Through the arachnoid villi, a protrusion of arachnoid membrane into the central venous sinus and other sinuses

• A valve opens when CSF pressure exceeds venous pressure

2. Absorption by veins and capillaries of CNS

arachnoid granulation

• It is suggested that CSF flow along the cranial nerves and spinal nerve roots allow it into the lymphatic channels.

• plays a substantial role in CSF reabsorbtion, in the neonate, where arachnoid granulations are sparsely distributed.

Absorption of CSF

Composition of CSF

Normal CSF

• Thin, colourless, clear fluid• Pressure 90-180mm WATER (10-100 neonates)• 0-5 WBC’s /mm3 (neonates 0-30/ mm3 ) (Lymphocytes & monocytes)• Occasional ependymal or choroid plexus cells• Protein 15-45mg/dl• Glucose 50-80mg/dl• Chloride 113-130 mEq/L• Sterile

CSF GLUCOSE

• Glucose enters the CSF by selective transport across the blood-brain barrier.

• normal value 60 – 70 percent that of the plasma glucose.

• The diagnostic significance. low CSF glucose can be considerable

diagnostic value in determining the causative agents in meningitis.

Clinical significance of elevated protein values

• Elevated total protein values are most frequently seen in pathologic conditions.

• elevated CSF protein due to damage to the blood brain barrier.

CSF GLUTAMINE

• Glutamine is produced in the CNS by the brain cells from ammonia and alpha-ketoglutarate.

• removes the toxic metabolic waste product ammonia from the CNS.

• Normal concentration of ammonia is 8-18 mg/dl.

• Elevated levels associated with liver disorders.

CSF LACTATE

• Aid in the diagnosis and management of meningitis cases

• Destruction of tissue within the CNS owing to oxygen deprivation (hypoxia) causes the production of increased CSF lactic acid levels.

Blood-Brain Barrier (BBB)

• physiological barrier to flow of substances from blood to brain tissue

• The BBB functions to preserve a stable environment for neurons of the CNS

Blood-Brain Barrier (BBB)

Brain capillary

• Tight junctions• Surrounded by astrocytes• Carrier mediated transport of glucose and amino

acids

Blood-Brain Barrier

• Lipid soluble molecules will cross easily.

• High CO2/low O2 produce vasodilation and decrease resistance of BBB

• Injury or inflammation

decreases the resistance of BBB (allows some antibiotics to be used for treatment)

Circumventricular organs (CVO)

• Selected brain areas are not protected by the BBB – the circumventricular organs (CVO) bordering on the 3rd and 4th ventricles– parts of the hypothalamus - median eminence– neurohypophysis– pineal gland– area postrema– subfornical organ– subcommissural organ

Hydrocephalus

• An abnormal increase in the volume of CSF

• Symptoms: sleep changes, spastic paresis, papilledema, bulging of skull in young, seizures, cranial nerve deficits, depression.

Hydrocephalus

CAUSES OF HYDROCEPHALUS

• Meningitis: pneumococcal, TB

• Intrauterine infections

• IVH

• Lesions, Tumors or malformations of the posterior fossa

PATHOLOGY• AQUEDUCTAL STENOSIS:

– Abnormally narrow aqueductus of sylvius.

Hydrocephalus

• Communicating

– due to excessive formation of CSF or lack of absorption

•Non-communicating – due to obstruction of flow through ventricle system

Ventriculo-peritoneal shunts

Jugular compression maneuver (Queckenstedt maneuver)

• Compress jugular veins in neck - increases CSF pressure at the cerebellomedullary cistern and the lumbar cistern (normal)

• Decreased pressure at lumbar cistern indicates blockage of spinal central canal

Lumbar puncture

• a lumbar puncture (or LP, and colloquially known as a spinal tap)

• is a diagnostic  procedure that is performed in order to collect a sample of cerebrospinal fluid (CSF) for biochemical, microbiological, and cytological analysis

lumbar puncture

Spinal cord terminates at L1; needle entry must occur distal to this location

Proper angle of entry through the L3-L4 interspace

full flexion

Level of entry

Spinal needle

Spinal needle

Under strict aseptic precautions.,

Lp - layers

1- Skin2- Facia and SC fat3- Surpaspinous ligament4- Interspinous ligament5- Ligamentum flavum6- Epidural space (epidural anesthesia needle stops here)7- Dura8- arachnoid

Right after that the needle pops into the subarachnoid space where the CSF is.

The opening pressure 

Collecting the CSF

Appearance of CSF

• clear and colourless (normal); • bright red - This indicates the presence of blood.

The appearance of fresh blood in all three tubes supports the diagnosis of a subarachnoid hemorrhage.

• xanthochromic (yellow) - jaundice • xanthochromic (yellow) - suggests a

subarachnoid hemorrhage has recently occurred • turbid - This indicates the presence of white cells

and is suggestive of a CNS infection.

Cell counts

• increased neutrophils - This indicates a bacterial meningitis, cerebral abscess,

• increased lymphocytes - This indicates a viral meningitis, tuberculosis, syphilis, fungal and parasitic infections.

• Degenerative diseases of the CNS, such as multiple sclerosis, will also generate elevated lymphocyte counts.