Cerebrospinal fluid and meninges

Student: Gustavo Duarte Viana, Gomo M.S.Group: 17

Kursk State Medical University2012

What is liquor cerebralis? Clear liquid, derived from

the plasma and circulates around the brain and its cavities (ventricles) and spinal cord.

The volume of spinal fluid in an adult is approximately 2.0 ml per kg, or approximately 150ml. In infants up to 4 weeks, average 10 to 60 mL.

500mL/day about.

Quantity of cerebrospinal fluid

Location of the cerebrospinal fluid Cerebrospinal fluid originates

in the choroid plexus. The choroid plexus is composed of a mass of tiny blood vessels that are located in the lateral third and fourth ventricles.

The remaining CSF, approximately 30%, is formed in other places like the sub-arachnoid and ependymal layer of the ventricles.

The CSF is formed in the lateral ventricles, circulates through the interventricular foramen ( foramen of Monro) into the third ventricle which has one more choroid plexus and is going accumulating, and then via the cerebral aqueduct into the fourth ventricle, where has one more choroid plexus to produce more cerebrospinal fluid. Here the fluid scapes via the lateral apertures (Luschka, opening to the brain) and the medial foramen (Magendie, opening to the spinal cord) of the fourth ventricle into the subarachnoid spaces, where it diffuses over the brain and spinal cord and from the cisterns it circulates through the freely communicating subarachnoid cisterns at the base of the brain, most of the CSF is directed upward over the cerebral hemispheres and smaller amounts pass downward around the spinal cord. It has been calculated that 430 to 500 ml of CSF are produced every day, so the fluid must be changed every 6 to 7 hours. Respiratory and circulatory changes are believed to change the pressure within the closed system and promote the mixing and diffusion of fluid for reabsorption into venous sinus blood via arachnoids granulations.

Circulation of the cerebrospinal fluid

Illustrational picture of the circulation of the cerebrospinal fluid

Protecting the brain and spine trauma. Supplying nutrient to the nervous tissue. Remove degradation products of cellular metabolism. Serves as a pathway for pineal secretions to reach the

pituitary gland

Three main functions of the cerebrospinal fluid

Chemical level

Sodium 136.0 – 150 .0 m Eg/L

Potassium 2.3 – 2.7 m Eg/L

Chloride 1180.0 – 130.0 m Eg/L

Magnesium 2.4 – 3.0 m Eg/L

Protein 20 – 4 gm/dl (normally diffuses in blood-brain-barrier)

Glucose 45.0 – 60.0 gm/dl

Calcium 2.1- 2.7 m Eg/L

Cholesterol Present in small amount

Creatinine 0.5 – 1.2 gm/dl

Latic acid deohydrogenase Present in small amount

Phosphorus (inorganic) 1.0 – 2.0 gm/dl

Urea 6.0 – 16.0 gm/dl

Uric acid 0.5 – 3.0 gm/dl

Examples of chemicals present in the CSF

1. Pulsation of the cerebral & spinal arteries

2. Movements of the vertebral column

3. Respiration & coughing

4. Changing of the positions

Factors that facilitate the flow of CSF in subarachnoid space

CSF sample is obtained by a physician, usually via lumbar puncture in the region L3 andL4.

Sterile technique is often used to reduce the risk of infection.

Care must be taken to avoid damage to neural tissue. Although the sub-araquinoid can be accessed

from other levels, the lower back is preferable, because the needle is inserted below the end of the spinal cord.

Collection of the cerebrospinal fluid

A syringe is used to collect 6 to 15 ml (babies and small children).

Sample is divided into 3 or 4 tubes (glass tubes should be avoided due to cell adhesion).

2 to 4 ml are placed in each tube.

The tubes are numbered in the order they are obtained.

Collection of the cerebrospinal fluid

Tube 1: chemical and serological test

Tube 2: Microbiological test

Tube 3: Hematological test

Tube 4: cytological and Miscellaneous

Each tube is used for a specific purpose:

important precaution The opening pressure is always measured (90-180 mm of

water), it is high, greater than200 mm, not more than 2 mL of CSF should be removed.High pressure:Eg ICC, meningitis, cerebral edema.Reduced pressure:Eg dehydration, circulatory collapse, loss of CSF.

colorless

clear

Absence of clot

Density 1.006 to 1.008

pH 7.3

When the sample is received in the laboratory microscopic examination is performed immediately.

general characteristics of the cerebrospinal fluid

One or more are found:•turbidity•Clot / film•bloody appearance•xanthochromic

abnormalities of the cerebrospinal fluid.

Turbidity can be caused by leukocytes, erythrocytes, fungi, bacteria, parasites, contrast media, etc.

200 WBC / microl can cause slight turbidity, the greater number of leukocytes = higher turbidity,

At least 400 RBC / microl are needed to cause slight turbidity,

May appear oily after radiological procedures

turbity

Clot is always abnormal and is always due to increased level of proteins, especially fibrinogen,

The clot formation is common in protein levels above 1,000 mg / dL (also present at lower levels)

Film is composed of fibrinogen and white blood cells,

clot / pellicle

Specimens from patients who suffered subarachnoid hemorrhage or cerebral haemorrhage may have a pink-

colored supernatant and yellow when the sample is centrifuged within an hour after you collected.The term that describes

the colored supernatant is xanthochromic. The color varies with the substance that causes the coloration and the time interval after the incident that the sample is examined.

Xanthochromic

Meningis are menbrane covering the brain and spinal cord.

Meningis consists of three menbranes. 1- Dura mater 2- arachinoid mater 3- Pia mater strong “tough mater” spidery, holds blood vessesl “delicate mother”A- Falx cerebriB- Falx cerebelliC- Tentorium cerebelliD- Diaphragma sella

Meningis

The meninges

Thick dense inelastic membrane and the outermost layer of the meninges.(pachymeninx)

Bilaminar: • Endosteal layer: ◦Peristoneum, inner surface of the skull bone. ◦Not contineous with dura mater of the spinal cord. • Meningeal layer: ◦Dura mater proper covering the brain and contineous with

dura mater of the spinal cord. ◦Folded inwards as 4 septa between part of the brain. ◦The function of this septa is restrict the rotatory

displacement of the brain. They are closely united except along certain lines, where they

separate to form venous sinuses.

Dura mater

1. Falx cerebri- lies between the cerebral hemisphere in the longitudinal cerebral fissure.

◦contains the superior and inferior sagittal sinuses between its two layers. 2. Falx cerebelli- it is a small sickle-shaped fold, attached to the internal

occipital crest and projects forward between the two hemispheres of the cerebellum.

3. Temtorium sellae- separates posterior cranial fossa from the middle cranial fossa.

◦ separates the occipital and temporal lobes from the cerebellum and intentorial brainstem.

4. Diaphragma sellae – forms the roof of the hypophyseal fossa. ◦ contains an aperture through which the hypophyseal stalk

(infundibulum) passes.

Septa of the dura mate

Septa of the meningesFalx cerebri

Falx cerebeli

Tentorium cerebeli

Diaphragma Sellae

Falx cerebi

Tentorium cerebeli

Delicate, impermeable and avascular membrane covering the brain.

Lying between dura and pia mater. Separete from dura mater by a potential space, the

subdural space. Separed from pia mater by the arachinoid space. The outer and inner surface are covered with flattened

mosothelial cells.

Arachinoid mater

1- epidural space- is located between the peristoneum and the outer layer of the Dura mater, contains venous tissue, loose connective tissue and lymphatics.

2-subdural space – is a potential space between the Dura and Arachinoid mater, intracranially transmits the superior cerebral veins venous lacunae of the superior sagittal sinus.

3- arachnoids space- located between the Arachinoid and Pia mater, contains the CFS, surrounds the entire brain and spinal cord.

Spaces between the meninges

Pia mater (leptomeninx) is a delicate and highly vascular membrane, closely covers the surface of the brain and spinal cord.

Filum terminale – extends from the conus medulares to the end of the dural sac and fuses with it.

Pia mater

The Pia mater

Pia mater close to the brain

The meninges

Meningitis is inflammation of the meninges. The infection occurs most often in children, teens, and young adults. Also at risk are older adults and people who have long-term health problems, such as a weakened immune system.

There are two main kinds of meningitis: ◦Viral meningitis is fairly common. It usually does not cause serious illness.

In severe cases, it can cause prolonged fever and seizures. ◦Bacterial meningitis is not as common but is very serious. It needs to be

treated right away to prevent brain damage and death. The two kinds of meningitis share the same symptoms. It’s very important to

see a doctor if you have symptoms, so that he or she can find out which type you have.

Meningitis can also be caused by other organisms and some medicines, but this is rare.

Meningitis is contagious. The germs that cause it can be passed from one person to another through coughing and sneezing and through close contact.

Meningitis

Dandy-Walker Syndrome: A congenital brain malformation of the openings called foramina Luschka and Magendie, it is characterized by increased fluid in the brain.

Symptoms of Dandy-walker Syndrome:◦Hydrocephalus◦Increased intracranial pressure◦Sow motor development◦Progressive macrocrania (abnormally enlarged of skull)◦Irritability◦Vomiting ◦Convulsions◦Ataxia◦Nystagmus (Jerky eyes)

Dandy-walker Syndrome

Hydrocephalia

The term hydrocephalus is derived from the Greek words "hydro" meaning water and "cephalus" meaning head.It is excessive accumulation of fluid in the brain.

Nystagmus

Nystagmus is a condition of involuntary eye movement, acquired in infancy or later in life, that may result in reduced or limited vision, it is cause by the high cranial pressure due the big amount of CSF.