Oh you who believe, stay away from bad suspicion (Al - Hujurat )

Describe topographic Anatomy of Meninges

• Innervation

• Blood supply

Describe the Blood Brain Barrier (BBB)

Enlist Dural Venous Sinuses & with their function

Role of Ventricular system in CSF production, circulation

Interpret CSF report in case of meningitis

What is the causes , Clinical presentation consequences & management of meningitis

Meninges

Three layers of tissue covering brain & spinal cord:

Dura mater

Arachnoid mater

Pia mater

Two spaces:

Subdural space

Sub-arachnoid space

Dura Matter

Tough, dense connective tissue, extends to 2nd

sacral vertebra

Divides into two layers:

Periosteal layer

Meningeal layer

Falx cerebri

Tentorium cerebelli

Falx cerebelli

Diaphragma sellae

Having 4 folds

Arachnoid Matter

Thin layer, pressed

against inner wall of

Dura by

cerebrospinal fluid

pressure in

subarachnoid

space

Pia Matter

Lies on surface of brain &

spinal cord

Dural

Nerve

Supply

Branches of the trigeminal, Vagus, and

first three cervical nerves and branches

from the sympathetic system pass to the

dura.

The dura is sensitive to stretching, which

produces the sensation of headache.

Dural Blood Supply

Dural Arterial Supply

The Dura matter’s arteries supply from:

Internal carotid

Maxillary

Ascending pharyngeal

Occipital

Vertebral arteries.

From a clinical point, the most important is the middle meningeal artery(branch of Maxillary), which is commonly damaged in head injuries.

Dural Venous Drainage

The meningeal veins lie in the

endosteal layer of dura.

The middle meningeal vein

follows the branches of the

middle meningeal artery and

drains into:

• Pterygoid venous plexus

or

• Sphenoparietal sinus.

The veins lie lateral to the

arteries.

Dural Venous Sinuses

Sinus Drain into

• superior sagittal sinus confluence of sinuses

• inferior sagittal sinus unites with great cerebral vein to form straight

sinus

• straight sinus confluence of sinuses

• confluence of sinuses transverse sinuses

• transverse sinus sigmoid sinus

• sigmoid sinus internal jugular vein

• cavernous sinus superior & inferior petrosal sinuses

• occipital sinus confluence of sinuses

• inferior petrosal sinus internal jugular vein

• superior petrosal sinus sigmoid sinus

Their main function is to drain CSF

Physiology of BBB

In the brain, endothelial cells are packed

much tighter together due to the existence of

tight junctions between them, blocking the

passage of most molecules.

The BBB blocks most of the molecules except

those that cross cell membranes by means of

lipid solubility (like steroid hormones, oxygen,

carbon dioxide) and those that are allowed

by specific transport systems (like sugars and

some amino acids)

Condition in which BBM disturb

The BBB can be disturb by:

Hypertension

Hyper osmolality

Radiation

Infection

Trauma

Inflammation

Pressure

Ventricular System

Ventricle is an internal cavity

of the brain which is filled

with CSF.

Composed of:

Two lateral ventricles

Third ventricle

Fourth ventricles

All these ventricles are

connected through:

Foramen Monro

Cerebral Aqueduct

Foramen Magendie

Foramen Luschka

Formed by Choroid Plexus

Plexus is formed by invaginating of vascular pia mater into the ventricular cavity

It becomes highly convoluted & produce a spongy-like appearance

It enters the 3rd and 4th ventricles through their roofs, and the lateral ventricles through the choroid fissure

C

S

F

Choroid plexuss

Appearance Clear and colourless

Volume 130 ml

Rate of production 0.5 ml/min

Pressure 60-180 mm of H2O

Composition

protein 15-45 mg/ dL

glucose 50-85 mg/ dL

chloride 720-750 mg/100 ml

No. of cells 0-5 lymphocytes/µL

Appearance & Composition of the CSF

Glucose (mg/dL):

Normal to marked

decrease. <40

mg/dL.

Protein (mg/dL)(Marked increase) >

250 mg/dL.

WBCs (cells/µL)

>500 (usually >

1000). Early: May be

< 100.

Cell differential:Predominance of

Neutrophils (PMNs)

Culture: Positive

Opening Pressure Elevated

Glucose (mg/dL): <40 mg/dL (Low)

Protein (mg/dL)

(moderate to marked

increase) 50 -500

mg/dL

WBCs (cells/µL)Variable (10 -1000

cells/µL) <500cells/µL.

Cell differential:Predominance of

Lymphocytes

Culture: Positive for AFB

Opening Pressure Variable

Bacterial Meningitis Tubercular Meningitis

Changes In Composition In Disease

Meningitis

Inflammation of the meninges

Common causes of meningitis include:

Bacteria

Virus

Fungi

Parasites.

Organisms Causes Meningitis

Birth to 4 weeks: GBS, E.coli

4 to 12 weeks: GBS, E.coli, Pneumococcus,Salmonella, Listeria, H. Influenza

3 months to 3 years: Pneumococcus, Meningococcus, H. Influenza

3 years to adult: Pneumococcus, Meningococcus

Pathogenesis

Infection of upper respiratory tract

Invasion of blood stream

Seeding & inflammation of meninges

Increase in ICP due to inflammatory exudate

Headache

Fever

Irritability

Lethargy

Poor feeding(in child)

Convulsions

Photophobia

consequences

Hydrocephalus

Spinal & cranial nerve palsy

Hearing loss

Cortical blindness

Seizures

Intellectual deficit

Management Lumbar Puncture

Antibiotic