Meninges, Ventricles And Csf

Front 1

Meninges 3 connective tissue layers

Back 1

1. Pia mater- (vascular) closely covers brain
2. arachnoid- (non-vasc)
3. Dura matar- outer layer and dense

Front 2

3 meningial spaces

Back 2

1. subarachnoid- terminates atthe second sacral level and consist of CSF
2. Subdural;
- in cranium it carries veins
- in spinal cord; potential space
3. Epidural:
- cranium; potential space, with meningeal aa and vv
- spinal cord, it contains fatty areolar tissue, lymphatics and venous plexuses (LA injection causing paravertebral or saddle nerve block)

Front 3

Meningial Pathologies

Back 3

- meningial tumours
- subdural & epidural hematomas
- meningitis

Front 4

Meningiomas

Back 4

- benign, well circumscribed, slow growing
- 15% of intracranial tumours
- 90% supratentorial

Front 5

Subdural Hematoma

Back 5

- laceration of superior cerebral vv.

Front 6

Epidural Hematoma

Back 6

- laceration of middle meningeal aa.
- they may cross dural attachments
- CT: biconvex or lentiform shape
- anterior, middle or posterior meningeal aa.

Front 7

Meningitis

Back 7

inflammation of pia-arachnoid arewas of brain and/or spinal cord

Front 8

CSF Flows

Back 8

- made @ choroid plexuses of ventricles
- exits @ 4th
- circualtes subarachnoid space
- enter super sagittal sinus through arachnoid granulations

Front 9

Bacterial Meningitis Sx

Back 9

- fever, headache, nuchal rigidity (neck stiffness, cant flex the neck) and Kernig's sign (patient supine, examiner flexes the hip but cant extend the knee without causing pain)
- cranial nerve palsies and hydrocephalus

Front 10

Common Causes of Bactrial Meningitis

Back 10

- NEWBORN: GBStrep & E.Coli
- YOUNG CHILDREN: HiB
- YOUNG ADULTS: N.meningitidis
- OLDER ADULTS: S.pneumoniae

Front 11

CSF Finding sin Bacterial Meningitis

Back 11

1. LOTS of PMN leukocytes
2. Dec. G
3. Inc. Protein

Front 12

Viral Meningitis (aka aseptic meningitis)
Sx

Back 12

- fever, headache, nuchal rigidity and kernigs sign

Front 13

Viral Meningitis Common Causes

Back 13

mumps
echovirus
coxsackie virus
EBV
HSV-2

Front 14

Viral CSF

Back 14

1. LOTS of PMN leukocytes
2. Normal G
3. Moderately Inc. Protein

Front 15

Choroid Plexus

Back 15

- lateral, 3rd & 4th ventricles
- modified ependymal cells secrete the CSF and tight junctions form the blood-CSF barrier

Front 16

Pathway through Ventricles

Back 16

1. 2 lateral ventrical
2. connect to 3rd via interventricular foraina of monro
3. 3rd V between the diencephalon
4. Connects to 4th via the cerebral aqueduct (no chorid here and blockage cause hydrocephalus)
5. 4th V communicates with subarachnoid space with 3 outlets
a. foramen of magendie (median aperture)
b. 2x foramina of luschka (lateral aspects)

- then to cerebellomedullary cistern
- downwards and around spinal cord
- anteriorly and upwards into the pontine and interpeduncular cisterns
- upwards and posteriorly, around the cerebellum and into the cistern posterior to the midbrain

Front 17

Hydrocephalus
- 5 types

Back 17

dilation of V due to blockage of CSF flow
1. Noncommunicating Hydrocephalus (within)
2. Communicating; within the subarachnoid (adhesions from meningitis) or no obstruction just lack of absorption
3. Normal pressure; when CSF isnt abs by arachnoid villi (triad; progressive dementia, ataxic gait, urinary incontinence; wacky, wobbly and wet)
4. Hydrocephalus ex vacuo; due to a loss of cells in the caudate nucleus (eg HD)
5. Pseudotumor cerebri; benign redults from INC. resistance to CSF outflow at the arachnoid villi. Occurs in obese young women

Front 18

CSF-
Function

Back 18

-colourless, acellular
1. supports CNS and protects against concussive injury
2. transport of hormones
3. Removes metabolic waste
4. buoyancy (red. effective brain weight to 50g)

Front 19

CSF formed & abs.

Back 19

@ chroid plexus (80% some by ependyma cells of brain); choriod is found all over ventricle sysem except anterior and posterior horns of LV (500ml/day) when we only have 150ml at one point
@ arachnoid villi in super sagittal sinus (connect SAS with venous lumen). It is pressure & volume dependent (unlike production)

Front 20

CSF Composition

Back 20

COLOUR: clear
1. mononuclear cells less than 5/uL
2. RBC indicates subarachnoid hemorrhage
3. G; 50-75mg/dl
4. Protein: 15-45mg/dl
5. CSF pressure; lateral recumbent position 80-180mmH2O

differs from plasma in having excess Na, Mg and little K, Ca

Front 21

Brain Herniations

Back 21

1. Transtentorial (uncal) herniation
2. Transforaminal (tonsillar) herniation; through foramen magnum
3. Subfalcial herniation; below falx cerebri

Front 22

Subdural Hematoma

Back 22

Front 23

EDH

Back 23

Front 24

Where do the cerebral blood vessels at the brain surfeace travel?

Back 24

Sub-arachnoid space

Front 25

Cistern

Back 25

space between the aracnoid and pia matar, esp around the brainstem
(i) cerebellomedullary (cisterna magna): space between inferior surface of cerebellum and dorsal surface of medulla.
(ii) pontine: space around anterior surface of pons: continuous caudally with cerebellomedullary
(iii) interpeduncular: between cerebral peduncles, which contains Circle of Willis
(iv) superior cistern (cistern of great cerebral vein of Galen): a radiological landmark above midbrain. Occupies interval between splenium of corpus callosum and superior surface of cerebellum. Contains great cerebral vein of Galen and pineal gland and continues rostrally into transverse fissure.

Cistern ambiens: group around midbrain encircling it

Front 26

Dural Venous sinuses

Back 26

form between the 2 dural layers

Front 27

3 dural folds in the brain

Back 27

1. falx cerebri
2. falx cerebelli
3. tentorium cerebelli

Front 28

Subarachnoid Bleeds

Back 28

- most common (aneruysms)
- blood in Sas mixes with CSF coating the pia with RBCs
- With time the RBCs die and release Hb which vasoconstricts the aa. and may cause a stroke

Front 29

Lateral ventricle Componenets

Back 29

i) anterior horn (frontal lobe)
(ii) body: in frontal and parietal lobes, extending posteriorly to splenium of corpus callosum.
(iii) posterior horn: projecting into occipital lobe.
(iv) inferior horn: curving down and forward into temporal lobe.
(v) collateral trigone: region near splenium of corpus callosum where body and posterior and inferior horns meet

Front 30

The 3rd ventricle continuity is broken by?

Back 30

inter thalamic adhesions

Front 31

CSF production per day

Back 31

500mL
replaced 4 x a day
- no feedback system limiting its production

Front 32

BBB function

Back 32

- maintain electrolyte levels
- control entry of particular substrates (eg, glucose)
- protect from circulating hormones (eg, systemic neurotransmitters)
- remove waste products
- exclude toxins

Front 33

Astrocytes cover ___% of blood vessel surface

Back 33

85

Front 34

3 barriers of the BBB

Back 34

1. Arachnoid: tight junctions, passively keeps out hydrophillic substances
2. Choroid Plexus: choriod epithelium regulate things that leave chorioid capillaries not allowing direct acess to the CSF
3. Cerebral Non-fenestrated Capillaries

therefore; only LMW or lipid soluble substances can diffuse across

Front 35

3 types of spina bifida

Back 35

1. Spina bifida Cystica; myelomeningocele
- form a sac that protrudes leaking CSF, teethered cord, hydrocephalus LEAKS!
2. OCCULTA: mildest form occuring in 10% of pop. where the arch of a single vertebra is open (L5 or S1)
3. CYSTICA- meningocele: same as occulta but several vertebra involved, thus protusion with a fluid filled sac
- normal spinal cord and no leakage
CAN SHINE A LIGHT THROUGH IT

Front 36

Causes of INC. ICP

Back 36

(1) Mass: expanding mass that is replacing and/or compressing brain; eg abscess, tumours
(2) Oedema: brain oedema may develop from tumour/abscess mass and/or pus.
(3) Blood Volume: excessive vasodilation
(4) Cerebrospinal Fluid: impaired absorption or excessive secretion rate.

Front 37

MEchanism of CSF secretion

Back 37

passive and active
- carbonic anhydrase drives Cl and water secretions into plasma and CSF

Front 38

The Biggests 3 differences between CSF and plasma composition

Back 38

1. CSF has 99% water content vs 93%
2. Lower protein
3. Higher Cl

Front 39

Name the 3 main dural venous sinuses?

Back 39

1. SSS
2. Straight sinus
3. Transverse Sinus

Front 40

Davson's Equation

Back 40

CSF absorption depends on
Abs= Pressure of CSF - (P SSS + 3mmHg) / R CSF

normal pressure 7-15cmCSF or 5-12mmHg
- erect (vs supine)

Front 41

CSF Ix

Back 41

1. radiology and ventricular size
2. Lumbar puncture (l4-5)
3. CSF infusion studies (measure baseline pressure then insert more fluid and measure pressures again)
4.

Front 42

How to perform an LP?

Back 42

@ L4-5
in line with the Iliac crest

Front 43

Different colous of CSF

Back 43

1. xanthochromic (breakdown of blood)
2. Turbid (lots of protein)
3. Blood stained (haemorrage or a **** job)

Front 44

Aetiology of Hydrocephalus INFANT

Back 44

Newborn
 Congenital
• Aqueduct stenosis
• Communicating
• Myelomeningoceles
 Acquired
• IVH of Prematurity
• Meningitis

Front 45

Aetiology of Hydrocephalus ADULT

Back 45

Adults
 Meningitis
 Haemorrhage – SAH
 Tumour
 Surgery
 Aqueduct stenosis - LOVA
 Idiopathic – NPH

Front 46

High, Normal and Low CSF pressures

Back 46

High Pressure
 Acute, obstructive
Normal
 NPH, LOVA, chronic, arrested
Low
 Infection, haemorrhage – rare cases

Front 47

Sx of Acute Hydrocephalus

Back 47

 Headache, nausea and vomiting
 Lethargy, drowsiness, stupor and coma

Front 48

Signs of acute hydrocephalus

Back 48

 Papilledema, Diplopia
 Setting sun sign
 False localising signs – 6th nerve signs
 Decreased level of consciousness

Front 49

Munro-Kellie Doctrine

Back 49

 Cranium is a rigid sphere
 Filled to capacity with
 Brain
 CSF
 Blood
 These are non-compressible (nearly)
“An increase in volume of one of these
components or the introduction of a mass lesion
must be accompanied by a decrease in volume
of the other components”

Front 50

Normal Pressure Hydrocephalus Triad

Back 50

 Gait disturbance (short, shuffling, magnetc, broad based; like PK without tremor)
 Dementia
 Urinary incontinence
Idiopathic: Condition of the elderly
Secondary: Trauma, SAH, meningitis

Front 51

Chiari II Malformation

Back 51

- tonsils a pulled down into the spinal cord due to teethering
- myelomeningocele assoc. with Chiari II

Front 52

Tx of Hydrocephalus

Back 52

1. third ventriculostomy
2. CSF Shunting; valve regulated
 Ventriculo – peritoneal
 Ventriculo – pleural
 Ventriculo - atrial
 Lumbo – peritoneal etc

Front 53

Pseudotumor Cerebri

Back 53

aka
Idiopathic intracranial hypertension
benign intracranial HT
DEFINITION: Increased intracranial pressure in the
absence of a mass lesion or hydrocephalus

young overweight females of childbearing age AFFECTED
S&S Increase ICP
 Headache
 Blurred vision / restricted vision
 Papilledema
Blindness

Front 54

Pseudotumor Cerebri Tx

Back 54

 Acetazolamide
 Lumbar Punctures
 Optic Nerve Sheath Fenetrations (to protect their eyes from the papioedema)
 CSF Shunting
 Bilateral Subtemporal decompressions (making a little more room in the cranial cavity)
 Venous sinus stenting (by stenting tehe venouse pressure is lowered therefore lowering the required CSF pressures)

Front 55

Normal the CSF pressure needs to be __________ than the ________ pressure

Back 55

CSF and venous

Front 56

Definition of Hydrocephalus ex-vacuo

Back 56

Hydrocephalus ex-vacuo: What is termed "hydrocephalus ex-vacuo" occurs when there is damage to the brain caused by stroke or injury, and there may be an actual shrinkage of brain substance. Although there is more CSF than usual, the CSF pressure itself is normal in hydrocephalus ex-vacuo.

Hydrocephalus is an abnormal buildup of cerebrospinal fluid (CSF) in the ventricles of the brain. The fluid is most often under increased pressure and that pressure can compress and damage the brain.

Front 57

Chorois plexus Locations

Back 57

Choroid plexus is present in all components of the ventricular system except for the cerebral aqueduct, frontal horn of the lateral ventricle,[1] and occipital horn of the lateral ventricle.[1]


Choroid plexus
It is found in the superior part of the inferior horn of the lateral ventricles. It follows up along this boundary, continuous with the inferior of the body of the lateral ventricles. It passes into the interventricular foramen, and is present at the top of the third ventricle.
There is also choroid plexus in the fourth ventricle, in the section closest to the bottom half of the cerebellum.