The nature of the CSF and its expected pathways and the diversion devices and complications.

1. CSF Dynamics
Basic items
Mohamed Elsayed Elsebaey
Neurosurgery Registrar
Egypt, Ismailia
Ministry of Health
Seba3y700025@gmail.com
Mohamed E Elsebaey

2. Sylvius Monro
magendie
Cotungo Lushcka

3. CSF
• Pathway
• Production & Rate
• Drainage
• Composition
• Pressure
• Volumes
• Blood supply
• Nerve supply

5. Ant.
Post.

6. Production
• Choroid plexus (The choroid plexus consists of
modified ependymal cells )
• Capillary Ultrafiltrate
• Metabolic water production
Active process
Na/ K / ATP pump

7. Choroid plexus are present in
• Lateral ventricle ( temp. horn )
• 3rd Ventricle
• 4th Ventricle ( post. Portion )

8. Rate
• Produced 0.3 – 0.4 ml per minute
• Total Volume is 150 ml
• Totally replaced about 3 times per day ( 450-600)
The ventricular system contains:
Only about 1/6 of the total volume ( 25 ml )
The remainder is present in spinal canal & S.A. spaces

9. Drainage
• Cranial absorption:
85% - 90% through the SSS through the
Arachnoid villi
• Spinal absorption:
15% through the Dural sinusoids on the dorsal
nerve roots

10. Drainage
• ICP / Venous pressure
• Arachnoid Villi ( Pressure dependent valves )

11. Composition
PlasmaCSFItem
140141Na
4.62.9K
1.72.4Mg
5.02.5Ca
101124Cl
2321HCO3
9261Glucose
7.47.3pH
700028Protein
1.0251.007Specific Gravity

12. Pressure
• Children is 3.0 - 7.5 mmHg
• Adult is 4.5 - 13.5 mmHg

13. Volumes
• Infant  40 – 60 ml
• Young children  60 – 100 ml
• Older children  80 – 120 ml
• Adult  100 – 160 ml

14. Circulation
• CSF hydrostatic pressure
• Cilia of ependymal cells
• Respiratory ventilation
• Vascular pulsation of cerebral arteries

15. Blood supply
Posterior choroidal A
Anterior choroidal A
Superior Cerebellar A
PICA

16. CSF Dynamics

17. Dynamics CSF
It is not well understanding process up till
now although these researches and from this
point, the CSF dynamics research gain its
attractiveness

19. CSF
• French physiologist ( Magendie ) is who
gave the cerebrospinal fluid this name
• Clear colorless fluid
Function:
Reduces the effective weight of the brain
Protect the brain
Removes the metabolites

20. To assess CSF system dynamics
an infusion test can be performed
• This process of measuring is divided into 3
parts:
1. Mathematical model
2. Infusion protocol
3. Parameter estimation method

21. “Monroe” said
“ Cranium is rigid box
Filled with a nearly incompressible brain
Making the total cranial volume unchanged.”

29. CSF
• Choroidal plexus source
• Extrachoroidal source
• formation rate:
0.3 – 0.4 ml / minute

30. CSF Absorption
• Main absorption is through the
Arachnoid granulations and villi (unidirectional)
Other absorption sites:
1. Around Spinal nerve roots
2. Choroid plexus
3. Around cranial nerves

31. ,
• Hakim & Adam in 1960 publish phrase
“ Normal Pressure Hydrocephalus ”
Syndrome of:
1. Gait disturbance
2. Dementia
3. Incontinence
adams Hakim

32. Normal Pressure HCP
• Idiopathic
No clear cause
• Secondary
For known cause like:
Traumatic brain injury
Subarachanoid Hge
Post meningitis
Post 4th vent. Tumour
surgery

33. Challenge here is to
• Diagnose the patient
• Predict patients who will gain benefit from
shunt surgery

34. Pathophysiology of INPH is still not
fully understood , so
Researches done for reaching the evidence
So
Importance of CSF hydrodynamics

35. INPH thoeries
• Effect of CerebroVascular disease
• Spinal aetilogy
• Non symptomatic HCP that become
symptomatic with increasing age
• Mechanical compression of the brain by
ventricles
• Increase intracranial arterial pulsations lead to
increase ICP lead to Periventricular damage

36. Diagnostic tests why ?
• Support diagnosis
• Decide if patient will gain benefit from
Treatment or not

37. Diagnostic tests
• CT brain
• MRI brain
• Neurophysiological studies
• NeuroPsychological studies
• Infusion test
• Tapping test
• Ext. lumbar drainage
used as simulating the effect of shunt by withdrawing
CSF then assess the clinical performance

38. Mathematical model
• Marmarou in 1973 put the basic model of CSF
system
Assumes
Total CSF formation rate + possible rate of
external infusion
equals
CSF absorption rate + rate of change of fluid stored
in the system

39. .
• Conductance outflow ( C out )
Physiological parameter of the filtration process
and describes the ease of flow across the CSF
outflow pathways while ( R out ) is the
resistance to flow
Conductance outflow is equal to
Outflow resistance

40. .
• Compliance:
Ratio of volume and pressure change, or
It is description of how the system is affected
by the change in volume or pressure

41. Infusion test
• Used to assess the Hydromechanic Properties
of CSF system
• Procedure:
2 needles inserted into the spinal canal at L3-
L4 interspace.
Sitting position
One needle used for infusion or withdrawal of
fluid ( Ringer )
Other Needle used for pressure measurement

42. It is so important to minimize CSF leakage
during puncture
Then supine position
The Zero pressure reference level is placed at
the Centre of the auditory meatus
Re-measuring done
Putting results into the equations then results
appeared

44. Infusion protocols
2 approaches:
 Constant infusion protocol
 Bolus infusion protocol

45. Parameter estimation methods
• Constant pressure infusion
• Constant infusion
• Bolus infusion
• Adaptive observer
• Prediction error
• Simulation error
• Real time estimation and investigation time
analysis
Complex
physical
mathematical
equations

46. Why we do this ?
Understanding them will increase basic
knowledge of the CSF system while these
variations have previously been suggested
as indicators for shunt surgery

47. So

48. Definition
Increase in CSF volume
Associated with increasing Ventricular size
Decreased absorption increased production

49. 4 research arms
1. Basic science … understanding diseases
on cellular level like edema, tumors
2. Computer based mathematical
modelling …… 
3. Animal studies
4. Clinical correlation 

50. Methods include
• CSF infusion study
• Overnight ICP monitoring
• Assessment of slow ICP waves
• Testing pressure reactivity
• Cerebral Auto regulation
• CO2 reactivity
• CBF studies combined with MRI co- registeration

51. Hydrocephalus
Obstructive
• Congenital
Aqueduct stenosis or forking
Dandy walker $
Arnold chiari malformation
Vein of Galen malformation
• Acquired
Aqueductal stenosis
Supratentorial masses : tentorial
herniation
Tumours: Ventricular, colliod cyst
– pineal region – post. Fossa
Abscesses / granuloma
Arachanoid cysts
• Communicating
Thickening of the meninges
Involvement of the arachnoid
granulations:
Infection
SAH : spontaneous, traumatic,
post op.
Meningitis
Increased CSF viscosity ,
high protein viscosity
Excessive CSF production,
choroid plexus papilloma

52. Pathological effects
CSF flow obstruction or impaired absorption 
Ventricular dilatation 
CSF permeates through the ependymal lining into
the periventricular white matter 
• Raised intracranial pressure
• White matter damage, If untreated  grey
matter damage
• Some CSF absorption occurs from periventricular
blood vessels

53. Clinical picture
Infants & young children Juvenile / adult

54. Tense ant. fontanelle
Impaired conscious level
& vomiting
Gradual onset- mental
retardation
Tense scalp with dilated veins
Cracked pot sound on skull
percussion
Increased skull circumference
Lid retraction
Impaired upward gaze
Setting sun appearance
Infants young children

55. Juvenile / Adult
Acute
Signs and symptoms of
increased ICP
Impaired upward gaze
Chronic
Dementia
Gait ataxia
Incontinence

56. Investigations
CT scan
• Pattern of ventricular enlargement help
determine the cause
Lateral + 3rd Vent. Dilatation
With normal 4th ventricle  aqueduct stenosis
With deviated or absent 4th ventricle 
posterior fossa mass
• Generalized dilatation  communicating HCP

57. • Isotope Cisternography / CSF infusion studies
/ ICP monitoring
In pts suspected normal pressure HCP
• Developmental assessment & psychomotor
analysis
To detect impaired cerebral function and
provide basal line for comparison

58. Management
• Acute deterioration
Ventricular drainage
VP or VA shunt
• Gradual deterioration
VP or VA shunt
Removal of a mass lesion if present
• Just observation, mostly in arrested HCP cases

59. Shunt complications
Any shunt
• Obstruction  proximal, Valve, distal
• Disconnection
• Infection
• Malposition
• Hardware erosion through skin
• Seizures
• Conduit for extraneural metastases of certain
tumors
• Silicone allergy

60. Shunt complications
VP Shunt
• Inguinal hernia
• Need to lengthen the catheter with growth
• Hydrocele
• CSF ascites
• Tip migration into viscus, anus
• Volvulus, intestinal obstruction
• Overshunting

61. Shunt complications
VA Shunt
• Repeated lengthing
• Infection, septicemia
• Retrograde blood flow into ventricles
• Shunt embolus

62. Shunt complications
LP shunt
• Lumbar nerve root irritation
• Arachnoiditis, adhesions
• Difficult access to proximal end if need
revision

63. Undershunting
Acute symptoms of increased ICP
Headache, nausea, vomiting , diplopia,
ataxia,seizures
Acute signs of increased ICP
Upward gaze palsy, abducent palsy, visual field
loss, papilledema
Swelling around shunt track