2. Physiology of the Cerebrospinal Fluid and Intracranial Pressure
Chapter 10
Presentation:
S. Bahram Seif,
Resident of Neurosurgery
Isfahan University of Medical Sciences

3. Protective and Homeostatic Systems of the CNS
Skull Bones (physical protection)
CSF (hydraulic shock absorption)
Continuous Turnover of Extracellular Fluid (substrate supply and cellular homeostasis)
BBB

4. Protective Systems can Become Detrimental

5. Elevated ICP Congenital lesions Neoplasms Metabolic syndromes
Infectious syndromes
Infarction
Hemorrhage
Trauma

6. HISTORICAL CONSIDERATIONS
Galen
Hippocrates
Early Egyptian physicians
Removing Pieces Of Skull

8. Monro-Kellie Doctrine
19th Century
Alexander Monro
George Kellie
Monro-Kellie Doctrine

10. Lumbar Puncture
1911
Quincke
1951 continuously ICP monitoring
Lundberg

11. NORMAL INTRACRANIAL PRESSURE
Upper limit of normal ICP: 15 mmHg
Usual range is 5 to 10 mmHg
Coughing or Sneezing: 30 to 50 mmHg

12. mmHg x 1.36 = cmH2O

13. ICP Evaluation
Intraventricular
Intraparenchymal
Subdural
Epidural

14. CSF Pulsatility Associated with Cardiac and Respiratory activity
Changes in these pulsatile components can be one of the earliest signs

16. Cardiac Component Left ventricular contraction
Peripheral arterial pulse
Choroid plexus and pial arteries
High-compliance venous blood vessels

17. Respiratory Component
Generated by pressure changes in the thoracic and abdominal cavities

19. Percussion wave (WI), the most constant, Pulsations in large intracranial arteries.
Tidal wave (W2), brain elastance.
Dicrotic wave (W3), dicrotic notch in the arterial.

20. ICP
is synonymous with
CSF Pressure

21. Atmospheric pressure
Hydrostatic pressure
Filling pressure

23. As volume is added
there are two principal routes
for compensation

24. Distention of the spinal dura mater
Displacement of CSF and blood

25. ICP depends on the
total volume inside the skull

27. Intracranial Space: 1500-mL
87%: the Brain
9%: CSF (ventricles, cisterns, and subarachnoid space)
4%: blood

28. CSF
Compartmental
Extracellular space
164.5 mL

29. CSF Production
Choroid plexuses
Ventricular ependyma

30. Choroid Plexuses
Invaginations of the pia mater into the ventricular cavities
Roofs of the third and fourth ventricles
Walls of the lateral ventricles

31. Energy-dependent secretion and reabsorption processes
0.35 to 0.37 mL/min

32. Higher sodium, chloride, and magnesium
Lower potassium, calcium, urea, and glucose
Similar osmolality

33. Peak Production Rates
Late evening
Early morning

34. CSF pressures of less than 5 mm Hg
CSF Drainage
Dural Venous System
Even in
CSF pressures of less than 5 mm Hg

37. NPH
Ventricular enlargement
Absence of elevated ICP

38. Gait disturbance
Dementia
Incontinence

39. Lumbar Pressures: 6 to 24 cm H2O.

41. Symptoms and Signs of Elevated Intracranial Pressure
Depends greatly on the nature and anatomic location of the underlying pathologic condition
Headache, vomiting and papilledema.

42. Cranial nerve palsies may arise as a result of pressure on brainstem nuclei (particularly abducens palsies)

43. Papilledema Reliable Objective Good specificity
Sensitivity: observer dependent

44. Vital Sign Changes Cushing response:
Arterial Hypertension and Bradycardia

45. CPP = MAP - ICP

46. Abnormal Respiration Cheyne-Stokes: diencephalic region
Sustained hyperventilation: midbrain and upper pons
Slow respiration: Midpontine
Ataxic respirations: pontomedullary lesions
Rapid shallow breathing: upper medullary lesions

47. Herniation Syndromes
Most serious complication of raised lCP

49. Central Syndrome
Progressive dysfunction of structures in a rostral to caudal direction
1st Diencephalic Structures:
Change in behavior or even loss of consciousness, Cheyne-Stokes respiration
Pupils :small, with a poor reactivity
Contralateral hemiparesis
Pupils fall into a midline fixed position

50. Uncal Syndrome Unilaterally dilated and poorly reactive pupil
External oculomotor ophthalmoplegia
Ipsilateral hemiparesis: pressure on the contralateral cerebral peduncle on the
edge of the tentorium cerebelli

53. INTRACRANIAL PRESSURE MONITORING
Benefitial for Outcome

55. A Waves (plateau waves)
Increases of ICP for several minutes
Return spontaneously to a new baseline which is usually slightly higher

56. Vasodilation: normal compensatory response to decreases in CPP, effective management involves the use of vasopressors

57. B Waves Vasodilation: secondary to respiratory fluctuations in PaC02
Ventilated patients

58. C Waves
More rapid sinusoidal fluctuations occurring approximately every 10 seconds
Fluctuations in arterial pressure.

59. Intracranial Hypertension
40% to 60% of severe head injuries
Major factor in the deaths of 50% of all fatalities.
ICP above 20 mm Hg is highly significant in predicting outcome

60. Indications GCS: 3 to 8 and an abnormal CT
If CT is normal, 2 of these shoud be present:
1)Age older than 40 years
2)Unilateral or bilateral motor posturing 3)Systolic BP below 90 mm Hg
GCS>8 and significant mass lesions

61. Reye's syndrom
Fulminant Hepatic failure

63. METHODS Gold standard: Ventriculostomy
Infection rises after 5 days (10%)
Hemorrhagic Complications(2%)
Parenchymal monitors: less than 1% infective complications.
Parenchymal monitors: regional inaccuracy

65. Device is zeroed at the level of the foramen of monro, using the external acoustic meatus as an anatomic landmark.

66. There is no uniform agreement about the critical level of ICP beyond which treatment is mandatory.
15 mm Hg
20 mm Hg
CPP

67. MANAGEMENT OF INTRACRANIAL PRESSURE

69. VCSF Temporary external drainage Ventriculosubgaleal shunt
Ventriculoperitoneal shunt

70. Medications
Acetazolamide, furosemide, and corticosteroids can transiently decrease CSF production.
Acetazolamide also has a cerebral
vasodilator effect & contraindicated in patients with closed head injury.

71. VBLOOD Hyperventilation: vasoconstriction of pial vessles
Pa CO2 : 32-35
Head elevation

72. VBRAIN Prevention of cerebrovascular hypertension (Inderal)
Colloid (Lund Protocol)
Isotonic or hypertonic(Bollus) solutions

73. Steroids(Vasogenic & Intrestitial)
Not effective in cytotoxic edema(TBI, Stroke, SAH, Meningitis, DKA)

74. Barbiturates
Hypothermia
Osmotic agents

75. Thanks