CSF Dynamics and CSF circulation

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 [email protected] Mohamed E Elsebaey

2. Sylvius Monro magendie Cotungo Lushcka

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

4. Ant. Post.

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

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

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

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

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

10. Composition Plasma CSF Item 140 141 Na 4.6 2.9 K 1.7 2.4 Mg 5.0 2.5 Ca 101 124 Cl 23 21 HCO3 92 61 Glucose 7.4 7.3 pH 7000 28 Protein 1.025 1.007 Specific Gravity

11. Pressure Children is 3.0 - 7.5 mmHg Adult is 4.5 - 13.5 mmHg

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

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

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

15. CSF Dynamics

16. 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

17. 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

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

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

20. CSF Choroidal plexus source Extra choroidal source formation rate: 0.3 – 0.4 ml / minute

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

22. , Hakim & Adam in 1960 publish phrase “ Normal Pressure Hydrocephalus ” Syndrome of: Gait disturbance Dementia Incontinence adams Hakim

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

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

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

26. 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

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

28. 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

29. 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

30. . 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

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

32. 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

33. 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

34. Infusion protocols 2 approaches: Constant infusion protocol Bolus infusion protocol

35. 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

36. 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

37. So Hydrocephalus

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

39. 4 research arms Basic science … understanding diseases on cellular level like edema, tumors Computer based mathematical modelling ……  Animal studies Clinical correlation 

40. 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

41. Hydrocephalus Obstructive Congenital A queduct stenosis or forking D andy walker $ A rnold chiari malformation V ein of Galen malformation Acquired A queductal stenosis S upratentorial masses : tentorial herniation T umours : Ventricular, colliod cyst – pineal region – post. Fossa A bscesses / granuloma A rachanoid 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

42. 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

43. Clinical picture Infants & young children Juvenile / adult

44. 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

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

46. Investigations CT scan Pattern of ventricular enlargement help determine the cause Lateral + 3 rd V ent. Dilatation With normal 4 th v entricle  aqueduct stenosis With deviated or absent 4 th v entricle  posterior fossa mass Generalized dilatation  communicating HCP

47. 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

48. 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

49. 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

50. 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

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

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

53. 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

54. thanks