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CSF Dynamics and CSF circulation
This document discusses cerebrospinal fluid (CSF) dynamics, including CSF production, drainage, composition, and pressure. Key points include: - CSF is produced by the choroid plexus at a rate of 0.3-0.4 ml/min and is absorbed through the arachnoid villi and dural sinusoids. - Normal CSF pressure in adults is 4.5-13.5 mmHg. - Infusion tests can assess CSF system dynamics by measuring parameters like conductance and compliance. - Understanding CSF dynamics helps research hydrocephalus and could aid in deciding treatment like shunt surgery.
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CSF Dynamics and CSF circulation
- 1. CSF Dynamics Basic items MohamedElsayed Elsebaey Neurosurgery Registrar Egypt, Ismailia Ministry of Health Seba3y700025@gmail.com Mohamed E Elsebaey
- 2.
- 3. CSF • Pathway • Production& Rate • Drainage • Composition • Pressure • Volumes • Blood supply • Nerve supply
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- 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 arepresent 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 )
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- 12. Pressure • Children is3.0 - 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 hydrostaticpressure • Cilia of ependymal cells • Respiratory ventilation • Vascular pulsation of cerebral arteries
- 15. Blood supply Posterior choroidalA Anterior choroidal A Superior Cerebellar A PICA
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- 17. Dynamics CSF It isnot 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 CSFsystem 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 “ Craniumis rigid box Filled with a nearly incompressible brain Making the total cranial volume unchanged.”
- 29. CSF • Choroidal plexussource • Extrachoroidal source • formation rate: 0.3 – 0.4 ml / minute
- 30. CSF Absorption • Mainabsorption 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 isto • Diagnose the patient • Predict patients who will gain benefit from shunt surgery
- 34. Pathophysiology of INPHis still not fully understood , so Researches done for reaching the evidence So Importance of CSF hydrodynamics
- 35. INPH thoeries • Effectof 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 • CTbrain • 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 • Marmarouin 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 ofvolume and pressure change, or It is description of how the system is affected by the change in volume or pressure
- 41. Infusion test • Usedto 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 soimportant 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 dothis ? Understanding them will increase basic knowledge of the CSF system while these variations have previously been suggested as indicators for shunt surgery
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- 48. Definition Increase in CSFvolume 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 • CSFinfusion 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 stenosisor 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 flowobstruction 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 Impairedconscious 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 Signsand symptoms of increased ICP Impaired upward gaze Chronic Dementia Gait ataxia Incontinence
- 56. Investigations CT scan • Patternof 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 Ventriculardrainage 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 ofincreased 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