SINH lý physiology of CSF

PHYSIOLOGY OF CSF PRODUCTION AND CIRCULATION, ALTERATIONS IN VARIOUS PATHOLOGY LE DINH TUNG MD, PhD Department of Physiology Hanoi Medical University First few drops… Emanuel Swedenborg who discovered CSF, referred to it as “highly gifted juice” that is dispensed from the roof of the fourth ventricle to the medulla oblongata, and the spinal cord Albrecht von Haller found that that the “water” in the brain, in case of excess secretion, descends to the base of the skull resulting in hydrocephalus OUTLINE CSF SPACES CSF FORMATION-CIRCULATION-REABSORPTION METHODS OF DETERMINING Vf and Ra EFFECTS OF DRUGS REGULATION ALTERATION IN CSF DYNAMICS IN PATHOLOGIES Introduction CSF  flows via macroscopic & ECF spaces PRESSURES AND VOLUMES CSF PRESSURE [mm of Hg] CHILDREN 3.0-7.5 ADULTS 4.5-13.5 CSF VOLUME [mL] INFANTS 40-60 YOUNG CHILDREN 60-100 OLDER CHILDREN 80-120 ADULTS 100-160 CHOROID PLEXUS Invagination of blood vessels & leptomeninges covered by a layer of modified ependyma Epithelium is the blood-CSF barrier Carbonic anhydrase present in the epithelium & Na-K pump in luminal plasma membrane play major role in CSF formation Anatomy • • • • Choroid plexus projects into The temporal horn of each lateral ventricle, the posterior portion of the third ventricle & the roof of the fourth ventricle CHOROID PLEXUS BLOOD SUPPLY Body of lateral ventricle Posterior choroidal artery Body of third ventricle Anterior choroidal artery Temporal horns Superior cerebellar artery Fourth ventricles Posterior inferior cerebellar artery NERVE SUPPLY:IX,X, Sympathetic nerves MACROSCOPIC SPACES  Two lateral ventricles Third ventricle Aqueduct of sylvius Fourth ventricle Central canal of spinal cord Subarachnoid spaces MICROSCOPIC SPACES- BRAIN & SPINAL CORD ECF SPACES are small Capillary – ECF exchange is l i m i t e d Blood brain barrier Whats your diameter? ………TRANSLOCATION INTO SPINAL SPACES >INCREASED REABSORPTION Volume of intracranial blood/gas/tissue ↓  CSF volume ↑ MECHANISM: >CEPHALAD TRANSLOCATION >DECREASED REABSORPTION SUBDURAL HEMATOMA Adds volume  ↑ ICP  driving force for reabsorption  Va > Vf  CSF volume contracts  ICP↓ Va starts returning to normal Va & Vf in a new equillibrium– Here ICP & total intracranial volume are same as before SDH, but CBV is ↑ed and CSF volume ↓ed SURGICAL REMOVAL OF TUMOR Sx ↓ intracranial volume ↓ed ICP a weak driving force for reabsorption Va ↓, Vf same CSF accumulates and volume expand ICP↑ and reach pre surgical valuesstimulate Va  Va ↑ Va = Vf here,ICP same; brain volume ↓; CSF volume↑ INTRACRANIAL MASS ANIMAL STUDY IN GROUPS OF DOGS GROUP HYPOCAPNIA GROUP2 I.C MASS GROUP3 I.C.MASS + HYPOCAPNIA Hypocapnia ↓ed an increased ICP initially by decreasing CBV but with sustained hypocapnia,CBV reexpanded but H.C improved access of I.C CSF to spinal sites of reabsorption so CSF vol ↓ed ICP remained lower than initial values EFFECT OF ANESTHETICS FIVE GROUP OF DOGS Vf Ra ICP REASON ENFLURANE ↑ ↑ ↑ CSF VOL DIDN’T↓TO THE EXTENT OF CBV REEXPANSION HALOTHANE ↑ ↑ ↑ ISOFLURANE N N N CSF VOL CONTRACTION= CBV REEXPANSION FENTANYL N N N REEXPANSION MINIMAL THIOPENTAL N N N CSF VOL CONTRACTION= CBV REEXPANSION ACUTE SAH Itrathecal injection: W.Blood / plasma /dialysate of plasma/serum/saline Whole blood and plasma raised ICP and caused a to 10 fold rise in Ra respectively C/C CHANGES AFTER SAH Extensive fibrosis leptomeningeal scarring functional narrowing or blockage of CSF outflow tracts [Ra is increased] hydrocephalus Bacterial meningitis Animal study with 1.S pneumoniae 2.E coli ↓ is increased Even with antibiotics it remained high for weeks post Rx Methyl prednisolone ↓ed Ra to a value between control and infected PSEUDOTUMOR CEREBRI Increased Ra , Vf ,water movement into brain, CBF & CBV increased ICP Impaired reabsorption is the principal cause Prednisone decreased Ra Head Injury 20% of the raised ICP derived from changes in Ra &Vf It means… Vf changes: changes ICP Ra changes: changes ICP, alters pressure buffering capacity of brain Anesthetics induced changes in both, significantly alters Rx to reduce ICP So…… We demand more attention from you HEAD INJURY THANK YOU ... withdrawal of CSF and for measurement of accompanying CSF pressure change Resting CSF pressure [P0] is determined and a known volume of CSF is injected/withdrawn with timed recording of CSF pressure... action of CSF Brain ECF proteins cleared by glial uptake FUNCTIONS OF CSF- support,nutrition The low specific gravity of CSF (1.007) relative to that of the brain(1.040) reduces the effective mass of. .. ↑[relation linear upto ICP of 30 cms of H2O] CIRCULATION OF CSF Hydrostatic pressure of CSF formation Cilia of ependymal cells Respiratory variations Vascular pulsations of cerebral arteries,CP