INTRACRANIAL SURGICAL PHYSIOLOGY

Glucose: 60 mg/min which is 25% of total body consumptionOxygen: 45ml/min which is 20 %o of total body consumptionOxygen uptake depends upon: 1: cerebral blood flow 2: oxygen content of blood 3:pH 4:body temperature OXYGEN+ 1mole GLUCOSE 38 MOLES OF ATP In hypoxia 1 mole of glucose gives 2 molecules of ATP plus Lactic acid.

ENERGY(ATP)

1:Ionic gradient across the membrane2:neurotransmission/neurotransmitters Synthesis,release,uptake and destruction of neurotransmitters. 3:preservation of cellular structure in nervous system which includes complex process of lipid metabolism which includes process of myelinization of neurons. 4:synthesis of proteins for information storage 5:CSF formation process Total brain ischemia leads to loss of consciousness in 15 secondsIrreversible damage in 2 minutes.

Energy Crisis of the Brain 1: Hypoxia/ischemia2: Hypoglycemia

Effect is in the form of change in EEG depletion of tyrosine hydroxylase required for synthesis of noradrenaline/dopamine Fall in acetylcholine Decrease in brain Lipids such as phospatidylinositol Efflux of potassium and influx of calciumCLINICAL EFFECT OF INTERRUPTION LEADS\TO ALTERATION IN PERSONALITY,JUDGMENT,MEMORY,IMPAIRED TOLERANCE OF DRUGS AND ALCOHOLAND PROFOUND COMA

CELL DAMAGE DUE TO ENERGY CRISIS

1:Purkinje cell in cerebellum2:3-5-6 layer in cerbrum3:somersector of Ammons horn in hippocampus4:boundary zones

Venous(jugular) Po2 30 unconsciousness 15 EEG 10 cell death

0.3-0.5ml\mn150 normal vol

HypercapniaHypoxia