Raised intracranial pressureRaised intracranial pressureCerebral blood flowCerebral blood flow

Brain edemaBrain edemaDr. Sameer H. AboudDr. Sameer H. Aboud

The Intracranial CavityThe Intracranial Cavity

The contents of the The contents of the intracranial cavityintracranial cavity

1: The brain about 1400 ml.1: The brain about 1400 ml.

2: The blood 75-100 ml.2: The blood 75-100 ml.

3: The CSF 75-100 ml.3: The CSF 75-100 ml. All these three compartments are All these three compartments are

essentiallyessentially non compressiblenon compressible,, and any and any change in the volume of the brain, causes change in the volume of the brain, causes a reciprocal change in the volume of one or a reciprocal change in the volume of one or both of the other two compartments. This both of the other two compartments. This is called theis called the Monro-KellieMonro-Kellie doctrine.doctrine.

CSFCSF

Obstruction to the flow of CSF at any point, results in dilatation of the venticular system proximal to the obstruction with profound

effect on intracranial pressure.

csf_unlab.mov

Indications Indications forfor Access Access & contraindications& contraindications

1. CSF analysis: Bacteriological, Immunological , Cytology,2. Measuring CSF pressure in cases of pseudotumor cerebri, and normal pressure hydrocephalus.3. The administration of antimicrobial and antineoplastic agents normally excluded by the BBB.4. Therapeutic CSF drainage. in cases of CSF fistula, pseudotumor cerebri or communicating hydrocephalus.

Methods of access Contraindications 1. Lumbar puncture * Local inf.2. Cisternal puncture. * ^ICP. Due to SOL3. Ventricular puncture. * Blood dyscrasias. Anticoaggualnt therapy.

C.B.FC.B.FBV= 75 mlBV= 75 ml

I.C.VP= ICPI.C.VP= ICP

CBF: 50ml/100gm/minCBF: 50ml/100gm/min

CPP=CrAP- VP(ICP)CPP=CrAP- VP(ICP)

CBF= CPP/ CVRCBF= CPP/ CVR

CrAP-(VP) ICPCrAP-(VP) ICP

CBF=--------------------CBF=--------------------

CVRCVR

Cerebral AutoregulationCerebral Autoregulation

Brain VolumeBrain Volume An increase in brain volume is produced either An increase in brain volume is produced either

by a:by a: S.O.L S.O.L Edema: increase in brain water.Edema: increase in brain water.1. 1. Vasogenic edemaVasogenic edema: extra cellular, disturbance of : extra cellular, disturbance of

BBB. localized around tumors, abscesses, BBB. localized around tumors, abscesses, hemorrhages and localized cerebral contusions. It hemorrhages and localized cerebral contusions. It may lead to herniation.may lead to herniation.

2. 2. Cytotoxic edemaCytotoxic edema: intracellular, hypoxia (cardiac : intracellular, hypoxia (cardiac arrest), Intoxication, sever hypothermia. It is usually arrest), Intoxication, sever hypothermia. It is usually generalized.generalized.

3. 3. Osmotic edemaOsmotic edema: ECF, Abnormal ADH sec. Sever : ECF, Abnormal ADH sec. Sever hemodialysis, or excessive ingestion of water hemodialysis, or excessive ingestion of water (Hysterical).(Hysterical).

4. 4. Hydrostatic EdemaHydrostatic Edema: ECF due to acute hypertension.: ECF due to acute hypertension.

ElastanceElastance and and ComplianceCompliance

Compliance:Compliance: Is that quality of distensibility Is that quality of distensibility available within the intracranial contents, which available within the intracranial contents, which enable them to adapt to an expanding IC lesion. enable them to adapt to an expanding IC lesion.

Elastance:Elastance: Is the resistance offered by the Is the resistance offered by the intracranial contents to the expansion of an intracranial contents to the expansion of an intracranial mass. It is the inverse of complianceintracranial mass. It is the inverse of compliance

Compliance Compliance is decreased byis decreased by increased by:increased by: 1. Hypercarbia. 1. Hypercarbia. Hypocarbia.Hypocarbia.

2. Hypoxia. 2. Hypoxia. Hyperoxia (PaOHyperoxia (PaO2 2 >1000 >1000 mm Hg)mm Hg)

3. Sleep. 3. Sleep. Hypothermia.Hypothermia. 4. Anesthesia. 4. Anesthesia. Barbiturates.Barbiturates.

Intracranial pressure Intracranial pressure measurementmeasurement

Normal I.C.P. this is Normal I.C.P. this is 50-200 mm. water (10 mm Hg.)50-200 mm. water (10 mm Hg.) it is it is pulsatile owing mainly to I.C. arterial pulsation. It also shows pulsatile owing mainly to I.C. arterial pulsation. It also shows fluctuations reflecting the respiratory and cardiac cycles.fluctuations reflecting the respiratory and cardiac cycles.

MeasurementMeasurement1.1. L.P L.P: with the patient on his side, the L.P. needle is connected to: with the patient on his side, the L.P. needle is connected to a manometer. This method is not accurate, can not be used a manometer. This method is not accurate, can not be used

forfor monitoring and can be dangerous.monitoring and can be dangerous.2. 2. Ventricular cannulationVentricular cannulation: It is more accurate, can be used for long: It is more accurate, can be used for long periods, but may be complicated by infection.periods, but may be complicated by infection.3. 3. Subdural sensor {Subdural sensor { These are the safest and most reliable, and These are the safest and most reliable, and4. 4. Extradural sensor{Extradural sensor{ and are usually used for monitoring. and are usually used for monitoring.

Effects of increased ICPEffects of increased ICP

A: Effects on vital signs:A: Effects on vital signs:

These appear to be due to compression and distortion of the These appear to be due to compression and distortion of the brain stem. These effects are noticed in patients with brain stem. These effects are noticed in patients with critically raised intracranial pressure, and in experimental critically raised intracranial pressure, and in experimental animals.animals.

1. Decrease in respiratory rate.1. Decrease in respiratory rate.

2. Bradycardia.2. Bradycardia.

3. Cardiac arrhythmias.3. Cardiac arrhythmias.

4. Pupillary constriction, followed by unilateral pupillary 4. Pupillary constriction, followed by unilateral pupillary dilatationdilatation

5. Increase in pulse pressure.5. Increase in pulse pressure.

6. Increase in arterial blood pressure.6. Increase in arterial blood pressure.

Effects of increased ICPEffects of increased ICP B: Effect on cerebral blood flow:B: Effect on cerebral blood flow: CAP - JVP (ICP)CAP - JVP (ICP)

CBF = --------------------CBF = -------------------- CVRCVR

When ICP increases, cerebral blood flow remains When ICP increases, cerebral blood flow remains constant by auto regulation. the efficiency of this constant by auto regulation. the efficiency of this compensation depends on the rate of expansion of the compensation depends on the rate of expansion of the lesion, it's nature and site. And also on the compliance lesion, it's nature and site. And also on the compliance of the intracranial contents. of the intracranial contents. CBF is increased in response to raised ICP, by CBF is increased in response to raised ICP, by cerebral cerebral vasodilatationvasodilatation, However this causes increase in , However this causes increase in cerebral blood volume and produces further brain cerebral blood volume and produces further brain swelling. When maximal vasodilatation occurs, further swelling. When maximal vasodilatation occurs, further increase in ICP causes reduction in cerebral BF.increase in ICP causes reduction in cerebral BF.

Effects of increased ICPEffects of increased ICP

C: Clinical effectsC: Clinical effects (symptoms and signs): (symptoms and signs): Significant raised intracranial pressure can be Significant raised intracranial pressure can be present with out symptoms or signs. present with out symptoms or signs.

1. 1. HeadacheHeadache: Is typically maximal in the morning and : Is typically maximal in the morning and is relieved by vomiting. It is caused by distortion, is relieved by vomiting. It is caused by distortion, stretching or invasion of pain sensitive structures stretching or invasion of pain sensitive structures such as the bridging veins, basal and meningeal such as the bridging veins, basal and meningeal arteries. arteries.

2. 2. VomitingVomiting: Usually associates headache and : Usually associates headache and typically occurs with out nausea.typically occurs with out nausea.

3. 3. PapilledemaPapilledema: This is the most reliable sign of : This is the most reliable sign of raised ICP. It's main features are:raised ICP. It's main features are:

PapilledemaPapilledema

Effects of increased ICPEffects of increased ICP D :Internal Brain herniation:D :Internal Brain herniation: resulting in strangulation, compression resulting in strangulation, compression

of of vital structures and blood vessels. vital structures and blood vessels.

1. Cingulate herniation1. Cingulate herniation: compress the internal cerebral vein and the : compress the internal cerebral vein and the anterioranterior

cerebral artery.cerebral artery.2. Central transtentorial herniation:2. Central transtentorial herniation:

* Compression of the 3rd. nerve -------------> Dilated pupils .* Compression of the 3rd. nerve -------------> Dilated pupils . * Compression of the post. cerebral art. ----> Hemianopia. Total * Compression of the post. cerebral art. ----> Hemianopia. Total blindness.blindness. * Compression or ischemia of the brain stem.-> Decerebration. Coma.* Compression or ischemia of the brain stem.-> Decerebration. Coma. * Distortion of the brain stem --------------> Hemorrhages.* Distortion of the brain stem --------------> Hemorrhages.3. Uncal herniation.3. Uncal herniation. compression of the mid-brain, 3rd nerve and the post. compression of the mid-brain, 3rd nerve and the post.

cerebral art.cerebral art.4. Tonsilar herniation4. Tonsilar herniation: Occurs when the cerebellar tonsils, : Occurs when the cerebellar tonsils,

herniate through the foramen magnum, resulting in compression of herniate through the foramen magnum, resulting in compression of medulla, Decerebration, coma, cardiovascular and respiratory medulla, Decerebration, coma, cardiovascular and respiratory abnormalities (apnea).abnormalities (apnea).

1.Cingulate herniation1.Cingulate herniation

2.Central transtentorial 2.Central transtentorial

herniationherniation

3.Uncal herniation3.Uncal herniation

4.Tonsilar herniation4.Tonsilar herniation

Brain Brain herniationherniation

Medical Treatment ofMedical Treatment of raised intra cranial pressure. raised intra cranial pressure.

1. Sedation, and positioning: 1. Sedation, and positioning: 2. Hypertonic solutions: 2. Hypertonic solutions:

* Manitol: 0.5- 1gm/ Kg body wt. over 30 min. bolus injection. * Manitol: 0.5- 1gm/ Kg body wt. over 30 min. bolus injection. * Furosemide: is effective in reducing brain edema, and reducing * Furosemide: is effective in reducing brain edema, and reducing CSF CSF

production. 40-120 mg daily.production. 40-120 mg daily.* Glycerol: can be given orally as well as I.V. 0.5-2 gm/ Kg. every 4 * Glycerol: can be given orally as well as I.V. 0.5-2 gm/ Kg. every 4 hrs.hrs.

3. Steroids:3. Steroids: Dexamethasone 4mg four times a day.Dexamethasone 4mg four times a day.4. Hyperventilation: 4. Hyperventilation: 5. Hyperbaric oxygen: (rarely used).5. Hyperbaric oxygen: (rarely used).6. Hypothermia: 6. Hypothermia: 7. Induced barbiturate coma: Has been used to reduce intracranial 7. Induced barbiturate coma: Has been used to reduce intracranial

pressure in head injuries, and to increase brain tolerance to focal pressure in head injuries, and to increase brain tolerance to focal ischemia in aneurysm surgery , strokes and SAH.ischemia in aneurysm surgery , strokes and SAH.