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Content: Content: Clinical practiceClinical practiceTime:Time: 2:00pm 2:00pm this Thursday this Thursday Address: Address: Department of Neurosurgery,Department of Neurosurgery, the 8th floor, No.5 Building the 8th floor, No.5 Building ， ， No.1, Hospital.No.1, Hospital.

NeurosurgeryNeurosurgery

INTRACRANIAL DYNAMICSINTRACRANIAL DYNAMICS

The The first principlefirst principle is obvious: the cranial is obvious: the cranial cavity has a fixed volume that is filled by various cavity has a fixed volume that is filled by various things:things: 1. Brain tissue1. Brain tissue2. CSF2. CSF3. Blood vessels and intravascular blood volume3. Blood vessels and intravascular blood volume4. Volume associated with any pathologic 4. Volume associated with any pathologic process, which can include tumor, cyst, process, which can include tumor, cyst,

abscess, hemorrhage, edema, necrosisabscess, hemorrhage, edema, necrosis

A consequence of this principle:A consequence of this principle:

If there is an elevation in the If there is an elevation in the volume of any one compartment, volume of any one compartment, there is a stage of compensation in there is a stage of compensation in which the volume of one or more which the volume of one or more other compartments can be other compartments can be reduced to avoid elevations in ICP.reduced to avoid elevations in ICP.

QUESTION: What is Intracranial QUESTION: What is Intracranial Pressure (ICP)?Pressure (ICP)?

ICP ： the pressure produced by the content of the cranial cavity (brain tissue, CSF and blood) on the cranial cavity wall.

Normal ICP ： Adult ： 0.7 ～ 2.0 kPa （ 70 ～ 200mmH2O ）。 Child ： 0.5 ～ 1.0kPa （ 50 ～ 100mmH2O ）。

The The second principlesecond principle is not obvi is not obvious and may seem counterintuitivous and may seem counterintuitive: e:

The spinal fluid is produced at a cThe spinal fluid is produced at a constant rate ( 15-20 mL/hr) large∼onstant rate ( 15-20 mL/hr) large∼ly by the ly by the choroid plexuschoroid plexus of the ven of the ventricles by an energy-dependent, ptricles by an energy-dependent, physicochemical process.hysicochemical process.

The The third basic principle:third basic principle:

The cerebral blood flow (CBF) noThe cerebral blood flow (CBF) normally varies over a wide range (3rmally varies over a wide range (30-100 mL per 100 g brain tissue pe0-100 mL per 100 g brain tissue per minute), depending on metabolic r minute), depending on metabolic demand from neuronal activity widemand from neuronal activity within a particular area of the brain.thin a particular area of the brain.

For any brain regionFor any brain region

CBF=Cerebral perfusion pressure/CBF=Cerebral perfusion pressure/ Cerebral vascular resistance Cerebral vascular resistance

The The fourth principlefourth principle::

Injured tissue swells, making obvious the Injured tissue swells, making obvious the potential for a cascading injury by a vicious potential for a cascading injury by a vicious cycle. If the stage of compensation mentioned cycle. If the stage of compensation mentioned earlier, even with therapy, is exceeded and ICP earlier, even with therapy, is exceeded and ICP is elevated high enough by whatever mechanism is elevated high enough by whatever mechanism so that cerebral perfusion pressure (CPP) so that cerebral perfusion pressure (CPP) declines, CBF can decline to levels where tissue declines, CBF can decline to levels where tissue

injury occurs.injury occurs.

EdemaInfarction

ICP CPP

The vicious cycle. CPP, cerebral perfusion pressure; ICP, intracranial pressure.

Cerebral perfusion pressure (CPP) = Cerebral perfusion pressure (CPP) = mean systemic arterial pressure mean systemic arterial pressure

(MAP)-ICP(MAP)-ICP

The The fifth principle:fifth principle:

Focal mass effect and its Focal mass effect and its progression within the complex progression within the complex anatomy of the cranial cavity.anatomy of the cranial cavity.

A A sixth principle:sixth principle:

The separateness of the phenomenoloThe separateness of the phenomenology of the following:gy of the following: 1. Focal mass effect1. Focal mass effect2. Diffuse raised ICP2. Diffuse raised ICP3. Ventriculomegaly (enlargement of 3. Ventriculomegaly (enlargement of

the cerebral ventricles) the cerebral ventricles)

The pure form of raised ICP (withoThe pure form of raised ICP (without focal mass lesion, and without enlut focal mass lesion, and without enlargement of the ventricular system) argement of the ventricular system) is a condition known as is a condition known as pseudotumor pseudotumor cerebri.cerebri.

The pure form of ventriculomegaly iThe pure form of ventriculomegaly is a condition known as s a condition known as normal-pressnormal-pressure hydrocephalusure hydrocephalus (NPH). (NPH).

Question: What is intracranial hQuestion: What is intracranial hypertension? ypertension?

Cranial cavity volume increase, ICP Increase above 2.0 kPa (200mmH2O), resulting in a series of corresponding syndrome.

Causes of intracranial hypertensionCauses of intracranial hypertension

1. the content of cranial cavity increase2. mass effect3. congential malformation

Clinical manifestationsClinical manifestations(( 一）一）

1. 1. 头痛头痛 (headache )(headache ) ： ： the most common symthe most common symptomptom ofof intracranial hypertension. intracranial hypertension.2. 2. 呕吐呕吐 (vomit )(vomit ) ：： projectile vomitingprojectile vomiting3. 3. 视神经乳头水肿视神经乳头水肿 (papilloedema)(papilloedema) ：：

Above three is the typical manifestations of intAbove three is the typical manifestations of intracranial hypertension. racranial hypertension.

Clinical manifestations (Clinical manifestations ( 二）二）

4. disturbance of consciousness and 4. disturbance of consciousness and changes of physical signschanges of physical signs 5. others5. others

The diseases caused intracranial hyThe diseases caused intracranial hypertension pertension

1.1. craniocerebral injurycraniocerebral injury

Acute Acute subdural subdural

hematomahematoma

Subacute sSubacute subdural heubdural he

matomamatoma

2. intracranial tumor2. intracranial tumor ：：

3. intracranial infection 3. intracranial infection ：： intracerebral abscessintracerebral abscess 、、

tuberculous meningitistuberculous meningitis 、、 tuberculotuberculoma of brainma of brain 。。

脑脓肿 CT片 intracerebral abscessintracerebral abscess

Brain abscess

4. cerebrovascular disease4. cerebrovascular disease ：： cerebral hemorrhagecerebral hemorrhage 、 、

subarachnoid hemorrhagesubarachnoid hemorrhage 。。

5. 5. 脑寄生虫病脑寄生虫病 (cerebral parasitosis)(cerebral parasitosis) ：： 6.6. 颅脑先天性疾病颅脑先天性疾病 (congenital disease of (congenital disease of brain)brain) ：：7.7. 良性颅内压增高良性颅内压增高 (benign intracranial (benign intracranial hypertension)hypertension) ：：8.8. 脑缺氧脑缺氧 (cerebral anoxia)(cerebral anoxia)

Influence factors of intracranial Influence factors of intracranial hypertensionhypertension

1. 年龄 (Age) ：characteristics of Infants and the elderly

Influence factors of intracranial Influence factors of intracranial hypertensionhypertension

2. 病变扩张的速度 (Outstretched velocity of the disease) ：

Influence factors of intracranial Influence factors of intracranial hypertensionhypertension

3. 病变部位 (Position of the disease) ： the midline, posterior fossa and filling sinus near les

ions

4. 伴发脑水肿的程度 (Degree of hydrocephalus ）： Lesions of the inflammatory response may be associated with obvious cerebral edema, such as cerebral abscess

Influence factors of intracranial Influence factors of intracranial hypertensionhypertension

5. 全身情况 (General conditions) ：

Liver and kidney function obstacle, and pulmonary infection, acid-base imbalances the secondary brain edema

Acute cerebral herniaAcute cerebral hernia

Anatomical: the whole cranial cavity was separated into three each other mutually cavity by brain sickle and cerebellum tent. The cavity above the cerebellum tent were divided into control two cavity, respectively hold about cerebral hemisphere, The cavity under the tent accommodate cerebellum, bridge brain and the medulla oblongata.

The causes of the formation of The causes of the formation of cerebral herniacerebral hernia

When a certain cavity has the intracranial lesions, this cavity pressure is greater than adjacent cavity pressure, and brain from high to low pressure area shift and lead to brain tissue, vascular and cranial nerves, and other important structure compression and shift, resulting in a series of serious clinical symptoms and signs, called "the cerebral hernia".

Brain herniationBrain herniation

1.1. infrafalx cerebri herinfrafalx cerebri herniationniation

2.2. transtentorial transtentorial herniation herniation

3.3. Foramen magnum hForamen magnum herniationerniation

Management of cerebral hernia Management of cerebral hernia Principle of management

1. Rapid intravenous input permeability liquid, reduce intracranial pressure to alleviate temporarily condition. Commonly used medicines for mannitol 125 ~ 20% 250ml rapid static drops.

2. Early clear lesions properties and parts, seasonable purify for.

3. Causes difficult to express or lack of effective healer, can choose some palliative operation to alleviate increase intracranial pressure. Such as hydrocephalus can choose ventricle external drainage, cerebrospinal fluid diversion decompression, The cerebellum curtain cut trace hernia feasible temporal component decompression, Foramen magnum hernia feasible suboccipital decompression.

SummarySummary11 、、 the content of the cranial cavity2 、 ICP,ICP value3 、 the vicious cycle of ICP and CPP4 、 the relation between CBF 、 CPP and CVR 5 、 the relation between CPP 、 ICP and MAP 6 、 Intracranial hypertension 7 、 Clinical manifestations of Intracranial hypertension 8 、 pseudotumor cerebri9 、 brain herniation