Intracranial Pressure Pathology Flashcards
What is raised intracranial pressure e
Increase in the volume or mass of intracranial content within fixed capacity of skull which displaces CSF and compress the vasculature leading to increased pressure in cranial cavity
What is the capacity of the skull
Less than 30 cubic cm
Intracranial compartment division with percentages
Brain - 85%
Blood - 10%
CSF - 5%
Normal pressure in skull
10-15 mmHg
Upper normal limit of IC pressure
20 mm Hg
Moderate increase in IC pressure
20-40 mmHg
Severe increase in IC pressure
More than 40 mmHg
Causes of raised IC pressure
Intracranial expanding lesions like tumor , hematoma , abscess, granuloma, swollen infarct
Infections - meningitis , encephalitis
Hydrocephalus
Cerebral edema
What is hydrocephalus
Accumulation of excessive CSF in ventricular system
Specialized tissue that secretes CSF
Choroid plexus
Where is choroid plexus located
Lateral ventricle
Third ventricle
Fourth ventricle
Amount of CSF at all times
150-270 ml
Which structures on choroid plexus secretes the CSF
Villi
Circulation of CSF
Lateral ventricle -> inter ventricular foramen ->third ventricle -> cerebral aqueduct -> 4th ventricle ->
4th ventricle -> some go through obex narrow passage -> central canal
4th ventricle -> majority pass through median aperture and 2 lateral apertures -> cisterns magna and cerebelli pontine cisterns -
-> subarachnoid space of the brain and spinal cord -> reabsorption into Dural venous sinuses through arachnoid granulations
Absorption of CSF
Majority by arachnoid granulation which have arachnoid villi which pierce into dural venous sinuses
Minute channels in the cribiform plate and drain into lymphatic channels of nasal mucosa
Glymphatic system
Hydroc
Hydrocephalus causes
Overproduction of CSF by choroid plexus papilloma / hyperplasia
Obstruction to flow
Defective absorption - arachnoid villous fibrosis / destruction , sinus thrombosis
Types of hydrocephalus
Communicating
Non communicating
Hydrocephalus ex vacuo
What is hydrocephalus ex vacuo
Brain damage due to stroke or injury with brain substance shrinkage
Leads to filling of extra spACE by CSF
With normal CSF pressure and enlarged ventricles
People at risk of hydrocephalus ex vacuo
Very old persons
Alzheimer’s patients
People with degenerative disease of Brian
When do you see hydrocephalus in children
Before suture close or after
When do you see hydrocephalus in adults
After suture closure
Cerebral edema can be caused by raised intracranial pressure T or F
True
3 types of cerebral edema
Cytotoxic
Vasogenic
Interstitial
Cytotoxic cerebral edema
Intracellular , due to cell swelling
Seen in hypoxia when pump cant work to move sodium
Vasogenic edema
Extracellular
BBB is disrupted
Affect white matter via leakage of fluid from capillaries
Interstitial edema
Periventricular
Increased in brain fluid due to blockage of CSF flow
How can we evaluate the clinical consequences of the raised ICP
Degree or severity of increased intracranial pressure
Rates and speech of increased intracranial pressure
Nature of underlying reason leading to raise intracranial pressure
What are the different raised intracranial pressure effects
Spatial compensation
alterations in the brain
herniation
systemic effects
What are the different spatial compensation effects
Expanding lesions leading to compression and reduced csf volume
Reduce blood flow
What are the different alteration in the brain
Focal or localized destruction of neurons -> direct pressure effects
generalized neuronal degeneration with diffuse compression of blood vessels leading to ischemia
Brain tissue displacement with HERNIATION
Cranial nerve pressure creating cranial nerve palsies
Compression of intracranial vessels leading to kinking of vessels
Infarct
hemorrhage
Major her nations of the brain
Sub falcine herniation
transtentorial HERNIATION
cerebellar tonsi HERNIATION in foramen magnum
Clinical effects of Sub falcine herniation
Compression of anterior cerebral artery branches
Clinical effects of transtentorial HERNIATION
Third cranial nerve compromised leading to ocular changes
ischemia in the posterior cerebral artery affecting visual cortex
compression of contralateral cerebellar peduncle leading to hemiparesis
hemorrhages in the brainstem known as duret
Tonsillar herniation clinical effect
Compromises respiratory and cardiac centers
Systemic effects of raised intracranial pressure
Arterial hypertension because of local sympathetic activity
myocardial dysfunction damage ,necrosis ,subendocardial hemorrhage
respiratory dysfunction with damage to brainstem
Mucosal alterations in the G.I. tract and urinary system Due to increased sympathetic activity
