34 CSF & INTRACRANIAL PRESSURE Flashcards

1
Q

Two types of meninges

A

Pachymeninges and leptomeninges

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2
Q

Describe the pachymeninges

A

Dura mater. Two layers periosteal layer and meningeal layer.

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3
Q

Where do the venous sinus’s form

A

In between the two layers of the pachymeninges

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4
Q

Describe the leptomeninges

A

Arachnoid mater and pia mater. Separted by subarachnoid space which contains CSF and blood vessels

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5
Q

What are the falx cerebri and tentorium made from

A

Inner folds of the meningeal layer of the Pachymeninges

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6
Q

What are Virchow-Robinson spaces

A

As blood vessels enter or leave the brain/spinal cord the pia mater invaginates into the brain or sc to form perivascular spaces

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7
Q

Where is CSF produced

A

In the chorioid plexus mostly in the lateral ventricles some in 3rd and fourth ventricles

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8
Q

Describe the chorioid plexus

A

Bundles of fenestrated capillaries surrounded by ependymal cells (glial cells)

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9
Q

Two processes of CSF production

A

Mainly through filtration of choroidal blood some through secretion from ependymal cells

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10
Q

Typical total volume of CSF

A

150ml. 600ml created daily. Total volume replaced 4-5 times daily. Clinical relevance LP volume quickly replace

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11
Q

Major route of CSF absorption

A

Via arachnoid villi and arachnoid granulations which are invaginations of the pia mater into venous sinuses. Unidirectional bulk flow

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12
Q

Changes to CSF in disease states

A

Meningitis- increased WBC, protein and possibly glucose

SAH- RBC, xanthochromia

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13
Q

Functions of the CSF

A

Mechanical protection, homeostasis, counter changes in ICP, conduit for hormones

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14
Q

What may increases in ICP be caused by

A

Increase in brain volume (tumour, haemorrhage, hydrocephalus, abscess), increase in CSF volume (obstruction to flow, increased production, reduced absorption, increased blood flow)

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15
Q

Three kinds of cerebral herniations

A

Midline shift
Middle temporal lobe through tentorial notch
Inferior cerebellum through posterior fossa into SC

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16
Q

Systemic factors that affect IP

A

Arterial BP, venous pressure, posture, partial arterial pressure of O2 and CO2, temperature

17
Q

Three morphological features of the blood brain barrier

A

Absence of fenestration and presence of tight junctions
Fewer pinocytic vessels, thicker BM, more mitochondira (higher metabolic rate for active transport)
Astrocytic foot processes (regulators)

18
Q

Functions of BBB

A

Regulate ionic balance in brain
Facilitate transport of essential substrates (O2 and glucose)
Barrier against pathogens

19
Q

Clinical consideration in pathology of BBB

A

Tumours- new vessels don’t have BBB

Meningitis- breaks down BBB