Week 3 - H - Neuropathology 3 - Raised ICP, SOL, Trauma

Question 1

What suspends the brain within the skull?

Answer 1

The brain is suspended in the skull by the cerebrospinal fluid

Question 2

What are the functions of the CSF? (three functions)

Answer 2

Provides support for buoyancy of the brain - prevents the brains weight being of injury to itself Provides a buffer and absorber for energy impact to the brain Clears waste and accomodates to changes in intracranial volume

Question 3

What separates the right and left hemisphere of the brain? (ie the dura) What covers the cerebellum? What is the space in the cover of cerebellum that the brainstem passes through? What covers the pituitary gland which lies in the sella turcica ( saddle-shaped depression in the body of the sphenoid bone)?

Answer 3

The falx cerebri separates right&left hemispheres - The tentorium cerebelli lies over the cerebellum - has a hole for the brainstem known as the tentorial notch -Diaphragma sellae covers the pituitary gland with a circular hole allowing the vertical passage of the pituitary stalk.

Question 4

What is the normal intracranial pressure between?

Answer 4

Normal ICP is between 5-13mmHg

Question 5

If the brain enlarges, some blood +/- CSF must escape from cranial vault to avoid rise in pressure. Once this process is exhausted, venous sinuses are flattened and there is little or no CSF. WHat happens once the compensatory mechanism of blood or CSF escaping is exhausted?

Answer 5

Any further increase in brain volume will result in a rapid increase in intracranial pressure

Question 6

Accumulation of excessive CSF within the ventricular system of the brain. WHat is this?

Answer 6

Hydrocephalus - Hydrocephalus is a build-up of fluid on the brain. The excess fluid puts pressure on the brain, which can damage it

Question 7

What is the normal constant volume of CSF and what is the amount produced per day?

Answer 7

Constant normal volume of around 120-150mls of CSF Roughly about 500mls are produced daily meaning there is a CSF turnover at least 3-5 times per day

Question 8

Where is CSF produced? What lines the site of CSF production? What absorbs CSF? What drains the CSF from the fourth ventricle into the central canal of the spinal cord?

Answer 8

CSF is produced in the choroid plexus of the ventricles of the brain Ependymal cells are a type of glial cell that line the ventricles CSF is absorbed by arachnoid granulations The median aperture drains CSF from the fourth ventricle into the central canal of the spinal cord (foramen of Magendie)

Question 9

CSF is Produced in the lateral ventricles, passes to the 3rd ventricle, where further CSF is produced, passes through the aqueduct of sylvius downward to the 4th ventricle, where some CSF can escape through the foramen of Luschka (lateral aperture) or beneath the level of the cerebellum though the foramen of Magendie. (median aperture) What level is a lumbar puncture carried out at?

Answer 9

Lumbar puncture carried out at the L3/4 level - this is because the spinal cord ends at L2 and therefore wont be piercing this structure and at S1 there is no gaps in the fused vertebrae

Question 10

On a lumbar puncture What is usually the WCC? RBC? Protein cotnent? and glucose concentration?

Answer 10

White blood cell count - Less than 5 cells per mm 3 Red blood cell count - 0 per mm 3 Protein content - 150-450mg/L Glucose conetration - 60-70% of blood glucose conccentration

Question 11

What are the three way sin which hydrocephalus can occur?

Answer 11

Obstruction to the outlflow of CSF - ie space occupying lesions Decrease in the resorption of CSF Overproduction of the CSF - v.rare

Question 12

What could cause a decrease in resoprtion of CSF? What could cause the overproduction of CSF?

Answer 12

Decrease in CSF resorption - post-sub arachnoid haemorrhage or meningitis Overproduction of CSF - tumour of the choroid plexus

Question 13

Hydrocephalus classification can be communicating or non-communicating In non-communicating hydrocephalus, the obstruction occurs within the ventricular system. e.g. arnold chiari malformations What is a chairi malformamtion?

Answer 13

Chiari malformations (CMs) are structural defects in the cerebellum causing the cerebellum to push through the foramen magnum and compress the spinal cord

Question 14

What part of the CSF pathway to chairi malformations affect?

Answer 14

Due to the cerebellum herniating through the foramen magnum - this cause compression in the drainage of CSF from the fourth ventricle Fourth ventricle obstruction will lead to dilatation of the aqueduct as well as the lateral and third ventricles

Question 15

If non communicating occurs within the ventiruclar system, how does communicating occur?

Answer 15

Obstruction to flow of CSF outside of the ventricular system - basically decreased resorption of the CSF e.g. in subarachnoid space or at the arachnoid granulations - can be caused by post-SAH or meningitis

Question 16

If hydrocephalus develops before closure of cranial sutures, then cranial enlargement occurs What type of person does this happen in? What happens when hydrocephalus occurs when the cranial sutures have closed?

Answer 16

Hydrocephalus can develop before the closure of the cranial sutures in babies resulting in cranial enlargement In adults, the sutures have closed and hydrocephalus will cause a raised ICP

Question 17

Dilatation of the ventricular system and a compensatory increase in CSF volume secondary to a loss of brain parenchyma What is this known as? Name 2 disease where this may occur?

Answer 17

This is hydrocephalus ex vacuo Can occur in those Alzheimer’s disease or Pick’s disease (frontotemporal dementia)

Question 18

Raised intracranial pressure can cause intracranial shifts and herniations What is the equation used to calculate cerebral perfusion pressure? Impaired blood flow to the brain due to rising ICP can reduce the CPP

Answer 18

Cerebral perfusion pressure (CPP) = Mean arterial pressure (MAP) - Intracranial pressure (ICP)

Question 19

Herniation of brain tissue can occur through routes of “weakest resistance” due to an increase in intracranial pressure. What are the four common herniation types?

Answer 19

1. Subfalcine (cingulate) - part of the brain herniates under the falx cerebri 2. Tentorial (uncal) - medial aspect of temporal lobe the uncus herniates over the tentorium cerebelli 3. Cerebellar - upwards or dwonwards herniation of the cerebellar tonsils 4. Transcalvarial - swollen brain will herniate through a fracture site in the skull

Question 20

Why is a subfalcine herniation also known as a cingulate herniation?

Answer 20

This is because the cingulate gyrus (immediately superior to the corpus callosum) herniates under the falx cerebri Highlighted in green is the cingulate gyrus - corpus callosum sits inferiorly above the lateral ventricles

Question 21

What is compressed in a tentorial (uncal herniation), what are the clinical signs? Why is tonsilar herniation potentially life threatening?

Answer 21

Tentorial hernaition can compress the oculomotor nerve and the parasympathetics running beside causing ipsilateral pupillary dilation and impairment of ocular movements on the same side as the herniation Tonsilar herniation can cause brainstem compression impeding on vital respiratory centre in the medulla oblongata

Question 22

What are the clinical signs of raised intracranial pressure? This is the generalised signs before including the signs of the underlying cause of raised ICP

Answer 22

Papilloedema – occurs due to pressure on optic nerve Nausea and vomiting – due to pressure on vomiting centres in Pons and Medulla Headache – (worse on lying down, coughing, sneezing, and straining) – thought due to CSF drainage worse when flat and coughing/straining increased ICP Neck stiffness – due to pressure on dura around cerebellum and brainstem. Also fixed dilated pupils if bilateral oculomotor compression

Question 23

The mass effect of space occupying lesions is herniations and oedema as well as all the focal neurological problems What are some of the causes of space occupying lesions?

Answer 23

Neoplasms INfections Haemorrhages

Question 24

What are three main clincial signs of a tumour?

Answer 24

Focal neurological deficit - 2/3rds of people with a tumour will experience this Headaches - half of patients will have this Seizures - 1/4 of patients will have seizures

Question 25

When is the headache typically bad if a patient has a tumour?

Answer 25

In a patient with a brain tumour, the headache is typically bad in the morning - so bad that it wakes them from a sleep

Question 26

What percentage of all cancers are primary brain cancers?

Answer 26

3% of all cancers are primary brain cancers - ie they are not metastases

Question 27

Are secondary (brain metastases) or primary brain tumours more common?

Answer 27

Secondary brain tumours are far more common than primary

Question 28

Children 70% of the CNS tumours arise below or above the tentorium cerebelli ? Adults 70% of the CNS tumours arise below or above the tentorium cerebelli ?

Answer 28

In children, 70% of the CNS tumours arise below the tentorium cerebelli In adults, 70% of the CNS tumours arise above the tentorium cerebelli

Question 29

What are the common primary tumours to metastasise to the brain?

Answer 29

Breast, bronchus, kidney thyroid, colon and malignant melanomas

Question 30

For most cancers, the distinction between benign and malignant lesions is critical to determining outcome This is far less crucial in primary brain tumours Why is this less crucial?

Answer 30

This is because primary benign brain tumours have just as much a chance of causing death as primary malignant brain tumours- either can press on structures vital for living ie different brainstem structures

Question 31

CNS tumours are classified according to their presumed cell of origin. What is the commonest primary malignant tumour in adults and in children? What cell type do these tumours arise from? What is the second most common primary malignant tumour in children?

Answer 31

Commonest primary malignant brain tumour in both children and adults is the astrocytoma - arises from the astrocyte cells Medulloblastoma is the second most common primary malignant brain tumour in children

Question 32

What is the most common benign brain tumour in children and adults?

Answer 32

Meningioma is the most common benign brain tumour in adults Craniopharyngiomas are the most common benign tumour in children

Question 33

WHO have an astrocytoma grading from grade I to grade IV WHat is the name of the astrocytoma in children and what grade is this?

Answer 33

This is a grade I astrocytoma known as the pilocytic astrocytoma - only in children

Question 34

Can grade I astrcoytomas progress to further stages?

Answer 34

No they do not progress, grade II to IV however can progress

Question 35

When looking at a pilocytic astrocytoma, what is seen? (think what the word pilocytic actually means)

Answer 35

Long hair like process coming from a cystic tumour

Question 36

Well differentiated grade II lesions have an average of ~5 years survival What is thesurvival rate of glade IV astrocytomas? What is the name of grade III and grade IV astrocytomas?

Answer 36

Grade III - Anaplastic astrocytoma Grade IV - glioblastoma - approx 10month survival from diagnosis

Question 37

What are the features of gliobastoma on histology?

Answer 37

Extreme nuclear atypia Neovasuclariation or necrosis Mitotic activity

Question 38

What is the difference between primary and secondary gliobastoma?

Answer 38

Primary occurs on its own Secondary occurs as a progression of anaplastic astrocytoma

Question 39

What type of astrocytoma is this?

Answer 39

Can see the haemorrhaging and the necrosis therefore a grade IV gliobastoma

Question 40

2nd most common tumour in children after Pilocytic astrocytomas What is this and where does it occur?

Answer 40

This is a medulloblastoma and it occurs in the midline of the cerebellum

Question 41

What is the most common and second most common primary malignant brain tumour in adults and children? What is the most common benign brain tumours in adults and children?

Answer 41

Primary malignant - Adult

• 1st - Astrocytoma,
• 2nd - Oligodendroglioma (believed to originate from oligodendrocyte)

Children-

• 1st- Astrocytoma (pilocytic astrocytoma),
• 2nd - Medulloblastoma

Benign tumour -

• Adult - Meningioma
• Children - Craniopharyngioma

Question 42

What specific type of astrocytoma is seen most commonly in primary malignant brain tumours in adults?

Answer 42

Glioblastoma multiforme (GBM) is the most common and deadliest of malignant primary brain tumors in adults and is one of a group of tumors referred to as gliomas.

Question 43

Medulloblastomas tend to occur below the tentorium cerebelli in the midline • It starts in or near the cerebellum and can spread to other parts of the brain or spinal cord and will block the fourth ventricle causing hydrocephalus also How is it treated?

Answer 43

Surgical resection of the tumour and radiotherapy are shown to be highly effective in treating the medulloblastoma

Question 44

Oligodendrioglioma can arise in different areas in the brain ie temporal or parietal lobes If it presents with behavioural, mood or personality changes, where is the lesion? If it presents with difficulty in speech or memory, where is the lesion? If it presents with numbness or weakness, where is the lesion?

Answer 44

Behavioural, mood or personailty changes - frontal lobe Difficulty in speech or memory - temporal lobe Numbeness - Parietal lobe Weakness - Frontal lobe The majority of oligodendrogliomas occur in the frontal lobe, and the second most common site affected is the temporal lobe.

Question 45

What is the classic triad of a brain abscess?

Answer 45

Headache, fever and focal neurological sign (ie seizure)

Question 46

How is a brain abscess diagnosed and treated?

Answer 46

Diagnosed with a contrast CT Treated with IV ceftriaxone and IV metronidazole followed by CT stereotactic drainage

Question 47

Not only does the abscess represent a space occupying lesion in its own right, but it also triggers profound oedema, which can give rise to midline-shift. The inflammatory toxicity and oedema can be marked, contributing to surrounding ischaemic and excitotoxic injury. What are examples of organisms that can cause brain abscess?

Answer 47

Streptococcus (strep milleri in particular ), staphylococcus (staph aureus) and e.coli

Question 48

Bacterial meningitis is a clinical emergency Meningeal inflammation due to bacterial micro-organisms Derived from haematogenous spread Rapidly spread through subarachnoid space Name the causative organisms in neonates, children, 10-21 year olds, over 21 and over 65 year olds?

Answer 48

Neonates - Listeria monocytogenase, Group B strep, E.coli Children - H.influenza 10-21 year olds - Neisseria meningitis 21+ - Streptococcus pnemumoniae > Neisseria meningitis 65+ Streptococcus pneumoniae > Listeria monocytogenase

Question 49

What is the gram stain of listeria? Strep pneumoniae? What type of streptococcus is strep pneumoniae? E.coli? H.influenza? Neisseria meningitis?

Answer 49

Listeria - Strep pneumonaie - gram positive cocci - Group A (partial haemolytic) strep E.coli - gram negative bacilli (large) - coliform H.influenza - gram negative bacilli (small) Neisseria meningitis - gram negative diplococci

Question 50

What is the initial treatment for bacterial meningitis? What is added to the treatment if patient is over 60, immunocompromised or a neonate?

Answer 50

IV dexamthasone + IV ceftriaxone Add IV amoxicillin to cover listeria if over 60, neonate or immunocompromised

Question 51

When is dexamthasone stopped and when is it continued? Should dexamethasone or ceftriaxone be administered first? If penicillin/cephalosproin resistant pneumococcus what is given? If penicillin or cephalsporin allergic what is given?

Answer 51

Dexamethasone is given if the bacteria is cultured and proves to be a pneumococcal (strep pneumoniae) cause, it is stopped if any other bacteria is proved to be the cause Dexamthasone should be administered with or just before first dose of antibiotics If penicillin/cephalosproin resistant pneumococcus - add vancomycin IV If cephalsoproin allergy - chloramphenicol, Penicillin allergy - co-trimoxazole

Question 52

Trauma to the head can be missile or non-missile What do these terms mean?

Answer 52

Missile head trauma would be penetrating Non-missile head trauma would be non-penetrating

Question 53

The distinction between high and low velocity penetrating injuries is important In fast moving projectiles, the extent of injury can be far greater. One of the main reasons, is something called cavitation occurs (small bubbles appearing at low pressure): Does cavitation occur in fast movement or slow?

Answer 53

Cavitation occurs in fast movement and can cause widespread surrounding damage

Question 54

Non-missile injury is when there is a sudden acceleration and/or deceleration Falling off a bike and landing on your head Or being hit with a baseball bat The severity of non-missile head injury depends upon the initial velocity, the mass of the object hitting the cranium (or the mass of the cranium itself). But crucially on the contact time. If contact time is greater, what does that say about force?

Answer 54

F = (mv-mu) / t A smaller contact time means there is a greater force applied Ie if the person is moving at a higher velocity, there will be a smaller contact time when the head its something as the force is far greter

Question 55

Most traumatic haematomas are supratentorial and unilateral and most are intradural. 20% are extrdural What usually causes an extradural haematoma?

Answer 55

usually injury to the pterion (weakest part of the skull) resulting in middle meningeal artery to rupture causing the haematoma - does not cross suture line

Question 56

A lucid interval may occur with an extra dural haematoma, what does this meaan? What is used to show an extradural haematoma? How does the extradural haemaomta usually present?

Answer 56

The lucid interval means that after the injury to the brain, there is a oeriod where the persons condition improves before the haematoma causes an increased ICP leading to symptoms CT scan and will see a lens shaped blood region Usually presents with a head injury where a few hours later there is an increasing headache with vomiting and potentially loss of consciousness

Question 57

Subdural haematomas are collections of blood between the internal surface of the dura mater and arachnoid, which tend to occur over the cerebral convexities. Caused by disruption of bridging veins that extend from the surface of the brain into subdural space What patients do subdrural haematomas usuually occur in?

Answer 57

usually happen in elderly - bridging veins are weak and vulnerable in the elderly Also in acoholics and falls

Question 58

What can happen to the contents of the cranial vault due to a subdrual or epidrual haematoma?

Answer 58

A midline shift can occur potentially compressing other brain structures or even herniation can occur