L17 - Neuropathology

Question 1

describe the histology of the brain

Answer 1

• Neurons
• Glia
• Meninges
• Blood vessels

Question 2

look at slide 4 to label the histology of a sample of brain tissue

Answer 2

how was it

Question 3

describe the structure of the stuff surrounding the brain from hair

Answer 3

• SKIN
• Aponeurosis
• periosteum
• Bone
• Meninges- Dura mater, Arachnoid, Pia mater

Question 4

describe how cerebrospinal fluid is absorbed and produced

Answer 4

Production by choroid plexus in the lateral ventricles (450ml per 24h)

Resorption by arachnoid granulations in the subarachnoid space

Question 5

describe the normal volume of cerebrospinal fluid

Answer 5

Normal volume 150ml

Question 6

give 4 importances of cerebrospinal fluid

Answer 6

Metabolic importance

Cushioning of the CNS

Role in immune regulation and defense

Cerebral autoregulation of blood flow

Question 7

describe hydrocephalus

Answer 7

Obstruction to CSF flow

Impaired resorption at arachnoid granulations

Shrinking of brain tissue (e.g. dementias) = ex vacuo

Very rarely overproduction

Question 8

what are the 2 types of hydrocephalus

Answer 8

• communicating

- non-communicating

Question 9

describe what happens if hydrocephalus occurs before fusion of the cranial sutures

Answer 9

causes enlargement

of the head circumference.

Question 10

describe what is classified as raised intracranial pressure

Answer 10

-Mean CSF pressure above 200mm H2O

Question 11

what can cause raised intracranial pressure

Answer 11

Increased CSF volume (hydrocephalus)

Intracranial space occupying lesion (neoplasm, haemorrhage, abscess)

Cerebral oedema

Question 12

what are the different types of herniations in the brain

Answer 12

Subfalcial (cingulate)

Central/transtentorial

Tonsillar/cerebellar

Question 13

where do the different types of herniations occur in the brain

Answer 13

slide 13

Question 14

what can a tonsillar/cerebellar herniation cause

Answer 14

Tonsillar/cerebellar herniation
may cause compression of the
medulla with impairment of
vital respiratory and cardiac
functions.

Question 15

what can be observed on autopsy of a brain that has had tonsillar herniation occur

Answer 15

Coning herniation

&

compression of the medulla oblongata

&

Duret haemorrhages

Question 16

describe the different classifications of a space occupying lesions

Answer 16

Extradural/epidural haemorrhage

Subdural haemorrhage

Subarachnoid haemorrhage

Intracerebral haemorrhage

Ischaemic infarct with subsequent oedema or haemorrhage

Neoplasm

Abscess

Question 17

what are the different types of head trauma

Answer 17

• skull fracture
• parenchymal injury
• Coup and Countercoup
• Vascular injury

Question 18

describe different types of parenchymal Injury

Answer 18

• Contusion (bruising) Concussion is a clinical term/syndrome
• Laceration (penetration or tearing)
• Diffuse axonal injury

Question 19

describe coup and countercoup

Answer 19

CSF plays a major role in coup and countercoup injuries to the brain.

When a moving object impacts the stationary head, coup injuries are typical, while contrecoup injuries are produced when the moving head strikes a stationary object

Question 20

describe vascular injury types

Answer 20

Extradural: Severe trauma with arterial laceration (m. mening. a.)

Subdural: Trauma may be minor in atrophy (bridging veins)

Subarachnoid: Rupture of saccular (berry) aneurysm (circle of Willis)

Intraparenchymal:
(hypertension)

Question 21

look at slide 19-21 for pictures of different types of haemorrhages

Answer 21

how was it?

Question 22

describe the different causes of cerebral oedema

Answer 22

Vasogenic:
-Increased vascular permeability

Cytotoxic:
-Neuronal, glial or endothelial cell damage

Question 23

describe cerebral infarction

Answer 23

15% of cardiac output

20% of O2 demand

Stroke = sudden onset of neurological symptoms

Hypoxia vs ischaemia (global vs focal)

Neurons are the most O2 sensitive cells

Haemorrhagic infarction in emboli (petechial lesions e.g. BM)

Ischaemic infarction in thrombosis

Question 24

describe the histology of ischaemic infarction

Answer 24

• Acute neuronal injury
• ‘Red neurons’
• Pyknosis of nucleus
• Shrinkage of the cell body

-Loss of nucleoli
Intense eosinophilia of
cytoplasm

-Owing to irreversible
hypoxic/ischaemic insult

(look at slide 26)

Question 25

describe where neoplasms occur

Answer 25

Gliomas (astrocytoma, oligodendroglioma, glioblastoma)

Neural tumours (ganglion cell tumours)

Meningiomas

Poorly differentiated neoplasms (medulloblastoma)

Primary CNS lymphoma

Metastasis (lung, breast, skin/melanoma, kidney, GI tract)

Peripheral nerve tumours (schwanoma, neurofibroma, MPNST

Question 26

describe the type of infections that can occur in the brain and which pathogen causes them

Answer 26

• Meningitis ,bacterial (acute or chronic), viral , fungal ,RMSV, neurosyphilis, lyme disease, malaria
• Abscess- Usually bacterial
• Encephalitis-Viral (HSV, CMV, HIV, JC polyoma virus)

Localised-Toxoplasmosis, cysticercosis

Question 27

name some progressive degenerative diseases

Answer 27

Neurodegenerative diseases (Alzheimer d., Parkinson d.,)

Spinocerebellar degenerative diseases:
-Accumulation of protein aggregates leading to loss of cellular and subsequent loss of CNS functions: Dementia, behavioural and personality changes, language disturbance, movement and coordination disturbance, paralysis.

Demyelinating diseases (Multiple sclerosis)

Prion diseases (Creutzfeldt-Jakob disease)

Genetic metabolic diseases (Neuronal storage diseases)

Toxic & aquired metabolic diseases (Vit B1 & B12 def., CO toxicity, alcohol toxicity, radiation toxicity)