Neuropathology Flashcards
(36 cards)
What are the layers of the meninges
- Dura mater
- Arachnoid
- Pia mater
What are the arachnoid trabeculae
- are delicate strands of connective tissue that loosely connect the two innermost layers of the meninges – the arachnoid mater and the pia mater
- They are found within the subarachnoid space where cerebrospinal fluid is also found
What is the normal volume of CSF
- 150ml
What is hydrocephalus
- Obstruction CSF flow
- Impaired reabsorption at arachnoid granulations
- Shrinking of brain tissue(eg dementias) = ex vacuo
- Very rarely overproduction
What does hydrocephalus before fusion of the cranial sutures cause
- It causes enlargement of the head circumference
What is the classification for raised intracranial pressure
- Mean CSF pressure above 200mm H2O
What can caused raised intracranial pressure
- Increased CSF volume(hydrocephalus)
- Intracranial space occupying lesion(neoplasm, haemorrhage, abscess)
- Cerebral oedema
Give examples of types of herniation
- Subfalcial(cingulate)
- Central/transtentorial
- Tonsillar/cerebellar
What is the clinical significance of a tonsillar/cerebellar herniation
- May cause compression of the medulla oblongata with impairment of vital respiratory and cardiac functions
What are duret haemorrhages
- are small lineal areas of bleeding in the midbrain and upper pons of the brainstem
- They are caused by a traumatic downward displacement of the brainstem
Give examples of types of haemorrhages
- Extradural/epidural haemorrhage
- Subdural haemorrhage
- Subarachnoid haemorrhage
- Intracerebral haemorrhage
- Ischaemic infarct with subsequent oedema or haemorrhage
What is coup and contrecoup in head trauma
Coup - brain moves forward due to collision
Contrecoup - heads hits the back as well due to intertia
- If hit by a mobile object, there will only be one area of impact as the object moves away
What is an extadural haematoma usually caused by
- Severe trauma with arterial laceration(m.meningeal artery)
What is a subdural haematoma usually caused by
- Trauma may be minor in atrophy(bridging veins)
What is a subarachnoid haematoma usually caused by
- Rupture of saccular(berry) aneurysm (circle of willis)
What is an intraparenchymal haematoma usually caused by
- Hypertension
Why does the chance of a subdural haematoma increase with age
- As brain drecreases in size with increasing age, the veins become stretched which increases chance of a subdural haemorrhage
- Very little force required for a subdural haemorrhage
Where does a subarachnoid haemorrhage usually occur
- Usually occurs at the base of the skull around the circle of willis
- Can occur due to aneurysms that develop over life
What are the effects of a spinal cord injury dependent on
- The level of injury
What is vasogenic oedema
Vasogenic cerebral oedema refers to a type of cerebral oedema in which the blood brain barrier (BBB) is disrupted (cf. cytotoxic cerebral oedema, where the BBB is intact). It is an extracellular oedema which mainly affects the white matter via leakage of fluid from capillaries.
It is most frequently seen around brain tumours (both primary and secondary) and cerebral abscesses, though some vasogenic oedema may be seen around maturing cerebral contusion and cerebral haemorrhage.
What is cytotoxic oedema
- In cytotoxic edema, the blood–brain barrier remains intact but a disruption in cellular metabolism impairs functioning of the sodium and potassium pump in the glial cell membrane, leading to cellular retention of sodium and water
What can cause cytotoxic oedema
- Alcohol
Difference between hypoxia and ischaemia
- Global vs focal
What is an ischemic stroke and what are the two types
- Occur when blood blow to the brain is blocked by a blood clot
1) Thrombotic stroke - Caused when a blood clot forms in the artery leading to the brain
2) Embolic stroke -
Begin with a clot forming elsewhere in the body - such as the heart or neck - that breaks loose and travels to the brain
