HISTO: Neuropathology Flashcards
What is cerebral oedema including the 2 types? What is the consequence?
Where is the CSF produced?
Choroid plexus
What is the normal flow of CSF?
- Made in choroid plexus
- Flows lateral ventricles–> intraventricular foramina –> 3rd ventricle
- Down the cerebral aqueduct–>4th ventricle
- The floor of the 4th ventricle is the pons and the roof is the cerebellum
- Into medulla –>central canal of the spinal cord
- Most of it exits via a number of foramina in the 4th ventricle into the subarachnoid space
- Then circulate through subarachnoid space and via arachnoid granulations which pierce the superior sagittal sinus, returning the CSF to the systemic circulation
What are the two types of hydrocephalus?
- Non-Communicating: obstruction to the flow of CSF (usually involving the cerebral aqueduct)
- Communicating: NO obstruction but is associated with problems in reabsorption of CSF into venous sinuses
What is the normal ICP?
7-15 mm Hg for supine adult
What are the main 3 herniation sites for the brain in raised ICP?
- Subfalcine - cortex forced under rigid falx cerebri
- Uncal/Transtentorial - medial temporal lobe through posterior cerebral fossa/tentorial notch
- Tonsillar - tonsil of cerebellum pushed through foramen magnum
What is the consequence of raised ICP on brain structure?
Herniation
Menti: When the integrity of the blood brain barrier is disrupted the resultant oedema is described as?
Vasogenic
Menti: Which of the following types of herniation does not involve the cerebral cortex?
- Uncal
- Subfalcine
- Transtentorial
- Tonsillar
Tonsillar
What is the mortality associated with stroke?
3rd biggest cause of death in the UK / largest single cause of severe disability
Define stroke.
a clinical syndrome characterised by rapidly developing clinical symptoms
and/or signs of focal, and at times global loss of cerebral function,
with symptoms lasting more than 24 hours or leading to death,
with no apparent cause other than that of vascular origin
The definition of stroke includes which types of infarction and haemorrhage?
-
Includes:
- Infarct –> cerebral infarction
- Haemorrhage –>primary intracerebral, intraventricular or sub-arachnoid (most common) haemorrhage
-
Excludes:
- Subdural haemorrhage
- Epidural haemorrhage
- Intracerebral haemorrhage
- Infarction caused by infection or tumour
What is a TIA? What does it mean for stroke risk?
- Caused by a clot but the blockage is temporary
- 1/3rd people with TIA get a significant infarct within 5 years
- I.E. TIA is a predictor of a future infarct
- Symptoms resolve within 24 hours (most TIAs last < 5 mins)
- There is usually NO permanent injury to the brain
What is non-traumatic parenchymal haemorrhage? What is the usual cause? Where do they usually occur?
Haemorrhage into the substance of the brain (parenchyma) due to rupture of a small intraparenchymal vessel
Hypertension plays a role in >50% of bleeds
Most common in the basal ganglia
How does non-traumatic intra-parenchymal haemorrhage present?
- Severe headache
- Vomiting
- Rapid loss of consciousness
- Focal neurological signs
Where can AVMs occur? When do they become symptomatic?
- Arteriovenous malformations can occur anywhere in the CNS
- Symptomatic from 2nd and 5th decade (mean = 31 years)
How are AVMs visualised? What is the pressure within these?
- Occur under high pressure and can cause MASSIVE BLEED
- Morbidity 50-80%; mortality at 15%
- Can be visualised on angiography
How do AVMs present?
- Haemorrhage
- Seizures
- Headache
- Focal neurological deficits
What are the treatment options for AVMs?
- Surgery
- Embolisation
- Radiosurgery
What are cavernous angiomas? What is the pressure within them?
“Well-defined malformative lesion composed of closely-packed vessels with no parenchyma interposed between vascular spaces” - similar to an AVM but no brain substance wrapped up amongst the vessels
Occur under lower pressure –> recurrent bleeds
Where do cavernous angiomas occur? When do they occur in life?
- Can be found anywhere in the CNS
- Usually symptomatic over the age of 50 years
- Pathogenesis is unknown
How do cavernous angiomas present?
- Headache
- Seizures
- Focal deficits
- Haemorrhage
How are cavernous angiomas ddiagnosed?
T2-weighted “Target Sign” – black ring around lesion (AVM has no ring) – no brain parenchyma
What is the treatment for cavernous angioma?
- May not be necessary
- Surgery
What is sub-arachnoid haemorrhage? What is the cause of these in most cases?
Rupture of berry aneurysms (1% of general population, congenital)
Where do subarachnoid haemorrhages usually occur?
- 80% occur at the internal carotid bifurcation
- 20% occur within the vertebrobasilar circulation
- 30% of patients will have multiple berry aneurysms
What size of SAH is at highest risk of rupture?
HIGHEST risk of rupture when 6-10 mm in diameter
How do SAH present?
- Sudden-onset severe headache
- Vomiting
- Loss of consciousness
What is the treatment of SAH?
Endovascular coiling - stops blood flow in the aneurysm
Clipping is sometimes also done with craniotomy.
What is the most common form of cerebrovascular disease? What is the most common cause of this?
Cerebral infarction
Cerebral atherosclerosis
Where does atherosclerosis usually affect the cerebal vessels?
- Atherosclerosis can particularly badly affect the larger, extracerebal vessels = carotid bifurcation** or the **basilar artery
- Can also be from emboli from the heart (i.e. AF) –> middle cerebral artery branches
What % of stroke are due to infarction?
70-80%
What are 3 main risk factors for stroke?
- HTN
- DM
- Smoking
What is the difference between focal and global cerebral ishcaemia?
- Focal cerebral ischaemia – due to lack of blood flow to a particular vascular territory
- Global cerebral ischaemia – when the systemic circulation fails
Where is the supply of the ACA, MCA and PCA?
What are the differential diagnoses for infarcts?
- Tissue necrosis (stains)
- Rarely haemorrhagic
- Permanent damage in the affected area
- No recovery
What are the differential diagnoses for haemorrhage?
- Bleeding
- Dissection of parenchyma
- Fewer macrophages
- Limited tissue damage (periphery)
- Partial recovery
Menti: What percentage of patients who experience a TIA will get a significant infarct within 5 years?
- 10
- 25
- 33
- 50
33% - about a third will go on to have a stroke within 5 years unless whatever caused the stroke is modified in some way
Menti: What is the most common cayuse of non-traumatic intraparenchymal haemorrhage?
Hypertension
What is the largest cause of trauma death in young people (<45yrs)?
TBI - traumatic brain injury
Accounts for 25% of all trauma deaths
High morbidity
- 19% in a vegetative or severely disabled state
- 31% good recovery
How is head trauma classified?
Focal or diffuse OR
-
Non-missile
- Acceleration/deceleration
- Rotation - around midline puts pressure on midline brain structures
- RTA, falls and assaults
- Missile i.e. missile most commonly caused by firearms.
What is shown?
- Battle sign – basilar skull fracture – bruise over mastoid process; takes 1 day to appear
- Racoon eyes – basal skull fracture – takes 1 day to appear
Where do skull fractures affect usually? What can be seen when there is loss of CSF due to fracture?
- Fissure fractures often extend into the base of the skull
- May pass through the middle ear or anterior cranial fossa
Can cause otorrhoea and rhinorrhoea (i.e. loss of CSF through the ear or nose)
- Increases risk of infection (because you have ruptured the containment of the CSF, which could act as a route of infection into the cranial cavity
What is a contusion? When is it a laceration?
Contusion = brain collides with the internal surface of the skull
If this causes rupture of the pia mater, it is called laceration
What are two common locations for contusions?
Due to direct contact with the skull:
- Lateral surfaces of the hemispheres
- Inferior surfaces of frontal and temporal lobes
What is the consequence to the other side of the brain when there is rebound of the brain after direct impact on the opposite site?
Contrecoup damage
What is diffuse axonal injury?
When shearing and tensile forces cause damage to the axons
Occurs at the moment of injury
What are the consequences of diffuse axonal injury?
Coma - DAI is the MOST COMMON cause of coma when there is no bleed
Cognitive and degenerative problems - potentially due to persistent inflammation
Which locations in the brain are most affected by diffuse axonal injury?
Midline structures are particularly affected e.g.
- corpus callosum,
- rostral brainstem
- septum pellucidum
