Brain Imaging Flashcards
What is the first line brain imaging modality?
CT
When would MRI be used?
High res soft tissue required, takes longer so used in non-emergency, detailed specialist investigations
How are ischaemic strokes categorised?
By the teritory affected or mechanism
Interruption of blood flow through an intercranial artery results in deprivation of oxygen and what else?
Glucose
What are the three vascualr teritories of the brain?
Anterior (ACA)
Middle (MCA)
Posterior (PCA)
Learn the circle of willis, dumfuk
Also learn the somatosensory and motor cortex homunculus, dumfuk
The frontal lobe is responsble for what fucntions?
Executive function, inteligence, behaviour control, personality
The temporal lobe is responsible for what functions?
Memory, understanding, hearing
What lobe is brocas area in and what is it responsible for?
It’s in the frontal lobe and it is responsible for speech production
What lobe is wernickes area in and what is it responsible for?
It is in the temporal/parietal lobes and it is responsible for speech comprehension
What is the parietal lobe responsible for?
Sensation and taste
What is the earliest sign of stroke on CT?
A hyperdense segment of a vessel
What other signs can be seen on an early stroke ct?
Cortical hypodenseity (looks a bit darker), cant differentiate beteen white and grey matter as easily
What happens with time after a stroke has occured?
Increase in swelling and hypoattenuation and eventually gliosis (low desnity, loss in volume)
What colour does acute blood appear on an unhanced scan?
White
What is an intra-axial haemorrhage?
Haemorrhage within the brain substance
What is an extra axial haemorrhage and what are the three types?
Haemorrhage outwith brain parenchyma but within the skull.
- Extra dural
- Sub dural
- Sub arachnoid
How would you describe this? When is this a typical presentation?
Acute haematoma in the right basal ganglia (thalamus). This is typical in hypertensive bleeding
What does an extra-dural haemorrhage look like?
BICONVEX shape w/ mass effect
What does a subdural haemorrhage look like?
Semi-lunar, crosses sutures, mass effect
What is the difference between subacute subdural haematoma and chronic?
Subacute is ISODENSE (can see the mass effect). Chronic becomes HYPODENSE.
What is acute-on-chronic subdural haematoma?
New (white) blood can be seen in a chronic (hypodesne) subdural haematoma
Describe a sub-arachnoid haemorrhage
Haemorrhage in the sub-arachnoid space meaning it ‘follows’ the folds of the brain
Where is the most common site of sub arachnoid haemorrhage?
Circle of Willis
What is the most common cause of sub-arachnoid haemorrhage?
Berry aneurysm
What structures can blood infiltrate in a sub-arachnoid haemorrhage?
- Suprasellar cistern
- Sylvian fissures
- Sulci
Once subarachnoid blood is found, what investigation is done and why?
CT angiogram to look for berry aneurysm
What are some complications of sub arachnoid blood?
Hydrocephalus
Vasospasm
Infarction
Are the majority of intracranial tumours primary or metastatic?
Metastatic
What are common cancers which metastasise to the brain?
- Lung
- Breast
- Melanoma
- Renal cell
- colorectal
Does contrast enhance intracranial tumours?
Depends - can make them more inconspicuous, depends on integrity of blood brain barrier
Are brain mets usually mutiple or solitary?
Multiple
In primary brain tumours, what does the degree of oedma and mass effect depend on?
GRADE of tumour
What can result from mass effect?
Brain herniation
Desribe tonsilar herniation (coning)
Herniation of cerebellar tonsils through the foramen magnum
What is a potentially fatal complication of coning?
brainstem is compressed resulting in respiratory or caaridac failure
how does blood in the sub arachnoid space affect the CSF?
The CSF cannot be resorbed - results in hydrocephalus
Is spinal cord compression an emergency?
take a wild fucking guess
What needs to be done asap rocky in spinal cord compression?
Surgical decompression (to prevent permanent neurological damage)
What is it called when the spinal roots below the conus medullaris are compresed?
Cauda equina syndrome
Why wont CT suffice when looking for cauda equina syndrome?
You cannot see the spinal cord or conus
