CT imaging Flashcards
When to do CT scan
Stroke
TIA
RTA - loss of consciousness
Thunderclap headache - a sign of subarochnal haemorrhage.
I suspected a space-occupying lesion.
EXTRA CRANIAL
- Orbital cellulitis
- Facial trauma
- Evaluation of skull base for bone lesions
Criteria for CT within 1 hour when there is a history of trauma
GCS < 13 initial
GCS < 15 2 hours after injury
Suspected open or depressed skull fracture
Any sign of a basal skull fracture
Post-Traumatic seizure
Focal nuerological deficit
More than an epsidoe of vomiting since the head injury.
CTB within 8 hours for trauma for head injury
Patient on anticoagulation
LOC
- age >65
- bleeding disorder
- retrograde amnesia
What view is a CT ?
CAUDAL
Look as if looking at patients feet
Age ?
7-8 Y
AGE ?
70-80
SHRINKED
ALOT MORE FLUID ABLE TO MOVE AROUND.
CONSIDERING HEAD TRAUMA THE BRAIN CAN BOUNCE WHICH CAN BE DANERGOUS.
contrecoup injury
Age ?
Regular 35
Interpreting greyness, what colour will
- bone
- Blood
- air
- CSF
What is this location circled where all sutures come together?
Pterion
THE P IS SILENT
+++TERION +++
What artery lies under the pterion ?
Middle meningeal artery
supplies the majority of the skin
Can cause …
Explain the Monroe-Kellie Doctorine
THE FIRST THINGS TO GO WILL BE VENOUS VOLUME AND CSF.
IF IT CONTINUES AND ARTERIAL BLOOD DOES NOT GO TO THE BRAIN, HYPOXIA WILL OCCUR, AND CELL DESTRUCTION AND DEATH WILL OCCUR.
WHERE WILL THE BRAIN GO ? Concern about raised ICP?
Shift brain structures, cause brain herniation through the foramen magnum, and restrict blood supply to the brain.
LIKELY DEATH.
What are the three meninges ?
What seperates the cerebella form cerebum
Tentorium
Explain a epidural hematima
LEMON SHAPE
OUTSIDE THE DURA
ARTERIAL BLEEDING
DURA IS TORN AWAY FROM THE SKULL.
Explain a Subdural hepatoma
Just under the dura
Likely to be an older patient
Rather than arterial blood it’s venous blood so it is not rapidly expanding.
DURA STAYS ATTACHED.
Signs of the base of skull fracture?
Bruising over the mastoid
Blood behind the tympanic membrane (ear)
Racoon/ panda eyes (bruising around the eye) because the base runs where the line is in the image.
What would you see at the base of skull CT scan ?
Base of skull
A lot of white, because we see a lot of bone
Note the nasal cavities (black because of air)
The globes, optic nerve, pinna of the ear
Pinna is a tiny bit of the ear.
What is the suprasellar cistem ?
Suprasellar cistern is star shaped
Sella turcica is below it
Sella turcica (where pituitary gland sits)
Suprasellar cistern—where the circle of willis sits
Common site for aneurysm, with rupture will see blood in this space (subarachnoid)
What is the main blood supply to the brain?
Circule of willis
What can happen to the circle of Willis?
it can Annurism.
If it does, we can see blood in the suprasellar cistern and this is a subarachnoid heamorridghe.
What is myelanated out of white and grey matter
White matter is myelinated grey matter is not.
(ON A CT THE GREY IS THE WHITE MATTER)
What is falx cerebri
Dura that separating the two hemispheres
How to assess a CT? (ABC’S)
A – Adequacy & Alignment
B – Bones, Blood & Brain
C – CSF spaces
S – Soft tissue +SYMMETRY
What is this?
What has happened?
Epidural
Caused by TRAUMA
ARTERIAL BLEED
Mid-line shift
RIGHT SHIFT
Middle meningeal artery - Rappid expansion.
Lead to brain herniation.
Treatment - BEAR HOLES or craniotomy.
What is this?
What has happened?
Sub-dural
Elderly
On blood thinners
VENOUS BLOOD.
Treatment - WATCH AND WAIT.
What is this?
Subarochnoid haemmorage
This can be due to trauma or aneurysm.
What is this ?
Intracerebral haematoma
The irregular shape is consistent with the sulci and gyro. Shift of the mid-line.
This could be due to trauma
What is the more common ischemic or haemorrhagic stroke?
Ischemic
That’s why we rarely see things.
That’s why MRI is better than CT.
However, CT must be done first to ensure no bleeding.
THEN GIVE BLOOD THINNERS AND MRI.
What is it called when there is not symmetry of the brain?
Mid-Line shift.
What are the different types of brain herniation?
Because herniation puts extreme pressure on parts of the brain and thereby cuts off the blood supply to various parts of the brain, it is often fatal. Therefore, extreme measures are taken in hospital settings to prevent the condition by reducing intracranial pressure, or decompressing (draining) a hematoma which is putting local pressure on a part of the brain.
1Uncal (or transtentorial) herniation causes temp lobes pushed into upper cerebellum, against the midbrain leading to compression of Post C Art; IIIn compression and midbrain haemorrhage
4)Always check before you stitch someones scalp that there isn’t brain tissue sticking out
Is there a skull fracture within this image?
I would want the bone window.
However, there is air (black space) within; therefore, there must be a way for it to get in! Probable fracture.
Coup Contrecoup Injury
A coup injury happens at the point of impact with an object, whereas a contrecoup injury takes place on the opposite side of the skull from the impact.
