Pathology of head injury Flashcards
Head injury split into 2 categories
Primary
Secondary
Cause of primary head injury
Focal/diffuse brain trauma
Causes of secondary head injury (4)
Hypotension
Hypoxia
Infection
Haematoma
What scale used to initially assess head injury
GCS
GCS 3=
comatosed; probably brain dead
GCS 9-12 =
moderate injury
GCS 13-15=
Mild injury
What is punch drunk dementia
aka chronic traumatic encephalopathy
- in people who have suffered repeated blows to head –> progresses to dementia
Head lacerations often look clean cut so can mimic what
Incised wound
Types of skull fractures (5)
Linear Depressed Comminuted (mosaic) Ring Contre-coup
Linear skull fractures are commonly found where
Temporo-parietal from blow to side or top of head
What is a depressed skull fracture
Focal impact pushing bone fragments inwards –> damaging meninges, vessels and brain tissue
What is a comminuted skull fracture
Fragmented skull all over
What is a ring skull fracture
Fracture line encircling foramen magnum caused by FALL FROM HEIGHT, usually landing on feet –> skull base and c spine forced together
What is a contre-coup skull fracture
Fracturing of the orbital plates (IN ANTERIOR FOSSA) caused by a fall on the BACK OF HEAD
due to Injury radiating from back to front of skull – isolated fracture in the anterior cranial fossa
3 types of brain haemorrhages/haematoma
Extradural
Subdural
Subarachnoid
Extradural haemorrhage/haematoma is bleeding between what layers
Between dura and inner surface of skull, so dura is stripped off inner surface of skull
Extradural haemorrhages classically due to bleeding from what artery + why
Middle meningeal
- commonly due to skull fracture at pterion where middle meningeal lies on the inner surface of
Subdural haemorrhage/haematoma due to bleeding from what vessels
Small bridging veins
Subdural haemorrhages happen slower than an extradural - why?
Blood accumulates under venous pressure (which is less than arterial pressure) therefore accumulates slower
- bleeding from small bridging veins, not arteries
Subdural haemorrhages are usually not due to skull fracture, but what?
Rotational or shearing forces
-created from rapid acceleration then sudden deceleration so brain impacts front on skull then backward movement causes it to impact back of skull causing the small bridging veins to tear from the forces
Commonest cause of subarachnoid haemorrhage
Ruptured aneurysm, often berry aneurysms in the circle of willis
Name 3 intrinsic brain injuries
Cerebral oedema
Cerebral contusion
Cerebral laceration
What is cerebral oedema
Generalised brain swelling in response to focal/diffuse injury
What is a cerebral contusion
aka bruising of the brain
- damage to brain substance
- occurs when there’s a heavy blow to the head
What is a coup contusion
Contusion found directly under site of impact
What is a contre coup contusion
Contusion on opposite side of the brain due to secondary brain movement
What is a diffuse traumatic axonal injury (tDAI)
Tearing of axons in white matter of brain due to SERIOUS ROTATIONAL FORCES applied to brain tissue causing shearing (tearing of axons)
Diffuse traumatic axonal injuries are often due to what scenarios (2)
RTAs
Fall from height
Diagnostic investigation of diffuse traumatic axonal injury
Microscopy of brain tissue
Areas of brain susceptible to diffuse traumatic axonal injury (3)
Corpus callosum
Post. Internal capsule
Cerebellar peduncles
