pathology of head injury Flashcards
what is a primary insult of a head injury?
Focal and/or diffuse brain trauma
what are secondary insults of a head injury?
Hypotension – low arterial BP
Hypoxia – low blood oxygen
Infection
Haematoma – bleeding in/around brain
how is conscious level assessed?
Glasgow Coma Scale
what are the consequences of head injuries?
Permanent physical disability
Post traumatic epilepsy
Intracranial infection
Psychiatric illness
Chronic subdural haemorrhage
‘Punch-drunk’ dementia
Fatal outcome (uncommon)
what are the kind of scalp injuries that occur?
Similar to those which can affect the skin, e.g. abrasions, bruises, lacerations, incisions (and burns/scalds)
what are the type of skull injuries?
Skull fractures caused by application of force causing deformation of the skull; adult skulls less able to cope with distortion than those of infants
what is a linear skull fracture?
commonly temporo-parietal from blow or fall onto side or top of the head and may continue onto the skull base; “hinge” fracture
what is a depressed skull fracture?
focal impact which may push fragments inwards to damage the meninges, blood vessels and the brain; risk of meningitis and post-traumatic epilepsy. Not typical of a fall from standing onto a flat surface, e.g. pavement - fractures tend to be linear in this scenario
what is a ring fracture?
: fracture line encircling the foramen magnum caused by a fall from height, usually landing on the feet, but sometimes the head, leading to the skull base and cervical spine being forced together
what is a contre-coup fracture?
: fracturing of the orbital plates (anterior fossa) caused by a fall onto the back of the head
what does accumulation of blood within the rigid skill cause?
increase in intracranial pressure (ICP) and results in compression of the brain —> this compression causes symptoms, including reduction in conscious level.
what is an extradural haemorrhage?
Bleeding occurring between the dura and the skull; accumulating blood strips the dura off the inner surface of the skull
why do extradural haemorrhages occur?
Vast majority arise from damage to an artery in association with a skull fracture (80-90%) and, therefore, under higher pressure than with venous bleeding, but very occasionally large venous channels can cause EDH
Classically caused by bleeding from the middle meningeal artery where it crosses the inner aspect of the squamous temporal bone due to fracture of the squamous temporal bone with secondary damage to the artery in the vicinity of the fracture
what is subdural haemorrhage?
Bleeding occurring beneath the dura (and above the arachnoid)
what causes a subdural haemorrhage?
Usually caused by bleeding from bridging veins which pass from the surface of the brain to drain into the large venous channels within the dura
Any motion which causes rotational or “shearing” forces can cause the veins to be stretch and torn due to the relative movement between the brain and the dura
Frequently occurs without a skull fracture
