Head Trauma Flashcards
Describe the classification of head trauma
- Primary head injury is one that happens immediately after trauma
- Focal - haematoma, contusion
- Diffuse - concussion, diffuse axonal injury - Secondary head injury happens as a result of indirect injury
Define contusion and describe how it occurs in head trauma
- Bruising of brain whereby blood mixes with cortical tissue due to microhaemorrhages and small blood vessel leaks
- Happens when the brain strikes the skull during trauma
- Trauma -> microhaemorrhages -> cerebral contusion -> cerebral oedema/intracerebral bleed -> raised ICP -> coma
Describe the two types of contusions
- Coup - contusion at site of impact to skull
- Contre-coup - contusion at site opposite to impact
- Due to force of impact causing brain to bounce on opposite side
Define concussion and describe how it occurs in head trauma
- Head injury with a temporary loss of brain function
- Trauma -> stretching and injury to axons -> impaired neurotransmission, loss of ion regulation, and a reduction in cerebral blood flow -> temporary brain dysfunction
Describe the concept of post-concussion syndrome
- Symptoms that occur weeks to years after concussion
- Due to structural damage to brain or neuronal damage
- Problems with thinking/memory, headache, dizziness, irritability, sadness, sleeping
Define diffuse axonal injury
Shearing of interface between grey and white matter following traumatic acceleration/deceleration or rotational injuries to the brain damaging the intra-cerebral axons and dendritic connections
Describe the pathophysiology of diffuse axonal injury
- Grey and white matter have different densities, which allows shearing
- Disconnect millions of axons at the grey and white matter boundary
- Trauma -> shearing of grey and white matter interface -> axonal death -> cerebral oedema -> raised ICP -> coma
Describe the pathophysiology of basilar skull fractures
- Bony fracture within the base of skull (temporal, occipital, sphenoid, ethmoid)
- Trauma -> tears in the meninges -> CSF leakage
Describe the clinical signs of a basilar skull fracture
- Racoon eyes
- CSF rhinorrhoea or CSF otorrhea due to tears in meninges leading to CSF leak
- Battle sign - blood leakage along posterior auricular artery
- Haemotympanum - blood in tympanic cavity
- Bump
Describe the management of basilar skull fractures
- Traumatic brain injury management - including ICP control
- Elevation of depressed skull fractures
- Persistent CSF leak management - surgery
Define extradural haemorrhage and its cause
- Collection of blood between inner table of skull and periosteal dura mater
- Nearly always secondary to trauma and/or skull fracture in younger patients
- Involve a severed artery - most commonly middle meningeal artery
Describe the clinical presentation of extradural haemorrhage
- Patients present with loss of consciousness due to impact of initial injury
- Followed by transient recovery with ongoing headache known as ‘lucid interval’
- As haematoma enlarges, ICP will increase causing rapidly deteriorating level of consciousness
- Cranial nerve palsies may be found on examination as brain structures herniate
Describe how extradural haemorrhages are seen on CT
- Convex (lemon) shaped haemorrhage
- Does not cross suture lines
- Hyperdense blood seen during acute bleeding
- Becomes darker (hypodense) hours after acute bleeding
- Midline shift
- Lateral ventricle smaller than normal due to compression by haematoma
Describe the management of extradural haemorrhage
- Small EDH can be managed conservatively with neurological follow up
- Large EDH requires referral to neurosurgery for craniotomy and clot evacuation
List complications of extradural haemorrhage
- Permanent brain damage
- Coma
- Seizures
- Weakness
- Pseudoaneurysm - blood vessel wall ruptures but blood contained within surrounding tissue
- Arteriovenous fistula - abnormal connection between artery and vein
Define subdural haemorrhage and its cause
- Collection of blood between meningeal dura mater and arachnoid mater
- Bleeding occurs due to shearing forces on cortical bridging veins (connect brain to dural venous sinus)
Describe how acute and subacute/chronic subdural haemorrhage presents
- Acute SDH usually present due to head trauma
- Neurological abnormalities common
- Acute bleeds appear hyperdense - brighter than brain tissue on CT
- Falx cerebri stops blood flowing to other hemisphere
- Subacute/chronic SDH more common in the elderly with vague or absent history of head trauma
- May present with confusion and general cognitive decline similar to dementia
- Bleeding appears hypodense over time - darker than brain tissue
- May present with confusion and general cognitive decline similar to dementia
Describe the management of subdural haemorrhages
- Acute collections need immediate surgical intervention to relieve raised ICP
- Symptomatic subacute/chronic SDH are often treated via one or more burr holes - drill into cranium to remove fluid
Define subarachnoid haemorrhage and its cause
- Collection of blood between arachnoid mater and pia mater
- Vast majority occur spontaneously secondary to ruptured berry aneurysm but may also be traumatic
Describe the clinical presentation of subarachnoid haemorrhage
- Sudden onset ‘thunderclap’ headache
- Meningism - neck stiffness, photophobia
- Fever
- Loss of consciousness
- Focal neurological deficits
- An aneurysm or damage to posterior communicating artery and lead to visual disturbances as CN III runs next to PCA
Describe berry aneurysms and their formation
- Largely asymptomatic but symptoms may arise of compressing on nearby structures or during early stages of rupture
- Risk factors - family history, hypertension, alcohol, abnormal connective tissue
- Aneurysm formation normally occurs at junctions of blood vessels - turbulent flow
- Mainly in the anterior circulation
- Aneurysm forms due to gradual thinning of walls until blood is able to rupture from the vessel
Describe the management of subarachnoid haemorrhage
- Lumbar puncture performed to aid diagnosis - presence of RBC
- Xanthochromia - RBC breakdown into yellow substance, which appears in CSF
- Stabilise patient and prevent rebleeding - monitor BP
Describe the different age groups for the 3 haemorrhage types
- Extradural - usually young
- Subdural - acute at any age, chronic usually elderly
- Subarachnoid - typically older middle aged <60
