Pathology and Surgery on head injuries Flashcards
Classify traumatic brain injuries
Focal
- scalp lacerations
- lacerations/contusions
- skull fracture - general, basilar,comminuted, linear,depressed
- intracranial haemorrhage
- focal lesions sec to raised intracranial pressure
Diffuse
- global ischaemic injury
- diffuse vasular injury
- traumatic axonal injury
- brain swelling
Describe different types of skull fractures
General -caused by a break in the bones in the skull due to HEAD INJURY -a/w dissection of cerebral arteries -fragments may cause ;bruising of brain(contusion)/ laceration ;damage to blood vessels ;intracranial haematomas ;epidural haematomas
Comminuted
multiple fragments of bone which can be driven into brain
Linear- 89% of pts - most common ;widely distributed forces ;growing fracture - brain swelling ;diastatic features: sep of bones at sutures, wall trauma
Depressed - 11% , very serious
comminuted fractures ; thus bones displaced inwards can cause raised ICP and crushing of delicate tissue. Dura mater is torn- complex- surgery indicated
Basilar - rare CSF in eyes or nose CSF rhinorrhea, otohrrea battle's sign-blood clot behind ear raccoon eyes haemotympanum-blood in tympanic membrane cranial nerve palsy 1-10% ; entrapment of ocular nerve
Which skull fracture are you likely to get meningitis?
Basilar
Which skull fracture is a/w a particular haematoma?
general - epidural haematoma
Define contusion
bruising or the brain
What occurs in a contusion?
- damage to small blood vessels causing haemorrhage
- pia mater intact overlying contusions
- May become larger as a result of further haemorrhage; may cause rapid clinical deterioration in conscious patients in the absence of further haemorrhage.
Typical areas a contusion occurs at?
frontal lobes and inferior aspect
temporal lobes and inferior and lateral aspect
cortex above and below Sylvian fissure
Define sylvian fissure?
The groove that sections off the temporal lobe
Define FRACTURE contusions
Pieces of bones/fractures of the skull become displaced and directly insult the brain tissue
What are the typical areas involved in fracture contusions
Superficial injuries- apex of gyri this grey area is involved
Can go to white matter
What is formed when a fracture contusion enters white matter
haematoma
Define coup injury/contrecoup injury
When the contusion is as a result of impact (acceleration/deceleration) eg fall- injury may occur under pt of impact or distant to pt of impact
What is the proposed mechanism of pts with contusions?
pts become coagulopathic post traumatic injury (45% pts) - further microvascular haemorrhage (delayed/continuous)
Frank rupture of vessels at time of injury occurs sec to forces initiating molecular change that causes structural change in vessels.
When does delayed traumatic intracerebral haematoma occur?
48 hrs after injury
What drug exacerbates contusional haemorrhage?
Mannitol can transiently increase cerebral blood flow and has been suggested to exacerbate delayed contusional haemorrhage.
Classify intracranial haemorrhages
Intracranial haemorrhages are classified by anatomical location:
• Extradural /epidural (EDH), subdural (SDH), subarachnoid (SAH) or intracerebral (ICH)
a/w lucid interval in pts- clinical deterioration esp in EDH w/ minimal primary brain injury
What are the factors that determine the clinical complications of a haematoma?
size/volume of the lesion, the anatomical location, and the rapidity with which the haematoma develops
What type of injury is EDH most associated with?
skull fracture - 98%
linear
Define EDH
- blood in extradural space due to falls, RTAs, assaults (from most common to least)
- two types: Arterial, venous EDH
Which type of EDH shows symptoms first?
Arterial(middle meningeal artery) - develops over hours
(Venous EDH develops over hours to days)- middle meningeal vein
What is a common mechanism that causes the damage to the a/ artery and vein in EDH
fracture of the squamous temporal bone that results in damage to the underlying middle meningeal artery or vein.- 50%
What are the macroscopic/microscopic features of the EDH?
- Extradural bleeding strips the dura (periosteum) from the inner table of the skull, forming a circumscribed ovoid blood clot that progressively flattens and indents the adjacent brain.
- Biconvex due to attachment of dura to skull sutures
- focal ischaemic injury seen in most fatal cases
What are some RARE, non traumatic causes of EDH?
paracranial infections, coagulopathies (both acquired and congenital), vascular malformations and neoplastic conditions, including metastatic disease
Where else can EDH be seen and how does it present?
fire related deaths
- pink foamy lesions
- a/w heat related fissuring of skull
- mechanism unknown
Treatment for extradural haematoma
emergency craniotomy
Define subdural haematoma
collection of blood (mostly venous) in subdural space(between dura and arachanoid)
can be acute/chronic
Common causes of acute subdural haematoma
seen after falls/assaults
ASDH may be due to rupture of a bridging vein, the so-called ‘pure’ subdural haematoma, or secondary to contusions with damage to cortical veins or arteries and overlying leptomeninges
Prognosis of ASDH
high overall mortality; 30–50 % for ASDH and a good outcome in about 30–50 % of cases
What is the key factor in determining outcome of ASDH
Key factor in determining outcome is the extent of associated parenchymal pathology, particularly contusions and brain swelling.
Macro/Microscopic appearance of ASDH
covers entire cerebral surface
crescent shaped - With large lesions, there is deformation of the underlying cerebral hemisphere, often with accentuation of the gyral pattern on the same side as the haematoma, and flattening of the gyri on the contralateral side.
a/w parenchymal injury
Tx of ASDH
emergency craniotomy
What other conditions may cause SDH
- neurosurgical complications
- metabolic disorders-menkes disease, galactosaemia, glutaric aciduria
- perinatal-complication of labour
- coagulation-both inherited and acquired, haematological malignancies
- hypernatraemia/severe dehydration
- cardiac malformation
- cerebrovenous sinus thrombosis
How does ASDH present on post mortem
as soon as dura is reflected ASDH pours out
What is a sequalae of ASDH
- can become a subacute subdural haematoma due to organization and resorption of the haematoma
- by 12 months haematoma has resolved and resembles normal dura
- in children, resolves spontaneously
Define chronic SDH
- a separate entity
- refers to the formation of a thick-walled membrane encasing altered blood, prone to rebleeding and having a high incidence of recurrence
- often follows a relatively trivial head injury (and having risk factors)