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HEAD INJURIES. Forensic Pathology. RAISED INTRACRANIAL PRESSURE. Compensatory Mechanisms: ----Displacement of blood ----Displacement of CSF ----Loss of Brain Tissue. RAISED INTRACRANIAL PRESSURE. EFFECTS: -Compression of Brain -Stretching of IIIrd nerve
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HEAD INJURIES Forensic Pathology
RAISED INTRACRANIAL PRESSURE • Compensatory Mechanisms: • ----Displacement of blood • ----Displacement of CSF • ----Loss of Brain Tissue
RAISED INTRACRANIAL PRESSURE • EFFECTS: • -Compression of Brain • -Stretching of IIIrd nerve • -Stretching of Posterior Cerebral Artery • HERNIATION---Subfalcine (supracallosal) • ---Tentorial • ---Cerebellar Tonsillar Coning
RAISED INTRACRANIAL PRESSURE • SIGNS & SYMPTOMS: • -----Headache • -----Vomiting • -----Papilloedma • DANGER OF LUMBAR PUNCTURE!
IMPACT INJURIES • Scalp (abrasions,bruises,lacerations) • Skull Fractures • Cerebral Contusions • Extradural Haemorrhage • Intracranial Haemorrhage
ACCELERATION/ DECELERATION INJURIES • Subdural Haemorrhage • Diffuse Axonal Injury (DAI)
Scalp Injuries • Abrasions • Contusions • Lacerations(with or without avulsion) • Risk of: Haemorrhage • Infection
SKULL FRACTURES • Does NOT always correlate with Brain Injury • May have skull # without significant Brain Injury • May have severe Brain Injury without a skull #
SKULL FRACTURES • May involve Calvaria or Base • Mechanism of Skull Fractures due to Blunt Force Trauma • “Deformed Hoop” • --outbending of skull away from impact site—fracture begins here and runs back to impact site
SKULL FRACTURES • HIGH VELOCITY IMPACT • ---produces Penetrating or Depressed Fractures • FLAT IMPACTS • ---produce Linear,Non-Displaced Fractures
SKULL FRACTURES • Skull impacting hard,unyielding surface---33-75 ft.lb energy needed to produce a linear fracture (6ft man 29-45 mph) • Skull impacting soft,yielding surface----268-581 ft.lb energy needed to produce a linear skull fracture(6ft man 13.5 mph)
Probability of Skull Fracture with BFT Depends on • Severity of Blow (speed of impact) • Object Impacted or Impacting Head (weight,shape,consistency) • Thickness of Hair • Thickness of Scalp • Thickness of Skull • Age of Victim (elasticity,brittleness of bone)
Types of Skull Fracture • Linear # -straight or curved lines • -tend to follow lines of force • -course modified by suture lines and convolutions of skull • Depressed #s –localised impacts,intrusion of bone • -radiating fissures (spider’s web) • -may injure underlying brain • Ring #s –circular,around foramen magnum • -falls onto feet from a height
Complications of Skull Fractures • Possible associated Brain Damage • Intrusion of bone fragments in depressed #s • Epilepsy • Infection-Meningitis or Encephalitis • (through # from scalp,ear or air sinuses)
EXTRADURAL HAEMORRHAGE • POTENTIAL space between inner skull and the dura • Fall, RTA, Strike on side of skull • 90% have skull # (squamous portion of temporal bone) • Lacerated middlle meningeal artery • Unilateral • Disc-shaped,centrally thickened • Classically have a Lucid Interval • Symptoms 4 to 8 hours after injury • 25-30% immediate Loss of Conciousness • Death due to displacement & herniation of brain
SUB-DURAL HAEMORRHAGE • Actual space between Brain and Dura • Acceleration/Deceleration injuries with tearing/shearing forces affecting the para-sagittal bridging veins • May be Ipsilateral, Contralateral or Bilateral • May or may not be accompanied by Cerebral injuries
SUBDURAL HAEMORRHAGE • May or may not be associated with a skull # • If skull # present, may be ipsilateral or contralateral to the haematoma • Common in Elderly people • Common in Alcoholics • Falls and Assaults
SUBDURAL HAEMORRHAGE • ACUTE --within 72 hours of injury • SUBACUTE --3 days to 2-3 weeks • CHRONIC --more than 3 weeks • Organise – Resorption Possible • Chronic may Re-bleed • May increase due to breakdown and Osmosis
SUB-ARACHNOID HAEMORRHAGE • Natural—Berry Aneurysms and Arterio-Venous Malformations • Trauma—may be diffuse or focal & patchy • may be minor or severe • TRAUMATIC SAH----blow to lateral neck with resulting damage to Vertebral Artery
CEREBRAL CONTUSIONS • Bruises on surface of Brain,esp crests of gyri • Fresh—haemorrhage and necrosis • Old---depressed,shrunken,haemosiderin-stained (golden-brown) • Affect principally the Frontal and Temporal Poles
CEREBRAL CONTUSIONS • Produced as Brain moves and impacts with bony irregularities of skull at these sites • COUP ---at Point of Impact • CONTRE-COUP --occur diametrically opposite the site of primary impact ---more common than Coup lesions • True example—fall on back of head with frontal and temporal contusions
CEREBRAL CONTUSIONS • Fracture Contusions----from overlying # • Deep Contusions • Gliding Contusions • Herniation Contusions
Lacerations of Brain • Skull fractures • Gunshot Wounds
DIFFUSE AXONAL INJURY • Acceleration/Deceleration • Stretching and/or Shearing of Nerve Fibres • Neuronal Dysfunction • Directional---Coronal > Sagittal motion • Coma • No Lucid Interval
DIFFUSE AXONAL INJURY • Common cause of Persistent Vegetative State in Survivors • Associated Haemorrhagic Lesions in Corpus Callosum,Gliding Contusions(Parasagittal White Matter),Rostral Brainstem • Histology with Special Stains
BRAIN SWELLING • May occur as a complication of Blunt Force Trauma • May be Diffuse • May be Focal • May be adjacent to a specific area of injury (contusion or laceration) • May be unilateral following evacuation of SDH or EDH
BRAIN SWELLING • Due to—Vasodilatation (increased intravascular blood volume) • --Cerebral Oedema (water content of brain) • Effects on Cerebral Perfusion • May cause Herniation • May be Delayed (esp. in children)
ALCOHOL and Head Injuries • Many Accidents,Assaults occur in the setting of excessive alcohol intake • Intoxication----worse outcome,even with relatively lesser degrees of head trauma • Muscle Laxity • “Unprotected” when fall • Concussion • Period of post-injury apnoea lengthened by Alcohol Intoxication