Describe the intracranial haemorrhages and brain injuries. Add a note on coup and contrecoup injury.

Intracranial Haemorrhage

• Traumatic subarachnoid haemorrhage from vertebral artery tear is of particular medicolegal importance: a relatively light blow to the side or back of the neck, or to the face, especially with sudden rotation or hyperextension of the head and often in an intoxicated person, tears the vertebral artery where it enters the skull, causing basal subarachnoid haemorrhage and almost instantaneous death. The assailant may have used little force, yet is responsible — and the case turns on demonstrating the arterial tear, which requires special dissection of the vertebral arteries
• The distinction between aneurysmal and traumatic subarachnoid haemorrhage is therefore critical, and rests on finding either an aneurysm or an arterial tear; the vessels must be examined specifically in every case
• Intracerebral haemorrhage — traumatic (from contusion, often in the frontal and temporal lobes) or spontaneous (hypertensive, classically in the basal ganglia); the distinction may be difficult and depends on the site, the associated injuries and the history

Brain Injury

• Concussion — a transient, reversible disturbance of function with loss of consciousness and post-traumatic amnesia but NO gross structural damage. The autopsy is negative, and death from pure concussion is exceptional. It is diagnosed clinically and cannot be demonstrated after death
• Contusion — bruising of the brain surface, characteristically on the crests of the gyri, and concentrated where the brain moves against irregular bone: the frontal poles, the orbital surfaces and the temporal poles, whatever the site of impact
• Laceration — actual tearing of the brain substance, usually with a depressed fracture or severe contusion
• Diffuse axonal injury (DAI) — widespread shearing of axons from rotational acceleration-deceleration without any direct impact. The patient is unconscious from the moment of injury with NO lucid interval, and there may be little to see macroscopically beyond small haemorrhages in the corpus callosum and the dorsolateral brain stem. The diagnosis is histological, by demonstrating axonal retraction balls with silver stains or, far better and much earlier, beta-amyloid precursor protein (β-APP) immunostaining. It is a leading cause of persistent vegetative state and of death without gross findings

Coup and Contrecoup

• The asymmetry is important and often asked: a fall on the back of the head produces severe frontal and temporal contrecoup contusions, whereas a fall on the front rarely produces occipital contrecoup. The reason is anatomical — the floor of the anterior and middle fossae is rough and ridged, so the brain is grated against it, while the occipital region is smooth
• The distinction supports but does not prove the mechanism; both may coexist, and a person who is struck and then falls shows both. The opinion must be framed as what the findings favour

Survival and the Sequelae of Head Injury

• The pattern of consciousness is diagnostically decisive and should be elicited in every case:
• Unconscious from the moment of impact and never recovering — suggests diffuse axonal injury or severe primary brain damage
• Unconscious, then lucid, then deteriorating — the classical extradural pattern, and the one that must never be missed
• Conscious throughout, deteriorating over days or weeks — chronic subdural haematoma, particularly in the elderly and the alcoholic, in whom the original injury may have been trivial and forgotten
• Sequelae of head injury — post-traumatic epilepsy, which may appear months or years later and remains attributable to the injury; the post-concussion syndrome of headache, dizziness, poor concentration and irritability; personality change and cognitive impairment; chronic traumatic encephalopathy ("punch-drunk" syndrome, dementia pugilistica) in boxers and others exposed to repeated head impacts; hydrocephalus; anosmia; and a persistent vegetative state
• Each of these has compensation implications, and the causal link to the original injury may be disputed years afterwards — which makes the contemporaneous record of the injury and of the initial conscious level exceptionally important

Applied Aspects

• Observe every head injury with loss of consciousness; the lucid interval of an extradural haematoma is the classical trap, the condition is entirely treatable, and missing it is among the commonest grounds of negligence claims against casualty officers
• Dissect the vertebral arteries specifically in any death from a blow to the head or neck with basal subarachnoid haemorrhage; the tear will not be found unless it is looked for, and the case depends on it
• Take histology for diffuse axonal injury with β-APP staining where a person was unconscious from the moment of impact and the brain looks normal; without it the death appears unexplained
• Examine the circle of Willis in every subarachnoid haemorrhage to distinguish a ruptured aneurysm from trauma; the whole question of criminal liability turns on it
• Note the distribution of contusions and state whether the pattern favours a blow or a fall, with the reasoning; this is one of the more useful contributions the autopsy makes to the manner of death
• A chronic subdural haematoma may present weeks after a trivial injury in an elderly or alcoholic person, and the original injury may have been forgotten; the assailant remains liable if it can be traced
• Extradural is arterial and biconvex; subdural is venous and crescentic, and the shapes follow from the dural attachments — extradural stops at sutures and subdural crosses them
• Ask about the pattern of consciousness; unconscious throughout, or lucid then deteriorating, or conscious then declining over weeks, each points to a different lesion
• Post-traumatic epilepsy and chronic traumatic encephalopathy may appear months or years later and remain attributable to the original injury, with compensation consequences
• A trivial blow to the neck can be instantly fatal through a vertebral artery tear, particularly in an intoxicated person — and the assailant is responsible although the force was slight
• Contrecoup is severe after an occipital fall and rare after a frontal one, because the floor of the anterior fossa is rough and the occiput is smooth
• Send the vertebral arteries for histology where a tear is suspected; the site of rupture is small and may be confirmed only microscopically
• Beta-APP immunostaining is far more sensitive than silver stains for diffuse axonal injury, and detects it much earlier after the injury
• Diffuse axonal injury has no lucid interval — the patient is unconscious from the instant of impact, which distinguishes it clinically from an expanding haematoma
• Concussion cannot be demonstrated at autopsy; it is a clinical diagnosis with a negative examination, and death from pure concussion is exceptional
• Contusions concentrate at the frontal and temporal poles whatever the site of impact, because those are where the brain meets rough bone
• An extradural is treatable and a diffuse axonal injury is not, which is why the distinction has to be made quickly and why observation matters so much
• Examine the circle of Willis in every subarachnoid haemorrhage; a berry aneurysm and a traumatic arterial tear have entirely different legal consequences
• Chronic subdural is a disease of the elderly and the alcoholic, in whom the shrunken brain stretches the bridging veins and trivial trauma suffices
• Extradural is commoner in young adults, in whom the dura is less adherent to the skull and can be stripped by arterial pressure
• An intracerebral bleed in the basal ganglia is usually hypertensive, and one with contusion in the frontal or temporal lobe is usually traumatic