Head Injuries Overview and Statistics

Learning Outcomes for Head Injuries

• Learning outcomes include describing various scalp injuries, types and complications of skull fractures, types and pathologies of brain haemorrhage, features and types of cerebral contusion, causes and pathology of diffuse axonal injury, pathophysiology of raised intracranial pressure, types and effects of brain swelling, and pathologies of alcohol related head injuries.

Significance of Head Injuries

• Significance of head injuries includes clinical, pathological, and legal aspects.

Head Injuries (H.I.) Statistics

• Head injury is the most common cause of attendance at A&E in Ireland.
• 90% of head injury attendees are experiencing minor injuries.
• 40-50% of head injury attendees are children.
• Minor head injuries rarely result in long-term complications.
• 0.2% of head injuries result in death, typically severe head injuries.
• 19,000 new brain injuries occur annually in Ireland.
• 10,000 people are hospitalised with traumatic brain injuries annually in Ireland.
• 8,000-8,500 new strokes happen every year in Ireland.
• 300 new brain tumors occur annually in Ireland.
• 120,000 people live with disabilities after brain injury in Ireland.

Pathological Significance of Head Injuries

• Head injuries are the leading cause of death in young adults in developed countries, with 50% of deaths for 15-19 year olds.
• Common causes of death are accidents, suicides, and homicides.

The Central Nervous System

• The skull protects the brain and spinal cord.
• The brain and spinal cord are housed within a protective but rigid structure.
• The skull helps to dampen shock waves during impacts.
• The skull will not expand and can result in potentially dangerous outcomes if broken.

Cross-section of Skull and Meninges

• The subarachnoid space contains cerebrospinal fluid, and provides a cushioning role.

Spectrum of Injuries

• Surface injuries include the scalp and face.
• Skull injuries include various types of fractures, simple or compound.
• Meninges are also affected by injury.
• Brain injury is also a possibility.

Blunt Force Trauma

• Resulting injuries can include bruising, external or subcutaneous wounds (e.g., from punching, kicking, falling), abrasions (scrapes), lacerations (cuts) or imprints (e.g., from stamping).
• Linear injuries, or specific injuries (e.g., hammer blows), are also possibilities.

Sharp Force Trauma

• Incised wounds are surface injuries.
• Stab wounds have the potential for brain injury.

Complications of Scalp Injuries

• Haemorrhage can occur due to the highly vascular nature of the scalp.
• Acute blood loss can cause immediate death.
• Blood can obstruct airways.
• A fractured skull is an outcome of significant force.
• Bleeding around the brain (extradural, subdural, subarachnoids) is another possibility.

Injury to Brain Itself

• Surface injuries can cause contusions (bruising), lacerations (cuts) and haemorrhage (bleeding)
• Diffuse damage can occur from hypoxia (lack of oxygen), axonal injury, and oedema (swelling).

Skull Fractures

• Fractures can be simple or compound.
• Fractures may indicate the amount of force used.
• Fractures are not always life-threatening.
• Linear fractures, comminuted fractures, depressed fractures, basilar fractures, and ping-pong fractures and diastatic fractures are possible.
• High-velocity impacts can lead to penetrating or depressed skull fractures; flat impacts often result in linear, non-displaced fractures.

Risk Factors for Skull Fractures

• Severity of the blow.
• Speed of impact.
• Object involved in the impact (its weight, shape, and consistency).
• Thickness of hair, scalp, and skull involved.
• Age and elasticity/brittleness of the bone of the victim.

Complications of a Skull Fracture

• CSF leakage, especially at basal fractures.
• Infection.
• Extradural haemorrhage (bleeding between the skull and dura mater).
• "Black eyes" or "panda eyes" from trauma to frontal bone.

The Meninges

• Meninges injuries include tears often associated with fractured skulls.
• Haemorrhage can occur, independent of skull fractures.

Extradural Haemorrhage (EDH)

• Bleeding occurs between the skull and the dura mater.
• 90% of extradural hemorrhages involve the petrous temporal bone (above or behind the ear).
• EDHs can occur without visible fractures, especially in children.
• High mortality rates.
• Can be treatable, but delayed treatment can result in intellectual and emotional disabilities.
• May occur with a recognisable “lucid interval.”

Subdural Haemorrhage (SDH)

• Blood accumulation occurs between the dura and arachnoid mater.
• Acute phase of bleeding (3-14 days).
• Subacute phase of Bleeding (3-14 days).
• Chronic phase of Bleeding (>14 days)
• Can be caused by bridging veins or venous sinuses.
• Symptoms may not be noticeable immediately.
• Elderly, alcoholic individuals, children, and individuals who suffered whiplash injuries are at increased risk of this type of injury

Subdural Haemorrhage (SDH): Problems

• Less immediately apparent or easily associated with impact events.
• Doesn't always involve fractures.
• Shearing forces are often the cause.
• Symptoms may take several hours to develop.

Subarachnoid Haemorrhage (SAH)

• Blood accumulation occurs over the surface of the brain, under the arachnoid mater.
• Causes include tearing of pial vessels.
• Shearing and rotational injuries can be causative factors.
• Minor SAH may indicate previous concussions (“knocked out”).
• Severe cases may involve severe trauma.
• Damage to neck (vertebral arteries).
• Rupture of an aneurysm inside the skull.
• Extension of intracranial bleeding are possible causes.

Transmural tear of Vertebral Arteries (TSAH)

• Transmural tear of a vertebral artery can cause basal SAH.
• Usually no pre-existing pathology.
• Biomechanical and temporal consistency with blunt impact.

The Brain

• Brain injury can manifest as localized or generalized, diffuse trauma.
• Direct force, rotational forces, acceleration/deceleration are causative factors depending on injury type.

Brain Damage: Primary vs. Secondary

• Primary damage occurs at the time of impact, and involves cortical contusions/lacerations, diffuse axonal/vascular injury.
• Secondary damage involves hypoxia, ischemia, brain swelling, intracranial haematoma, epilepsy or infection that develops after the initial injury.

Localized Brain Injury

• Surface contusions (bruises), lacerations (cuts), can occur directly as a consequence of the impact.

Contusions

• Bruising on the brain's surface.
• Associated with fractures (in some cases).
• Can involve the crests of gyri causing either superficial or deeper injury.
• May extend into underlying white matter regions forming a haematoma or bruising directly under the area of a fracture.
• Coup and contrecoup contusions may occur at sites opposite of the impact location.

Brain - Surface Injuries

• Location relative to front, top, side and back of the head will indicate the areas of injury, and severity.

Brain - Secondary Injuries

• Intracerebral haemorrhage can occur on or in the surface of the brain, and can be small or significant (burst lobe); small bleeds are less serious, but burst lobes are typically fatal.

Brain ‐ Internal Injuries

• Deep-seated intracerebral haemorrhage is indirect injury resulting from twisting and tearing of vessels due to significant rotational injuries (e.g., RTA).
• Intracerebral haemorrhages can occur if the head is violently shaken or violently impacted with no visible external damage to the skull in cases of young individuals.

Diffuse/Generalised Damage

• The result of acceleration/deceleration and shearing/rotational forces.
• This type of impact is associated factors such as falls (from significant heights), major car accidents, or direct hits/assaults.

DAI/DVI

• Can have a range of outcomes from concussion to a persistent vegetative state.

DAI ‐ Brain

• Gliding contusions involve brain rubbing against external surfaces.
• Haemorrhage in the corpus callosum and adjacent areas of the brain stem can occur.
• These areas can be prone to haemorrhages that can cause significant additional damage.

Secondary Damage from Generalized/Diffuse Cerebral Injury

• Cerebral oedema as a result of many causes and resulting complications include: vasogenic oedema (secondary to BBB breakdown); cytotoxic/ionic/cellular oedema (result of cellular energy failure), interstitial/hydrocephalic oedema (due to increased intraventricular pressure and/or impaired fluid outflow), and osmotic/hypostatic oedema (secondary to imbalances in osmolality).
• These damaging phenomena can have potentially serious outcomes.

Brain Swelling

• Brain swelling is a separate entity from cerebral oedema.
• Occurs frequently at the same time, or following cerebral insult (trauma) or other incident.
• Engorgement of the cerebral vessels causes increased intravascular blood volume.
• Brain swelling can lead to cerebral oedema.
• Swelling can take time to develop, especially in children

Raised Intracranial Pressure

• Raised intracranial pressure can result from localized mass lesions (extradural, subdural, intracerebral haemorrhage); obstruction of major venous sinuses; focal oedema due to trauma, infection or tumors; diffuse brain swelling due to head injury, SAH,meningitis, near-drowning; neoplasms; infections or problems with CSF circulation (obstructive hydrocephalus, communicating hydrocephalus, etc.); or idiopathic intracranial hypertension.
• Associated symptoms include; headache, changes in mental status (e.g., lethargy, irritability); vomiting, ptosis (drooping of the eyelid), nerve palsies, papilloedema, haemorrhages (flame shaped to retinal haemorrhages).
• The brain uses several compensatory strategies—displacement of blood and cerebrospinal fluid, loss of brain tissue—to cope with increased intracranial pressure, but eventually, these compensatory strategies fail. A series of potentially life threatening events can occur leading to herniations and death.

Other Secondary Damages from Head Injuries

• Hypoxic (lack of oxygen) injuries; facial injuries with blood loss; cardiac arrest; seizures; pulmonary oedema; gastric erosions; and acute pancreatitis, are all possible consequential injuries.

Cause of Death Following Head Injury

• Brain damage is most common.
• Raised intracranial pressure can also cause death.
• Other associated injuries may also be factors affecting outcomes (e.g., haemorrhage, inhalations, or infections).

Alcohol and Head Injuries

• Alcohol use is a significant contributing factor in accidents and assaults involving head injuries
• Those intoxicated before an accident may face worse outcomes (even for a minor head injury) than those whose injuries occurred sober.
• Alcohol intake results in greater chances of increased severity and/or more prolonged periods of apnoea (no breathing) after an injury event.
• Alcohol causes muscle laxity (“unprotected” when falling).

Brainstem and Spinal Cord Injuries

• Midbrain, pons, and medulla oblongata are affected by injury.
• Stroke is possible.
• Brainstem injuries can cause coma or locked-in syndrome.

Causes of Brain Stem Injuries

• Infections (e.g., encephalitis).
• Vascular problems (e.g., thromboembolism, occlusions, hypertension).
• Traumatic brain injury resulting in herniation.
• Traumatic brain injury may result in falls.
• Sudden cardiac death—a variety of factors can be involved and contribute to other secondary causes.
• Tumours

Spinal Cord Injuries

• Spinal cord injuries include compression injuries due to falls, hyperextension, hyper flexion, car accidents, assaults or accidents during sports/recreational pursuits .
• injuries to the spinal cord may cause a loss of reflexes and result in balance or gait issues, impair vision, dizziness, loss of sense of smell, and affect heart rate and breathing, and cause paralysis.
• Injuries can include coma, swallowing and respiratory issues, impaired sensory function.
• Spinal cord fractures can result in direct compression.
• Cervical cord and cervicomedullary injuries can be seen in incidents of shaking, infants and in non-accidental child abuse.
• Age-related neurological injury severity and outcome are contributing factors involving the extent of injuries.

This quiz covers key learning outcomes related to head injuries, including types of scalp injuries, skull fractures, and brain haemorrhages. Additionally, it addresses the significance of head injuries from clinical, pathological, and legal perspectives, while also presenting statistical data on head injuries in Ireland. Test your knowledge on this critical topic!