Head Injuries: Types and Effects

Head Injuries

• There are two main types of head injuries: closed head injuries, which are the most common, and open head injuries.
• Closed head injuries are associated with blunt trauma and can result in skull fractures, focal brain injuries, and diffuse brain injuries.
• Open head injuries occur when the dura mater and cranial contents are penetrated, often resulting in substantial neurologic deficit and decreased quality of life.
• Gunshot wounds are the most common type of open head injury.

Skull Fractures

• Skull fractures can be open or closed and are often indicated by deformities, visible cracks in the skull, or bleeding behind the ear or over the mastoid process.
• Linear skull fractures are non-displaced and account for most skull fractures.
• Depressed skull fractures result from high-energy direct trauma to the head and can cause bony fragments to be driven into the brain.
• Basilar skull fractures are associated with high-energy trauma and can cause CSF drainage from the ears or nose.

Traumatic Brain Injuries

• Traumatic brain injuries can be classified as primary or secondary.
• Primary brain injuries occur instantly and result from impact to the head.
• Secondary brain injuries occur as a result of the primary brain injury and can include cerebral edema, intercranial hemorrhage, increased ICP, and infection.

Motor Vehicle Crash

• Motor vehicle crash is the most common cause of brain injury.
• Coup-counter coup injuries occur when the brain strikes the front of the skull and then rebounds to the rear of the skull.
• The injured brain will initially swell due to cerebral vasodilation and trauma, which can lead to cerebral edema.

Signs and Symptoms

• Vomiting is a common response to head injuries.
• Clear or pink watery CSF from the nose or ear indicates a disruption of the dura and skull.
• Seizures are not uncommon and can occur as a result of head injuries.
• Cushing's Triad is a sign of increased ICP and includes increased blood pressure, decreased pulse, and irregular respiration.

Increased ICP

• Increased ICP occurs when there is bleeding inside the skull, which can occur between the skull and dura mater, beneath the dura mater but outside the brain, or within the brain tissue itself.
• Increased ICP decreases cerebral perfusion pressure and cerebral blood flow.
• If increased ICP is not promptly treated, cerebral herniation may occur.
• Monitor for signs and symptoms of increased ICP, including vomiting, headache, altered mental status, and seizures.

Posturing

• There are two forms of posturing: decorticate and decerebrate.
• Decorticate posturing involves flexion of the arms and extension of the legs.
• Decerebrate posturing involves extension of the arms and legs.

Focal Brain Injury

• Focal brain injuries are specific, grossly observable brain injuries, such as a cerebral contusion, where the brain tissue is bruised and damaged in a specific area.
• The frontal lobe is the most commonly affected area.

Epidural Hematoma

• Epidural hematomas occur when there is an accumulation of blood between the skull and dura mater.
• They are often associated with a linear fracture of the temporal bone and can cause a disruption of the middle meningeal artery.
• Patients may become unresponsive immediately following the injury, followed by a brief period of awareness called the lucid interval.

Subdural Hematoma

• Subdural hematomas occur when there is an accumulation of blood beneath the dura mater but outside the brain.
• They are the most common type of intercranial hemorrhage and may or may not be associated with a skull fracture.
• Patients may experience fluctuating levels of consciousness, focal neurological signs, or slurred speech.

Inter-Cerebral Hematoma

• Inter-cerebral hematomas occur when there is bleeding within the brain tissue itself.
• They have a high mortality rate, even if the hematoma is surgically evacuated.

Subarachnoid Hemorrhage

• Subarachnoid hemorrhages occur when there is bleeding into the subarachnoid space.
• They are often associated with trauma, rupture of an aneurysm, or an arteriovenous malformation.
• Patients may present with sudden, severe headaches, and as bleeding increases, signs and symptoms of increased ICP will appear.

Diffuse Brain Injuries

• Diffuse brain injuries affect the entire brain.
• They can cause cerebral contusion, which is caused by a blow to the head or face.
• Diffuse brain injuries can also cause a coup-counter coup injury, which produces mild TBIs.

Concussion

• A concussion is a type of diffuse brain injury that is caused by a blow to the head or face.
• It can cause a direct blow to the head or face, or a rapid onset of short-lived impairment of neurologic function that resolves spontaneously.
• Signs and symptoms of concussion include confusion, disorientation, amnesia, dizziness, weakness, visual changes, nausea, vomiting, ringing in the ears, slurred speech, inability to focus, and a lack of coordination.

Spinal Cord Injuries

• Spinal cord injuries can occur in a variety of ways, including compression, flexion, and rotation injuries.
• Vertebra fractures can occur with or without associated SCI.
• Stable fractures pose less risk to the spinal cord, while unstable injuries involve multiple columns of the spine.
• Injuries to the C1 and C2 of the spine are often unstable and result from high-velocity mechanisms.

Primary Spinal Cord Injury

• Primary spinal cord injury occurs at the moment of impact.
• Spinal cord concussion is characterized by a temporary dysfunction that lasts from 24 to 48 hours.
• Spinal cord contusion is caused by fracture, dislocation, or direct trauma.

Secondary Spinal Cord Injury

• Secondary spinal cord injury results from primary SCI progressing to further deterioration.
• The effects can be exacerbated by exposing neural elements to further hypoxemia, hypoglycemia, and hypothermia.
• Minimizing heat loss and maintaining oxygenation and perfusion are key in these patients.

Spinal Cord Shock

• Spinal cord shock is a temporary local neurologic condition occurring immediately after spinal trauma.
• It presents with varying degrees of acute spinal injury, and sensory function below the level of injury is impaired.
• It usually subsides in hours to weeks depending on the severity of the injury.

Neurogenic Shock

• Neurogenic shock is a result of temporary loss of autonomic function.
• It is often characterized by hypotension, bradycardia, and warm, flushed, and dry skin below the level of spinal lesion.

Head Injuries

• Two main types of head injuries: closed head injuries (most common) and open head injuries
• Closed head injuries associated with blunt trauma, resulting in skull fractures, focal brain injuries, and diffuse brain injuries
• Open head injuries occur when dura mater and cranial contents are penetrated, often resulting in substantial neurologic deficit and decreased quality of life
• Gunshot wounds are the most common type of open head injury

Skull Fractures

• Can be open or closed
• Often indicated by deformities, visible cracks in the skull, or bleeding behind the ear or over the mastoid process
• Linear skull fractures: non-displaced, accounting for most skull fractures
• Depressed skull fractures: result from high-energy direct trauma to the head, causing bony fragments to be driven into the brain
• Basilar skull fractures: associated with high-energy trauma, causing CSF drainage from the ears or nose

Traumatic Brain Injuries

• Classified as primary or secondary
• Primary brain injuries: occur instantly, resulting from impact to the head
• Secondary brain injuries: occur as a result of primary brain injury, including cerebral edema, intracranial hemorrhage, increased ICP, and infection

Motor Vehicle Crash

• Most common cause of brain injury
• Coup-counter coup injuries: occur when the brain strikes the front of the skull and then rebounds to the rear of the skull
• Initial brain swelling due to cerebral vasodilation and trauma, leading to cerebral edema

Signs and Symptoms

• Vomiting: common response to head injuries
• Clear or pink watery CSF from the nose or ear: indicates disruption of the dura and skull
• Seizures: not uncommon, occurring as a result of head injuries
• Cushing's Triad: sign of increased ICP, includes increased blood pressure, decreased pulse, and irregular respiration

Increased ICP

• Occurs when bleeding inside the skull, occurring between the skull and dura mater, beneath the dura mater but outside the brain, or within the brain tissue itself
• Decreases cerebral perfusion pressure and cerebral blood flow
• If not promptly treated, cerebral herniation may occur
• Monitor for signs and symptoms of increased ICP, including vomiting, headache, altered mental status, and seizures

Posturing

• Two forms: decorticate and decerebrate
• Decorticate posturing: involves flexion of the arms and extension of the legs
• Decerebrate posturing: involves extension of the arms and legs

Focal Brain Injury

• Specific, grossly observable brain injuries, such as cerebral contusion, where brain tissue is bruised and damaged in a specific area
• Frontal lobe: most commonly affected area

Epidural Hematoma

• Accumulation of blood between the skull and dura mater
• Often associated with linear fracture of the temporal bone, causing disruption of the middle meningeal artery
• Patients may become unresponsive immediately following injury, followed by a brief period of awareness called the lucid interval

Subdural Hematoma

• Accumulation of blood beneath the dura mater but outside the brain
• Most common type of intercranial hemorrhage, may or may not be associated with a skull fracture
• Patients may experience fluctuating levels of consciousness, focal neurological signs, or slurred speech

Inter-Cerebral Hematoma

• Bleeding within the brain tissue itself
• High mortality rate, even if surgically evacuated

Subarachnoid Hemorrhage

• Bleeding into the subarachnoid space
• Often associated with trauma, rupture of an aneurysm, or an arteriovenous malformation
• Patients may present with sudden, severe headaches, and as bleeding increases, signs and symptoms of increased ICP will appear

Diffuse Brain Injuries

• Affect the entire brain
• Can cause cerebral contusion, resulting from a blow to the head or face
• Can also cause a coup-counter coup injury, producing mild TBIs

Concussion

• Type of diffuse brain injury caused by a blow to the head or face
• Can cause direct blow to the head or face, or rapid onset of short-lived impairment of neurologic function that resolves spontaneously
• Signs and symptoms include confusion, disorientation, amnesia, dizziness, weakness, visual changes, nausea, vomiting, ringing in the ears, slurred speech, inability to focus, and lack of coordination

Spinal Cord Injuries

• Can occur through compression, flexion, and rotation injuries
• Vertebra fractures can occur with or without associated SCI
• Stable fractures pose less risk to the spinal cord, while unstable injuries involve multiple columns of the spine
• Injuries to the C1 and C2 of the spine are often unstable and result from high-velocity mechanisms

Primary Spinal Cord Injury

• Occurs at the moment of impact
• Spinal cord concussion: temporary dysfunction lasting from 24 to 48 hours
• Spinal cord contusion: caused by fracture, dislocation, or direct trauma

Secondary Spinal Cord Injury

• Results from primary SCI progressing to further deterioration
• Exacerbated by exposing neural elements to further hypoxemia, hypoglycemia, and hypothermia
• Minimizing heat loss and maintaining oxygenation and perfusion are key in these patients

Spinal Cord Shock

• Temporary local neurologic condition occurring immediately after spinal trauma
• Presents with varying degrees of acute spinal injury, and sensory function below the level of injury is impaired
• Usually subsides in hours to weeks depending on the severity of the injury

Neurogenic Shock

• Result of temporary loss of autonomic function
• Often characterized by hypotension, bradycardia, and warm, flushed, and dry skin below the level of spinal lesion

Learn about the two main types of head injuries, their causes, and their effects on the brain and quality of life.