Head injury

Question 1

What is the definition of Traumatic Brain Injury (TBI)?

Answer 1

TBI refers to a non-degenerative, non-congenital brain injury caused by an external mechanical force, which may result in temporary or permanent impairment of cognitive, physical, and psychosocial functions, often with altered consciousness.

Question 2

What are the mechanisms of injury in TBI?

Answer 2

TBI mechanisms include blunt trauma (e.g., motor vehicle accidents) and penetrating trauma. Alcohol is often a major contributing factor in many TBIs​

Question 3

How is TBI classified based on the Glasgow Coma Scale (GCS)?

Answer 3

Mild TBI: GCS 13-15
Moderate TBI: GCS 9-12
Severe TBI: GCS 3-8

Question 4

What is the Monroe-Kellie Doctrine?

Answer 4

The doctrine states that the cranial cavity is non-distensible and is filled to capacity with non-compressible components (CSF, blood, brain tissue). An increase in one component must result in a decrease in another or lead to an overall increase in intracranial pressure (ICP

Question 5

What is cerebral perfusion pressure (CPP) and how is it calculated?

Answer 5

CPP is the net pressure gradient that drives oxygen delivery to cerebral tissue. It is calculated as CPP = MAP - ICP (or CVP), where MAP is mean arterial pressure and ICP is intracranial pressure​

Question 6

What are the primary injuries associated with TBI?

Answer 6

Primary injuries include skull fractures, intracranial hematomas, brain contusion, axonal injury, and blood-brain barrier disruption

Question 7

What are the causes of secondary brain injury in TBI?

Answer 7

Secondary injuries result from cerebral ischemia, cerebral edema, intracerebral hypertension, excitotoxic processes (e.g., glutamate release), inflammatory processes, and hypoxia

Question 8

What is the significance of increased intracranial pressure (ICP) in TBI?

Answer 8

Raised ICP, when above 20 mmHg, can lead to cerebral ischemia, hydrocephalus, herniation, and is considered a medical emergency requiring prompt treatment

Question 9

What are the signs of raised intracranial pressure (RICP)?

Answer 9

Signs of RICP include Cushing’s triad (hypertension, bradycardia, irregular respiration), headache, vomiting, and visual disturbances​

Question 10

What are the management strategies for traumatic brain injury (TBI)?

Answer 10

Prevention of secondary injury by avoiding hypoxia, hyper/hypoglycemia, hyperthermia, and raised ICP
Maintaining adequate cerebral perfusion pressure (CPP)
Surgical evacuation of hematomas when necessary
Use of osmotherapy (e.g., mannitol) to reduce ICP​

Question 11

What are the common types of intracranial bleeds associated with TBI?

Answer 11

Epidural hematoma: Caused by impact loading to the skull, often involving dural artery/vein laceration.
Subdural hematoma: Due to injury to cortical veins or pial arteries, associated with high mortality.
Subarachnoid hemorrhage: Bleeding into the space around the brain.
Intracerebral hemorrhage: Occurs within the brain parenchyma, often

Question 12

What is cerebral edema and how does it develop in TBI?

Answer 12

Cerebral edema can be either:

Cytotoxic edema: Due to disruption of the cell membrane and failure of sodium-potassium pumps.
Vasogenic edema: Caused by disruption of the blood-brain barrier, leading to fluid extravasation into the brain tissue​

Question 13

What are the components of the Cushing’s triad?

Answer 13

Cushing’s triad consists of hypertension, bradycardia, and irregular respirations

Question 14

What are the types of cerebral edema in TBI?

Answer 14

Cytotoxic edema: Results from cell membrane disruption and sodium-potassium pump failure, leading to intracellular fluid accumulation.
Vasogenic edema: Caused by blood-brain barrier (BBB) disruption, allowing fluid to leak into the brain parenchyma​

Question 15

What is the primary cause of secondary brain injury after TBI?

Answer 15

The key cause of secondary brain injury is cerebral ischemia, often due to brain edema, microvascular pathology, or cerebral vasospasm​

Question 16

What role does cerebral autoregulation play in TBI?

Answer 16

Cerebral autoregulation allows the brain to maintain a constant blood flow despite fluctuations in blood pressure. This helps prevent both hyperperfusion and ischemia in the brain

Question 17

What is the treatment goal for raised intracranial pressure (ICP)?

Answer 17

The goal is to prevent secondary injury by reducing ICP, maintaining adequate cerebral perfusion pressure (CPP), and ensuring sufficient oxygenation and venous drainage from the brain​

Question 18

What are the indications for using anti-convulsant therapy in TBI patients?

Answer 18

Anti-convulsant therapy is indicated to reduce the incidence of early post-traumatic seizures, especially in patients with severe TBI, depressed skull fractures, intracranial hematomas, or contusions​

Question 19

How does mannitol reduce intracranial pressure (ICP) in TBI management?

Answer 19

Mannitol increases plasma osmolality, drawing water out of the brain across the blood-brain barrier, thereby reducing ICP​

Question 20

What are the risks associated with the use of mannitol in TBI management?

Answer 20

Risks include acute kidney injury, hyponatremia, hypokalemia, and osmotic nephropathy

Question 21

What is the significance of maintaining normocapnia in TBI patients?

Answer 21

PaCO2 is a powerful determinant of cerebral blood flow (CBF), and hypercapnia can lead to increased cerebral blood flow and raised ICP. Therefore, normocapnia helps prevent secondary brain injury​

Question 22

What are the extracranial causes of secondary brain injury?

Answer 22

Extracranial causes include hypoxia, hypotension, hypercarbia, hyponatremia, acidosis, hyperglycemia, and hyperthermia​

Question 23

the formula for CPP

Answer 23

CPP = MAP -ICP-central venous pressure