Head Injuries and Intracranial Pressure Flashcards
What is the rigid structure that contains non-compressible components in the head?
The skull
What are the three components that maintain intracranial pressure (ICP)?
- The Brain
- Cerebrospinal fluid
- Blood
What is the normal range for intracranial pressure (ICP)?
5 - 15 mmHg.
What is considered an abnormal ICP level that requires treatment?
Greater than 20 mmHg
What can cause transient rises in intracranial pressure?
Activities such as coughing, sneezing etc.
What happens to the volume of the components maintaining ICP if there is an alteration in one of them?
An alteration in the volume of any one of the components will result in changes in the other two components to maintain ICP.
What is the physiological significance of maintaining a uniform intracranial pressure?
Crucial for protecting the brain ensuring adequate blood flow and fostering normal neurological function.
How does the body respond to an increase in volume of one of the components of ICP?
The body responds to an increase in the volume of one of the components by decreasing the volume of the other two components to keep the ICP within a normal range.
What can cause raised intracranial pressure (ICP)?
- Brain tumours
- Haematomas
- Increases in cerebral blood flow due to hypercapnia or hypoxia
- Increased production of cerebrospinal fluid
- Decreased absorption of CSF
- Blockages in the CSF pathways.
What is cerebral perfusion pressure (CPP)?
A critical measure that indicates the adequacy of blood flow to the brain.
How is CPP calculated?
Mean arterial pressure (MAP) minus the intracranial pressure (ICP)
What is the normal range for cerebral perfusion pressure (CPP)?
70 - 100 mmHg.
What may happen to CPP following a head injury?
Can fall below 60 mmHg which indicates inadequate blood flow to the brain and can lead to further brain injury.
What are common signs and symptoms of raised ICP?
- Headache
- Nausea and vomiting
- Visual disturbances
- Alterations in pupil reaction and size
- Depressed consciousness
- Late signs include hypertension bradycardia and respiratory irregularities.
What is the difference between primary and secondary traumatic brain injury?
Primary traumatic brain injury occurs at the moment of impact and is considered irreversible. Secondary traumatic brain injury occurs after the initial injury and is a result of processes related to the initial injury; it may be prevented or reduced.
What is hypercapnia and how does it affect cerebral blood flow?
Hypercapnia is a condition characterized by an increase in carbon dioxide (CO2) levels in the blood. It can cause increases in cerebral blood flow which may contribute to raised ICP.
What is hypoxia and its effect on cerebral blood flow?
Hypoxia is a deficiency in the amount of oxygen reaching tissues. It can lead to increased cerebral blood flow which can be one of the factors causing raised intracranial pressure.
How does increased production of cerebrospinal fluid (CSF) lead to raised ICP?
By adding volume within the cranial cavity leading to pressure increases against intracranial structures.
What role does decreased absorption of CSF play in raised ICP?
Can result in an accumulation of CSF within the cranial cavity contributing to increases in intracranial pressure.
What are potential late signs of raised ICP to be aware of?
- Hypertension
- Bradycardia
- Irregular respiratory patterns.
What is the primary goal of management in traumatic brain injury (TBI)?
To prevent secondary injury to the brain.
What are the different types of head injury?
- Concussion
- Contusion
- Extradural haemorrhage
- Subdural haemorrhage
- Intracerebral haemorrhage
What is an extradural haematoma?
A collection of blood that occurs in the ‘potential’ space between the skull and the outer protective lining covering the brain known as the dura mater.
What is a subdural haematoma (SDH)?
A type of bleeding where a collection of blood gathers between the inner layer of the dura mater and the arachnoid mater of the meninges surrounding the brain. It typically results from tears in bridging veins that cross the subdural space.
What is an intracerebral haematoma (ICH)?
A serious condition that occurs when a blood vessel within the brain ruptures leading to bleeding in the brain tissue itself.
What type of haematoma is also known as a haemorrhagic stroke?
Intracerebral haematoma
How does an extradural haematoma typically occur?
Due to trauma that causes a tear in the blood vessels often associated with skull fractures.
What are common symptoms of a subdural haematoma?
- Headache
- Confusion
- Changes in consciousness
- Nausea and vomiting
What are potential complications of an intracerebral haemorrhage?
- Increased intracranial pressure
- Further brain damage
- Coma
- Possible death.
What is the potential space between the skull and the dura mater called?
Extradural space or epidural space.
What are bridging veins?
Veins that traverse the subdural space and connect the brain’s surface with the venous sinuses
How are bridging veins related to SDH?
They can tear during trauma leading to a subdural haematoma.
What imaging techniques are commonly used to diagnose head injuries like haematomas?
CT scan and/or MRI
What steps are taken to manage increased intracranial pressure in TBI patients?
- Elevating the head
- Administering diuretics
- Surgical intervention to relieve pressure
- Managing fluid balance.
What does a normal CT scan indicate in the context of brain injuries?
A normal CT scan indicates that there are no visible signs of brain injury such as bleeding swelling or fractures. It is essential for ruling out major intracranial problems after head trauma.
What is meant by ‘midline shift’ in a CT scan?
Midline shift refers to the displacement of the brain’s midline structures due to increased pressure or mass effect often associated with swelling or a hematoma. This finding indicates potential serious complications from a traumatic brain injury.
What are ‘coup’ and ‘contrecoup’ injuries?
Coup and contrecoup injuries occur during a traumatic brain injury. The coup injury is where the brain impacts the side of the skull directly beneath the point of impact. Contrarily contrecoup occurs on the opposite side of the impact where the brain rebounds and strikes the skull.
What complications can arise from base of skull fractures?
Cerebrospinal fluid (CSF) leaks which can manifest as rhinorrhea (CSF leak from the nose) or otorrhea (CSF leak from the ear). These leaks can increase the risk of infection and damage to the brain.
What precautions should be taken while managing a suspected base of skull fracture?
Avoid nasal intubation nasal airways or nasogastric (NG) tubes until the fracture has been excluded to prevent potential damage or infection of the brain.
How do you assess neurological status in a patient with brain injury?
Neurological status can be assessed using the Glasgow Coma Scale (GCS). which evaluates a patient’s eye verbal and motor responses to determine the level of consciousness and neurological function.
What is the aim of maintaining cerebral perfusion in patients with traumatic brain injury?
This ensures adequate blood flow to the brain -> prevents secondary brain injury due to ischemia ensures the brain receives sufficient oxygen and nutrients during recovery.
What are general management measures for traumatic brain injury?
1) Ventilation support as needed
2) Monitoring vital signs
3) Prevention and management of seizures
4) Maintaining normothermia
5) Venous thromboembolism (DVT) prophylaxis
6) Electrolyte balance management
7) Gastrointestinal tract protection
8) Nutritional support.
What role does carbon dioxide play in brain injury management?
It influences cerebral blood flow. Hypercapnia (increased CO2 levels) can lead to vasodilation and increased intracranial pressure whereas hypocapnia (decreased CO2 levels) can cause vasoconstriction and reduce cerebral perfusion affecting the patient’s recovery.
What effect does carbon dioxide have on blood vessels in the context of brain injury?
Carbon dioxide causes dilatation of blood vessels which can increase cerebral blood flow and subsequently raise intracranial pressure in cases of brain injury.
How can hyperventilation be used in the management of brain injuries?
To reduce intracranial pressure by decreasing the levels of carbon dioxide in the blood thus leading to constriction of the blood vessels.
What is the consequence of excessively reduced cerebral blood flow during brain injury treatment?
Can lead to cerebral ischaemia (inadequate blood supply to the brain) -> can cause tissue damage.
What are burr holes in the context of surgery for head injuries?
Burr holes are holes that are drilled into the skull typically performed to relieve mild pressure on the brain.
What is a craniotomy?
A craniotomy is a surgical procedure in which a portion of the skull is removed to expose the portion of the brain that requires surgical intervention and the bone is usually replaced after the procedure.
What is a craniectomy?
A craniectomy is a surgical procedure where a portion of the skull is removed and not immediately replaced. It is typically performed to relieve a higher level of pressure on the brain and the bone flap may be replaced at a later date.
How does increased intracranial pressure relate to cerebral blood flow during brain injuries?
Can reduce cerebral blood flow which if it decreases too far can lead to cerebral ischaemia.
What is a major concern with anticoagulant therapy in the context of blunt head trauma?
The risk of delayed intracranial haemorrhage which can occur in patients who are taking direct oral anticoagulants.
