[22] Raised ICP Flashcards
What is raised ICP?
When the pressure inside the skull (and thus the brain and CSF) is increased
What is a normal ICP at rest in a supine adult?
7-15mmHg
Is raised ICP acute or chronic?
Can be either
What are the ways in which the body can regulate the ICP?
- Changes in CSF production and absorption
- Autoregulation
- Chemoregulation
What happens in autoregulation (re: ICP)?
Vasoconstriction and vasodilation can occur in response to changes in blood pressure
What happens in chemoregulation (re: ICP)?
There is vasodilation in response to low cerebral pH
What are changes in ICP attributed to?
Changes in the volume of one or more of the constituents within the cranium
What can change in volume within the cranium to lead to raised ICP?
- Blood
- CSF
- Brain (and other tissue)
What are the common causes of raised ICP?
- Localised mass lesions
- Neoplasms
- Abscess
- Focal oedema
- Disturbance of CSF circulation
- Obstruction to major venous sinuses
- Diffuse brain oedema and swelling
- Idiopathic intracranial hypertension
What is an example of a localised mass lesion that can lead to raised ICP?
Traumatic haematoma
Give examples of neoplasms that can cause raised ICP?
- Glioma
- Meningioma
- Metastases
What can lead to focal oedema causing raised ICP?
- Trauma
- Infarction
- Tumour
What are the types of CSF disturbance?
- Obstructive hydrocephalus
- Communicating hydrocephalus
What happens in obstructive hydrocephalus?
There is blockage to the circulation of the CSF causing back pressure to build up
What happens in communicating hydrocephalus?
There is impaired absorption of the CSF but no obstruction to flow
What can cause obstruction to major venous sinuses?
- Depressed fractures overlying the venous sinuses
- Cerebral venous thrombosis
What can lead to diffuse brain oedema and swelling?
- Encephalitis
- Meningitis
- Diffuse head injury
- Subarachnoid haemorrhage
- Reye’s syndrome
- Lead encephalopathy
- Water intoxication
- Near drowning
What are the typical presenting signs and symptoms of raised ICP?
- Headache
- Papilloedema
- Vomiting
- Changes in mental state
Describe a typical headache seen in raised ICP?
- Nocturnal or starts on waking
- Worse on coughing or moving head
What can also be seen on fundoscopy as well as papilloedema?
- Blurred disc margins
- Loss of venous pulsations
- Disc hyperaemia
- Flame-shaped haemorrhage
How does vomiting present in early raised ICP?
With nausea
What can happen to vomiting later in raised ICP?
Progress to projectile
What changes to mental state can occur in raised ICP?
- Lethargy
- Irritability
- Slow decision making
- Abnormal social behaviour
What are the late signs of raised ICP?
- Motor changes (hemiparesis)
- Raised BP
- Widened pulse pressure
- Slow irregular pulse
What investigations may be useful in assessing raised ICP?
- CT/MRI scan
- Blood glucose
- Renal function
- U&E’s
- ICP monitoring
Why can CT/MRI be useful in assessing raised ICP?
To look for an underlying lesion
What can ICP monitoring be useful for?
Diagnosing and guiding treatment
When is ICP monitoring most commonly used?
Management of a severe closed head injury
When is ICP monitoring appropriate?
This is a bad card no way around it sorry
- Severe head injury and abnormal CT scan
- Severe head injury and normal CT scan if two of; over 40, motor psoturing, systolic BP <90mmHg
- Subarachnoid haemorrhage with hydrocephalus
- Reye;s syndrome
- Brain tumour
- Idiopathic intracranial hypertension
What are the differentials for raised ICP?
Other causes of headache
What are some other causes of headache?
- Tension headache
- Migraine
- Cluster headache
What are some possible first line therapies for raised ICP?
- Avoiding pyrexia
- Managing seizures
- CSF drainage
- Head of bed elevation
- Analgesia and sedation
- Mannitol
- Hyperventilation
How should seizures be managed in raised ICP?
Aggresively with standard anticonvulsant loading regimens
How are patients with raised ICP usually sedated?
IV propfol, etomidate or midazolam
How are patients with raised ICP given pain relief?
Morphine or alfentanil
What is mannitol?
An intravascular osmotic agent
What problems are associated with mannitol use?
Hypovolaemia and hyperosmotic state
What second line therapies may be used to treat raised ICP?
- Barbiturate coma
- Optimised hyperventilation
- Hypothermia
- Decompressive craniotomy
Who with raised ICP are high dose barbiturates harmful to?
Those with head injuries
What are the potential complications of raised ICP?
- Seizures
- Stroke
- Neurological damage
- Death