ICP and Head Injuries Flashcards
What is the normal range of intracranial pressure?
5-15mmHg
Which brain herniation is most common?
Subfalcine herniation (beneath falx cerebri)
What is the uncus?
The medial part of the temporal lobe, at the base of the cerebrum
What part of the brain does an uncal herniation compress?
The midbrain: ipsilateral oculomotor nerve, cerebral peduncle
What are the symptoms of subfalcine herniation?
Headache, contralateral leg weakness (if anterior cerebral artery affected)
On a CT, the midline shifts
What are the symptoms of uncal herniation?
Ipsilateral dilated pupil, contralateral leg weakness, decreased consciousness level.
(May be false localising if midbrain pushed against opposite side of tentorium)
Where do the cerebellar tonsils herniate through?
The foramen magnum
What structures does a tonsillar herniation compress?
Medulla and upper spinal cord
What effect does tonsillar herniation compression of the spinal cord have?
Cardiac and respiratory dysfunction
What is Cushing reflex?
A physiological nervous system response to continual raised ICP, resulting in Cushing’s triad of raised BP, irregular breathing, and bradycardia
What are the four causes of raised ICP?
Increased cerebral blood volume, increased CSF volume, expanding mass (eg: abscess, tumour), cerebral oedema (eg: meningitis, encephalitis, infarction)
What is the most common cause of raised ICP?
Traumatic brain injury (often due to hemorrhage)
Where are the two age peaks for brain tumours?
Childhood and late middle age
What are the most common types of childhood brain tumour?
Astrocytomas (astrocytes), medulloblastomas (neuroectodermal cells)
What are the most common types of adult brain tumour?
Gliomas and meningiomas, metastases from lung/breast/kidney
What is idiopathic intracranial hypertension?
Raised ICP without evidence of hydrocephalus or mass lesion, with normal investigations and brain imaging.
Usually obese young women after weight gain, treatment involves weight loss, carbonic anhydrase inhibitors, CSF drainage, shunts.
What are the main causes of raised intracerebral blood volume?
Venous outflow obstruction, venous sinus thrombosis.
Treat with anticoagulants, may require venous sinus tenting (rare)
What can occur as a result of increased CSF volume?
Choroid plexus papilloma
How is an expanding mass within the cranium treated?
Surgical resection, steroids
How is cerebral oedema treated?
Cause treating. Mannitol, hypertonic saline.
How is raised CSF volume treated?
Shunts, tumour resection, diuretics for use while awaiting intervention (eh: carbonic anhydrase inhibitor)
Is a lumbar puncture advised in acute management of raised ICP?
No
What is a cerebral contusion?
Bruising of the brain; blood mixes with cortical tissue due to microhaemorrhages and small vessel leaks.
What is a concussion?
Head injury with temporary loss of brain function
(Stretching and axonal injury, causing impaired neurotransmission, reduction in cerebral blood flow, and loss of ion regulation)
Signs of basilar skull fracture
Raccoon eyes, CSF rhinorrhea, CSF otorrhoea, bruising behind the ear, blood behind the eardrum, bump.
What is a diffuse axonal injury?
Shearing of interface between grey and white matter following traumatic acceleration/deceleration/rotational injury, damaging intracerebral axons and dendritic connections
What is a basilar skull fracture?
A bony fracture of the base of the skull
Temporal, occipital, sphenoid, or ethmoid bone
