Brain Herniation Flashcards
The intracranial space is divided into compartments by folds of what?
Dura mater
The skull is a closed box so any increase in ICP causes parts of the brain to do what?
Shift between compartments
In brain herniation, vital brain structures can get compressed against what?
Bone or tough dura mater
What are the two important meningeal folds?
Falx cerebri and tentorium cerebelli
What is the function of the falx cerebri?
Divides the two hemispheres of the cerebrum
The free edge of the falx cerebri is in close contact with what structure?
Corpus callosum
What is the function of the tentorium cerebelli?
Separates the cerebrum from the cerebellum
The free edge of the tentorium cerebelli is in close contact with which structure?
Brainstem
What are the two main types of herniation?
Supratenorial and infratentorial
What is supratentorial herniation?
Displacement of the cerebrum
What is infratentorial herniation?
Displacement of the cerebellum
What are the 4 types of supratentorial herniation?
Uncal, central, cingulate and transcalvarial
What happens in uncal herniation?
The medial part of the temporal lobe slops down through the tentorium and puts pressure on the brainstem (especially midbrain)
What are the 4 clinical features that uncal herniation could present with?
3rd nerve palsy, contralateral hemiparesis, reduced conscious level, macular sparing homonymous hemianopia/blindness
3rd nerve palsy in uncal herniation occurs as a result of compression of which structure? What does this involve?
Ipsilateral CNIII - causes an ipsilateral fixed, dilated pupil and down and out gaze
Contralateral hemiparesis in uncal herniation occurs as a result of compression of which structure?
Ipsilateral cerebral peduncle
Reduced level of consciousness in uncal herniation occurs as a result of compression of what structure?
Reticular activating formation
Macular sparing homonymous hemianopia/blindness in uncal herniation occur as a result of compression of which structure?
Ipsilateral posterior cerebral artery
‘The diencephalon and parts of the temporal lobe slip under the free edge of the tentorium’ describes which type of herniation?
Central
What functions of the diencephalon can be affected in central herniation?
Processing sensory information and emotions, as well as hormone production
What are some specific clinical features of central herniation?
Loss of vertical upgaze, bilateral fixed and small pupils, Cushing’s triad and cardiac arrest
Loss of vertical upgaze in central herniation occurs as a result of compression of which structure?
Vertical gaze centres in the midbrain
Bilateral small and fixed pupils in central herniation occurs as a result of compression of which structure?
Hypothalamic sympathetic pathways
Cushing’s triad and cardiac arrest in central herniation occurs as a result of compression of which structure?
Medulla and cardiorespiratory centres
‘The medial part of the frontal lobe passes under the falx cerebri to the opposite side’ correctly describes which type of herniation?
Cingulate (Subfalcine)
What is the main structure that is compressed in a cingulate herniation and what does the result in?
The anterior cerebral artery - ischaemic stroke causing hemiparesis
‘The brain squeezes out of the skull at a fracture or surgical site’ correctly describes which type of brain herniation?
Transcalvarial
What are the 2 types of infratentorial herniation?
Upward and tonsillar
What happens in upward herniation?
The cerebellum is displaced upwards through a notch in the tentorium cerebelli
What happens in tonsillar herniation?
The cerebellar tonsils pass through the foramen magnum and compress the lower brainstem
What are the main earlier clinical features of tonsillar herniation?
Headache, neck stiffness, altered consciousness, flaccid paralysis
What are the later clinical features of tonsillar herniation?
Cushing’s triad and cardiac arrest
Cushing’s triad and cardiac arrest occur in tonsillar herniation due to compression of where?
Medulla and cardiorespiratory centres
