High yield questions Flashcards
what type of mutation occurs in a Glioblastoma multiforme?
mutation in IDH1
What is T1 weighted MRI?
Makes Grey matter light and White matter dark
Name 3 clinical uses of ultrasounds?
- Suspected meningitis
- perinatal ischaemia
- Hydrocephalus
- pregnancy
what is a Glioblastoma Multiforme?
It is a fast-growing type of tumour of the brain or spinal cord. It is the most common primary malignant brain tumour in adults.
- effects multiple glial brain cells ( astrocytes, oligodendrocytes, microglia and cells of the blood vessels.) and almost never spreads outside of the central nervous system
what is anaplastic oligodendroglioma?
- A type of brain tumour Grade 3 that occurs primarily in adults but also found in children.
- These tumours effect the neuroepithelium of the nervous system.
- There is a chromosome deletion of 1p19q
What is T2 weighted MRI?
- Makes Grey matter dark, and White matter light
what is the cause of Extradural Haemorrhage?
- Commonly caused by traumatic rupture of the middle meningeal artery following a temporal Bone fracture.
what is the clinical use of MRI angiography?
- Atherosclerosis
- Sternosis
- Aneurysms
Describe the structure of the Organ of Corti
Tectorial membrane
Outer hair cell with hair Stereocilia
Reticular lamina
Outer hair cells + Inner hair cells
Each connected to a nerve fibre
Connected to Modiolus (bony structure in cochlea)
Rods of Corti
Basilar membrane
Vestibulocochlear nerve
How does the Cochlea work?
- Vibration of stapes (caused by the other ocicles) causes wave in perilymphatic fluid to travel through the Scala vestibuli.
- At a specific frequency, when a vibration is set up in the Basillar membrane they cross into the Scala tympani to round window.
- Causes displacement of basilar membrane and Organ corti
4.Basillar membrane most stiff nearest to base of cochlea and least stiff at helicotrema – only high frequency sounds can displace basilar membrane at the base, lower frequencies must travel further along
How does the inner hair cells send information to the brain?
Via spiral ganglion and the vestibulocochlear nerve
How does the medial superior olivary nuclei compare to the lateral?
Medial SON detects differences in the time that sounds reach each ear – Low frequency
Lateral SON detects differences in sound intensity reaching each ear – High frequency
If the sterocillia move in the direction towards the kinocilium what happens?
Displacement in the direction of the kinocillium stimulates hair cells.
what is the perilymph layer?
fluid with high Na+ conc
Where is the Auditory cortex?
Temporal lobe
Brodmann areas 41 and 42
Tonotopic – Different areas correspond to different frequency of sound
what solute is in high concentration in the labyrinth?
potassium
How does lacunar anterior circulation stroke present ?
ataxic hemipariesis
- Pure motor hemiplegia
- Pure sensory loss
what are the 4ps when imaging for stroke or TIA?
P- parenchyma: Assess early signs of acute stroke, rule out haemorrhage and some stroke mimics
P- pipes including collaterals: Assess extracraial and Intracranial circulation
P- perfusuion: Assess cerebral blood volume, cerebral blood flow and transit time
P- penumbra: Assess tissue at risk of dying if ischaemia continues without repercussion.
what are the clinical clues that a patient is experiencing a peripheral vestibulopathy?
- New tinnitus/hearing loss
- No other neurological symporoms/signs
- No vertical or bidirectional nystagmus
dix-hallpike positive
what are the functions of temporal lobe?
- Auditory cortex
- Learning and memory
- Olfactory sensation
- Emotional behaviour
what hospital tools can be used for TIA and stroke assessment?
Rosiers
what is a TIA?
- Sudden focal loss of neurological function with complete recovery within 24 hours.
- Caused by inadequate perfusion in the partial or complete distribution of the carotid or vertebro-basilar arteries.
what is Metabolic encephalopathy?
- Flucturating onset
- Attention deficits/confusion
- Often pre-existing cognitive problems
- Accompanying metabolic derangement
What is the most common type of ischaemic stroke?
- Lacunar stroke – occlusion of small penetrating arteries that provide blood to the brains deep structures
What is the treatment for an ischaemic stroke?
- Tissue plasminogen activator (tPA)
- Thrombolysis - ( within 4 hours from onset of symptoms)
- Then aspirin and statin
What kind of occlusion can cause brain stem syndromes?
- Branch occlusion
what pre hospital assessment tools for stroke or TIA?
- Fast ( face and speech)
- Be fast ( balance eyes face and speech)
4 types of posterior stroke syndromes?
Basilar artery occlusion
Anterior inferior cerebellar artery
Wallenberg’s syndrome
Weber’s syndrome/medial midbrain syndrome
how does the posterior stroke syndrome of basilar artery occlusion commonly present?
Basilar artery occlusion is more likely to present with locked in syndrome (quadriparesis with preserved consciousness and ocular movements), loss of consciousness, or sudden death.
how does the posterior stroke syndrome of anterior inferior cerebellar artery occlusion commonly present?
Anterior inferior cerebellar artery results in lateral pontine syndrome, a condition similar to the lateral medullary syndrome but with additional involvement of pontine cranial nerve nuclei.