MSCP
What is the most likely cause of Vasogenic edema? Which brain matter does it affect?
Suggestive of inflammatory disorder and affects white matter tracts (loss of integrity of BBB)
In contrast, cytoxic suggestive of stroke or hypoxic encephalopathy, affects grey matter (BBB retained)
Where are the sensory receptors for dynamic equilibrium and stable equilibrium located?
Dynamic equilibrium involves acceleration of the head in rotational, horizontal, and vertical movements - ampullae of semicircular canals
Static equilibrium involves movement of the head in respect to gravity - maculae of the utricle and saccule
Define delirium and provide 5 risk factors
Acute confusional state characterised by disturbances of awareness (+/- consciousness), changes in cognition (attention and orientation), with a fluctuating course, often accompanied by disturbance of sleep-wake cycle and delusions. Triggered by acute precipitant(s) and Hx,Ex,Ix reveal physiological cause.
RF: medications, infections, age, preexisting dementia, drugs/alcohol, surgery
Clinical sign required for orthostatic syncope and provide 3 causes
systolic drop >20mmHg from lying to standing
volume depletion, medication (B blockers, diuretics, ACEi), autonomic failure (e.g. diabetes)
Describe the pathophysiology of Alzheimer's disease
Extracellular accumulation of B amyloid plaques (increase production and/or decreased clearance) and intracellular accumulation of tau protein neurofibrillary tangles within neurons lead to loss of synapses and degeneration of cholinergic neurons; ultimately result in gross atrophy of the affected areas of the brain.
RF: APOE e4, CVD RF (HTN, T2DM, obesity), brain trauma, advanced age, FHx
What structures form the roof, floor and lateral walls of the lateral ventricles?
Roof: corpus callosum
Lateral walls: caudate nucleus and thamalus
Provide 5 clinical differentiators for UMN v LMN
UMN: hypertonia, no wasting (or disuse atrophy), absent fasciculations, positive babinsky, hyperreflexic
What MRI features may one expect to see for a patient with Alzheimer's dementia? How can a clinician differentiate this from hydrocephalus?
On MRI: Cortical atrophy, indented sulci, enlarged ventricles
In normal pressure hydrocephalus (extra CSF in ventricles), brain tissue may not appear shrunken even though the ventricles are enlarged.
Describe the mechanism of reperfusion injury post stroke
Re-canalisation influx of blood carries ROS and cytokines: 1. endothelial dysfunction, BBB damage, vascular permeability, vasogenic edema, decrease microvascular perfusion 2. cytokines cause vasoconstriction also causing lack of perfusion 3. infiltration causes oxidative stress and mitochondrial dysfunction -> collectively cause neuronal damage & glial reactivity
Describe the anatomical pathway for sound from spoken word to interpretation
sound wave transmission through external ear, hit the tympanic membrane causing vibration, transmitted via the ossicles (malleus, incus, stapes).
Oval window creates vibrations in endolymph fluids within the cochlear, movement of basilar membrane causes stereocilia of hair cells in organ of corti to bend, hair cells bend causes depolarisation of ganglion spinal cells which transmit signal via cochlear nerve -> superior olivary complex, inferior colliculus, MGN, primary auditory cortex (temporal lobe)
Compare and contrast precipitating factors, prodrome, quality, associated features and period after the event for vasovagal syncope v seizure
- pain, emotion, prolonged standing v spontaneous (sleep deprivation or stress may contribute)
- light-headed, dizzy, nausea v aura
- sweaty, pallor, injury uncommon v tongue biting, incontinence, moan or froth
- rapid recovery no confusion v post-ictal >2min
What are Charcot's neurologic triad symptoms for multiple sclerosis?
Dysarthria, nystagmus, intention tremor (plaques in brainstem, eye nerves and motor pathways)
Explain the pathophysiology of cytotoxic edema
↓ ATP production (i.e. cerebral ischaemia) → cells unable to maintain ATP-depedent Na+/K+ membrane pump that facilitates high extracellular Na+ and low intracellular Na+ → Na+ accumulates in cell → water/cl- enter into cell along an osmotic gradient → cellular swelling/death and loss of neurons
What visual field defect would you expect to observe in a patient with R sided PCA occlusion
contralateral homonymous hemianopia (occipital infarction) with macular sparing due to collateral flow from the middle cerebral artery
Explain LEMS clinical features and why a warming-up phenomenon may be observed
LEMS: Ab against Ca2+ channels which decrease Ach release at NMJ → muscle weakness, Trouble walking, Tingling sensation in the hands or feet, Eyelid drooping, Fatigue, Dry mouth, common cranial nerve involvement
Weakness is relieved after temporary use because repeated stimulation and action potentials allows sufficient Ca2+ to enter cell for Ach release
Explain the importance of a positive RAPD finding and provide three potential DDx
Relative Afferent Pupillary Defect - asymmetric pupillary reaction to light when shined back and forth between the eyes; common sign of asymmetric optic nerve disease
Demyelination Optic neuritis (e.g. MS), ischaemic optic neuropathies (e.g.GCA), glaucoma, Sjogrens, Lyme, TB, optic nerve tumour, post surgical damage, ischaemic ertinal disease, retinal detachment or infection