neurology Flashcards
layers of the cerebral cortex
molecular layer
external granular layer
external pyramidal layer
internal granular layer
internal pyramidal layer
multiform layer
risk factors for stroke
age
hypertension
smoking
diabetes mellitus
cardiac disease
which type of stroke happens when an aneurysm ruptures
subarachnoid
which stroke is due to hypertension
intracerebral
effects of stroke involving anterior cerebral artery
paralysis of contralateral structure - leg
abulia - disturbances in intellect, judgement and executive function
loss of appropriate social behaviour
effects of stroke involving middle cerebral artery
hemiplegia of contralateral structure - arm
contralateral hemisensory deficits
hemianopia
aphasia (left sided lesion)
- expressive - broca’s area
- receptive - wernicke’s area
effects of stroke involving posterior cerebral artery
visual problems
- homonymous hemianopia
- visual agnosia
name 3 basal ganglia diseases
parkinsons
huntingtons
ballism
what is ballism
contralateral uncontrolled swinging of the extremities due to stroke affecting subthalamic nucleus
role of vestibulospinal tract
stabilises head during body movements
coordinates head and eye movements
mediates postural adjustments
role of reticulospinal tract
from medulla to pons
changes muscle tone associated with voluntary movements
postural stability
role of rubrospinal tract
from red nucleus of midbrain
innervates lower motor neurones which go to the flexors of the upper limb
role of tectospinal tract
from superior colliculus of midbrain
orientates head and neck during eye movements
what are the positive and negative signs of an upper motor neuron lesion
negative:
loss of voluntary movements (paresis)
plegia
positive:
clonus (involuntary rhythmic muscle contractions)
babinski’s sign (when bottom of foot is stroked big toe is dorsiflexed)
spasticity (stiffness - can cause jerky movements such as clonus)
hyper-reflexia
what are the signs of a lower motor neurone lesion
weakness
hyporeflxia
hypotonia
fasciculations
fibrillations
what and where is the supplementary motor area
anterior and medial to the primary motor area
involved in planning complex and internally cued movements
what and where is the premotor area
anterior to the primary motor cortex
involved in planning externally cued movements
what is the primary motor cortex
in the precentral gyrus, anterior to the central sulcus
involved in fine discrete voluntary movements
what is apraxia
disorder of skilled movements
happens when there is a lesion in frontal lobe or inferior parietal lobe
common causes are stroke and dementia
what is ataxia
poor muscle control that causes clumsy voluntary movements
what is dysmetria
inaproporiate force and distance for target-directed movements
what is scanning speech
staccato
what is disdiadochokinesia
inability to perform rapidly alternating movements
what is intention tremor
increasingly oscillatory trajectory of a limb in a target directed movement
5 main signs of cerebellar dysfunction
dysdiadochokinesia
intention tremor
dysmetria
scanning speech
ataxia
what does motor neurone pool contain
all the alpha motor neurones innervating a single muscle
describe the size of responses to an action potential by the different types of motor units
1) slow - type 1 –> smallest reponse
2) fast fatigue resistant - type 2a —> larger response
3) fast fatiguable - 2b –> largest response
what is the jendrassik manoeuvre
when you clench your teeth, make a fist, or try to pull apart locked fingers during your patella tendon being tapped, the reflex is larger
list tests for assessing cortical structure and function
structure: DTI (diffusion tensor imaging)
function: fMRI, PET, EEG, MEG, TMS, tDCS
functions of the prefrontal cortex
attention, adjusting social behaviour, planning, personality expression, decision making
function of supplementary motor area
complex movements - internally cued
function of premotor area
externally cued movements
examples of commissural fibres
corpus callosum, anterior commissure
where/how do projection fibres travel
radiate as the corona radiata through internal capsule between thalamus and basal ganglia
limbic lobe functions
learning
emotions
memory
motivation
reward
insular cortex functions
visceral sensations, autonomic control, auditory processing, visual-vestibular integration, interoception
describe the microscopic organisation of the cerebral cortex
into columns —> cortical columns
and
into layers —> molecular, external granular, external pyramidal, internal granular, internal pyramidal, multiform
3 types of white matter tracts
association fibres, commissural fibres, projection fibres
5 types of association fibres
superior longitudinal fasciculus
inferior longitudinal fasciculus
arcuate fasciculus
uncinate fasciculus
short fibres
where does the corona radiata converge through from cortex to lower brain structures
converges through internal capsule between thalamus and basal ganglia
difference between primary and secondary cortices
primary: function is predictable, organised topographically, is symmetrical
secondary: function is less predictable, not organised topographically, weak/absent symmetry
consequences of temporal lobe lesion
agnosia (inability to recognise)
anterograde amnesia (inability to form new memories)
consequence of lesion in primary visual cortex of occipital lobe
blindness in corresponding visual field
what are the symptoms of MS
blurred vision, fatigue, difficulty walking, paraesthesia, muscle spams and stiffness
how do you find TMCT (total motor conduction time)
brain stimulation: find MEP latency - the time for stimulus to travel from brain to muscle
how does Brain stimulation and peripheral nerve stimulation prove that MS is a central ns issue
by brain stimulation, can find TMCT - which is longer than normal - shows that there is a problem with either upper or lower motor neurones
by peripheral nerve stimulation, can find F latency - which is normal - shows that there is no problem with peripheral nerves
so problem is with central nerves —> autoimmune demyelination of central nerves
what are the 3 waves produced by peripheral nerve stimualtion
M wave: motor axon stimulated, fast response causing muscle to twitch
H wave: sensory axon stimulated, impulse travels to spinal cord, activating the LMN in the spinal cord and causing muscle to twitch - reflex activation of muscle
F wave: strong impulse causes signal to travel antichromically up the motor neurone to spinal cord, activating the LMN in the spinal cord (not a reflex)
what is the response of brain stimulation on an MEG
MEP (motor evoked potential)
how to calculated PMCT
(M latency + F latency - 1) / 2
what can you get from a middle cerebral artery stroke if it causes a left sided lesion
Aphasia
a stroke in which part of the brain causes “clumsy, wobbly, drunk - like” symptoms
cerebellum eg intracerebellar haemorrhage
list the phases of a migraine
premonitory, aura, headache, resolution, recovery
describe the premonitory phase of a migraine
neck pain
concentration difficulty
irritability
mood disturbances
polyuria
photophobia
yawning
describe the recovery phase of a migraine
food intolerance
mood disturbance
“hungover” like
which medications should be avoided for pharmacological management of migraines
mixed analgesics
opiate-based medication
pharmacological management for migraines
NSAIDs
pro kinetics
triptans
paracetamol
acute and long term treatment of cluster headache
acute:
triptan
high flow oxygen
long term:
verapamil (used for grater occipital nerve, get ECG first)
greater occipital nerve block
what makes a tension headache different from a migrain
tension is
always bilateral
shorter, only lasts around 30 mins
no nausea/vomiting
not aggravated by movement
no photophobia/phonophobia
describe the symptoms of aura
visual
- elemental visual disturbance
- expanding C’s
sensory
- numbness
- paraesthesia
- weakness
- speech arrest
is cluster headache aggravated by movement
no
associated symptoms of a cluster headache
facial sweating
miosis (contracted pupils)
ptosis (drooping eyelids)
restlessness/agitation
ipsilaterally
- nasal congestion/rhinorrhea
- conjunctival redness/lacrimation
- eyelid oedema
which medications should you not offer for cluster headaches
NSAIDs, opioids, ORAL triptans, ergots, paracetamol
what are the roles of high and low order areas of the motor system
High order areas - programme and coordinate movements
low order areas - execute movements
describe how the motor system is organised
hierarchical segregation: high order and low order areas
functional segregation: different parts control different aspects fo movements
is ballism ipsilateral or contralateral
contralateral
pathology behind Parkinson’s
degeneration of dopamingeric neurones from subtstantia nigra to striatum
pathology behind Huntignton’s
degeneration of GABAergic neurons in caudate, striatum and putamen
due to CAG repeat
symptoms of Huntington’s
unstable gait
choreic movements
uncontrolled jerking
swallowing difficulty
speech impairment
cognitive decline
cause of Ballism
stroke affecting subthalamic nucleus
causes of sensineural hearing loss
inner ear: prescubysis, noise, ototoxicity
nerve: acoustic neuroma aka vestibular schwannoma
causes of conductive hearing loss
outer ear: foreign body, wax (cerumen impaction)
middle ear: otitis, otosclerosis
what is the difference between outer and inner hair cells
outer: arranged in 3 rows, carry efferent signals from the brain - modulate the sensitivity of the response from the brain
inner: arranged in single row, carry afferent signals to the brain - transduction of sound
which nerve are the outer and inner hair cells connected to
auditory nerve
what is the order of nerves/nuclei in the auditory pathway
cochlea –> vestibular cochlear nerve –> cochlea nucleus –> superior olive –> inferior colliculus –> medial geniculate body –> auditory cortex
what are the two clinical hearing tests using a tuning fork
weber test: place tuning fork on top of head
Rinne test: place tuning fork in air in front of ear, and on mastoid behind ear
what is an audiogram used for
to test hearing thresholds to see if there is hearing loss or not
What are OAE’s, how are they produced and what are they measured for
Otoacoustic emissions
low frequency sounds produced by the cochlea when the outer hair cells expand and contract
they are measured as part of newborn hearing test and hearing loss monitoring
what is contained within the maculae of the utricle and saccule
hair cells, gelatinous matrix, otoliths (carbonate crystals)
which direction is the macula placed in the utricle and saccule, and therefore which kind of movement do the utricle and saccule detect
utricle: macula is placed horizontally - detects horizontal linear movement
saccule: macula is placed vertically - detects vertical linear movement
which liquid fills the semi circular canals
endolymph
describe the composition of the ampulla of the semi circular canals
contain ampullary crista on base to which the hair cells are attached
then top of hair cells are attached to cupula which helps with transmitting the motion of the fluid (endolymph)
which is located next to the cochlea, utricle or saccule
saccule
name the two vestibular reflexes
vestibulo ocular reflex
vestibulo spinal reflex
describe the vestibulo ocular reflex
keeps images fixed on retina
eye moves in opposite direction to head but at same velocity and amplitude
connection between vestibular nuclei and oculomotor nuclei
eye clinical test to check for problems with vestibular system
“skew”:
cover one eye, other pupil/irirs goes up
uncover the eye, pupil/iris goes back down
how to differentiate between vestibular neuritis and stroke
HINTS exam
- Head Impulse test
- Nystagmus
- Test of skew deviation
what are the acute vestibular balance disorders
vestibular neuritis
stroke
what is the intermittent balance disorder
BPPV
what are the recurrent balance disorders
migraine
meniere’s disease
what is the border between the cornea and sclera called
limbus
what is the lipid layer of the tear film produced by
Meibomian glands along the eyelid margin
how is the conjunctiva nourished
has tiny blood vessels
how is the cornea nourished
oxygen from the air - dissolves into aqueous layer of tear film
glucose from aqueous humour - fluid between cornea and iris
cornea has a low water content, what happens if you hydrate it
it changes from transparent to white
where does the eye’s refractions power come from
2/3 from the cornea
1/3 from the lens
5 layers of the cornea
epithelium
bowmans membrane
stroma
descemet’s membrane
endothelium
what is the role of the endothelium of the cornea
pumps fluid out of the cornea to prevent corneal oedema
what are the 3 parts of the uvea
iris
choroid
ciliary bodies
role of ciliary body
controls thickness of lens
clears aqueous humour
what us it called when the lens loses elasticity with age
cataract
what is the innervation of tear production
afferent: ophthalmic branch of trigeminal nerve - from cornea to CNS
efferent: parasympathetic fibres - from CNS to lacrimal gland
neurotransmitter: Ach
describe how tear are drained
- tears drain into superior and inferior puncta - small openings on upper and lower medial lid margins
- drain into superior and inferior cannaliculi
- superior and inferior cannaliculi converge to form one canaliculus
- drains into tear sac
- drains into tear duct
what is the macula
in the centre of the retina
responsible for detailed central vision
no rod cells
what is the fovea
in centre of macula
has the highest concentration of cones and the lowest concentration of rods
only place with highest enough number of cones to be able to see in detail
what is central vision, how is it tested and what happens when it is lost
seeing detail in light and colour
eg reading, facial recognition
tested by visual acuity assessment
if lost, have poor visual acuity
what is peripheral vision, how is it tested and what happens when it is lost
night vision, seeing shape, movement, navigating
tested by visual acuity assessment
if lost, have extensive loss of peripheral field and unable to navigate
contrast the sensitivity, response, and vision type for rods and cones
rods: slower response, higher sensitivity to light, scotopic vision (ie night vision)
cones: faster response, less sensitive to light, photooptic vision (ie light vision)
describe the layers of the retina
1) 1st order neurones - photoreceptors (rods and cones)
detect the light
2) 2nd order neurones - bipolar neurones
local signal processing
3) 3rd order neurones - retinal ganglion neurones
transmit signal form eye to brain
what colours do S, M, L cones detect
S - blue
M - green
L -red
s-sea, l-love, m-me
what is the most common form of colour blindness
deuteranomaly / daltonism –> can’t see colour red
what is the name for complete colour blindness
achromatopsia
how to calculate index of refraction
speed of light in vacuum / speed of light in medium
what effects do concave/convex lenses have on light rays
concave: spreads the rays out
convex: converges the lenses, brings them to a point
what is emmetropia
adequate correlation between axial length and refractive power
what is ametropia and what are the 4 types
mismatch between axial length and refractive power
- myopia
- hyperopia
- astigmatism
- presbyopia
causes of myopia
excessive long globe
excessive refractive power
myopia treatment
use a diverging/negative lens
use contact lenses
remove eye lens to reduce refractive power
hyperopia causes
excessively short globe
insufficient refractive power
what is axial hyperopia
excessively short globe
what is refractive hyperopia
insufficient refractive power
symptoms of hyperopia
blurry vision - straight away when looking at close things OR intermittently
–> is worsened by tiredness, poor light
asthenopic symptoms:
- headache in frontal region
- eye pain
- burning eye sensation
- blepharoconjunctivitis (inflammation of eyelid margin and conjunctiva)
symptoms of hyperopia
blurry vision - straight away when looking at close things OR intermittently
–> is worsened by tiredness, poor light
asthenopic symptoms:
- headache in frontal region
- eye pain
- burning eye sensation
- blepharoconjunctivitis (inflammation of eyelid margin and conjunctiva)
what happens if hyperopia is left uncorrected
amblyopia - lazy eye
what is the circle of least confusion
in astigmatism
the area between the focal points of the 2 meridians where the image is the least blurry
astigmatism symptoms
asthenopic symptoms
blurred vision
distorted vision
head tilting and turning
treatment for regular astigmatism
cylindrical lens with or without spherical lens
surgery
treatment for irregular astigmatism
rigid cylindrical lens
surgery
what is the near response triad
pupillary miosis
- sphincter pupillae
- increase depth of visual field
convergence
- medial recti of both eyes
- align eyes on a close object
accomodation
- circular ciliary muscles
- increase refractive power of the lens
what is a zonule of the eye
the circumferential suspensory ligament that connects the lens of the eye to the ciliary body
what is presbyopia
loss of accommodation when looking at close objects due to age
treatment of presbyopia
convex lense to allow to see near objects - monodical or multifocal
- reading glasses
- bifocal glasses
- trifocal glasses
- progressive power glasses
complications of contact lenses
infectious keratitis
giant papillary conjunctivitis
severe chronic conjunctivitis
corneal vascularisation
what are the options for surgical correction of eyesight problems
keratorefractive surgery - laser
ICL (intra collated lens) implant on top of natural eye lens
clear lens extraction and IOL (intraocular lens)
describe the process of keratorefracrive surgery
cut the corneal flap
flip the corneal flap
apply photo-refractive treatment
reshape corneal stroma
put corneal flap back into position
what is the disadvantage of intraocular lenses
lose accommodation so will need reading glasses
describe the signal transmission along the visual pathway from the eye to the brain
eye (photoreceptors, bipolar cells, ganglion cells)
optic nerve
optic chiasm
optic tract
lateral geniculate nucleus
optic radiation
visual cortex
cause of homonymous hemianopia
stroke
cause of bitemporal hemianopia
pituitary gland enlargement/tumour
name for when you’re blind in only one eye
monocular blindness
name for being blind in the inner field of your right eye
right nasal hemianopia
name for being blind in one quadrant of each eyes visual field
quadrant hemianopia
cause of contrallateral homonymous hemianopia with macula soaring
stroke affecting primary visual cortex
macula is not affected as has dual blood supply from posterior cerebral arteries on both sides
difference between crossed and uncrossed fibres (their origin and which visual filed they are responsible for)
crossed
- originate in nasal retina
- responsible for temporal visual field
uncrossed
- originate in temporal retina
- responsible for nasal visual field
consequence of damage at the optic chiasm
homonymous hemianopia
consequence of damage on the left side, posterior to optic chiasm
right homonymous hemianopia
consequence of damage on the right side, posterior to optic chiasm
left homonymous hemianopia
are constriction/dilatation mediated by the sympathetic/parasympathetic systems
constriction - parasympathetic
dilatation - sympathetic
which muscles contract in pupil constriction/dilation
pupil constriction - circular muscles contract
pupil dilatation - radial muscles contract
describe the efferent pathway from the brain to the eye
Edinger westphal nucleus
oculomotor nerve efferent
ciliary ganglion
short posterior ciliary nerve
pupillary sphincter
what is the pupillary constriction response with a right afferent defect
afferent is eye to brain
so right pupil doesn’t construct when light is shone in right eye (as can’t sense the light)
but constricts when light is shine in left eye (consensual reflex)
what is the pupillary constriction response with a right efferent defect
efferent is brain to eye
so right pupil doesn’t constrict whether light is shone in left or right eye
but left pupil constricts when light is shone in either left or right eye
how to test for relative afferent pupillary defect and results
swinging torch test
both pupils constrict when light is shone in undamaged eye
both pupils dilate when light is shone in damaged eye
how to test for relative afferent pupillary defect and results
swinging torch test
both pupils constrict when light is shone in undamaged eye
both pupils dilate when light is shone in damaged eye
where is the superior oblique muscle attached and how does it move the eye
attached high on the temporal side of the eye
moves eye down and out
where is the inferior oblique muscle attached and how does it move the eye
attached low on the nasal side of the eye
moves the eye up and out
medial rectus innervation
inferior branch of oculomotor
superior rectus innervation
superior branch of oculomotor
inferior oblique innervation
inferior branch of oculomotor
lateral rectus innervation
abducens
superior oblique innervation
trochlear nerve
inferior rectus innervation
inferior branch of oculomotor nerve
how to test for superior rectus
elevation and abduction
how to test for inferior rectus
depression and abduction
how to test for superior oblique
depression and adduction
how to test for inferior oblique
elevation and adduction
what is eye torsion
rotation of the eye around its anterior posterior axis
what is dextroversion
movement of both eyes to right
what is levoversion
movement fo both eyes to left
what is the role and innervation of levator palpebrae superioris
raises the eye lid
superior branch of the oculomotor nerve
how to test visual acuity in preverbal children
test the optokinetic nystagmus reflex
what is optokinetic nystagmus
smooth pursuit followed by fast phase reset saccade
what is nystagmus
oscillatory eye movement
what are the signs of 3rd nerve palsy
droopy eyelid
affected eye is moved down and out
what are the signs of 6th nerve palsy
affected eye deviates inwards and cannot be abdcuted
a pts pupil is dilated and cannot constrict, which nerve is affected
(parasympathetic part of) inferior branch of oculomotor
causes of third nerve palsy
medical causes
surgical causes eg posterior communicating artery aneurysm
which cause of third nerve palsy is pupil sparing and why
medical cause
the inner portion is more affected, parasympathetic fibres are found in the outer surface of the nerve
- in surgical causes, the aneurysm causes compression of the nerve from the outside, so it affects the parasympathetic fibres and is not pupil sparing
what is the site if damage that causes absent knee jerk reflex and impaired sweating
dorsal root ganglion of spinal cord
what is Adie’s pupil and what is the cause
light near dissociation (have miosis in response to acommodation but not light)
it is due to abnormal reinnervation that takes place as a result of ciliary body damage
–> the fibres target the iris instead of the ciliary body
