Neuro Flashcards
Gyri vs sulci?
Gyri are ridges/folds
Sulci are grooves
What is the microscopic organisation of the cerebral cortex?
Layers and columns
What is the basis of cytoarchitecture?
cell size
spacing/packing density
layers
Functions of the frontal lobe?
Motor function Language motor aspects Cognitive functions eg planning atttention memory
Parietal lobe functions?
Sensations
Language sensory aspects
Spatial orientation
Self perception
Occipital lobe function?
Processing visual info
Temporal lobe function?
Auditorty processing
emotions
memories
What structures make up the limbic lobe?
Mamillary body
Amygdala
Cingulate gyrus
Hippocampus
What are the functions of the limbic lobe?
Learning
memory
emotion
motivation and reward
where is the insular cortex found?
deep in lateral fissure
What are the functions of the insular cortex?
Visceral sensations Autonomic control Interoception Auditory processing Visual-vestibular integration
Describe the internal structure of the cerebral cortex
grey matter - neuronal cell bodies and glial cells
white matter - myelinated neuronal axons in tracts
What are the three types of fibres in white matter tracts?
Association
Commissural
Projection
What do association fibres connect?
connect areas in same hemisphere
What do commissural fibres connect?
connect homologous structures in left and right hemispheres
What do projection fibres connect?
connect cortex with lower brain strcutures
what are the 4 association fibres? what do they connect?
superior longitudinal fasciculus - frontal → occipital
arcuate fasciculus - frontal → temporal
inferior longitudinal fasciculus - temporal → occipital
uncinate fasciculus - anterior frontal → temporal
What are the three types of projection fibres?
afferent - towards cortex
efferent - away from crotec
corona radiata - deeper to cortex
Where do projection fibres converge?
through internal capsule between thalamus and basal ganglia
What are three differences between primary and secondary/association cortices?
Primary : have predictable functions, organised topographically, left and right symmetry
What are the three frontal lobe motor areas?
primary
supplementary
premotor
What are the functions of the primary motor cortex?
controls fine, discrete, voluntary movements
descending signals
What are the functions of the supplementary and premotor area?
Planning complex movements
s - internally cued
pm - externally cued
What are the two parietal lobe areas?
primary somatosensory
somatosensory assoication
What are the functions of the primary somatosensory cortex?
process somatic sensations from body receptors
eg. touch, vibration, pain, temp, etc.
What are the functions of the somatosensory association?
interpret significance of sensory information
self awareness and of personal space
two areas of the occipital lobe and their functions?
primary visual cortex - process visual stimuli
visual association - interpretation and meaning of visual input
two areas of the temporal lobe and their functions?
primary auditory cortex - process auditory stimuli
auditory association - interpretation and meaning of auditory input
functions of the prefrontal cortex?
attention social behaviour planning personality decision making
functions of Brocas area?
production of language
function of wernickes area?
understanding language
what would you observe in a frontal lobe lesion?
personality change
inappropriate behaviour
what would you observe in a parietal lobe lesion?
contralateral neglect i.e. lack of awareness of self and extraperosnal space on opposite side
what would you observe in a temporal lobe lesion?
agnosia
anterograde amnesia
what is agnosia?
inability to recognise objects
what is anterograde amnesia?
cannot form new memories
what would you observe in a lesion to broca’s area?
expressive aphasia - slurred speech but able to understand speech
what would you observe in a lesion to wernicke’s area?
receptive aphasia - can speak but cannot comprehend speech
what would you observe in a primary visual cortex lesion?
blindness in corresponding visual field
what would you observe in a visual association lesion?
prosopagnosia (face blindness)
unable to interpret visual information
two types of imaging to assess cortical function?
PET - positron emission tomography
fMRI - functional magnetic resonance imaging
what does PET look at?
Blood flow directly to brain region (take up of glucose using radioactive isotope)
More glucose uptake = more brain activity
what does fMRI look at?
the amount of blood oxygen in a brain region
What can you use to measure evoked/event-related potentials?
EEG
MEG
two methods of brain stimulation?
transcranial magnetic stimulation (TMS)
transcranial direct current stimulation (tDCS) to increase or decrease neuronal firing rates
two types of imaging to assess cortical structure?
diffusion tensor imaging (DTI) based on diffusion of water molecules
DTI with tractography to assess neuronal tracts
Where in the skull is the ear found? How is this beneficial?
The petrous part of the temporal bone. It’s v hard so provides the necessary protection
name 3 functions of the outer ear?
to capture sound and direct it to the tympanic membrane
to amplify sound via resonance
protection via hairs and wax
How does the middle ear amplify sound?
vibrations move from the tympanic membrane w a large surface area to the oval window (smaller sa) via the ossicles → sound pressure increases and it is amplified
name the 3 ossicles?
malleus
stapes
incus
why does sound need to be amplified in the middle ear?
bc the sound waves are moving from air in the middle ear to fluid in the inner ear where it is more difficult for sound waves to travel
what is the function of the cochlea?
to transduce sound waves to electrical impulses that can be interpreted by the brain
allows pitch and volume to be analysed
describe the structural components of the cochlea
scala vestibuli (contains perilymph) scala media (contains endolymph) basilar membrane organ of cortisol scala tympani
how is the basilar membrane arranged? what does this mean?
Tonotopically (think xylophone)
narrow and thicker at the base compared to the apex
means the base can receive higher frequencies and thE apex lower ones
what cells does the organ of corti contain and how are they arranged? functions?
Inner hair cells - one column (fewer), sound transduction
outer hair cells - three columns, modulate sensitivity, amplify sound
what are the hair cells connected to?
tectorial membrane (only OHC in constant contact)
what are the hairs on hair cells called?
sterocillia
how do the Scala vestibuli and the Scala tympani communicate?
helicotrema
explain how sound is transduced?
sound travels through perilymph of scala vestibule and scala tympani
causes basilar membrane to vibrate → tectorial membrane is pushed against hair cells → stereo cilia are deflected → potassium channels open → potassium from endolymph enters hair cell → cell depolarises → calcium enters through VGCCs → glutamate vesicle exocytosis → glutamate to afferent nerve → auditory cortex
what happens in transduction of louder sounds?
theres more deflection of steroecilia and more potassium channels open leading to greater depolarisation
describe the auditory neural pathway
nerves from hair cells → spiral ganglia → vestibulocochlear nerve → ipsilateral cochlear nuclei → superior olive in brainstem (bilateral) → inferior colliculus → medial geniculate body → auditory cortex
human range of hearing?
20 - 20000 Hz
0 - 120 dB
Which frequencies are affected first
higher frequencies
what is a tuning fork used for?
to establish the probable presence or absence of hearing loss with a significant conductive component
what are the two tuning forks tests?
weber test (over the head) rinne test (next to ear)
what is pure tone audiometry?
science of measuring acuity for variations in sound intensity and frequency
what device is used in PTA? how are results measured?
audiometer
audiogram
What does the central processing assessment assess?
Hearing abilities other than section
Verbal and non-verbal testing
What is tympanometry?
testing the condition of the middle ear and the mobility of the tympanic membrane and the ossicles
does this by creating varying pressures in the ear canal
What are otoacoustic emissions?
low intensity sounds produced by outer hair cells in the cochlea when they expand and contract
When are OAEs measured?
Newborn hearing screening
Hearing loss monitoring
3 methods of measuring auditory evoked potentials?
Electrocochleography (cochlea and CN8) 0.2-4.0ms
auditory brainstem response (CN8 and brainstem nuclei and tracts) 1.5.10ms
late responses (primary auditory and association cortex) 80-500ms
Benefits of auditory brainstem response?
objective
patients doesn’t need to pay attention
most commonly used in clinics
when are cortical potentials useful?
In neurological conditions or processing problems
name and describe the 3 types of hearing loss
conductive - outer or middle ear problem
sensorineural - inner ear or auditory nerve
mixed - conduction and transduction are affected
causes of conductive hearing loss?
outer ear - foreign body or wax buildup (cerumen impaction)
middle ear - otitis or otosclerosis
causes of sensioneural hearing loss?
inner ear - presbycusis or ototoxicity
nerve - CN8 tumour
what is presybycutis?
loss of outer hair cells, occurs with age
4 types of hearing loss treatment?
Underlying cause (eg. remove earwax)
Cochlear implant
Hearing aids
brainstem implant
How do hearing aids work?
amplify sound
How does the cochlea implant work?
Replaces hair cells → receives and analyses sound → transforms it to electrical signals → auditory nerve
(requires functional nerve)
When can a brainstem implant be used?
When auditory nerves are damaged
electrical signals sent directly to electrodes in brainstem
very risky
what are the 3 inputs of the vestibular system?
visual
proprioceptive
vestibular
vestibular system outputs?
reflexes to help maintain posture and a stable gaze
where is the vestibular system found?
in the posterior region of the inner ear
what does the vestibule consist of?
three semicircular canals - anterior , lateral and posterior
all 3 connected (via ampullae) to utricle which is joined to the saccule by a conduit
What are the hairs on vestibular hair cells called?
Stereocillia and kinocilium ( the biggest cilia)
When are vestibular cells depolarised?
when endolymph is moved via head movement
what are the otolith organs? what do they consist of?
utricle and saccule
carbonate crystals that help deflect hairs
what are the maculae? how do they differ in the utricle and the saccule?
hair cells → gelatinous metric → otoliths
saccule is placed vertically
utricule is placed horizontally
outline the structure and contents of the semicircular canals
canal contains potassium rich endolymph
ends in ampulla which opens into utricle
ampulla has crista where hair cells are found
hair cells are surrounded by the cupula
what is the function of the cupula?
helps movement of hair cells in ampulla of semicircular canals
where do primary vestibular afferents end?
vestibular nuclei
cerebellum
where do vestibular nuclei project to? (4)
spinal cord
extraocular muscle nuclei
cerebellum
CV and respiratory control centres
where is the main vestibular cortex found?
parietal lobe as parieto-insular vestibular cortex
3 main functions of the vestibular system?
control posture
detect and inform about head movements
keep images fixed during movement
why do neurons still fire at the resting potential of hair cells? what do you call this discharge?
Because there is the force of gravity and information that you are stationary is still being processes
Required to keep you upright
Basal discharge
what are the three hair cell potentials in the vestibular system and how are they generated?
Resting - always there
Excitaion - occurs when sterocilia move towards the kinocilium → depolarisation → ↑ nerve discharge
Inhibitoin - stereo cilia move away from kinocilium → hyperpolarization → ↓ nerve discharge
What do the otolith organs detect?
Tilt and linear acceleration
utricule - horizontal movement
saccule - vertical movement
What does the semilunar canals detect? And how?
angular acceleration
endolymph flow moves the cupula which then moves hair cells
how do opposite semicircular canals work?
lateral work together
anterior of one side works with posterior of opposite side
what are the two main vestibular reflexes?
vestibul-ocular reflex
vestibule-spinal reflex
Describe the VOR and how it works?
connects the vestibular and oculomotor nuclei
keeps images fixed in the retina
the eyes move in the opposite direction to the head but at the same velocity and amplitude
Describe the VSR and how it works?
from vestibular nuclei:
motor neurones to the limbs via the lateral tract
motor neurons to the neck and back via the medial tract
controls posture and prevents you from falling
what 7 things are considered in vestibular assessment?
anamnesis (history) posture & gait cerebellar function eye movements vestibular tests imaging symptoms & impact assessment
what are the main symptoms of a balance disorder?
vertigo (objects spinning)
dizziness
2 main types of balance disorders?
peripheral & central vestibular disorders
give 4 examples of peripheral vestibular disorders
vestibular neuritis (acute) benign paroxysmal positional vertigo (intermittent) Meniers disease (recurrent) unilateral and bilateral vestibular hypofunction
explain bppv
benign paroxysmal positional vertigo
crystals detach from gelatinous matrix in the utricle which move to the ampulla of the canals and put extra pressure on the cupula making you feel dizzy
give 3 examples of what can cause central vestibular disorders
stroke (acute)
MS (progresive)
tumour eg schwanoma (progressive)
differentials for dizziness? (7)
heart disorders orthostatic hypotension presyncopal episodes psychological gait problems anaemia hypoglycaemia
What can have ‘modest symptomatic benefit’ in the early stages of dementia?
Acetylcholinesterase inhibitors
Name 4 common differentials for dementia
Depression
alcohol related brain damage
vitamin b1/6/12 deficiency
endocrine disorders
define preclinical dementia?
there is deterioration in neurological cells but no clinical symptoms yet
risk factors for dementia? (7)
ageing oral health brain trauma genetics mid-life obesity ↓ physical activity infections/ systemic inflammation
define dementia
severe loss of memory and other cognitive abilities which lead to impaired daily functions
what 3 examinations can you carry out if you suspect dementia?
neurological (i.e. testing cranial nerves)
mini mental state exam
addenbrookes cognitive exam
what would you see on an MRI where the patient has dementia?
dilated ventricles
atrophied hippocampus
wider sulci and narrower gyri
what 2 proteins present in the brain are associated with AD?
B amyloid
tau
what is the management of dementia? (5)
acetlycholintesterase inhibitors
treat behavioural and psychological symptoms eg. w/ antidepressants and antipsychotics
monitor progression
occupational therapy/social services
2 defining features of vascular dementia?
associated w/ cerebrovascular diseases
step wise deterioration
3 features of Lewy body dementia?
parkinsonian features
fluctuating cognition
visual hallucinations
2 features of FTD?
behavioural changes
progressive non-fluent aphasia
what is the head-turning sign in dementia patients?
they turn to partner/relative because they are unsure/don’t know the answer
what protein is associated with Lewy body dementia?
a-synuclein
outline the production. of tears?
parasympathetic efferent nerves use Ach
tears produced by lacrimal gland, drain through 2 punch into superior and inferior canaliculi into tear sac and exit via tear duct into nasal cavity
what is the function of the tear film?
maintains smooth cornea air surface
oxygen supply to cornea
removes debris
bactericide
what’s the structure of the tear film?
3 layers
superficial lipid layer - reduce tear film evaporation
aqueos layer
mutinous layer on corneal surface - surface wetting
what is the conjunctiva?
thin. transparent tissue that covers outer surface of eye (starts at cornea, covers visible eye and inside of eyelids)
nourished by tiny blood vessels
what are the 3 layers of the eye? (outer to inner)
sclera
choroid
retina
what is the sclera?
outer coat of the eye, protective
high water content
what is the cornea? structure and function?
transparent
low water content
powerful refracting surface - 2/3 eye focusing power
5 layers: epithelium bowman membrane stroma descemets membrane endothelium
what is the uvea?
vascular coat of eyeball
between sclera and retina
iris, ciliary body and choroid
what is the iris? function?
controls light levels inside eye
opening in centre → pupil
has tiny muscles which dilate/constrict pupil
structure and function of the lens?
outer acellular capsule
regular inner elongated fibres - transparency
refractive power - 1/3 of eyes focusing power
accommodation
elasticity
what happens when lenses lose transparency?
cataracts form
function of the retina?
capturing light rays that enter the eye
structure and function of the optic nerve?
electrical impulses from retina to brain
connects to eye near macula
visible part = optic disc
what is the blind spot?
where optic nerve meets retina - no light sensitive cells
optic disc
structure and function of the macula?
centre if retina, temporal to optic nerve
responsible for detailed central vision eg. reading
fovea is the centre of macula
what is the proportion of cell types at the fovea?
highest concentration of cones, low of rods
how is central vision assessed? what is loss called?
visual acuity assessment
loss of foveal vision = poor visual acuity
how is peripheral vision assessed? what does loss lead to?
visual field assessment
loss of visual field = unable to navigate
what is the structure of the retina?
outer - photoreceptors detect light
middle - bipolar cells, local signal processing
inner - retinal ganglion cells , transmit from eye to brain
2 types of photoreceptors and differences?
rod cells - more sensitive to light (more pigment, higher spatial and temporal summation) , slow response, night/scotopic vision, more numerous, peripheral
cone cells - faster response, fine & colour vision (photopic), central
different cone cell types and colours?
S - blue
M - green
L - red
what is the commonest form of colour blindness?
deuteranomaly - don’t perceive the colour red
what is full colour blindness called?
achromatopsia
what test can be used for red green colour blindness?
Ishihara test
what is emmetropia?
adequate correlation between axial length and refractive power, parallel light rays fall on retina
(normal)
what is ametropia?
mismatch between axial length and refractive power
parallel rays don’t fall in retina
types of ametropia?
hyperopia
myopia
astigmatism
presbyopia
what is myopia? symptoms? causes?
parallel rays converge anterior to retina (near sightedness)
blurred distance vision → squint → headache
excessive long globe (axial myopia)
excessive refractive power (refractive myopia)
treatment for myopia?
diverging lenses
contact lenses
remove eye lens to reduce refractive power
what is hyperopia? symptoms? causes?
parallel rays converge at a point posterior to the retina (far sightedness)
blurred near vision, can be intermittent, worse when tired
eyepian, headache, burning sensation
excessive short globe (axial hyperopia)
insufficient refractive power (refractive hyperopia)
what can uncorrected hyperopia leas to?
amblyopia (lazy eye)
treatment for hyperopia?
converging lenses ± cataract extraction
contact lenses
intraocular lenses
what is astigmatism? cause? symptoms?
paralle rays focus in 2 lines
hereditary
refractive media is not spherical
headache, eyepain, blurred distorted vision, head tilting/turning
treatment for astigmatism?
regular :
cylinder lenses ± spherical lenses
surgery
irregular:
rigid cylinder lenses
surgery
what is the near response triad?
adaptation for near vision
pupillary miosis (constriction) with sphincter pupillae to increase depth of field
convergence with medial recti
accommodation with circular cillary muscles contracting → ↑ refractive power (lens thickens)
what is presbyopia?how is it corrected?
naturally occurring loss of accommodation
onset ≥40yrs
distant vision fine
corrected w reading glasses (convex lens) to ↑ refractive power
what are the types of optical correction?
contact lenses
intraocular lenses
surgical - keratorefractive or intraocular
what is the visual pathway from the eye to the visual cortex?
eye (1st&2nd order) → optic nerve (3rd order) → optic chiasm (half fibres cross) → optic tract → lateral geniculate nucleus (fibres synapse) → optic radiation (4th order) → primary visual cortex in occipital lobe
which fibres cross in the optic chiasma?
those from nasal retina - temporal visual field
what visual field defects occur if theres a lesion anterior to the optic chiasm? eg. optic nerve compression
only one eye affected - whole visual field affected
what visual field defects occur if theres a lesion at the optic chiasm? eg. pituitary tumour
damages crossed fibres (nasal retinal fibres)
→ bitemporal hemianopia
what visual field defects occur if theres a lesion posterior to the optic chiasm? eg right sided stroke
affects right temporal fibres and left nasal fibres → left homonymous hemianopia (right temporal and left nasal fields affected)
how does homonymous hemianopia with macular sparing occur?
stroke affecting primary visual cortex
maculae receive blood supply from posterior cerebral arteries on both sides
what happens to the pupil when exposed to light? how is it mediated?
constriction (miosis) mediated by parasympthateic nerve in CN III → circular muscles contract
decreases glare
increases depth of field
reduces bleaching of photopigments
what happens to the pupil when exposed to dark? how is it mediated?
pupillary dilation mediated by sympathetic nerves → radial muscles contract
↑ light sensitivity → more light can enter eye
what is the pathway of the pupillary reflex?
rod& cone photoreceptors → bipolar cells → retinal ganglion cells → optic tract → lateral geniculate nucleus → edinger-westphal nuclei → occulmotor nerve efferent → ciliary ganglion → short posterior cilliary nerve → pupillary sphincter
direct vs consensual reflex?
direct = constriction of pupil of the light stimulated eye consensual = constriction of pupil of the other eye
afferent vs efferent defects and affects in eye?
afferent defect eg damage to optic nerve → no constrcition of either pupil when damaged side is stimulated with light, normal contraction in both eyes when other side is stimulated
efferent defect eg. CNIII lesion, no constriction on affected side no matter which side is stimulated. unaffected side will constrict regardless
how can a relative afferent pupillary defect be tested for?
swinging torch test
2 different types of eye movement?
saccade - short fast burst
smooth pursuit - slow movement
different types of saccade?
reflexive
scanning
predictive
memory guided
what direction does the superior oblique move the eye?
down and out
trochlear nerve
what direction does the inferior oblique move the eye?
up and out
what is levoversion and dextroversion?
levo - eyes both move to left, left abduction, right adduction
dextro - eyes both move right
symptoms of third nerve palsy?
occulmotor affcvetd → superior, inferior, medial rect & inferior oblique
eye is down and out (unopposed superior oblique and lateral rectus)
droopy eye lid (levator palpabrae superioris)
symptoms of sixth nerve palsy?
eye cannot abduct (no lateral rectus) → deviates inwards
double vision
what is the optokinetic nystagmus reflex?
useful in testing visual acuity in preverbal children
smooth pursuit & fast phase reset saccade
what happens when theres damage to the posterior colliery ganglion? what is it known as?
tonically dilated pupil - Adie’s pupil
parasympathetic fibres have no effect
what is pilocarpine?
muscarinic receptor agonist on M3 receptors in iris sphincter muscle → miosis
(independent of parasympathetic nerves)
explain Adie’s pupil?
light-near dissociation
damage to posterior cilliary ganglion → ↑ regulation of postsynaptic receptors in iris instead of ciliary body → more meiosis with accommodation than with light
manoeuvres for BPPV?
epley and semont manouvers
3 main blood supply arteries to the brain?
vertebral artery
internal and common carotids
circle of willis?
vertebral arteries → basillar artery → posterior cereal → posterior communicating → middle cereal & internal carotid → anterior cerebral →anterior communicating
4 types of brain haemorrhage?
extra dural - arterial, trauma esp @ pterion
subdural - venous, trauma
subarachnoid - circle of willis, ruptured aneurysm
intracerebral - spontaneous hypertensive
what is a cerebrovascular accident?
rapidly developing focal disturbance of brain function of presumed vascular origin and go ≥24hrs
thromboembolic or haemorrhagic
how does a TIA differ from a CVA?
it resolves completely within 24 hours
infraction vs ischaemia?
degenerative changes in tissue following artery occlusion vs
lack of sufficient blood flow → permanent damage if blood flow not restored
5 risk factors for stroke?
age smoking hypertension cardiac disease diabetes
symptoms of an anterior cerebral artery stroke?
paralysis of contralateral structures
abulia → disturbance of intellect, judgement
loss os appropriate social behaviour
symptoms of middle cerebral artery stroke?
contralateral hemiplegia
contralateral hemisensory defects
hemianopia
aphasia if L sided lesion
symptoms of posterior cerebral artery stroke?
homonymous hemianopia visual agnosia (cannot recognise objects)
why can you get a headache with a subdural bleed?
build up of intracranial pressure
sy,tpoms of a cerebellar lesion?
wobbly eye movements
ataxia
broad hesitant gait
slurred speech
what are the major motor descending tracts?
pyramidal : (pass though medulla pyramids), voluntary, motor cortex to spinal cord
corticospinal
corticobulvar
extrapyramidal: involuntary, brainstem nuclei to spinal cod vestibulospinal reticulspinal tectospinal rubrospinal
function of the primary motor cortex?
precentral gyrus
fine, discrete, precise voluntary movements
function of the premotor area?
anterior to primary motor cortex
planning movements
regulates externally cued movements
function of supplementary motor area?
anteriomedial to primary motor cortex
planning complex movemnts, internally cued
active prior to voluntary movement
difference between anterior and lateral corticospinal tracts?
anterior - trunk, decussate in spinal cord
lateral - limbs, decussates at medulla
function of the vestibulospinal tract?
stabilise head
coordinate head and eye movements
postural adjustments
function of the reticulospinal tract?
from medulla and pons
changes in muscle tone
postural stability
function of the tectospinal tract?
superior colliculis to midbrain
orientation of head and neck during eye movements
function of the rubrospinal tract?
from red nucelus of midbrain
innervate LMNs of flexors of upper limb
signs of an UMN lesion?
negative :
loss of voluntary motor function - paresis or paralysis
positive : loss of inhibitory descending inputs spasticity hyperreflexia clonus babinskis sign
what is apraxia? lesion? causes?
disorder of skilled movement
lesion in SMA/premotor cortex
stroke and dementia
signs of an LMN lesion?
weakness hypotonia hyporeflxia muscle atrophy fasiculations - visible twitches fibrillations - can be seen on EMG
signs of motor neurone disease?
same as UMN and LMN signs
dysphagia
dysarthria
nasal speech
MND alternative name?
ALS - amyotrophic lateral sclerosis
what are the basal ganglia?
caudate nucleus lentiform nucleus (putamen and external globus pallidus) nucleus accumbens sub thalamic nuclei substantia nigra
what does the striatum consist of?
caudate and putamen
function of the basal ganglia?
decision to move
elaborating associated movements
moderating and coordinating movements
performing movements in order
pathophysiology of Parkinson’s?
degeneration of the dopaminergic neurons that originate in the substantial nigra and project to the striatum
signs of parkinsons?
bradykinesia hypomimc face akinesia rigidity tremor at rest
pathophysiology of Huntington’s disease?
degeneration of GABAergic neurons in striatum
genetic, chromosome 4, autosomal dominant, CAG repeat
signs of Huntington’s?
choreic movements rapid jerky involuntary movements speech impairment dysphagia unsteady gait cognitive decline→ dementia
what is ballism?
from stroke affecting sub thalamic nucleus
sudden uncontrolled flinging of extremities
contralateral symptoms
what separates cerebrum from cerebellum?
tentorium cerebelli
vestibulocerebellum function?
regulates gait and posture
coordinates head and eye movements
damage = gait ataxia
spinocerbellum function?
coordinate speech and limb movements
adjust muscle tone
damage = legs , abnormal gait and stance - usually caused by chronic alcoholism
cerebrocerebellum function?
coordinate skilled movements
cognitive function, attention, language processing, emotion control
damage = arms, tremor and speech
signs of cerebellar dysfunction?
ataxia dysmetria intention tremor dysdiadokinesia scanning speech
what are the alpha motor neurons?
LMNs of the brainstem and spinal cord
innervate extrafusal muscles
activation = contraction
define motor unit
all the muscle fibres innervated by a single motor neon , smallest functional unit able ton produce force
types of motor unit?
slow (I)
fast fatigue resistant (IIA)
fast fatiguable (IIB)
(cell bodies, dendritic trees, conduction velocity, thickness)
how are the motor unit types classified?
amount of tension
fatiguability
speed of contraction
how is muscle force regulated?
recruitment - size principle, smaller units recruited first, allows fine control
rate coding - sloe units with lower frequencies recruited first
what are neurotrophic factors?
growth factor
prevent neuronal death
promote neuronal growth after injury
what do motor unit characteristics depend on? how is it known?
on the nerve fibres that innervate them
cross innervation → muscle fibres changes characteristics
when do fibres Tina`ge from IIB to IIa?
after training
when do fibres change from I to II?
severe deconditioning /spinal coed injury
microgravity
why do contraction times get slower with age?
loss of type I and II fibres but II lost in greater proportion
what manoeuvre can be used to make reflexes larger?
jendrassik → reduces amount of inhibition CNS exerts on reflexes
what happens in decerebration? re reflexes
reveals excitatory control from supraspinal areas (loss of inhibitory control) → over active/tonic stretch reflex → rigidity and spasticity
what is the positive babinski sign?
toes curl upwards (should be downwards)
this is normal in babies
UMN lesion
what is MS?
autoimmune disorder → loss of myelin from CNS neurons
symptoms of MS?
blurred vision fatigue difficulty walking paraesthesia muscle stifness/spasms
what is the M wave?
fast response when motor axons are activated → muscle contraction
what is the h reflex?
stimulus activates sensory neurons
action potentials go nerve → spinal cord → LMN activated → motor neurons → muscle → twitch
what is the F wave?
large electrical stimulus - APS travel motor neurone → spinal cord (antidromic) → LMN activated → motor neurones → muscle → twitch
what does antidromic mean?
action potentials travel in the opposite direction to normal
orthodromic is normal
what is a motor evoked potential?
seen on EMG when UMN. are activated so that action potentials travel along upper and lower motor neurons to cause muscle contraction
gives total motor conduction time (TMCT)
how can the motor cortex be stimulated?
transcranial magnetic stimulation
what is peripheral motor conduction time?
time from spinal cord to muscle along motor axon
PMCT = (M wave + F wave - 1) /2
(-1 is for time estimated for action potentials at LMN to turn around)
how is central motor conduction time calculated?
TMCT - PMCT
effects of MS on TMCT and PMCT?
MEP latency longer than usual = TMCT delayed
normal F wave latency = normal PMCT
→ problem in CNS
red flags for headaches?
thunderclap, acute onset meningism systemic - fever, rash, wt loss visual loss, seizures, confusion, Horner syndrome, 3rd nerve palsy orthostatic strictly unilateral
presentation of a subarachnoid haemorrhage?
sudden headache
stiff neck
photophobia
subarachnoid haemorrhage management?
nimodipine and BP control neurosurgical assessment CT brain lumbar puncture (RBCs and xanthochromia) MRA angiogram fill aneurysm with platinum coil
what can an acute intracerbeal haemorrhage lead to?
coning due to ↑ ICP
what is papilloedema?
optic disc swelling due to raised ICP
treatment for carotid/vertebral artery dissection?
aspirin/anticoag for 6/12
signs & symptoms of temporal arteritis?
unilateral headache
jaw claudication
scalp tenderness
↑cRP and ESR
what will a biopsy show in temporal arteritis?
inflammation
giant cells
treatment for temporal arteritis?
high dose steroids
aspirin
what can cause blindness in temporal arteritis?
posterior cilliary artery involvement
what is affected in temporal arteritis?
internal elastic lamina
risk factors for cerebral venous thrombosis?
thrombophilia
pregnancy
Bechets
dehydration
viral causes of meningitis?
coxsackie
echovirus
mumps
EBV
bacterial causes of meningitis?
meningo/pneumoccoci
symptoms of meningitis?
fever malaise photophobia neck stiffness headache confusion
management of meningitis?
treat then diagnose Abx blood and urine cultures CT/MRI lumbar puncture - ↑ WCC, ↓ glucose , antigens, cytology , culture
how will bacterial meningitis present on CT?
cerebral oedema
effacement of ventricles & sulci
inflamed meninges
how will sinusitis be seen on xray?
oppacifictaion of sinuses
symptoms of sinusitis?
malaise fever headache
loss of vocal resonance
anosmia
nasal catarrh
headache most often seen in obese young women?
idiopathic intracranial hypertension / pseudomotor cerebri
symptoms of IIH/PC?
headache visual obscurations diplopia tinnitus papilloedma visual field loss
causes of IIH/PC?
hormones eg OCP
vitamin E
Abx
steroids
treatment for IIH/PC?
weight loss
diurteics
optic nerve sheath decompression
lumboperitoneal shunt
↑ ICP on CT?
effacement of ventricles and sulci with cerebral oedema
what can cause a low pressure headache?
CSF leak - tear in dura, traumatic, post lumbar puncture, spontaneous
treatment for a csf leak?
rehydration
caffeine
blood patch
how can a low pressure headache present on MRI?
meningeal enhancement
what is the chiari malformation?
brain that sits very low in skull
cerebellar tonsils descend through foramen magnum
when coughing they descend further → tug on meninges → headache
how can OSA lead to a headache?
↑ CO2 retained → vasodilation of blood vessels → accumulation of blood → ↑ICP
what can trigeminal neuralgia be a symptom of?
MS
what can cause trigeminal neuralgia pain?
neurovascular conflict at point of entry into pons
treatment for trigeminal neuralgia?
carbamazepine
lamotrigine
gabapentin
posterior fossa decompression
management for atypical facial pain?
tricyclics
risk factors for atypical facial pain?
middle aged women
depresed
anxious
management for post traumatic headaches?
explanation
prevent analgesic abusee
NSAIDs
tricyclics eg amitriptyline
commonest cause of a new onset headache in older patients?
cervical spondylosis, narrowing of joint space
cervical spondylosis symptoms?
bilateral headache occipital pain → frontal steady pain no N&v worsened by moving neck
management for cervical spondylosis?
rest, deep heat, massage
NSAIDs
5 phases of migraine?
prodrome - mood changes, polyuria, cravings
aura - visual, sensory, weakness, speech
headache - w nausea and photophobia
resolution - rest and sleep
recovery - moody, food intolerance, hangover
what are the symptoms of migraine aura?
+ve - scintilations
-ve - blindpsots
treatment for an acute migraine attcak?
NSAIDs, paracetamol, metoclopramide
Triptans with NSAIDs
nap
TMS
migraine prophylaxis?
TCAs beta blockers serotonin antagonists CCBs anticonvulsants botox suppress ovulation erenumab - monoclonal antibody
management for a tension type headache?
NSAIDs
paracetamol
TCAS eg amitriptyline
symptoms of a cluster headache?
severe unilateral pain , 15-180 mins ipsilateral conjunctival redness, lacrimation, nasal congestion, eyelid oedema forehead/facial; sweating miosis/ptosis restelessness
what is a cluster headache classified as?
trigeminal autonomic cephalgia
treatment for acute cluster headache?
inhaled oxygen - inhibits neuronal activation in the trigeminocervical complex
sc or nasal sumatriptan
prevention for cluster headaches?
predinisolone
lithium
valproate
gabapentin
differences between migraines and cluster headaches?
women vs men
3-12hrs vs 45mins-3hrs
monthly vs daily
long remissions
N&V
pulsating hemicranial pain vs severe well localised unilateral pain
auras vs autonomic symptoms
lie in dark vs pacing aboutstructure of the BBB?
capillaries with ++ tight junctions → ↓↓ solute and fluids leakage cross capillary wall
symptoms of encephalitis?
flu like
pyrexia, headache
confusion, seizures, personality changes, dysarthria , weakness, loss of consciousness
commonest causes of encephalitis?
viral : HSV measebles varicella rubella
(mosquito, trauma, autoimmune, bacterial)
treatments for encephalitis?
anitvirals steorids Abx alagesics anticonvulsants ventilation
commonest causes of meningitis?
bacterial: meningococcla pneumococcal HIb streptococcal **neonates
what are MS relapses linked to?
inflammatory activity
what causes inflammation in MS?
perivascular immune celll infiltration (CD3 T and CD20 B cells)
what is myelitis?
infection of the spinal cord (encephamyelitis if brain too)
