Neuro 2 Flashcards
explain the pathophysiology of myasthenia gravis
an autoimmune disease, producing antibodies to nicotinic ACh receptors, which interfere with neuromuscular transmission by depleting receptor sites.
immune complexes of anti-ACh receptor IgG and complement are deposited at the post-synaptic membranes.
what drug can cause a transient form of myasthenia gravis?
penicillamine
what is the main clinical feature of myasthenia gravis?
increasing muscular fatigue - weakness on sustained/repeated activity, that improves after rest
which muscle groups are affected by mysathenia gravis, in order of most affected
extra-ocular, bulbar (swallowing, chewing), face, neck, limb girdle, trunk
give some examples of things you can look for to assess mysathenia gravis
ptosis (eyelid droop), diplopia, mysathenic snarl on smiling.
voice fades when asked to count to 50.
what specific test would you carry out to investigate myasthenia gravis?
tensilon test - IV edrophonium given, shows improvement in weakness for about 5 minutes
what might you seen on serology of a patient with myasthenia gravis?
anti-AChR and anti-MUSK antibodies
what eye test might you perform to confirm a diagnosis of myasthenia gravis?
see if ptosis improves by >2mm after ice applied to affected lid for >2 mins
how would you treat myasthenia gravis?
symptom control - anticholinesterase (pyridostigmine).
immunosuppression - prednisolone for relapses ± azathioprine/methotrexate.
thymectomy may be considered.
how does pyridostigmine help treat symptoms of myasthenia gravis? name a possible side effect and how you would treat it.
inhibits acetylcholinesterase enzyme from breaking down ACh - thereby increasing level and duration of action of ACh.
colic, diarrhoea - atropine.
name a gene that causes MND. is this the usual cause?
SOD1.
causes rare familiar MND - most cases are sporadic.
what distinguishes motor neurone disease from MS/polyneuropathies?
NO sensory loss or sphincter disturbance in MND.
affects upper and motor neurones.
what happens to the nervous system in MND? what is the prognosis?
selective loss of neurones in motor cortex, cranial nerve nuclei and anterior horn cells.
relentless and unexplained destruction of these neurones.
most die in 3yrs from respiratory failure due to bulbar palsy and pneumonia.
how could you distinguish MND from myasthenia gravis?
MND never affects eye movement, myasthenia gravis will.
name the 4 clinical patterns of MND
ALS (amyotrophic lateral sclerosis).
progressive bulbar palsy.
progressive muscular atrophy.
primary lateral sclerosis.
describe the features of ALS MND and what part of the CNS it affects.
disease of lateral cortiospinal tracts.
causes weakness with UMN signs and LMN wasting.
progressive spastic tetraparesis with LMN signs and fasciculation.
who should you suspect MND in?
> 40yrs.
stumbling spastic gait, foot drop ± proximal myopathy.
weak grip and shoulder abduction.
give some UMN and LMN signs that may feature in MND
UMN - spasticity, brisk reflexes, upgoing plantars.
LMN - wasting, fasciculation of tongue, abdomen, back, thigh
how would you treat a patient with MND?
antiglutamatergic drugs - riluzole - only drug that slows progression.
for drooling - amitriptyline.
muscle spasticity - beclofen.
give 3 organisms that can trigger Guillain-Barre syndrome
Campylobacter jejuni, CMV, mycoplasma zoster, HIV, EBV
describe the pattern of disease progression seen in Guillain-Barre syndrome
a few weeks after infection, symmetrical ascending muscle weakness starts.
advances quickly - affects all limbs, can lead to paralysis.
progressive phase of up to 4 weeks, followed by recovery
describe the clinical features seen in Guillain-Barre
symmetrical ascending muscle weakness.
proximal muscles more affected e.g. trunk, respiratory, cranial nerves.
pain common (e.g. back limb), but no sensory signs.
autonomic dysfunction - sweating, raised pulse, BP changes, arrhythmias.
if you were to perform lumbar puncture on a patient with Guillain-Barre syndrome, what might you see?
increased protein
how would you treat a patient with Guillain-Barre syndrome?
IV immunoglobulin/plasmapharesis.
heparin to prevent DVT.
give 3 possible clinical features of dementia besides memory loss
agitation, aggression, apathy, depression, wandering, hallucination, slow repetitive speech, mood disturbance
list some possible causes of dementia
alzheimer’s.
vascular dementia.
Lewy body dementia.
Fronto-temporal dementia.
explain how vascular dementia arises
cumulative effects of many small strokes.
sudden onset, with stepwise deterioration.
what are the features of Lewy body dementia?
fluctuating cognitive impairment, detailed visual hallucinations, Parkinsonism.
histology = Lewy bodies in brainstem and neocortex.
what are the features of fronto-temporal (Pick’s) dementia and what causes it?
frontal and temporal atrophy without Alzheimer’s histology.
genes on chromosome 9.
executive impairment, behavioural/personality change, preservation of episodic memory, disinhibition, hyperorality, stereotyped behaviour, emotional unconcern
how would you diagnose dementia?
clinical history + timeline of progression - ask relatives/spouse!
cognitive testing - AMTS/TYM (dementia screens), mental state examinations.
CT/MRI.
how would you manage dementia?
develop routines early on - retained until later, prolongs independence.
trazodone, lorazepam.
watch for depression - SSRIs (citalopram).
what genetic disorder is associated with Alzheimer’s disease?
Down’s syndrome - will inevitably progress to Alzheimer’s
describe the pathology behind Alzheimer’s disease
accumulation of beta-amyloid peptide (a degradation product of amyloid precursor protein) results in progressive neuronal damage, neurofibrillary tangles, raised numbers of amyloid plaques and loss of ACh.
neuronal loss is selective - hippocampus, amygdala, temporal neocortex and subcortical nuclei.
give 3 risk factors for Alzheimers disease
1st degree relative with AD.
Down’s syndrome.
homozygous for apolipoprotein e (ApoE) 4 allele, vascular risk factors, decreased physical/cognitive activity, depression, loneliness
give some clinical features of Alzheimers disease
general dementia features.
plus - enduring, progressive and global cognitive impairment, loss of visuo-spatial skill.
memory, verbal abilities and executive function affected.
late features - irritability, mood changes, behavioural change, psychosis, agnosia.
anosognosia - lack of understanding of the problems caused by the disease.
how might you treat Alzheimer’s disease dementia?
acetylcholinesterase inhibitors (rivastagmine, donezepil, galantamine). antiglutamatergic treatment (memantine). folic acid and B vits.
give 2 mechanisms by which you can develop neuropathy
demyelination - Schwann cell damage.
Axonal degeneration - axon damage, conduction remain intact.
Wallerian degeneration - follows nerve section.
Compression - disruption of myelin sheath.
Infarction - microinfarction of vasa nervorum.
Infiltration - by inflammatory cells, granulomas and neoplastic cells.
what are Tinel’s sign and Phalen’s test and what are they used for?
Tinel’s - lightly tap over a nerve to induce irritation in it e.g. over the wrist.
Phalen’s - ask patient to hold wrists in full flexion (reverse prayer position) for 30-60s, press on wrist if needed, should get tingling sensation/pain.
they are diagnostic for carpal tunnel.
give 3 diseases carpal tunnel is associated with
diabetes mellitus, acromegaly, hypothyroidism, amyloidosis, rheumatoid disease.
what is otherwise known as ‘Saturday night palsy’?
radial nerve compression - causes wrist drop and weakness of brachioradialis and finger extension, sensory loss in anatomical snuff box
what nerve controls the ankle jerk reflex?
S1
a slim female yoga instructor comes to see her doctor complaining that her left foot keeps dragging on the floor, what do you think could be causing her problem?
common peroneal palsy - her symptoms are due to weakness of ankle eversion and extension, she probably also has numbness over anterolateral border of dorsum of foot and lower shin
a patient comes in having had an accident on the rugby pitch with a suspect elbow fracture, he’s now complaining of sensory loss over his little finger and medial side of his hand, what do you think could be causing his symptoms and if left untreated, what could he go on to develop?
ulnar nerve compression, could go on to develop weakness/wasting of medial wrist flexors, interossei, medial 2 lumbricals and hypothenar eminence
what changes in the spine could there be in cervical/lumbar degeneration?
osteophytes, thickening of spinal ligaments, narrowing of spinal canal, disc degeneration and protrusion, vertebral collapse, ischaemic changes
what would be felt in the myotome and dermatome affected by a spinal nerve root lesion?
myotome - pain of root compression.
dermatome - tingling discomfort.
give 2 causes of nerve root lesions
spondylosis, herpes zoster, tumours, meningeal inflammation.
give 2 causes of anosmia caused by an olfactory nerve palsy
respiratory tract infection, olfactory groove tumour, meningitis
if someone is referred to you with suspected Horner’s syndrome, what do you expect to find on examination?
unilateral pupillary constriction with slight ptosis and enophthalmos, loss of sweating on same side