Nerve and Muscle Disease Flashcards
which enzyme is deficient in McArdle’s disease?
myophosphorylase
when does McArdles usally present?
first decade of life
how does McArdles usally present?
severe and cramping muscle pain shortly after starting exercise
levels of which enzyme are raised in the majority of people with McArdles?
Creatinine Kinase
vigourous exercise if you have McArdles increases risk of which complications?
rhabdomyolysis with myoglobinuria
subsequent AKI
how does myotonic dystrophy affect you muscles?
delayed muscular relaxtion and muscle wasting
myotonic dystrophy is due to a tri-nucleotide repeat on which chromosome?
chromosome 19
myotonic dystrophy follows which mode of inheritance?
autosomal dominant
the sternocleidomastoid and distal limb muscles are usually affected in first in myotonic dystrophy- this results in what?
grip myotonia
foot drop
(porximal limbs muscles affected later)
what kind of cataracts can be seen in myotonic dystrophy?
christmas-tree like cataracts
facial weakness (‘haggard’), early frontal balding, temporalis muscle wasting and jaw muscle atrophy are seen in which muscle disease?
myotonic dystrophy
which muscle disease is caused by impaired release of acetylcholine by the pre-synaptic terminal?
Lambert-eaton Myasthenic syndrome
lambert Eaton syndrome is assoc w which cancer?
small cell lung
what clinical features are seen in lambert eaton syndrome?
proximal muscle weakness- waddling gait
diminshed/absent deep tendon reflexes
what autonomic features are present in lambert eaton syndrome?
constipation
postural hypotension
impotence
dry mouth
presence of which antibodies confirm a diagnosis of lambert eaton?
anti-VGCC antibodies
why is CT used when investigating lambert eaton?
rule out malignancy
how is lambert eaton treated?
3,4- diaminopyridine (amifampridine)
blocks presynaptic Ca2+ channels and increases quantity of ACh released
which autoimmune disease affects the post-synaptic nicotonic acetylcholine receptors at the NM junction?
myasthenia gravis
who is affected by myasthenis gravis men/women?
women more so,
common in 2nd/3rd decade
muscle fatigue seen in myasthenis gravis improves upon rest/exercise?
improves on rest
are the facial muscles affected in myasthenia gravis?
yes- jaw, facial muscles, speech/swallow and resp muscles affected
what complications can occur with myasthenis gravis?
myasthenia crisis
cholinergic crisis
describe myasthenia crisis?
weakness of respiratory muscles causing ventilator failure
in myasthenia crisis urgent elective tracheal intubation should be considered when vital capacity falls below what threshold?
below 15mL/kg
what commonly precipitates cholinergic crisis?
high dose anticholinesterase medication
symtpoms include: sweating, hypersalivation and miosis→can lead to resp failure
which drugs can induce or exacerbate myasthenia?
gentamicin
B blockers
verapimil
lithum
phenytoin
chloroquine
which antibodies are present in myasthenia?
anti-AChR
if this is negative check anti-MuSK
how is myasthenia managed?
symptomatic control w acetylcholinesterase inhibiton using pyridostigmine
if thymoma is present in myasthneia what procedure can be performed?
thymectomy
schwann cell proliferation in an ‘onion bulb’ appearnace is classically seen in which disease?
charcot-marie-tooth disease
distal muscles in the lower limb are commonly affected in charcot-marie-tooth disease what is this apearance termed?
inverted champagne bottles appearance
many patients with guillian-barre syndrome have histroy of which preceding infections?
capylobacter
EBV
CMV
HIV
how are the nerves affected in Guiliian-Barre syndrome?
demyelination and axonal injury
how do pateints with guillian-baree present?
symmetrical, progressive ascending paralysis w absent reflexes
is guillian barre an acute or chronic condition?
acute- people can fully recover however this varies from weeks to months to years
what is CIDP?
Chronic Inflammatory Demyelinating Polyradiculoneuropathy
(proximal and distal muscle weakness with hypo/areflexia and distal numbness)
how can CIDP be treated?
oral steroids
IV immunoglobulins
what is spinal muscular atrophy sometimes termed?
Werdnig-Hoffmann disease
what aspect of the spinal cord is affected in spinal muscular atrophy (werdnig-Hoffman)?
degeneration of anterior horns (LMN)
leads to progressive muscular wasting and often early death
what is the mode of inheritance in spinal muscle atrophy?
autosomal recessive
the severe form of which disease causes ‘floppy baby syndrome’ wihtin first month of life?
spinal muscle atrophy (werdnig-hoffmann)
marked hypotonia and tongue fasciculations
poliovirus causes which nerve disease?
poliomyelitis
how is polio virus transmitted?
faecal-oral transmission
how does polio virus cause disease?
destruction of cells in the anterior horn of the spinal cord (LMN death)
what are the signs and symtpoms of poliomyelitis?
same as that of LMN disease: weakness, hypotonia, flaccid paralysis, fasciculations, hyporeflexia, muscle atrophy
