Peripheral Neuropathy Flashcards
does MS cause peripheral neuropathy
no
loss of reflexes means a problem where
peripheral nerves- large motor or sensory fibres
which type of fibres conduct the slowest
C- unmyelinated
what do Aalpha fibres do
motor- muscle control
what do large sensory Aalpha/ beta fibres do
touch, vibration, position perception
what do thinly myelinated Adelta sensory fibres do
cold perception
pain
what do un myelinated C sensory fibres do
warm perception
pain
what are the type of autonomic nerve fibres
Adelta- thinly myelinated
C- unmyelinated
what are the symptoms when a large motor fibre is affected
weakness, unsteadiness, wasting
what are the symptoms when a large sensory fibres is affected
numbness
paraesthesia
unsteadiness
what are the symptoms when a small sensory fibre is affected
pain dyesthesia (painful itchy sensation)
what are the symptoms when autonomic fibres are affected
dizziness due to postural hypotension
impotence
nausea and vomiting (gastroparesis)
what peripheral fibres are affected when there is reduced power
large motor fibres (Aalpha)
what fibres are affected when there is reduced vibration and joint position sensation
large sensory (Aalpha/beta)
what fibres are affected when there is reduces pin prick and temperature sensation
small sensory fibre (Adelta/ C)
what is pseudoathetosis
abnormal writhing movement (usually of the fingers) due to failure of proprioception
what does a high stepping gate result from
foot drop due to weakness of ankle dorsiflexion DDx -peroneal palsy -L5 root lesion -motor neuropathy
what is damages in a radiculopathy
nerve root
what commonly causes radioculopathy
prolapse
can be inflammatory
what is damaged in plexopathy
plexus
what is peripheral neuropathy
damage to the nerve distal to the plexus
what are the types of peripheral neuropathy
mononeuropathy (single nerve, e.g trauma)
mononeuritis multiplex (progressive sensory or motor deficits in a specific distribution of peripheral nerves caused by systemic illness- vasculitis, hypersensitivity, drugs etc)
length dependent peripheral neuropathy- small fibre
polyneuropathy- symmetrical distribution
what is the distribution of length dependent peripheral neuropathy
glove and stocking, usually symmetrical
what is the most common type of peripheral neuropathy
length dependent
what is symmetrical wasting suggestive of
PN, if asymmetrical less likely
what is the pattern of loss in mononeuritis/ mononeuropathy
loose function very quickly (blood supply lost due to inflammation)
asymmetrical
patchy sensory loss
patient can present with e.g. wrist drop/ foot drop
what is the pattern of loss in radiculopathy
loss of reflex and muscle function
asymmetrical
what most commonly causes a plexoathy
traction injury
how can peripheral nerves be damaged
axonal loss
demyelination (not MS)
what results from a demyelinating neuropathy
conduction is slowed
what causes an acute (days to weeks) demyelinating neuropathy
guillaine barre syndrome
what causes a chronic (months to years) demyelinating neuropathy
chronic inflammatory demyelinating polyradiculopathy
hereditary sensory motor neuropathy (used to be called charcot marie tooth disease)
what is the presentation and duration of GBS like
progressive paraplegia over days lasts up to four weeks
peak symptoms at 10-14 days
associated sensory symptoms (pain very common) proceed weakness
what infection is associated with GBS
campylobacter
-inflammation of axon- stripped myelin
what is the prognosis of GBS
25% require ventilation
10% die form autonomic failure (cardiac arrythmia)
what is the treatment for GBS
immunoglobulin infusion and/ or plasma exchange
what is exam like in GBS
initially reflexes will be normal, as they ‘ go off legs’ may loose them
what are the hereditary neuropathies
pure motor, sensory, sensorimotor, small fibre and autononmic variants
can be demyelinating or axonal
AD, AR, X linked types
what happens in the HMSN type 1 hereditary neuropathy
longstanding loss of muscle, pes cavus, thin distal musculature
what are the types of axonal neuropathies
idiopathic (age related)
vasculitis (mononeuritis multiplex)
paraneoplastic
infectious (HIV, syphillis, lyme, hepatitis)
drugs/ toxins
metabolic (diabetes, B12/ folate, hypothyroidism)
what are the causes of chronic autonomic neuropathy
diabetes (gastroparesis)
amyloidosis
hereditary
what are the acute causes of autonomic neuropathy
GBS porphyria (unexplained abdo pain in the young)
what is the treatment for axonal peripheral neuropathy
treat cause e.g. infection symptomatic relief (physio, orthotics, neuropathic pain relief)
if vasculitic
pulsed IV meythlprednisolone + cyclophosphamide
what is the treatment for demyelinating peripheral neurpathies
IV immunoglobulins
steroids
azathioprine, mycophenalate, cyclophosphamide
