110 - Peripheral Neuropathy Flashcards
What is axonotemesis?
Outer layer is still infact but damage has occured to the axon - can recover
What would you expect to find in demyelinating axonopathies?
Slow conducting velocities
What woudl you expect to find in axonal damage?
Normal conducting velocities but reduced compound motor action potential - as some don’t work.
What signs would you expect in a motor neuropathy?
Weakness
wasting
Fasiculations
Loss of reflexes
What signs would you expect in a sensory neuropathy?
Loss of sensation Abnormal sensation Hypersensitivity Loss of proprioception Loss/hypersensitivity to pain Burning feeling
What signs would you expect in autonomic neuropathy?
Dry eyes, mouth, skin Dizzy on standing GI/Bladder disturbance Loss of HR variability Sweating inapropriatly
What does a loss of reflexes point you towards?
A peripheral neuropathy
What drug can be given to treat neuropathic pain?
Amitriptyline, gabapentin
What happens to the conducting velocity in a compression neuropathy?
It slows
Action potential gets dispersed
Where are common places of compression in the peripheral nervous system?
Median nerve - carpal tunnel syndrome
Ulner nerve - at elbow
Radial nerve - over humorous - sat night palsy
Common peroneal nerve - around fibula - foot drop
Lateral cutaneous nerve - though inguinal ligament - meralgia parasthesia - sensory nerve only on path of thigh
What is guillain-Barré syndrome?
Acute inflam demyelinating neuropathy - sensory loss in hands + feet, over 3 days Difficulty getting up Normal bladder function Arflexia Recent respiratory infection
What is myasthenia Gravis?
A neuromuscular junction disorder- antibodies against Ach receptor.
Causes fatiguable weakness, eye drop, weak bulbar muscles, respiratory failure
Describe neuronal transmission across a synapse
1) excitory neurotransmitter binds to Na receptor - depolarisation initiated
2) Threshold reached, voltage gates Na channels open
3) rising phase - rapid depolarisation - Na channels close
4) Falling phase - voltage gated K channels open 1ms delay, K+ exflux out of cell - repolarises
5) hyperpolarisation - refractory period - cell becomes too repolarised, then goes back to resting phase - gives a break between neuronal transmissions.
= an action potential, which gets propagated along the next neurone
What neurotransmitters/receptors are used in the synpathetic NS?
Preganglionic = Ach -> Nicotinic Ach receptors Postganglionic = Noradrenaline -> alpha and beta adreno-receptors
What neurotransmitters/receptors are used in the parasympathetic NS?
Pre + post ganglionic = Ach -> muscarinic receptos
