Neuromuscular Disorders - Clinical Overview: Peripheral Neuropathy Flashcards
How can you classify neuropathy?
- Motor (weakness)
- Sensory (numbness)
- Small fibre (nerve that carry pain,temperature)
- Motor-neuronpathy (affect anterior horn cells
- Plexopathy (affect the plexus)
What is neuropathy classification based on?
Localisation anatomically
Inherited or acquired
What are inherited diseases broken down into?
- Purely sensory (hereditary sensory neuropathy)
- Purely motor (hereditary motor neuropathy)
- Sensory and motor disease (CMT)
What are the different causes that acquired neuropathy is broken down into?
- Diabetic
- Inflammatory
- Entrapment
- Toxic
What are examples of parts of the nervous system involved in neuropathy?
- Higher centres
- Supplemental motor areas
- Primary motor cortex
- Brainstem
- Spinal cord
- Peripheral nerve
- Neuromuscular junction
- Muscle
What are features of Upper Motor Neuron (UMN)?
- Central symptoms
- Asymmetry
- Increased reflexes
- Increased tone
- Up-going toes
What are features of Motor Unit?
- Autonomic symptoms
- Symmetry
- Reduced reflexes
- Muscle wasting
- Distal numbness
What is the motor unit?
Single anterior horn cells within the cell body of anterior horn of spinal cord
Single motor axon
All of the muscle fibre that single axon applies is the motor unit
What does the number of muscle fibre the motor unit supplies depend on?
Muscle
What can NCS/EMG tell you?
- Neuropathy: presence or absence
- Involvement: sensory, motor or mixed
- Pattern of involvement?
- symmetry
- length dependent
- focal or multifocal
What are the typical features of polyneuropathy?
- Longest nerves most vulnerable (distal and symmetrical)
- Nerves are trophic to muscle (muscle wasting)
- Involved in reflex arc (reduced reflexes)
- Sensory nerves similarly vulnerable (distal sensory loss)
- Confirmatory test to test localisation
What does the median nerve supply?
Abductor pollicis brevis muscle
What is a supramaximal stimulus?
A stimulus that has stimulated all of the axons in that nerve
What is Nerve conduction study (NCS) used to measure?
- How long it takes to get there (distal model latency)
2. How big the response is (amplitude)
What does the amplitude tell you?
The axons are intact and the response is the same throughout
What happens within myelin fibres?
The conduction is really fast
What is the normal conduction in the upper limbs?
50m per second
How long does it take for the message to get from your brain to the muscle along the periphery nerve?
1/50th of a second