Neuro-physiology Flashcards
What are nerve conduction studies?
How does it work?
Tests of sensory or motor nerve function
Sensory: electrical stimulation applied to nerve, measure the speed and size of response
Motor: electrical stimulation induces an action potential, measure speed and size of response
What nerve supplies the thumb?
Median
What nerve supplies the little finger and half the 4th finger?
Radial
On a nerve conduction study what does a small response indicate?
Axon loss
On a nerve conduction study what does a slow response indicate?
Myelin loss, so something like MS
What is electromyography (EMG)?
The use of a needle to pick up the electrical activity of a muscle
Records the individual activity of individual motor units and looks at whether they are too big or too small
If you see big motor units on an EMG, what does this imply?
Damage to a nerve, but it hasn’t been taken out completely
If you see small motor units on an EMG, what does this imply?
Myopathy: problem with muscle
If you see spontaneous activation of muscle, what does this imply?
Fasciculation
Myotonia: inability to relax muscle after vigorous use of it
What does EEG stand for?
Electroencephalogram
What does an EEG do?
Measures the electrical activity of the brain, electrodes are placed on the head
Good for investigating conditions like epilepsy
What are ‘evoked potentials’?
Tests that look at the integrity of pathways
Types of evoked potential tests?
Somatosensory:
- looks at integrity of DCML pathway
Visual evoked potentials :
- look at integrity of visual pathways
Transcranial-magnetic stimulation
- uses magnets to asses the motor pathways
Briefly describe transcranial-magnetic stimulation?
Magnet placed over motor cortex
Magnet stimulates the cells of the motor cortex
Measure the response in the contralateral muscles to the side you stimulated
