Clinical neurophysiology Flashcards
what is clinical neurophysiology
diagnostic specialty - like radiology but look a nerves
what studies are involved in neurophysiology
electromyography (EMG) - nerve conduction studies
EEG - electrical activity within the brain
evoked potential
what does EMG investigate
problems in the peripheral nerve and muscle
what does EEG investigate
electrical activity within the brain, epilepsy and states of altered consciousness
what do evoked potentials investigate
visual and somatosensory -problems in the pathway
what two aspects of nerve conduction are measured in nerve conduction studies
conduction velocity
amplitude
what does stimulating the sensory nerve fibres in the fingers allow
measurement of sensory function
where does ulnar neuropathy most commonly present
mostly at the elbow sometimes at the wrist
what are signs of ulnar neuropathy
ulnar distribution numbness
wasting of small muscles
what would you be looking for on electrophysiology of ulnar neuropathy
conduction block/slowing due to demyelination
nerve root damage
what would the electrophysiology results show for ulnar neuropathy from conduction block
slowing of motor response across elbow
small sensory response from ulnar nerve
what would the electrophysiology results show for ulnar neuropathy from nerve root damage
small but not slowed motor response
normal sensory response
what causes myasthenia gravis
antibodies to post-synaptic ACh receptors
decrease the effectiveness of released ACh
what is the presentation of myasthenia gravis
present with weakness, fatigue, normal sensation
often affects the eyes - diplopia, ptosis
how can myasthenia gravis be diagnosed
Detect Antibodies (takes some weeks, only +ve in 70%)
Neurophysiology
- Repetitive stimulation - for fatigue
- Single fibre EMG - for jitters
what does routine EMG look at
action potential from whole motor units
how can EMG be useful in diagnosis of myasthenia gravis
the needle can be positioned to record from two fibres within the same motor unit - if variation in time of firing between the two fibres = jitters
can be a sign of myasthenia gravis before presenting symptoms
what do EEGs record
electrical activity generated by cortical neurons across multiple points on the scalp
what can be seen on EEG readings
epileptic activity
states of consciousness - sleep, stages of sleep
encephalopathy
what can EMGs and EEGs help facilitate
medical or surgical treatment
