Clinical Neurophysiology Flashcards
What is clinical neurophysiology
medical specialty that studies the central and peripheral nervous systems through the recording of bioelectrical activity, whether spontaneous or stimulated.
What does an EMG investigate
To investigate problems of peripheral nerve and muscle
and
Investigate the function of the neuromuscular junction
What does nerve conduction studies ( + EMG) investigate
To investigate problems of peripheral nerve and muscle
What does EEG investigate in clinical neurophysiology
Electrical activity within the brain to investigate epilepsy and states of altered consciousness
What does evoked potential investigate in clinical neurophysiology
Visual and somatosensory, investigate problems in central pathways
In nerve conduction studies how do you examine if the nerve is functioning
By testing
Conduction velocity
and Amplitude
How does nerve conduction study work
During the test, the nerve is stimulated, usually with surface electrode patches attached to the skin
How do you test the velocity of conduction in nerve conduction studies
Measure distance and time between the onset of the two action potentials
how do test the amplitude in nerve conduction studies
Increase strength to they and stimulate more nerves
What is usually combined with nerve conduction studies
Electromyography
Define electromyography
Needle measures the AP at the top and the core, looking at the action potential from the whole motor unit
How do you measure sensory function separately to motor function in neurophysiology
Similar technique but stimulating the sensory nerve fibres in the fingers
What is the electrophysiology findings of a neuropathy in nerve conduction studies
Slowing of motor response where conduction block is located
small sensory response
What is the electrophysiology findings of a radiculopathy in nerve neurophysiology
Small but slowed motor response
Normal sensory response
How is sensory response normal in radiculopathy
If the signal is damaged at the nerve root the sensory signal remain intact as sensory cell body lives in dorsal root ganglion so patients sensory nerve can still be stimulated even though patient feels numbness
How do you reach a full diagnosis in nerve neurophysiology
Investigate nerve function with anatomy allows diagnosis of nerve entrapment
What is the pathology of myasthenia gravis
Autoimmune antibodies to post-synaptic ACh receptor, decreasing the effectiveness of released ACh
What is the clinical presentation of myastheniagravis
Weakness (can be generalised)
Fatigue
Normal sensation
Ptosis
Diplopia
How do you diagnose myastheniagravis
Detect antibodies
Neurophysiology:
- repetitive stimulation
- single fibre EMG
How does EMG manage to look at action potential from whole motor units
uses filter, sensitivity and timebase settings to isolate the action potentials from individual muscle fibres within one motor unit.
Where are EMGs useful
Needle can be positioned to record from two fibres within the same motor unit
(Normally little variation in time of firing between two such fibres)
What can EMG diagnose
diagnose neuromuscular abnormalities eg myasthenia, botulism
In a neuromuscular disease when relationship at the NMJ is lost how does an EMG diagnose this
Jitter
How does EEG diagnose worse myasthenia
There is block in signal
How does an EEG asses brain function
Recording electrical activity generated by cortical neurons across multiple points on the scalp
What can be seen in an EEG
Epileptic Activity
States of consciousness
(Sleep, stages of sleep)
Encephalopathy
Looking at brain function in an EEG allows you to diagnose
Epilepsy
Altered states of consciousness
- sleep disorders
- changes in sleep
Non-epileptic attacks
Facilitate medical or surgical treatment for epilepsy
