Clinical Neurophysiology Flashcards
Common investigations used by neurophysiologists?
- Nerve conduction studies
- Electromyography (EMG)
- EEG (electrical activity in the brain)
What does a nerve conduction study look at?
- Conduction velocity of AP
- Amplitude of AP
How is conduction velocity measured?
- Stimulate sensory nerves in fingers, device picks up AP near elbow and measure time taken for AP to travel distance of forearm
What is ulnar neuropathy?
- Muscle wasting and numbness at elbow or wrist. Elbow more common
- Usually due to entrapment of ulnar nerve (runs along elbow)
How can neurophysiology help treat ulnar neuropathy?
- Taken conduction velocity near wrist and at elbow to discover where the nerve is being affected (block)
- Localize nerve issue more closely at either of the two sites, potential for operative treatment?
If a patient has:
- Small but not slowed motor response neurop.
- Normal sensory response measured by neurop.
What may this indicate?
Damage at the nerve root (think dorsal / ventral horns)
Main purpose of nerve conduction studies?
- Combine with anatomy to allow diagnosis of nerve entrapment and guide subsequent surgery
Pathophysiology of Myaesthenia Gravis?
- Antibodies to post-synaptic ACh receptor, decrease effectiveness of released ACh
Presentation of Myaesthenia Gravis?
- Present with weakness and fatigue, normal sensation
- Most commonly diplopia and ptosis
How can neurophysiology be used to diagnose conditions like Myaesthenia Gravis?
- Can EMG muscles when patient tries to stimulate and look for “jitter” in results
What is jitter? How is it measured?
- Individual motor fibres in motor unit usually fire in time, in NM junction disease the relationship is lost
- Shows up on EMG as bands being further apart
What does severe myaesthenia gravis appear as on EMG?
- Block
- Very small amplitude, not in time
What conditions can be seen on EEG?
- Epileptic Activity
- States of consciousness (sleep stages etc.)
- Encephalopathy
