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Flashcards in Clinical Neurophysiology Deck (20):

What is the purpose of nerve conduction studies / electromyography?



Investigates problems of peripheral nerves and muscles

EMG is used in neuromuscular disorders and disorders of motor control


Nerve conduction studies are used in conjunction to measure the ocnducting function of nerves (unless it is a purely myopathic condition)


When is needle EMG and NCS indicated?

Needle EMG and NCSs are typically indicated when there is pain in the limbs, weakness from spinal nerve compression, or concern about some other neurologic injury or disorder


What are sensory studies?

Similar technique stimulating the sensory nerve fibres in the fingers allows measurement of sensory and motor function separately.


What is the purpose of EEG?

Electrical activity within the brain, investigate epilepsy and states of altered consciousness


What is the purpose of evoked potentials?

Monitor visual and somatosensory pathways to investigate problems in central pathways


What are the two measurable factors in nerve conduction studies?

Conduction velocity and amplitude


When is 


What diseases can EMG aid in the diagnosis of?

Needle EMG may aid with the diagnosis of nerve compression or injury (such as carpal tunnel syndrome), nerve root injury (such as sciatica), and with other problems of the muscles or nerves. Less common medical conditions include amyotrophic lateral sclerosis, myasthenia gravis, and muscular dystrophy.


What does wasting FDI stand for?

first dorsal interosseous muscle wasting


What syndrome is wasting FDI a part of?

Part of split hand syndrome


What are the causes of split hand syndrome?

 Neurological syndrome in which the handmuscles on the side of the thumb (lateral, thenar eminence) appear wasted, whereas the muscles on the side of the little finger (medial, hypothenar eminence) are spared. Anatomically, the abductor pollicis brevis and first dorsal interosseousmuscle are more wasted than the abductor digiti minimi


What causes split hand syndrome?

Lesions affecting branches of the ulnar nerve


Spinal root lesion affecting the anterior horn of C8-T1 - C8 radiculopathy


What evidence would suggest that the split hand syndrome is a result of ulnar neuropathy?

A slow onset and a lack of pain or sensorial symptoms are arguments against a lesion of the spinal root or plexus brachialis.


What woud an electrophysiology study on the arm show in 

  1. Ulnar neuropathy
  2. C8 radiculopathy

  1. Slowing across elbow, evidence for conduction block at elbow, small sensory response from ulnar nerve - due to demyelination and conduction block
    1. Small but not slowed motor response, normal sensory response (becaue cell ganglion is still intact?)



What does myasthenia graves present with?


What is the underlying pathology in myasthenia graves?

Antibodies to post synaptic ACh receptor which decrease the effectiveness of released Each


How do you diagnose myasthenia graves?

Detect antibodies (although this takes some weeks and is only positive in 70% of patients)


Neurophysiology - repetitive stimulation and single fibre EMG


What is the difference between routine EMG and single fibre EMG?


What is the finding of Myasthenia Graves on SF EMG? Why?


The needle is positioned to record from two fibres within the same motor unit, there is normally little variation in the time of firing between the two fibres. However in the NM junction in disease, the tight relationship between the two muscle fibres is lost and results in a jitter


What can EEG be used to see?

•Records electrical activity generated by cortical neurons across multiple points on the scalp.

 - Allows assessment of epileptic activity, states of consciousness and encephalopathy