Clinical Neurophysiology

Question 1

what is Electromyography (EMG) used for?

Answer 1

Nerve conduction studies
To investigate problems of peripheral nerve and muscle.
Conduction velocity
Amplitude

Question 2

what is EEG used for?

Answer 2

Assess brain function

records electrical activity within the brain generated by cortical neurons across multiple points on the scalp

Question 3

what are evoked potentials used for?

Answer 3

Visual and somatosensory, investigate problems in central pathways

Question 4

describe Ulnar neuropathy

Answer 4

Most often at elbow Occasionally wrist
Ulnar distribution numbness
Note dorsal cutaneous branch
Wasting of small muscles, esp FDI

Question 5

what is conduction block?

Answer 5

failure of impulse transmission at some point along a nerve fiber, although conduction along the segments proximal and distal to it are unaffected; clinically, most often the result of an area of focal demyelination

Question 6

what does a routine EMG look at?

Answer 6

action potentials from whole motor units.

Question 7

what does a single fibre EMG look at?

Answer 7

uses filter, sensitivity and timebase settings to isolate the action potentials from individual muscle fibres within one motor unit.

Question 8

why is a single fibre EMG useful?

Answer 8

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.
In NM junction disease that tight relationship between the two is lost.
Result is “jitter”

Question 9

what is Myaesthenia Gravis?

Answer 9

muscle weakness

Often affects eyes

Question 10

what does a Myaesthenia present as in a SF EMG?

Answer 10

Myaesthenia - jitter

Worse Myaesthenia - block

Question 11

what can EEG investigate?

Answer 11

epilepsy 
states of altered consciousness
Encephalopathy
Non-epileptic attacks
Facilitate medical or surgical treatment for epilepsy