Clinical Neurophysiology

Question 1

When is neurophysiology useful?

Answer 1

In treatment of;
Epilepsy 
Motor neurone disease 
Parkinson's disease 
Amyotrophic lateral sclerosis

Question 2

When is electroencephalography (EEG) useful?

Answer 2

In the diagnosis and management of epilepsy

Question 3

How does EEG work?

Answer 3

Monitors the electrical activity within the brain and uses it to investigate epilepsy and altered states of consciousness

Question 4

What can and EEG show in a patient with epilepsy/altered states of consciousness?

Answer 4

The areas of the brain where unusual electrical activity is coming from, and some types of seizures
Can be used to distinguish the type of epilepsy present and whether there is an epileptic focus

Question 5

How is brainstem death diagnosed?

Answer 5

Exclusion of reversible causes
Confirmation of absence of brainstem reflexes
Apnoea testing
Ancillary tests aimed at confirming presence/absence of cerebral blood flow or cerebral function

Question 6

Principal use of nerve conduction studies

Answer 6

Identify damage to peripheral nerves and to determine whether the pathological process is focal or diffuse and whether damage is principally axonal or demyelinating
Obtain some information about nerve roots

Question 7

How do nerve conduction studies work?

Answer 7

Examine nerve function through conduction velocity and amplitude
Stimulates peripheral nerve and monitors the transmission of the pulse and how quickly it reaches its target

Question 8

How does EMG work?

Answer 8

Looks at action potentials from whole motor units
SF EMG uses filter, sensitivity and timebase settings to isolate the action potentials from individual muscle fibres within one motor unit
Fine concentric needle electrodes can be inserted into muscles bellies to measure potential from individual motor units

Question 9

What abnormal spontaneous activity might be recorded by EMG?

Answer 9

Fibrillations

Myotonic discharges

Question 10

Abnormalities in the shape and size of muscle potentials can help in the differential diagnosis of

Answer 10

denervation and structural muscle diseases

Question 11

When can evoked potentials be measured?

Answer 11

Following visual, auditory or somatosensory stimuli, if electrodes are appropriately positioned

Question 12

Abnormalities of the evoked potential indicate damage to

Answer 12

the relevant pathway, either in the form of a conduction delay or reduced amplitude, or both