the goal of EDS is to determine id there is a problem along the peripheral NS pathway
& if so, where the problem is:
eg of locations of possible lesions & associated diagnoses include:

• motor nerve cell body (ant horn cell)- amyotrophic lateral sclerosis
• root- cervical or lumbar radiculopathy
• axon- toxic neuropathy
• myelin - Gullien- Barre syndrome
• NM junction- myesthenia gravis
• muscle- muscular dystrophy

• A normal response is obtained with ES.
• Sometimes the nerve and muscle are hyper-excitable and react to a lower intensity of current than that normally required.

• alternations in the electrical reactions occur.

• ES to the affected muscle - normal response.
• But loss of response if stimulus applied to the nerve trunk above the lesion.

• Weakness or disease of the muscle
• The reactions to ES are of normal type,
  but are reduced in strength.
• Absence of response - ischaemic contracture, advanced stages of the myopathies,
  firbrosis of muscles in long standing denervation.

• this is the waveform you see on the screen
  (in order to give more details about what you are describing, more specific terms may
  include compound nerve action potential, compound motor action potential,
  sensory nerve action potential, etc.)
  

• time interval between the onset of a stimulus and the onset of a response
  (can also be referred to as a motor latency or a sensory latency).

how fast the fastest part of the impulse travels
(can also be referred to as a motor conduction velocity or a sensory conduction velocity).

a compound ms action potential evoked by antidromically stimulating a motor nerve frm a ms using maximal electrical stimulus.
it represents the time required for a stimulus to travel antidromically toward the spinal cord & return orthodromically to the ms along a very small percentage of fibers.

a compound muscle action potential evoked by
orthodromically stimulating sensory fibers, synapsing at the spinal level
and returning orthodromically via motor fibers.
The response is thought
to be due to a monosynaptic spinal reflex (Hoffmann reflex) found in
normal adults in the gastrocnemius-soleus and flexor carpi radialis muscles.

when the electrical impulse travels in the same direction as normal physiologic conduction
(e.g., when a motor nerve electrical
impulse is transmitted toward the muscle and away from the spine or a sensory impulse travels toward the spine).

when the electrical impulse tracels in the opposite direction of normal physiologic conduction
(eg: conduction of a motor nerve electrical impulse away frm the ms & toward the spine)

• infection
• bleeding
• accidental penetration of the needle into something other than the intended ms