Electrodiagnostic Lab

Question 1

If there is a CNS lesion, what are the possible lesion locations?

Answer 1

• brain
• brainstem
• cerebellum
• spinal cord

Question 2

If there is a lesion in the PNS, what are the possible lesion locations?

Answer 2

• axon heads
• roots of axons
• nerve plexus
• peripheral nerve branches

Question 3

What do you need to remember to ask?

Answer 3

Good questions!
o They come in with numbness in the foot, ask about the whole body, they might also have it I the hands
o Ask about bowel and bladder retention – can you urinate like they used to be able? The nerves that go through your legs and back also go to their bowel and bladder
o So, numbness, tingling, pain, bowel or urinary retention or accidents

Question 4

What do you need to remember about the neurological physical exam?

Answer 4

o The questions in the history will lead you to a focused physical exam
o The physical exam (screen part) should be the same on everyone – need to know what normal feels like
o After your initial screen, you can do a focused physical exam that has been directed from you history

Question 5

Why is it so important to accurately judge the muscle strength?

Answer 5

o Can have 50% nerve function (half are dead), and still can walk and have almost normal function
o Need to find the lesion and stop progression since it is already 50% gone, need to stop it before it is 100% gone
o Muscle strength
- If you can push their leg down with a pinky, it is a 3
- Full ROM without gravity is a 2, but not against gravity

Question 6

Describe how you can test S1

Answer 6

S1 of the calf
o Very strong, hard to overcome it with your own hand
o If they walked in, they can do that
o Have them go to the wall and do 10 heel raises
o If they can do 1 = 3, 10=4, more =5

S1 of the knee flexor
o Knee all the way back, don’t let me pull it forward

Question 7

Describe a straight leg raise test

Answer 7

o If you have an L5/S1 disc pushing on the S1 nerve root
o Nerves are not elastic, they are supposed to glide in and out, but they can’t when they are pinched
o Raise the leg – pulls the nerve out of the hole, pain is present (POSITIVE test)

Question 8

What do you need to remember about testing reflexes?

Answer 8

o They are not good unless that are constant and reproducible

Question 9

What are the lower extremity reflexes?

Answer 9

• Babinski – need to do it without socks, need to look at the foot first (ulcer) – want to see the emotion of the first MPJ going down
• Patellar
• Achilles

Question 10

What is hyperreflexivity?

Answer 10

• Even with clonus

- Upper motor nerve lesion

Question 11

What is hyporeflexivity?

Answer 11

Lower motor nerve lesion

Question 12

If hyperreflexivity is on both sides, what doe that probably mean?

Answer 12

Not in the brain, on the spinal cord

Question 13

If hyperreflexivity is unilaterally, what doe that probably mean

Answer 13

Not on the spinal cord, in the brain

Question 14

What should you do if you have a patient with bilateral hyperreflexivity?

Answer 14

• Test the arms
• They are normal, so it is not the brain
• Lesion is in the thoracic region
• Know this because there is no cord in the lumbar or sacral region
• Know it isn’t in the cervical region because there would be symptoms in the arms as well
• Got an MRI, patient had a disc impinging the spinal cord

Question 15

What are the ways to test the major nerve roots (L2-S1)

Answer 15

o	Hib flexor L2 (knee up)
o	Knee flexor L3 (knee extended)
o	Dorsiflexion L4 
o	Extensor hallices longus L5 (big toe)
o	Plantar flexor S1

Question 16

If you’re trying to figure out a lesion and you find that there is a weak L5 (extensor hallices longus), L4 is slightly weak, but L2 and L3 were strong, what should you test?

Answer 16

A different muscle group innervated my the same nerves

Gluteal muscles - test this and you find that it is a L5 root problem - lumbar problem

Question 17

When would you get an EMG?

Answer 17

ONLY if it is hard to tell by strength test alone, you can get an EMG to localize

Question 18

What are the 4 muscle strength tests you should never be able to overcome?

Answer 18

o Shoulder
o Plantar flexors
o Elbow extension
o Knee extension

Question 19

Describe a NCS test

Answer 19

o Send a shock
o Should get an amplitude in the conductivity graph
o If you a small amplitude, some of the nerves are cut off**
o If it takes a long time to get an amplitude, the nerve is slow and it is demyelination **
o Demyelination is a much better prognosis than the nerve being cut off ***
o If you have both, you have broken nerves and demyelination occurring
o You need to shock them many times – not pleasant for the patient

Question 20

Describe an EMG test

Answer 20

o Needles into the muscle
o You send an antenna in, not a shock
o 1 axon with all the muscle fibers is considered a motor unit
o If the patient is not moving at all and you put the needle in, you will hear an initial noise
o You shouldn’t hear anything much when the patient is just lying there
o When you ask the patient to move a little you should get some more action
o If they move a lot and engage a lot of muscle units, you should get a lot more action on the screen (amplitudes)
o If you hit the muscle fibers themselves, you have is a myopathy, you will see just a little activity where you should see a lot more