Lecture 90 and 91 - Peripheral Nervous System Pathology

Question 1

In electrophys testing, if the amplitude of the wave is decreased with normal/near normal conduction velocity, this indicates loss of _______. If the conduction velocity is decreased with normal/near normal amplitude, this indicates loss of _______.

Answer 1

Axons (fibers)

Myelin

Question 2

In both Wallerian and Axonal Degeneration the innervated muscle becomes _______. This is NOT true for Segmental ________ (as is seen in Guillene-Barre).

Answer 2

Atrophic

Segmental Demyelination

Question 3

Charcot-Marie Tooth disease is a Hereditary ________ disease that decreases conduction velocity.

Because it’s hereditary and not acquired, what does this mean for the way axons will be demyelinated?

Answer 3

Demyelinating disease

It means the demyelination will be homogeneous and diffuse, whereas in acquired demyelinating disease (e.g. Guillene-Barre) the demyelination is patchy and typically focal.

Question 4

Radial nerve neuropathy distal to the elbow will result in weakness of wrist ______ (flexors or extensors?).

Answer 4

Extensors –> so wrist drop

Question 5

Remember that carpal tunnel syndrome is caused by impingement/neuropathy of the _______ nerve. These patients will have motor weakness of policis ______ (abduction or adduction?).

Answer 5

Median nerve

Adduction

Question 6

Ulnar neuropathy results in ________ (which muscle?) atrophy, and patients often present with a “____” hand.

Answer 6

Interosseous atrophy

Claw hand

Question 7

Testing muscle activity with electrophys can help you approximate when a peripheral neuropathy occured. There will be abnormal activity in the muscle between ____-____ weeks, and then it will likely resolve with compensation from other innervation.

Answer 7

3-6 weeks

Question 8

In neuropathic pattern of disease, you will see high ______ and Increased ________ on electrophys. With Myopathic pattern, you’ll see Low _______ and reduced ______.

Answer 8

High Amplitude

Increased Duration

Low amplitude

Decreased duration

Keep in mind myopathic means the axons are healthy, but the muscle has wasted –> less motor units.

Question 9

Guillain-Barre syndrome is characterized by _______ paralysis that often leads to paralysis of the diaphragm. The CSF in these patients will show HIGH _____ but NO _____. About 25% of these patients have _______ _______ infection.

Answer 9

Ascending paralysis

High Protein

No Cells

Campylobacter jejuni

Question 10

The most common cause of Axonal Polyneuropathy is ______. However, many metabolic diseases can cause this as well, including Diabetes, Uremia, Alcoholism, etc.

Answer 10

Idiopathic

Question 11

Testing the NMJ is part of Guilain-Barre diagnosis. You should see a decrease in firing with continued stimulus. What effect would cold ambient temperature have on this testing?

Answer 11

It would increase firing due to DECREASED Acetylcholinesterase activity.

Question 12

Myotonic Dystrophy has a characteristic ________ appearance on histology. This disease arises from a CTG repeat on the long arm of chromosome _____, and its inheritance shows Anticipation –> expansion of the repeats leading to appearance of symptoms earlier in life than previous generation.

Answer 12

Polynucleus

19

Question 13

Polymyositis presents as a rapidly progessive muscle weakness occurring more ______ (proximal or distal?) and is more frequently seen in adult _____ (men or women?).

Serum ______ levels are greatly elevated (upward of 5,000).

There is inflammation throughout the muscle _______, which is different than in Dermatomyosits.

Answer 13

Proximal

Women

Serum CK

Throughout muscle fascicles

Question 14

Dermatomyositis shows inflammation and changes at the ________ of the muscle fascicles, whereas Polymyositis shows inflammation Throughout the fascicles. Also keep in mind Dermatomyositis may also show skin rashes.

Answer 14

Periphery