5.2.2 Weakness

Question 1

What grading scale do they want us to use for muscle stretch reflexes?

Answer 1

Question 2

Answer 2

Question 3

Localize this lesion: diffuse weakness, no numbness, areflexia

Answer 3

Motor peripheral neuropathy, Anterior horn cell

Question 4

What scale is used to grade muscle strength? What are the levels of strength graded in this scale?

Answer 4

MRC Scale

5 - Full strength

4 - Gravity + Resistance

3 - Antigravity

2 - Joint Movement

1 - Visible Contraction

0 - No Contraction

Question 5

Answer 5

Question 6

Localize this lesion: diffuse weakness, no numbness, preserved reflexes

Answer 6

NMJ, muscle

Question 7

Answer 7

Question 8

Localize this lesion: Diffuse LMN weakness with numbness

Answer 8

Diffuse peripheral neuropathy

Question 9

If a patient presents with generalized LMN weakness and normal sensation, what are you thinking might the source of their symptoms?

Answer 9

A disease process affecting the motor unit (anterior horn cell, periheral nerve, NMJ, muscle)

Question 10

What are the four parts of the motor unit that can be affected by diffuse disease?

Answer 10

Anterior horn cell, peripheral nerve, NMJ, and muscle

Question 11

Answer 11

ALS (Lou Gehrig’s Dz, motor neuron dz)

Question 12

What is typically elevated in muscle-caused deficits?

Answer 12

Creatine Phosphokinase (CK)

When reflexes are normal in generalized LMN weakness, CK can be used to distinguish between an NMJ issue and muscle as the source of the dysfunction. CK elevated in muscular conditions. CK normal in NMJ-related conditions.

Question 13

See case.

EMG: neurogenic

Muscle biopsy shows grouped neurogenic atrophy

Genetic testing: deletion in SMN gene on chromosome

Answer 13

With absent DTRs (thinking Anterior Horn Cell or Peripheral Nerve)

Dx: Spinal muscular atrophy type 1

Question 14

If a patient presents with generalized LMN Weakness and numbness, what type of pathology are you thinking?

Answer 14

Peripheral Neuropathy

Question 15

Answer 15