1. Quiz RNS

2. 57EMG: Myasthenia?
Patient with bilat ptosis but no arm or leg weakness. RNS in nasalis and deltoid normal.
SFEMG in orb oculi and frontalis normal.
1. Ocular MG
2. Generalized MG
3. Myopathy
4. Bell palsy
Normal SFEMg findings are strong indications that symptoms are NOT MG. In this case, it may be
a myopathy, often with very little of jitter abnormalities

3. 57EMG: Myasthenia?
Patient with bilat ptosis but no arm or leg weakness. RNS in nasalis and deltoid normal.
SFEMG in orb oculi and frontalis normal.
1. Ocular MG
2. Generalized MG
3. Myopathy
4. Bell palsy
Normal SFEMg findings are strong indications that symptoms are NOT MG. In this case, it may be
a myopathy, often with very little of jitter abnormalities

4. Which is the optimal time for maximal voluntary activation in
RNS tests in MG and LEM respectively?
1

5. Which is the optimal time for maximal voluntary activation in
RNS tests in MG and LEM respectively?
45-60 sec to provoke MG exhaustion
10 sec to see LEM facilitation
1

6. RNS
• Is the head moving when you perform correctly RNS from trapezius
muscle (stim behind the sternocleid muscles)? NO, move stim
• Is it normal to have some degree of “biting” when you perform RNS
of the nasalis muscle? If not, what to do?
No, direct stim of masseter muscle, move stim
1

7. RNS
• Is the head moving when you perform correctly RNS from trapezius
muscle (stim behind the sternocleid muscles)? NO, move stim
• Is it normal to have some degree of “biting” when you perform RNS
of the nasalis muscle? If not, what to do?
No, direct stim of masseter muscle, move stim
1

8. Q 43. Tests of LEM?
The important finding is strong facilitation (> 60% amplitude
increase)
This is accomplished by
1. 10 sec voluntary activation
or
2. Stim 20 (-50) Hz for 1 sec. Note, the facilitation should be
assessed from the amplitude obtained after first single
stimulus after the train.
(during the train the muscle is shortening, which changes the
amplitude by up to 40%)
8

9. Q 43. Tests of LEM
The important finding is strong facilitation (> 60% amplitude
increase)
This is accomplished by
1. 10 sec voluntary activation
or
2. Stim 20 (-50) Hz for 1 sec. Note, the facilitation should be
assessed from the amplitude obtained after first single
stimulus immediately after the train.
(during the train the muscle is shortening, which changes the
amplitude by up to 43%)
9

10. 1
Which muscles are tested?

11. APB
trap
nasalis
1

12. 47 year old lady
HISTORY AND FINDINGS
• previously healthy
• since 3 months increasingly weak
• can walk 200 m, subjectively weaker right side
• last month in wheelchair
• hoarse, swallowing difficulties
• orthostatic hypotension
• obstipated
CLINICAL:
• fatigable neck muscles
• weak leg muscles
• no atrophy of facial muscles
• areflexia
Q3

13. NCS: motor nerves
Q3

14. Repetitive nerve stimulation: m. ADM sin
Q3
rest rest 0 after 20 sec act 60 sec after act 3 min afdter act

15. SFEMG: m. orbicularis oculi
Q3

16. CT thorax – normal
VGCC antibodies – positive
Diagnosis?
a. MG
b. LEM
c. axonal neuropati
d. AMAN
e. post polio syndrom
Comment: Not all muscles show the typical facilitation. No data from other muscles
20 sec may be too long, prefer 10 sec
Do not exclude LEM from normal study of ONE muscle
47 year old lady