The document provides guidance on interpreting various neurography results. It discusses potential reasons for low amplitude compound muscle action potentials including carpal tunnel syndrome, lumbar epidural mass, technical problems, and polyneuropathy. It also discusses diagnoses for other neurography findings including possible carpal tunnel syndrome based on abnormal sensory findings in fingers 1-3 with normal motor amplitudes. Other sections discuss distinguishing between lumbar root lesions versus plexopathies and evaluating possible myasthenia gravis. The document aims to instruct on drawing conclusions from neurography studies.

1. Neurography, routine

2. 50 Neurography: Low ampl CMAP
Normal sensibility, strong muscles: If the CMAP of APB has an amplitude < 4mV and CMAP from ADM is normal,
and the SNAP from dig III is normal which is a likely reason
1. CTS
2. LEM
3. Technical problem
4. Polyneuropathy

3. 50 Neurography: Low ampl CMAP
Normal sensibility, strong muscles: If the CMAP of APB has an amplitude < 4mV and CMAP from ADM is normal,
and the SNAP from dig III is normal which is a likely reason
1. CTS
2. LEM
3. Technical problem
4. Polyneuropathy
LEM is very rare and technical problems common. Answer on these grounds

4. 51Neurogaphy: Low ampl CMAP
If the CMAP of ADM and APB have an amplitude < 2mV , sensory signal OK
which is a likely reason
1. CTS
2. LEM
3. Technical problem
4. Slight polyneuropathy

5. 51Neurography: Low ampl CMAP
If the CMAP of ADM and APB have an amplitude < 2mV , sensory signals OK
which is a likely reason
1. CTS
2. LEM
3. Technical problem
4. Slight polyneuropathy

6. 52Neurography: ? CTS
Your patient has numbness of dig I,II and low sensory signals from Dig I-III but normal
CMAP amplitude
Normal latency from APB and normal sensory signals from dig V.
A likely diagnosis is:
1. CTS
2. radiculopathy
3. polyneuropathy
4. anterior interosseus syndrome

7. 52Neurography: ? CTS
Your patient has numbness of dig I,II and low sensory signals from Dig I-III but normal
CMAP amplitude
Normal latency from APB and normal sensory signals from dig V.
A likely diagnosis is:
1. CTS
2. radiculopathy
3. polyneuropathy
4. anterior interosseus syndrome
Usual that sensory findings are abnormal while motor is preserved I CTS.
Radiculopathy normal SNAP
Not pnp, see ulnar SNAP
Anterior inteross, is motor

8. Q 1. E2 positions
1
Which is the optimal position for E2 in study of these muscles
Deltoideus
Trapezius
Biceps brachii
´Tibialis anterior

9. Q 1. E2 positions
1
Which is the optimal position for E2 in study of these muscles
Deltoideus
Trapezius
Biceps brachii
´Tibialis anterior
Acromion/Sternum,
Acromion
Acromion
Patella

10. Q 6, Test for Martin-Gruber
1

11. Martin-Gruber
anastomosis
stimulation of median nerve
Q6
1
Type 1 anastomosis

12. Q 6.
Martin -Gruber
1

13. Q 6. Martin-Gruber
1

14. 4,7/5,6; -19%
71317
2,0/3,9; -49%
Q6
Dist is lower, Median nerve
1
Reduction by
Think of M-G

15. 4,7/5,6; 19% reduction
71317
2,0/3,9; 49% reduction
Q6
Dist is lower, Median nerve
1
Good routine to superimpose traces

16. 8.93, 8.45 mV
13,2 and 11,2 mV
Ampl dacay 15%
Dispersion =0%
Is this significant conduction block? Median nerve
Normal if diff < 20%
1
If ampl drops > 20%, with little
increase in duration, check for
conduction block
Ampl decay 5%
Dispersion = 15%

17. 52Neurography: ? CTS
Your patient has numbness of dig I,II and low sensory signals from Dig I-III but normal
CMAP amplitude
Normal latency from APB and normal sensory signals from dig V.
A likely diagnosis is:
1. CTS
2. radiculopathy
3. polyneuropathy
4. anterior interosseus syndrome

18. 52Neurography: ? CTS
Your patient has numbness of dig I,II and low sensory signals from Dig I-III but normal
CMAP amplitude
Normal latency from APB and normal sensory signals from dig V.
A likely diagnosis is:
1. CTS
2. radiculopathy
3. polyneuropathy
4. anterior interosseus syndrome
Usual that sensory findings are abnormal while motor is preserved I CTS.
Radiculopathy normal SNAP
Not pnp, see ulnar SNAP
Anterior inteross, is motor

19. 53Neurography: Root or plexus
Patient 80 yo, with right-sided weakness and numbness in the leg.
Low sensory amplitude in right fibularis superficialis but normal on the left side.
Reduced CMAP ampl in right EDB
EMG in Tib ant show denervation. EMG in lumbar paraspinals normal
1. L5 root
2. plexopathy
3. central lesion
4. polyneuropathy

20. 53Neurography: Root or plexus
Patient 80 yo, with right-sided weakness and numbness in the leg.
Low sensory amplitude in right fibularis superficialis but normal on the left side.
Reduced CMAP ampl in right EDB
EMG in Tib ant show denervation. EMG in lumbar paraspinals normal
1. L5 root
2. plexopathy
3. central lesion
4. polyneuropathy
Normal sensory and paraspinal EMG favors plexus lesion

21. 54EMG: Myasthenia?
Patient with ptosis but no arm or leg weakness. RNS in nasalis and deltoid normal.
SFEMG in orb oculi shows jitter and some blocking. Jitter abnormal in Ext dig.
1. Ocular MG
2. Generalized MG
3. Myopathy
4. Miller Fisher syndrome

22. 54EMG: Myasthenia?
Patient with ptosis but no arm or leg weakness. RNS in nasalis and deltoid normal.
SFEMG in orb oculi shows jitter and some blocking. Jitter abnormal in Ext dig.
1. Ocular MG
2. Generalized MG
3. Myopathy
4. Miller Fisher syndrome
MG classification is conventionally defined on clinical grounds.
Jitter is abnormal in ED in 60% of cases with Ocular MG

23. EMG: 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

24. EMG: 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

25. If the MCV is slower (diff > 10 m/sec) in
ulnar nerve across the elbow than distally,
what to do?
1

26. SSS = motor short segment study, bilateral
US
If the MCV is slower (diff > 10 m/sec) in
ulnar nerve across the elbow than distally,
what to do?
1

27. Median nerve. If the CV is 85 m/sec, what do you
expect?
1

28. Median nerve. If the CV is 85 m/sec, what do you
expect?
Martin-Gruber and CTS
1

29. If the sensory median amplitudes are high
(1.8 SD) and the sensory latency
prolonged, what to do?
1

30. If the sensory median amplitudes are high
(1.8 SD) and the sensory latency
prolonged, what to do?
Warm the hands
1

31. Which is the movement response for
fibular and tibial nerve stimulation
1

32. Which is the movement response for
fibular and tibial nerve stimulation
• Superficial fibular nerve – eversion of the foot and plantar flexion
• Deep fibular nerve – dorsiflexion, eversion
• Tibial nerve, plantar and toe flexion, inversion
1

33. Q 17. In a slight CTS the palm stimulation
(wrist recording) may have normal
orthodromic latency but abnormal ortho
from dig 3 stimulation. Why?
1

34. Q 17. In a slight CTS the palm stimulation
(wrist recording) may have normal
orthodromic latency but abnormal ortho
from dig 3 stimulation. Why?
Pure sensory CTS. Palm stim includes motor nerve fibers, which now
give normal latency
1

35. Q 22. Different signals will be shown here. Within each example
the recordings come from different patients. Where is the
recording obtained?
A B
5 ms
5 mV
5 ms
5 mV
1

36. Q 22. Different signals will be shown here. Within each example
the recordings come from different patients. Where is the
recording obtained?
A B
5 ms
5 mV
5 ms
5 mV
1
APB ADM

37. 5 ms
5 mV
C
1

38. 5 ms
5 mV
C
AH
1

39. 5 ms
5 mV
D
1

40. 5 ms
5 mV
D
EDB
1

41. 5 ms
5 mV
E
1

42. 5 ms
5 mV
E
Deltoid
1

43. 5 ms
5 mV
F Pronator quadratus
1

44. 5 ms
5 mV
F Pronator quadratus
1
Pronator quadratus

45. 5 ms
5 mV
G
1

46. 5 ms
5 mV
G Extensor indices
1

47. 5 ms
5 mV
sensory Usually you cannot tell the origin
of sensory recordings
1
Q23. Sensory nerves, ortodromic or antidromic.
Which nerves?

48. 5 ms
5 mV
sensory Usually you cannot tell the origin
of sensory recordings
1
Q23. Sensory nerves, ortodromic or antidromic.
Which nerves?
Cannot tell

49. In your patient with suspected PNP, the sural
response is only questionably present. You have
ruled out technical errors.
What is the most informative procedure for correct
interpretation now?
check sensitivity in sural area?
check the sural response on the contralateral side
reduce stim-rec distance
test of radialis sensory responses
test F-responses in the tibial nerves
Sural SNAP

50. In your patient with suspected PNP, the sural
response is only questionably present. You have
ruled out technical errors.
What is the most informative procedure for correct
interpretation now?
check sensitivity in sural area?
check the sural response on the contralateral side
reduce stim-rec distance
test of radialis sensory responses
test F-responses in the tibial nerves
Sural SNAP

51. 59Methods of choice
Which is the EDX method of choice for the following diagnostic questions
MG RNS
SFEMG
CTS EMG of APB and ADM
antidromic sensory neurography
GBS EMG
neurography
thermotest
Root EMG
neurography
evoked potentials
ALS EMG
neurography
Motor unit counting

52. 59Methods of choice
Which is the EDX method of choice for the following diagnostic questions
MG RNS
SFEMG
CTS EMG of APB and ADM
antidromic sensory neurography
GBS EMG
neurography
thermotest
Root EMG
neurography
evoked potentials
ALS EMG
neurography
Motor unit counting