Basic knowledge on clinical neurophysiology including EEG, nerve conduction, electromyography, evoked potentials

1. Seminar on clinical neurophysiology
for medical students
23rd January 2018.
Edina Timea Varga MD, PhD
University of Szeged
Department of Neurology
www.varganeuro.com

2. What is clinical neurophysiology?

3. What is clinical neurophysiology?
?

4. Clinical neurophysiology
• Specialty
• Extension of neurology + special lab examinations
• To study
central nervous system (CNS)
peripheral nervous system (PNS)
autonomic nervous system (ANS)
• To treat
PD - Parkinson’s disease: DBS – deep brain stimulation
Epilepsy: DBS/VNS – vagal nerve stimulation/operation
Tumors, lesions: resective surgery
Spinal cord lesions, etc…

6. EEG – electroencephalography
EP – evoked potentials:
visual/acustic/somatosensory/magnetic/cognitive
EMG - electromyography
ENG/NCS – electroneurography/nerve
conduction study
RNS - repetitive nerve stimulation
Sleep studies: PSG – polysomnopgraphy, …
Autonomic nervous system: sympathetic skin
respone test, RR-interval,…
Clinical neurophysiology

7. http://outreach.mcb.harvard.edu/animations/actionpotential_short.swf
axonmembrane

8. Resting potential
http://outreach.mcb.harvard.edu/animations/actionpotential_short.swf
-70 uV
axonmembrane

9. http://outreach.mcb.harvard.edu/animations/actionpotential_short.swf
axonmembrane
Na+/K+ pump: 3 Na+ out, while K+ in
depolarisation

10. http://outreach.mcb.harvard.edu/animations/actionpotential_short.swf
axonmembrane
depolarisation

11. repolarisation
http://outreach.mcb.harvard.edu/animations/actionpotential_short.swf
axonmembrane

12. http://outreach.mcb.harvard.edu/animations/actionpotential_short.swf
axonmembrane
return to resting potential

13. Purves et al. Life The Science of Biology IVth Edition 1995.
Action potential can be
visualized on an oscilloscope
oscilloscope
membranepotentail(mV)
Alternating electric charges on two plates
makes electrone beam sweep across screen
Amplified signal from axon moves electron
beam ↑&↓.
When inside on axon is +, beams move ↑.
When inside of axon is -, beam moves ↓.

15. research daily routine

16. www.google.com
M1
V1

17. daily routine

18. EEG - electroencephalography

19. localisation
International 10/20 system
F – frontal
P – parietal
T – temporal
O – occipital
C – central
Fp – frontopolar
z - zero (vertex):
Fz, Cz, Pz)
A – auricula
even number– right sideodd number– left side
www.ilae.org

20. http://stock-clip.com/video-footage/eeg

21. Electrodes
a-b-c : superficial
(Ag/AgCl)
d - clip
e – needle electrode
f –nasopharyngealis
needle electrode
Fisch & Spehlmann

22. Common reference

23. Double banana

24. Normal (adult) background activity

25. Amplitude redution for eye opening

26. Hyperventilation – normal reaction (8 years)
4 Hz, ampl. 500 uV

27. Muscle artifact

28. Myoclonus
(gen. spike and slow wave)

29. Myoclonus
(gen. spike and slow wave)

30. Myoclonus
(gen. spike and slow wave)

31. Left temporal (interictal) slow wave
and spike

32. Generalized spike and slow wave
activity
IGE – idiopathic generalized epilepsy

33. Nerve conduction studies (NCS)
motor NCS
sensory NCS
http://bcs.whfreeman.com/thelifewire9e
Purves et al. Life The Science of Biology IVth Edition 1995.
http://chadwaterbury.com
http://emedicine.medscape.com/article/1846028-overview
http://jdr.sagepub.com
http://www.erikstalberg.com/

34. Nerve conduction studies (NCS)
motor NCS
sensory NCS

35. Nerve conduction studies (NCS)
motor NCS
sensory NCS
time (ms)
voltage(uV)

36. Nerve conduction studies (NCS)
motor NCS
sensory NCS
latency
latency
duration
duration
amplitude
amplitude

37. AIM??

38. • axonal /demyelinating injury
• focal/genearlised
• localisation
↓amplitude=axonal loss
↓condiction velocity=demyelinisation
↑latency=demyelinisation

39. Carpal tunnel syndrome

40. Carpal tunnel syndrome

41. Medial and lateral plantar nerve

42.  superficial electrodes
 sensory nerve conduction
Medial and lateral plantar nerve

43. Motor nerve conduction study
registration with needle electroderegistration with superficial electrode

44. Near nerve technique
tarsal tunnel syndrome Morton’s metatarsalgia

45. Ulnar nerve neuropathy

46. Ulnar nerve neuropathy
Near nerve technique

47. Ulnar nerve neuropathy
Near nerve technique

48. Ulnar nerve neuropathy
Near nerve technique
closer to the nerve
higher detectable answer
more precise information

49. EMG - electromyography

52. AIM??

53. neurogen/myogen lesion
acute/chronic
reinnervation
↓amplitude, ↓duration,↑polyphasy→myogenic
↑amplitude, ↑duration,↑polyphasy→neurogenic
prescence of abnormal resting activity
reinnervation
potentials

55. Dystrophia
myotonica

56. http://www.thegirlwiththepurplecane.com/2014/01/23/mayo-day-2-an-emg-a-sweat-test-and-2-pee-jugs/

57. http://img.444.hu/stephen-hawking-s%C3%BAlytalans%C3%A1gban.jpg

58. A neuromuszkuláris junkció
http://stevegallik.org/sites/histologyolm.stevegallik.org/images/motorendplates.jpg

59. Investigation of neuromucular junction
Indication:
 Myasthenia gravis
 Lambert-Eaton Myasthenic Syndrome

60. • RNS - repetitive nerve
stimulation
sensitivity:
• Ocular MG= 50%,
• Generalised MG= 75%
• Single fiber EMG:
sensitivity: 95%
Stalberg, Uppsala
Nandedkar

61. EVOKED POTENTIALS
• VEP – visually evoked potentials
• (S)SEP – (somato)sensory evoked potentials
• MEP – motor evoked potentials
• BAEP (alias: ABR, BERA) – brainstem auditory
evoked potentials

62. VEP - visually evoked potentials
http://tidsskriftet.no/article/3011088/en_GB

63. SEP somatosensory evoked potentials
http://tidsskriftet.no/article/3011088/en_GB

64. SEP somatosensory evoked potentials: median nerve
• Erb
• Cv
• Fz-A1
• C4-A1
• P4-A1
• C4-Fz
• P4-Fz

65. SEP somatosensory evoked potentials: median nerve

66. SEP somatosensory evoked potentials: median nerve
missing cortical answer in an MS patient

67. F.pop.
L1
Cz-A1
Pz-A1
Cz-A2
Pz-A2
Cz-Fz
Pz-Fz
SEP somatosensory evoked potentials: tibial nerve

68. missing cortical answer in an MS patient
SEP somatosensory evoked potentials: tibial nerve

69. MEP - motor evoked potentials
http://www.gettyimages.co.uk/detail/photo/woman-having-a-transcranial-magnetic-high-res-stock-photography/487737741

70. BAEP - brainstem evoked potentials
I. wave: N. VIII.
III. wave: cochlear
nucleus,
oliva superior
IV-V. wave:
•lemniscus lateralis-
colliculus inferior
IPL – interpeak latency:
I-III, III-IV.
http://www.myvmc.com/investigations/brainstem-auditory-evoked-potential-baep/

71. Clinical neurophysiology in the
treatment…

72. Operative treatment of
epilepsy - lesionectomy
www.desitin.no/images/Epilepticus-sic-curabitur.jpg

73. Treatment of epilepsy (e.g.)
DBS -deep brain stimulation
VNS – vagal nerve stimulation
selective removal of the
lesion, e.g.
hippocampectomy

74. research daily routine future

75. https://www.youtube.com/watch?v=Al5RhaJgxxU

76. ?

77. Thank you for your attention
www.varganeuro.com