The document discusses the methodology for recording the cutaneous silent period (CSP) as an electrophysiological tool to assess small fiber function, particularly in individuals with small fiber neuropathy. It outlines the study's objectives, materials, methods, and results, highlighting normative data for latency and duration measurements in upper and lower limbs. Additionally, it compares CSP with other modalities for evaluating small fiber function, suggesting its potential benefit in clinical assessments.

1. Department of Neurology,
M S Ramaiah Medical
College and Hospitals

2. The Cutaneous Silent Period
An Electrophysiological tool to assess
small fiber function
Rahul Kumar, P V Meenakshi, Shripal Shah, M Vivekananda,
R Pavithra, P T Acharya, Pushparaja Shetty H, R Srinivasa
M S Ramaiah Medical College and Hospitals, Bangalore 560094
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3. Cutaneous Silent Period
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Introduction
Need for the study
Aims and Objectives
Materials and Methods
Results
Discussion
Conclusions
3

4. Outline for the session
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Introduction
Need for the study
Aims and Objectives
Materials and Methods
Results
Discussion
Conclusions
4

5. • The silent period consists in a transient suppression of the
EMG voluntary activity that occurs in response to an
electrical stimulus.
• Described for the first time by W. W. Hoffmann in 1922
5

6. Can be recorded from…
• Most skeletal muscles
• More pronounced in the distal muscles
• Consistent, reproducible
• Can be recorded on conventional EP equipment
• Non Invasive
6

7. Importantly ……
7

8. Need for the Study
• Small fibre neuropathy - 30% in IGT !!!
– Altered C-Fiber Function as an Indicator of Early Peripheral
Neuropathy in Individuals With Impaired Glucose Tolerance,
Alistair Q. Green, MRCP1, Singhan Krishnan, MD, MRCP1,
Francis M. Finucane, MD, MRCP, Gerry Rayman, MD, FRCP,
Diabetes Care January 2010vol. 33 no. 1 174-176
• Available techniques
– Sympathetic skin response
– Quantitative sensory testing
– Quantitative sudo-motor axon reflex test
– Skin biopsy
8

9. Aims and Objectives
 To establish the methodology for recording Cutaneous silent
period in humans, from upper and lower limbs
 To determine the normative values of onset, latency and
duration from various muscles in upper and lower limbs
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10. Materials and Methods
• Total Number of Volunteers - 50
• M:F – 28:22 (p=0.56)
• Rt handed : Lt handed - 27:13 (p=0.82)
• Normal NCS
• Ethics committee
• Informed consent.
10

11. Equipment
• Nihon Kohden Neuropack from Nihon Kohden
inc, Japan
• Surface Electrodes – ring, disc
• Stimulator
• Single Simulus
11

12. Pilot Phase
• 6 subjects
• Muscles sampled
• APB, ADM, FDI, Biceps Brachii, Triceps, Deltoid
• Quadriceps, TA, Triceps Surae, Peronei, EDB, AH
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13. Pilot Phase
• 6 subjects
• Muscles sampled
• APB, ADM, FDI, Biceps Brachii, Triceps, Deltoid
• Quadriceps, TA, Triceps Surae, Peronei, EDB, AH
13

14. Patient’s Position
• Supine on couch
• Muscles contracted voluntarily on command
• Maximum voluntary contraction was assessed by audiovisual
feedback.
14

15. Electrode placement
• Stimulating Electrodes –
• Ring Electrodes UL
• Conventional Stimulator LL
• Recording Electrodes • Surface electrodes
• Standard Belly-Tendon Montage
15

16. System Settings
• Maximum voluntary contraction was assessed by audiovisual
feedback.
• filters - 2 Hz to 10 kHz.
• sweep - 20 ms/div for UL and 50 ms/div for LL.
• Sensitivity 0.5 mV to 2 mV/div depending on the amplitude of
voluntary activity.
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17. Stimulus Intensity
• maximal voluntary contraction
• single stimuli of increasing intensities and 0.3 ms duration on
pre specified points
• repeated till a silent period of reproducible latency and
duration was obtained.
• When this could not be achieved, stimulus duration was
increased in steps of 0.1 ms, up to 1.0 ms.
• .
17

18. Stimulus Intensity vs Latency, UL
1.2
1
Stimulus Intensity
0.8
0.6
Onset latency
0.4
0.2
0
20 mA
40 mA
P=0.002
P=0.034
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19. Stimulus Intensity vs Latency, LL
Stimulus Intensity
Onset latency
42 mA
50 mA
P=0.04
P=0.036
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20. Stimulus Intensity vs Duration, UL
Stimulus Intensity
Duration
20 mA
36 mA
P=0.012
P=0.0354
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21. Stimulus Intensity vs Duration, LL
Stimulus Intensity
Duration
46 mA
74 mA
P=0.086
P=0.01
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22. Stimulus Intensity
• Based on these findings
– single stimuli of increasing intensities and 0.3 ms duration on pre
specified points
– repeated till a silent period of reproducible latency and duration was
obtained.
– If this cannot be achieved, stimulus duration can be increased in steps of
0.1 ms, up to 1.0 ms.
For Upper Limbs – 0.3msec, 30-50mA
For Lower Limbs – 0.3msec, 46-65mA
• .
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23. Results…
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24. CuSP Lat, UL
Recording
Site
Stimulation Site
Latency in ms,
Mean (SD)
Right
P value
R value
Left
APB
II
72.6(6.6) 71.7(5.9)
0.02
0.88
APB
V
71.5(5.9) 72.4(6.2)
0.35
0.72
ADM
II
73.2(6.1) 74.6(5.8)
0.003
0.66
ADM
V
74.1(6.3) 73.9(5.9)
0.04
0.98
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25. CuSP Duration, UL
Recording Site
Stimulation Site
Duration in ms, Mean
(SD)
Right
P value
R value
Left
APB
II
38.6(8.2)
37.8(7.8)
0.0024
0.92
APB
V
32.4(6.5)
33.2(6.3)
0.52
0.54
ADM
II
30.62(6.2)
32.3(5.9)
0.08
0.78
ADM
V
35.6(5.8)
36.1(5.7)
0.3
0.92
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26. CuSP Lat, LL
Recording
Site
Stimulation Site
Latency in ms, Mean
(SD)
Right
P value
R value
Left
EDB
Superficial Peroneal
98.6(12.2)
97.2(10.8)
0.9
0.5
TA
Superficial Peroneal
94.2(8.8)
96.6(9.4)
0.6
0.73
AH
Sural nerve
0.02
0.6
105.4(9.2) 104.9(10.6)
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27. CuSP Duration, LL
Recording
Site
Stimulation Site
Duration in ms, Mean
(SD)
Right
P value
R value
Left
EDB
Superficial Peroneal
54.2(10.6)
52.8(14.8)
0.02
0.88
TA
Superficial Peroneal
44.8(8.6)
46.6(9.4)
0.05
0.65
AH
Sural nerve
48.9(9.2)
51.6(9.8)
0.023
0.69
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28. Conclusions
• Methodology
o - Distal UL, LL Muscles, Max. voluntary contraction.
o - Current > 36mA UL, >45mA LL, pulse width 0.3 msec.
o - Higher intensities may be needed in patients.
o - Filters - 2 Hz to 10 kHz.
o - Sweep - 20 ms/div for UL and 50 ms/div for LL.
o - Sensitivity 0.5 mV to 2 mV/div depending on the
o amplitude of voluntary activity.
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29. Conclusions
• Normative Data
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Upper Limb Latency – 62 to 86 msec *
Upper Limb Duration – 26 to 40 msec *
Lower Limb Latency – 78 to 120 msec *
Lower Limb Duration – 36 to 48 msec *
* - Mean ± 2SD
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31. Comparison with other modalities to
assess small fibre function
– Sympathetic skin response – No data
– Quantitative sensory testing - equal
» Grazia Devigili, Valeria Tugnoli, Paola Penza, Francesca Camozzi,
Raffaella Lombardi, Giorgia Melli, Laura Broglio, Enrico Granieri and
Giuseppe Lauria The diagnostic criteria for small fibre neuropathy: from
symptoms to neuropathology; Brain;Volume131, Issue7; Pp. 1912-1925.
– Quantitative sudo-motor axon reflex test – no data
– Skin biopsy – 88%sensitive, 92% specific
» Lauria G, Morbin M, Lombardi R, Borgna M, Mazzoleni G, Sghirlanzoni
A,et al. Axonal swellings predict the degeneration of epidermal nerve
fibers in painful neuropathies. Neurology 2003;61:631-6.
31

32. Cutaneous silent period changes in Type 2 diabetes
mellitus patients with small fiber neuropathy
M.R. Onala, U.H. Ulasa, O. Oza, V.S. Beka, M. Yucela,
A. Taslıpınarb, Z. Odabasıa
• Conclusion
• The CSP evaluation together with nerve conduction study, has
been demonstrated to be beneficial and performance of latency
difference in addition to CSP latency and duration may be a
valuable parameter in electrophysiological assessment of
diabetic patients with small fiber neuropathy.
• Significance
• An additional CSP evaluation may be considered in cases
which nerve conduction studies do not provide sufficient
information.
» Clinical Neurophysiology; Volume 121, Issue 5, Pages 714-718 (May 2010)
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33. Renshaw
Cell
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