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

Cutaneous Silent Period

• Introduction

• Need for the study

• Aims and Objectives

• Materials and Methods

• Results

• Discussion

• Conclusions

3

Outline for the session

• 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

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Can be recorded from…

• Most skeletal muscles

• More pronounced in the distal muscles

• Consistent, reproducible

• Can be recorded on conventional EP equipment

• Non Invasive

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Importantly ……

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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

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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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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.

Equipment

• Nihon Kohden Neuropack from Nihon Kohden

inc, Japan

• Surface Electrodes – ring, disc

• Stimulator

• Single Simulus11

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Pilot Phase

• 6 subjects

• Muscles sampled

• APB, ADM, FDI, Biceps Brachii, Triceps, Deltoid

• Quadriceps, TA, Triceps Surae, Peronei, EDB, AH

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Pilot Phase

• 6 subjects

• Muscles sampled

• APB, ADM, FDI, Biceps Brachii, Triceps, Deltoid

• Quadriceps, TA, Triceps Surae, Peronei, EDB, AH

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Patient’s Position

• Supine on couch

• Muscles contracted voluntarily on command

• Maximum voluntary contraction was assessed by audiovisual

feedback.

Electrode placement

• Stimulating Electrodes –

• Ring Electrodes UL

• Conventional Stimulator LL

• Recording Electrodes -

• Surface electrodes

• Standard Belly-Tendon Montage

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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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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.

• .

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Stimulus Intensity vs Latency, UL

0

0.2

0.4

0.6

0.8

1

1.2

20 mA 40 mA

Stimulus Intensity

Onset latency

P=0.002 P=0.034

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Stimulus Intensity vs Latency, LL

42 mA 50 mA

Stimulus Intensity

Onset latency

P=0.04 P=0.036

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Stimulus Intensity vs Duration, UL

20 mA 36 mA

Stimulus Intensity

Duration

P=0.012 P=0.0354

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Stimulus Intensity vs Duration, LL

46 mA 74 mA

Stimulus Intensity

Duration

P=0.086 P=0.01

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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

• .

Results…

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CuSP Lat, UL

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Recording

Site

Stimulation Site Latency in ms,

Mean (SD)

P value R value

Right 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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Recording Site Stimulation Site Duration in ms, Mean

(SD)

P value R value

Right 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

CuSP Duration, UL

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Recording

Site

Stimulation Site Latency in ms, Mean

(SD)

P value R value

Right 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 105.4(9.2) 104.9(10.6) 0.02 0.6

CuSP Lat, LL

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Recording

Site

Stimulation Site Duration in ms, Mean

(SD)

P value R value

Right 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

CuSP Duration, LL

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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Conclusions

• Normative Data

• 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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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.

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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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Renshaw

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