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Compare Sequential NCV Tests

Lower Limb: Tibial and Peroneal Nerves

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Lower Limb:  NCV Tests Spaced 3 Weeks Apart

For my case of Guillain-Barre Syndrome, my neurologist performed two Nerve Conduction Velocity (NCV) tests spaced three weeks apart. The first NCV test was 10 days after the onset of symptoms. The second NCV test was four weeks from onset: this reflects the nadir, the point of maximum muscle weakness.

In this ascending symmetric paralysis, a single NCV test forms a snapshot of the damage to peripheral nerves at one point in time. Comparing two NCV tests side by side, performed a few weeks apart, shows the rate of disease progression. This page contains the NCV results for my lower limb (peroneal and tibial nerves), arranged in two columns:

Left column: NCV Test 1 / Graphs from September 29
Ten days from symptom onset

Right column: NCV Test 2 / Graphs from October 18
Four Weeks from onset (nadir)

An NCV test measures the compound muscle action potential (CMAP). This wave pulse is graphed as amplitude (in milliVolts) along a time axis (in milliseconds). A scale was assigned during the first NCV test, but when the second test was performed, the peak amplitudes had decreased, temporal dispersion was evident, and distal latency was markedly prolonged.

To keep each waveform centered on the page, the laboratory computer adjusted the scale of the X and Y axes; bear this in mind when comparing graphs. Each graph contains a compact table defining its own scale (see close-ups below).

NCV Test 1:  September 29
Peroneal and Tibial Nerves
M AMP/DIV ms/DIV TEST TIME
1 2.4 mV 2.0 15:42:29
2 2.4 mV 5.0 15:42:46
3 2.4 mV 2.0 15:44:23
4 2.4 mV 5.0 15:45:09

Vertical axis: Amplitude
Scale = 2.4 milliVolts per division

Horizontal axis: Time
Scale = 2 or 5 milliseconds per division

NCV Test 2:  October 18
Peroneal and Tibial Nerves
M AMP/DIV ms/DIV TEST TIME
1 2.4 mV 5.0 16:8:26
2 2.4 mV 5.0 16:8:39
3 0.9 mV 5.0 16:9:37
4 0.9 mV 5.0 16:9:49

Vertical axis: Amplitude
Scale = 2.4 or 0.9 milliVolts per division

Horizontal axis: Time
Scale = 5 milliseconds per division

Nerve Conduction Velocity Test 1 / Graph

Motor Nerves: Peroneal and Posterior Tibial CMAP
Horizontal Axis (Time): 2 ms per division (T1, T3)
5 ms per division (T2, T4)
Vertical Axis (Amplitude): 2.4 mV per division (all)
Polyneuropathy Onset / Nerve Conduction Velocity / Graph / Motor Nerves: Peroneal, Tibial CMAP Caliper 2ms and 5ms Caliper 2.4mV

Nerve Conduction Velocity Test 2 / Graph

Motor Nerves: Peroneal and Posterior Tibial CMAP
Horizontal Axis (Time): 5 ms per division (all)
Vertical Axis (Amplitude): 2.4 mV per division (T1, T2)
0.9 mV per division (T3, T4)
Acute Polyneuropathy / Nerve Conduction Velocity / Graph / Motor Nerves: Peroneal, Tibial CMAP Caliper 5ms Caliper Asterisk Caliper data / 2.4mV and 0.9mV

Nerve Conduction Velocity Test 1 / Table

Motor Nerves: Peroneal and Posterior Tibial CMAP
Polyneuropathy Onset / Nerve Conduction Velocity / Table / Motor Nerves: Peroneal, Tibial CMAP

Nerve Conduction Velocity Test 2 / Table

Motor Nerves: Peroneal and Posterior Tibial CMAP
Acute Polyneuropathy / Nerve Conduction Velocity / Table / Motor Nerves: Peroneal, Tibial CMAP

Nerve Conduction Velocity Test 1 / Report

Findings: Polyneuropathy
Polyneuropathy Onset / Nerve Conduction Velocity / Diagnostic Report

Nerve Conduction Velocity Test 2 / Report

Findings: Acute Polyneuropathy
Acute Polyneuropathy / Nerve Conduction Velocity / Diagnostic Report
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Georgena S. Sil
Saskatoon, Canada
Physicist & Technical Writer
Alumnus: University of British Columbia
TuumEstContact@protonmail.com

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