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Compare Sequential NCV Tests

F Waves and Upper Limb (Median/Ulnar)

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Upper Limb:  NCV Tests Spaced 3 Weeks Apart

When I developed symmetric ascending muscle weakness, my neurologist performed two Nerve Conduction Velocity (NCV) tests spaced three weeks apart. The diagnosis was classic Guillain Barre Syndrome, where an autoimmune process dissolves the myelin insulation of peripheral nerves, and sometimes the axon. Weakness rapidly turns into paralysis.

The NCV tests were performed 10 days and four weeks, respectively, from symptom onset. The rapid evolution of Guillain-Barre can readily be visualized by comparing sequential Nerve Conduction tests side-by-side. This page contains the NCV results for my upper limb (median and ulnar 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)

The first NCV portrays a polyneuropathy taking hold; the second NCV portrays the nadir, the point of maximum muscle weakness. Over intervening weeks, the amplitude of the compound muscle action potential (CMAP) decreased, there was temporal dispersion, and distal latency became markedly prolonged.

The changes were so severe that for the second test, the lab of necessity changed the scale on the graphs – for both the vertical axis (amplitude) and the horizontal axis (time). This must be kept in mind for accurate comparisons. Each graph displays a compact table defining the scale (see close-ups below).

NCV Test 1:  September 29
Median and Ulnar Nerves
M AMP/DIV ms/DIV TEST TIME
1 4.9 mV 2.0 15:48:06
2 4.9 mV 2.0 15:48:13
3 4.9 mV 2.0 15:49:05
4 4.9 mV 2.0 15:49:14
5 4.9 mV 2.0 15:49:21

Vertical axis: Amplitude
Scale = 4.9 milliVolts per division

Horizontal axis: Time
Scale = 2 milliseconds per division

NCV Test 2:  October 18
Median and Ulnar Nerves
M AMP/DIV ms/DIV TEST TIME
1 2.4 mV 5.0 16:14:14
2 2.4 mV 5.0 16:14:21
3 2.4 mV 5.0 16:15:05
4 2.4 mV 5.0 16:15:11
5 2.4 mV 2.0 16:15:17

Vertical axis: Amplitude
Scale = 2.4 milliVolts per division

Horizontal axis: Time
Scale = 5 milliseconds per division

Nerve Conduction Velocity Test 1 / Graph

Motor Nerves: Median and Ulnar CMAP
Horizontal Axis (Time): 2.0 ms per division
Vertical Axis (Amplitude): 4.9 mV per division
Polyneuropathy Onset / Nerve Conduction Velocity / Graph / Motor Nerves: Median, Ulnar CMAP Caliper 2ms Caliper 4.9mV

Nerve Conduction Velocity Test 2 / Graph

Motor Nerves: Median and Ulnar CMAP
Horizontal Axis (Time): 5.0 ms per division
Vertical Axis (Amplitude): 2.4 mV per division
Acute Polyneuropathy / Nerve Conduction Velocity / Graph / Motor Nerves: Median, Ulnar CMAP Caliper 5ms Caliper 2.4mV

Nerve Conduction Velocity Test 1 / Table

Motor Nerves: Median and Ulnar CMAP & F Waves
Polyneuropathy Onset / Nerve Conduction Velocity / Table / Motor Nerves: Median, Ulnar CMAP plus F Waves

Nerve Conduction Velocity Test 2 / Table

Motor Nerves (Median, Ulnar), Sensory Nerves, F Waves
Acute Polyneuropathy / Nerve Conduction Velocity / Table / Motor (Median, Ulnar), Sensory, F Waves

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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