Enter Study Inputs
The page stays single-column, while the calculator fields adapt to large, medium, and mobile screens.
Example Data Table
| Study | Distance (mm) | Distal Latency (ms) | Proximal Latency (ms) | Temperature (°C) | Velocity (m/s) | Comment |
|---|---|---|---|---|---|---|
| Median Motor Upper | 120 | 3.10 | 5.40 | 32.0 | 52.17 | Within a common upper limb motor range. |
| Ulnar Motor Upper | 100 | 2.80 | 5.00 | 31.5 | 45.45 | Borderline before temperature adjustment. |
| Tibial Motor Lower | 140 | 4.00 | 7.80 | 32.0 | 36.84 | Below many lower limb motor references. |
| Sural Sensory Lower | 120 | 2.50 | 5.20 | 31.0 | 44.44 | Correction may shift the final comparison. |
Formula Used
Core velocity formula
NCV = Distance / (Proximal Latency - Distal Latency)
When distance is entered in millimeters and latency in milliseconds, the result is directly expressed in meters per second.
Temperature-adjusted velocity
Adjusted Velocity = Raw Velocity + Coefficient × (Reference Temperature - Measured Temperature)
This is a simplified engineering correction model for comparing studies collected at different limb temperatures.
Amplitude drop
Amplitude Drop (%) = (Distal Amplitude - Proximal Amplitude) / Distal Amplitude × 100
This adds context for segment attenuation and waveform reduction across the tested path.
Uncertainty estimate
σv = v × √[(σd / d)² + (σt / Δt)²]
This uses simple propagation of measurement uncertainty from distance tracing and latency marking error.
How to Use This Calculator
- Choose the nerve segment type or switch to a custom reference limit.
- Enter the measured distance between stimulation points in millimeters.
- Enter distal and proximal onset latencies in milliseconds.
- Add the measured limb temperature and the comparison reference temperature.
- Keep temperature correction enabled if you want normalized comparison values.
- Optionally enter distal and proximal amplitudes for attenuation analysis.
- Add measurement errors to estimate uncertainty around the raw velocity.
- Press Calculate Velocity to show the result above the form, download CSV, or save a PDF report.
Frequently Asked Questions
1. What does nerve conduction velocity measure?
It measures how fast an electrical impulse travels across a tested nerve segment. The calculator estimates speed from distance and latency difference between two stimulation points.
2. Why are both proximal and distal latencies needed?
Using both values removes fixed delays that do not belong to the segment itself, such as neuromuscular junction and muscle activation components. That makes the segment velocity estimate more meaningful.
3. Why does temperature correction matter?
Cooler limbs often produce slower measured velocities. Applying a simple correction helps compare studies collected at different temperatures against a common reference condition.
4. Can I calculate velocity with only one stimulation site?
Not with this method. The calculation depends on a latency difference between two sites. One site alone does not isolate the conduction time of the tested segment.
5. What does a slow value usually suggest?
A slower value means the measured segment conducts below the chosen reference threshold. It can reflect cooling, technical error, or physiological slowing. Final interpretation should be done by a qualified specialist.
6. What is the purpose of the amplitude inputs?
They help estimate signal drop between distal and proximal stimulation. A large reduction can indicate attenuation, conduction block, poor electrode contact, or inconsistent waveform capture.
7. How accurate is the uncertainty estimate?
It is a simplified propagation model. It is useful for comparing setup quality and sensitivity to input errors, but it does not replace a full uncertainty analysis from instrument calibration.
8. Is this calculator suitable for diagnosis?
No. It is designed for technical estimation, education, and reporting support. Clinical diagnosis requires waveform review, full study context, and expert interpretation.