What is a Nerve Conduction Study (NCS)?
A Nerve Conduction Study (NCS) is a diagnostic test used to measure how fast and effectively electrical signals travel through your peripheral nerves. It helps determine whether a nerve is damaged and, if so, how severely.
It is often done alongside Electromyography (EMG) as part of a comprehensive electrodiagnostic evaluation.
Purpose of a NCS
NCS helps evaluate:
- Nerve damage (neuropathy)
- Nerve compression (e.g., carpal tunnel syndrome)
- Nerve degeneration (e.g., diabetic neuropathy)
- Transmission speed in sensory and motor nerves
How the Test Works
| Step | Description |
|---|---|
| Electrode Placement | Surface electrodes are placed on the skin over nerves and muscles. |
| Electrical Stimulation | A small, brief electrical pulse is delivered to the nerve. |
| Response Recording | The speed and strength of the nerve’s response are measured. |
| Data Interpretation | Results show how well the nerve conducts signals and whether there’s a block or delay. |
What NCS Measures
| Measure | Description |
|---|---|
| Latency | Time it takes for a signal to reach a muscle |
| Conduction Velocity | Speed at which the signal travels along the nerve |
| Amplitude | Strength of the nerve or muscle response |
Is It Painful?
- The electrical impulses may cause a brief tingling or snapping sensation.
- It’s non-invasive and generally well-tolerated.
- No needles are used (unlike EMG).
Conditions Diagnosed with NCS
| Category | Examples |
|---|---|
| Compression neuropathies | Carpal tunnel syndrome, ulnar neuropathy |
| Peripheral neuropathy | Due to diabetes, alcoholism, or vitamin deficiencies |
| Radiculopathy | Nerve root compression from a herniated disc |
| Neuromuscular disorders | Guillain-Barré syndrome, CIDP |
| Nerve injuries | Trauma-related damage |
✅ Summary
- NCS = Measures electrical conduction in nerves using surface electrodes
- Non-invasive, quick, and often combined with EMG
- Helps localize and characterize nerve dysfunction