A nerve conduction velocity (NCV) test is a diagnostic procedure that measures the speed and strength of electrical signals traveling through nerves. It helps detect nerve damage or dysfunction associated with conditions such as carpal tunnel syndrome, peripheral neuropathy, and nerve compression disorders.

SSEP: Somatosensory Evoked Potential: SSEP’s assess the speed of electrical conduction across the spinal cord and are sometimes ordered for patients with back pain. If the spinal cord is significantly pinched, the electrical signals will travel slower than usual. SSEP’s may also be used to monitor spinal cord function during surgical procedures, although since the spinal cord ends before the lumbar spine, this is usually of limited value during lumbar spinal surgery and it is used more often in cervical (neck) or thoracic (chest) spine surgery.

Sympathetic Skin Repsonse (SSR): Sympathetic skin response (SSR), defined as the momentary change of the electrical potential of the skin, may be spontaneous or reflexively evoked by a variety of internal or by externally applied arousal stimuli. Although the suprasegmental structures influencing the SSR in humans are not well known, SSR has been proposed as a non-invasive approach to investigate the function of the sympathetic system. SSR is easy to apply but current procedures are not sufficiently reliable for diagnostic purposes, and show imperfect correlations both with clinical features and other measurements of autonomic, in particular, sudomotor dysfunction.

Procedure Breakdown:

1. Preparation:
   • Patients should avoid applying lotions or oils to the skin before the test to ensure proper electrode contact.
   • No fasting or special preparations are required.
2. Electrode Placement:
   • Small electrode patches are placed on the skin over the nerve being tested.
   • One electrode stimulates the nerve with a mild electrical impulse, while the others record the response.
3. Nerve Stimulation & Signal Measurement:
   • A low-level electrical current is delivered through the stimulating electrode.
   • The response is recorded to measure how fast and efficiently the nerve transmits signals.
4. Repeated Testing (if needed):
   • Multiple nerves in different locations may be tested for comparison.
   • NCV may be performed alongside an electromyography (EMG) test to assess muscle activity.
5. Completion & Results:
   • The procedure typically lasts 30–60 minutes and is well-tolerated, with only mild discomfort from the electrical impulses.
   • A specialist interprets the results to determine if there is nerve damage, its location, and possible causes.

An NCV test is a crucial tool for diagnosing nerve-related conditions, helping doctors develop appropriate treatment plans.