EMG/NCV in Diabetic Neuropathy and Carpal Tunnel Syndrome

Diabetic peripheral neuropathy and carpal tunnel syndrome are two of the most common reasons patients are referred for nerve conduction studies. India’s large diabetic population makes these tests a high-volume service for neurology clinics and diagnostic centres.

Diabetic peripheral neuropathy

Typical pattern: a length-dependent, symmetrical, sensory-predominant axonal neuropathy. It affects the feet first.

NCS findings:

• Reduced or absent sural SNAPs (often the earliest finding).
• Reduced peroneal and tibial CMAP amplitudes.
• Mild slowing of conduction velocity.

Why test? To confirm the diagnosis, grade severity, exclude other neuropathies and set a baseline for follow-up.

Carpal tunnel syndrome (CTS)

Typical pattern: compression of the median nerve at the wrist.

NCS findings:

• Prolonged median distal sensory and motor latencies.
• Slowed median sensory conduction across the wrist.
• Comparison studies (median vs ulnar or radial) increase sensitivity.
• In severe cases, needle EMG of the thenar muscles shows denervation.

Why test? To confirm CTS, grade severity and support decisions about splinting, injection or surgery.

A high-volume service

Because both conditions are common, electrodiagnosis brings steady referrals from diabetologists, orthopaedic surgeons and physicians. A portable, easy-to-use system with built-in protocols, such as the NEUROSTIM NS-2, suits OPD workflows well.

Good practice

• Warm limbs (cold slows conduction).
• Use standard distances and protocols.
• Use age-adjusted reference values.
• Combine results with clinical findings.

Read our NCS basics guide or see the EMG/NCV price guide.