Makindo Medical Notes

⚡ Nerve Conduction Studies (NCS) are diagnostic tests used to assess the function of motor and sensory nerves. They are vital for diagnosing neuropathies, nerve compression syndromes, and other peripheral nerve disorders. Often combined with Electromyography (EMG) for a complete neuromuscular assessment.

🎯 Purpose of NCS

• Diagnosis 🧾:
  • Detect nerve damage or dysfunction.
  • Differentiate between motor vs sensory involvement.
  • Localise the site of nerve injury.
  • Assess severity and extent of nerve damage.
• Monitoring 🔄:
  • Track progression of neuropathies (e.g. diabetic).
  • Evaluate response to treatments.

🧪 Procedure

Small electrical impulses stimulate a nerve while surface electrodes record the response. The key parameters measured are **latency, amplitude, and conduction velocity**.

• Preparation 🛠️ – Clean skin, position patient comfortably.
• Electrodes ⚡ – Stimulating electrode over nerve; recording electrode over muscle/sensory distribution.
• Stimulation – Deliver a brief electrical impulse.
• Recording – Display latency (ms), amplitude (mV/µV), and velocity (m/s) on monitor.
• Repeat – For different nerves/sites as needed.

📊 Parameters Measured

• Latency ⏱️ – Time from stimulus to response. Prolonged → demyelination or compression.
• Amplitude 📉 – Size of waveform (number of fibres firing). Reduced → axonal loss.
• Conduction Velocity 🚀 – Speed of impulse. Slowed → demyelination.

🧠 Clinical Applications

• Peripheral Neuropathy 🩺: Diabetic, alcoholic, idiopathic.
• Nerve Compression 🤲: Carpal tunnel, ulnar neuropathy, radial palsy.
• Radiculopathy 🌐: Cervical or lumbosacral root lesions.
• Neuromuscular Disorders ⚡: Guillain-Barré, CIDP.
• Trauma 🚑: Assess recovery or extent of nerve injury post-surgery.

🔍 Interpretation

Results are compared to reference values (age, sex, limb length, and temperature matter!). Patterns help distinguish **axonal vs demyelinating pathology**, and **localise lesions**.

• ⏱️ Prolonged Latency → demyelination / conduction block.
• 📉 Reduced Amplitude → axonal loss.
• 🐌 Slowed Conduction Velocity → demyelination or compression.

⚠️ Limitations

• Technical 🧪 – Poor electrode placement, cold limbs.
• Patient Factors 👵 – Age, limb length, temperature affect results.
• Complementary Tests ➕ – EMG for muscle fibre assessment.

📌 Summary

Nerve Conduction Studies are key to diagnosing and monitoring nerve disorders. They measure latency, amplitude, and conduction velocity to distinguish axonal from demyelinating pathology. When combined with EMG, they form the gold standard for evaluating neuromuscular disease.