Nerve Conduction Studies

Referral Criteria for Nerve Conduction Studies (NCS) and Electromyography (EMG)

General Principles

1. The referral MUST state the clinical question to be answered.
2. There should be a reasonable chance of answering the clinical question.
3. There is a reasonable chance that NCS/EMG will guide patient management.
4. The relevant history and examination findings MUST be detailed.
5. The patient is likely to be able to tolerate the tests.
6. NCS/EMG should not be requested when there are more appropriate alternative investigations such as imaging.
7. The risks of needle EMG are justified e.g. anticoagulation
8. Complex cases should not be referred by junior medical staff or AHPS without discussing with their supervising senior clinician first. Neurophysiology should not be used as a substitute for senior clinical review.

Common scenarios when NCS/EMG is unlikely to be helpful

1. Intermittent ulnar sensory symptoms only.
2. Entrapment syndromes where neurophysiology is of dubious diagnostic value such as radial tunnel syndrome, meralgia paraesthetica and piriformis syndrome.
3. Pure small fibre neuropathy symptoms (burning and/or pain) with preserved reflexes. Standard neurophysiology assesses large nerve fibre function and will usually be normal.
4. Patients with diabetes and symptoms or signs of length dependent distal symmetrical neuropathy. Neurophysiology will not inform if neuropathy is due to diabetes or another cause.
5. Diffuse pain syndromes or nonspecific muscle discomfort.
6. Hemi- sensory or motor symptoms particularly if intermittent.
7. Non-specific fatigue symptoms.
8. Investigation of radiculopathy – MRI has a higher diagnostic yield. Neurophysiology not useful if mainly sensory or painful radicular symptoms.
9. Single fibre EMG for myasthenia gravis when antibody testing clearly positive.

This is not an exhaustive list and investigations should be guided by the individual clinical picture. Where there is uncertainty about whether a patient would benefit from referral please discuss with on call neurophysiology consultant by email ggc.neurophysoncall@nhs.scot