2024 Workshop Handout Bundle-W27AS Repetitive Nerve Stimulation Harrison

W27AS Repetitive Nerve Stimulation Harrison

Pdf Summary

The document is a comprehensive guide on repetitive nerve stimulation (RNS), primarily authored by Taylor Harrison, MD, and presented at the 2024 AANEM Annual Meeting. This workshop handout, prepared originally in May 1984 and updated by the AANEM Education Committee in 1995, serves to provide essential background information and support for hands-on workshop sessions in RNS.<br /><br /><strong>Key Points Covered:</strong><br /><br /><strong>Normal Physiology:</strong><br />- Understanding the normal neuromuscular junction physiology is crucial for electrodiagnostic studies involving RNS.<br />- The process involves the depolarization of nerve terminals leading to the release of acetylcholine (Ach), which binds to post-synaptic receptors and triggers muscle contraction.<br />- The 'safety factor' is the difference between the end plate potential (EPP) and the required depolarization for muscle action potential, highlighting its importance in diagnosing neuromuscular disorders.<br /><br /><strong>Disease Physiology:</strong><br />- In myasthenia gravis, autoantibodies affect Ach receptors, leading to decreased safety factors and reduced muscle fiber depolarization, visible as a decremental response in RNS.<br />- Lambert-Eaton Myasthenic Syndrome (LEMS) involves autoantibodies that reduce calcium conductance in nerve terminals, resulting in decreased Ach release and similar decremental responses on RNS.<br />- Botulism affects neurotransmission by preventing Ach vesicle docking and release, showing decremental and incremental responses on RNS and post-activation facilitation.<br /><br /><strong>Performance of RNS:</strong><br />- Patients undergo routine sensory and motor nerve conduction studies before RNS.<br />- Accurate technique and careful attention to stimulation parameters (supramaximal stimulation) are critical to avoid false positives.<br />- Slow RNS (2-3 Hz) is typically used, and multiple nerve-muscle pairs are studied to increase sensitivity, especially in proximal muscles.<br /><br /><strong>Recommended Reporting:</strong><br />- Reports should include details on the number of stimuli, rate of stimulation, muscle state during stimulation, and calculation method for decrement/increment.<br />- Waveforms should be included for independent review by referring physicians.<br /><br /><strong>Special Considerations:</strong><br />- In myasthenia gravis, post-exercise facilitation can help repair decremental responses.<br />- In LEMS and botulism, RNS shows unique profiles that aid in diagnosis.<br /><br />The document also cites key references and emphasizes the importance of continuous limb temperature monitoring during RNS to ensure accurate results. The inclusion of practical examples and figures helps highlight the methodology and potential technical pitfalls in conducting and interpreting RNS studies.

Keywords

Repetitive Nerve Stimulation

Taylor Harrison MD

AANEM Annual Meeting 2024

Neuromuscular Junction Physiology

Myasthenia Gravis

Lambert-Eaton Myasthenic Syndrome

Botulism

Electrodiagnostic Studies

Safety Factor

Supramaximal Stimulation