Abstract Details

Title Use of Repetitive Nerve Stimulation in the Geisinger Health System Neurophysiology Laboratory

Topic Neuromuscular and Clinical Neurophysiology (EMG)

Presentation(s) P1 - Poster Session 1 (9:00 AM-5:00 PM)

Poster/Presentation
Number 396

Objective To analyze the use of repetitive nerve stimulation (RNS) in the Geisinger Neurophysiology laboratory.

Background RNS is a special type of electrodiagnostic study used to evaluate for neuromuscular junction disorders. The test can be time consuming, technically challenging, and poorly tolerated by patients. Therefore, proper patient selection is critical. Acetylcholine receptor binding antibodies (AChR Ab) are the most specific test for myasthenia gravis (MG).

Design/Methods We reviewed RNS studies ordered and/or performed from January 2015 to December 2018 across the Geisinger Health System. We obtained indications for RNS, setting (outpatient or inpatient), nerves tested, study results, and testing of AChR Ab.

Results Ninety-one studies were reviewed. The most common indication was suspicion of MG (75%), either clearly stated in the RNS request (34%) or based on symptoms suggestive of the disease: Eyelid ptosis and/or diplopia (12%), bulbar weakness (7%), and weakness in other regions (22%). Most studies were ordered in the outpatient setting (87%). Nerves tested included: Ulnar (53%), median (31%), spinal accessory (25%), facial (18%), and fibular (23%). A single nerve was tested in 50 studies (55%) and multiple nerves in 39 studies (43%). RNS was interpreted as normal in 82 cases (90%), abnormal in 6 (7%) and equivocal in 1 (1%). In 2 cases, RNS was requested but not performed (2%). AChR Ab were ordered together with RNS in 35 cases (38%). Of those, 32 were negative (35%) and 3 were positive (3%). Five cases (6%) had previously positive AChR Ab when RNS was ordered. Thirty-one cases (34%) had negative AChR Ab before RNS was ordered.

Conclusions The selection of nerves for RNS varied widely in our laboratory. The yield of RNS was relatively low. The biggest opportunity for improvement is the creation of a system-based stepwise approach for the evaluation of MG, which includes testing AChR Ab before RNS

Authors/Disclosures
Christopher A. Houck, MD (Geisinger Medical Center) PRESENTER	Dr. Houck has nothing to disclose.
J. David Avila, MD, FAAN (Geisinger Medical Center)	Dr. Avila has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for AstraZeneca. Dr. Avila has received personal compensation in the range of $50,000-$99,999 for serving on a Speakers Bureau for Alnylam Pharmaceuticals. Dr. Avila has received personal compensation in the range of $10,000-$49,999 for serving on a Speakers Bureau for argenx. Dr. Avila has received personal compensation in the range of $10,000-$49,999 for serving on a Speakers Bureau for Alexion Pharmaceuticals. Dr. Avila has received personal compensation in the range of $10,000-$49,999 for serving on a Speakers Bureau for UCB. Dr. Avila has received personal compensation in the range of $10,000-$49,999 for serving on a Speakers Bureau for AstraZeneca. Dr. Avila has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Takeda.

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