Premium
Sensitivity and specificity of repetitive nerve stimulation with lower cutoffs for abnormal decrement in myasthenia gravis
Author(s) -
Lamb Christopher J.,
Rubin Devon I.
Publication year - 2020
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.26999
Subject(s) - myasthenia gravis , repetitive nerve stimulation , medicine , ulnar nerve , stimulation , cutoff , neuromuscular transmission , electromyography , anesthesia , surgery , elbow , physical medicine and rehabilitation , physics , quantum mechanics
The sensitivity of repetitive nerve stimulation (RNS) in myasthenia gravis (MG) is dependent on the cutoff for abnormal decrement. Methods RNS data of adults with and without MG from 2014 to 2017 were reviewed retrospectively. The maximum reliable RNS amplitude/area decrement before and after exercise from facial, spinal accessory (SA), ulnar, and fibular nerves was recorded. Sensitivity/specificity using 5%, 7%, and 10% cutoffs were calculated. Results Seventy‐nine of 141 patients had MG (46 generalized, 21 ocular, 12 bulbar). A total of 608 unique RNS recordings were analyzed. Overall RNS sensitivity/specificity at ≥5%, ≥7%, and ≥10% amplitude cutoffs were as follows: SA, 65.6%/86.3%, 49.2%/94.1%, and 29.5%/96.1%; facial, 51.0%/82.5%, 43.1%/95.0%, and 37.3%/100%; ulnar, 43.6%/100%, 41.0%/100%, and 41.0%/100%; and fibular, 52.6%/89.5%, 42.1%/94.7%, and 42.1%/100%. Discussion Lowering amplitude cutoff from 10% to 7% increased or maintained sensitivity with little loss in specificity. Post‐exercise and area analysis resulted in increased sensitivity in some circumstances.