Lamb CJ and Rubin DI. Muscle Nerve 2020.
ABSTRACT
INTRODUCTION: 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 2014-2017 was 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). Six hundred eight unique RNS recordings were analyzed. Overall RNS sensitivity/specificity at ≥5%, ≥7%, and ≥ 10% amplitude cutoffs were: SA 65.6%/86.3%, 49.2%/94.1%, 29.5%/96.1%; Facial 51.0%/82.5%, 43.1%/95.0%, 37.3%/100%; Ulnar 43.6%/100%, 41.0%/100%, 41.0%/100%; Fibular 52.6%/89.5%, 42.1%/94.7%, 42.1%/100%.
CONCLUSION: Lowering amplitude cutoff from 10% to7% increased or maintained sensitivity with little loss in specificity. Post-exercise and area analysis resulted in increased sensitivity in some circumstances. This article is protected by copyright. All rights reserved.
PMID:32530515 | DOI:10.1002/mus.26999
Source: https://pubmed.ncbi.nlm.nih.gov/3253051 ... 17&v=2.8.0
