Lowering the cutoff value for increment increases the sensitivity for the diagnosis of Lambert‐Eaton myasthenic syndrome

Muscle & Nerve, vol. 62, pp. 111–114

Abstract

BACKGROUND: Increment of compound muscle action potential amplitude is a diagnostic hallmark of Lambert-Eaton myasthenic syndrome (LEMS). Making a diagnosis can be challenging, therefore, a proper cutoff for abnormal increment is highly relevant for improved recognition of this rare disease. METHODS: We determined the sensitivity and specificity of 60% and 100% cutoff values in all consecutive patients who underwent increment testing in our hospital from 1999 to 2016. RESULTS: We included 156 patients, 63 with LEMS and 93 without LEMS. Sensitivity of a 60% cutoff for increment testing was 77.8% (95% confidence interval 65.5%-87.3%) and 58.7% (45.6%-71.0%) for 100%. Specificity was 98.9% (94.2%-100%) and 100% (96.1%-100%) using a threshold of 60% and 100%, respectively. CONCLUSIONS: Lowering the cutoff value for abnormal increment to 60% greatly increases sensitivity to diagnose LEMS without an overt loss in specificity.

Authors 4

1. Alexander F. Lipka corresponding Aachen Department of Neurology Leiden University Medical Center Leiden the Netherlands Department of Neurology, Leiden University Medical Center (LUMC)

   Leiden University Medical Center · Groene Hart Ziekenhuis

   Affiliation as printed

   Department of Neurology Groene Hart Hospital Gouda The Netherlands

   Department of Neurology Leiden University Medical Center Leiden The Netherlands

   Department of Neurology, Groene Hart Hospital, Gouda, The Netherlands

   Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands

2. Maarten J. Titulaer

   Erasmus MC

   Affiliation as printed

   Department of Neurology Erasmus University Medical Center Rotterdam The Netherlands

   Department of Neurology, Erasmus University Medical Center, Rotterdam, The Netherlands

3. Martijn Rudolf Tannemaat Aachen Department of Neurology Leiden University Medical Center Leiden the Netherlands Department of Neurology, Leiden University Medical Center (LUMC)

   Leiden University Medical Center

   Affiliation as printed

   Department of Neurology Leiden University Medical Center Leiden The Netherlands

   Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands

4. Jan J.G.M. Verschuuren Aachen Department of Neurology Leiden University Medical Center Leiden the Netherlands Department of Neurology, Leiden University Medical Center (LUMC)

   Leiden University Medical Center

   Affiliation as printed

   Department of Neurology Leiden University Medical Center Leiden The Netherlands

   Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands