Electrodiagnostic criteria for neuromuscular transmission disorders suggested by a European consensus group

Electrodiagnostic testing plays an important role in diagnosing disorders of neuromuscular transmission (NMT), especially in seronegative myasthenia gravis. However, electrodiagnostic criteria for the diagnosis are sparse. This study aimed at inferring evidence-based recommendations for the electrodiagnostic examination of NMT disorders.

A total of 164 cases with a consensus diagnosis of NMT disorder obtained by peer review by eight experienced neurophysiologists were analysed for differences in examination strategy, the sensitivity of different tests, and inferring minimal criteria. The diagnostic performance of the suggested criteria was validated on 24 MG patients and 50 patients with neuropathy (17), myopathy (15), or fatigue (18).

We recommend as minimal electrodiagnostic criteria for NMT disorders, either (a) 2 abnormal repetitive nerve stimulation (RNS), (b) 1 abnormal RNS and 1 abnormal single fiber electromyography (SFEMG) or (c) 2 abnormal SFEMG. These showed a good diagnostic performance with a sensitivity of 87.5 % and a specificity of 100 %.

Recommendations with high diagnostic sensitivity and specificity for the minimum number of RNS and SFEMG studies to diagnose NMT disorders developed by an international consensus group are suggested.

The suggested electrodiagnostic recommendations for diagnosing NMT disorders are reliable and suitable for use at different centres.