[How reliably does electromyography differentiate myopathies and neurogenic diseases?]

Electromyography is an essential part of neuromuscular diagnosis. Due to practicability, it mostly relies on qualitative judgement. Therefore, it is examiner dependent, and critical assessment of the EMG report is crucial. This may be furthered by (1) acquaintance with the genesis of the EMG, which has recently been rendered more transparent by computer simulation, and (2) experience with examiner-independent, quantitative diagnostic algorithms. By both approaches, it is intended to familiarize the reader with modern quality standards of EMG diagnosis. The diagnostic algorithm used to this end is discriminant MUP classification, which separated neurogenic and myopathic conditions without recourse to examiner judgements. This success shows that quantitative EMG, which has become available for routine practice, will add weight to EMG differential diagnosis.