Myasthenia gravis with presynaptic neurophysiological signs: Two case reports and literature review

Abstract

The distinction between myasthenia gravis and Lambert-Eaton myasthenic syndrome is based on clinical, neurophysiological and immunological features. We hereby report two cases with a clinical diagnosis of myasthenia gravis and neurophysiological features consistent with a pre-synaptic neuromuscular transmission defect. Both patients had increased anti-acetylcholine receptor antibody titres and showed a good response to cholinesterase inhibitors, along with a >100% facilitation of the compound muscle action potential on electrophysiological studies. We provide a review of English literature studies on co-existing features of myasthenia gravis and Lambert-Eaton myasthenic syndrome, and discuss diagnostic controversies.

Keywords: 3,4-Diaminopyridine; Cholinesterase inhibitors; Lambert–Eaton myasthenic syndrome; Myasthenia gravis; Presynaptic neurophysiological pattern.