Neuromuscular Junction Voice Disorders. Proposal of a Diagnostic Protocol

Abstract

We present our diagnostic protocol when neuromuscular conditions, due to voice abnormalities as the main symptom, are suspected, with special emphasis in NMJD. Results: We present our diagnostic protocol when a neuromuscular condition affecting the voice is suspected, emphasizing its benefits in NMJD. Neurophysiological studies are essential in the diagnosis, and we propose to perform them initially. Since NMJD could be due to secondary causes, we begin with electroneurography (ENG) to rule out neuropathies or motor neuron diseases. We follow with electromyography (EMG) to rule out myopathies that could also give secondary NMJD. If ENG and EMG were normal, repetitive nerve stimulation (RNS) is performed. Incremental or decremental responses would indicate different primary NMJD. If RNS was normal, but there is a high suspicion of NMJD, single fiber electromyography (SFEMG) is done. According to these results, laboratory tests are added. Tensilon and acetylcholine receptor antibody (AChR Ab) tests are equivocal and their role is discussed as part of the protocol. Conclusion:A detailed neurolaryngological examination along with neurophysiological studies can help otolaryngologists diagnose neuromuscular disorders when the altered voice is the primary complaint. Partnership with neurophysiologists and neurologists greatly improves patient care.