Emergent technologies in clinical neurophysiology to study the neuromuscular system: IFCN handbook chapter

The present chapter of the new third series IFCN Handbook focuses on how peripheral neurophysiology may develop in the next five years or more. While some are clinical relevant, others are more experimental. The first three sections detail the possible futures of EMG, motor unit number estimation, surface EMG and movement. In a section on magnetoneurography, electrically induced signals are visualized in sensory nerves whilst that on magnetomyography shows how motor units may be identified in greater detail than with surface EMG. Electrical impedance methods for assessing nerve and muscle are considered, with the latter having been used clinically in several neurological conditions already. The section on microneurography describes how single nerve cells' response properties are related to RNA activity from dorsal root ganglion cells, leading to the identification of sixteen peripheral sensory nerve populations. Hyperexcitability syndromes can be difficult to diagnose, so nerve and muscle excitability testing, measuring membrane properties and ion channelopathies, shows clinical promise. The last section details ultrasound methods used in peripheral nerve and muscle disease and shows how ultrasound is becoming a necessary adjunct to nerve conduction studies and EMG. Common considerations between these methods' future include the greater use of artificial intelligence and that being non-invasive means they may be used for both diagnosis and long-term monitoring. Common barriers to wider availability include access to complex software and appropriate machines.