Neurophysiological approaches to movement disorders

Abstract This chapter outlines the application of clinical neurophysiological techniques in the assessment and management of movement disorders. Emphasis is placed on the integration of electroencephalography-electromyography (EEG-EMG) studies, including back-averaging and the C-reflex, for the classification of myoclonus subtypes. The use of multi-channel surface EMG is described for the analysis of jerks, tremor, dystonia and tics, providing insight into muscle activation patterns and intermuscular coherence. Emerging diagnostic roles for neurophysiology in the context of movement disorder phenotyping are also discussed. Finally, the chapter addresses the most common EMG-guided treatment technique, EMG-guided botulinum neurotoxin injection, for dystonia and tremor, highlighting technical considerations for accuracy and efficacy. Overall, this chapter serves as a practical guide for applying neurophysiological tools to improve diagnostic precision and therapeutic planning in movement disorders. (Key reflex studies relevant to movement disorders can be found in the ‘Reflex studies’ section of Chapter 6, including long-latency reflexes, startle response and blink reflex testing; neuromodulation therapies, such as deep brain stimulation, are discussed in Chapter 16.)