LAUSR

Movement disorders are clinical syndromes which present either an increase or decrease of voluntary and involuntary movements. Although the neural mechanism underlying most of these syndromes involves the central nervous system, a much smaller group has a peripheral nervous system aetiology. While surface electromyography (EMG) is more conventionally used in movement disorders in order to characterize the abnormal muscle contractions, it is not as useful in the study movement disorders of peripheral origin. Nevertheless, conventional needle EMG provides information enough to determine the origin and suffices for diagnosis in these syndromes. We have revised all the movement disorders cases between 2015 and 2018. They were referred to our laboratory for a surface EMG study. In these period, 63 patients were studied. 3 of these patients (less than 5%) were finally diagnosed of a peripheral movement disorder. All the 3 patients were referred to the EMG department with the diagnosis of a central nervous system movement disorder. Due to the clinical examination, we suspected a peripheral involvement and thus, needle EMG was performed instead. EMG findings (fasciculations, fibrillations, normal MUPs) led to the diagnosis of a continuous muscle fibre activity syndrome of peripheral origin. Peripheral movement disorders are an infrequent condition and therefore difficult to suspect. Needle EMG studies are decisive for the correct diagnosis in this syndromes. Conventional needle EMG, even if not established as part of the diagnostic protocol, may contribute in those cases in which questions about a central or peripheral origin arise, since clinical manifestations often overlap.