The logical choice of muscles for the needle-EMG evaluation of lumbosacral radiculopathy

The objective of this study was to find the theoretically smallest subsets of muscles for needle-EMG (nEMG) screening of lumbosacral radiculopathies that ascertain that each root and its adjacent roots are represented by at least two muscles each, innervated by those roots via different peripheral nerves.A 23 and a 30 muscles muscle-sets and their myotomal innervation where derived from the literature, and rearranged into 15 and 19 unique muscle-groups by root and peripheral nerve innervation. All 215 and 219 subset combinations thereof were respectively identified. The criteria above were computed for each subset and the smallest subsets that qualified were retained. The number of muscles sampled per damaged root and the number of muscles sampled per adjacent roots in compliance with the objective above were computed.The smallest subsets satisfying the objective above were of 6, 7 and 9 muscles each, and are enumerated in Table 3 and Table 4. From these tables, each electromyographer may choose a set that best suits him, confident of its diagnostic parameters, while inflicting the least pain onto his patients, utilizing the shortest possible procedure, concluding a screen of all the roots at once, a screen that best differentiate between normal and damaged roots, and in most cases adequate for reaching the final diagnosis. Moreover, when needed, each set may be the basis for a more extensive workup.