Optimal E2 (reference) electrode placement in fibular motor nerve conduction studies recording from the tibialis anterior muscle

Abstract

elucidate a definitive time frame in which recovery was obtained. In addition, the scope of analysis was limited because of the small sample and lack of controls. However, the time of recovery was similar to that in a previous EMG outcome study. 3 This report describes EMG findings of recovery after decompression of paralabral cysts at the suprascapular or spinoglenoid notch with arthroscopy or ultrasound-guided aspiration. Our results show that neurophysiological findings of nerve entrapment normalized after decompression. Long-term studies with more patients and follow-ups are required to determine time to recovery.We thank Nicole Hurwitz, BS, and Jennifer Cheng, PhD, for their assistance with the manuscript preparation process.Ethical Publication Statement: We confirm that we have read the Journal's position on issues involved in ethical publication and affirm that this report is consistent with those guidelines. 2. Fehrman DA, Orwin JF, Jennings RM. Suprascapular nerve entrapment by ganglion cysts: a report of 6 cases with arthroscopic findings and review of the literature. Arthroscopy 1995;11 (6):727-734. 3. Feinberg JH, Nguyen ET, Boachie-Adjei K, Gribbin C, Lee SK, Daluiski A, et al. The electrodiagnostic natural history of Parsonage-Turner syndrome. Muscle Nerve 2017;56(4):737-743. 4. Ferretti A, De Carli A, Fontana M. Injury of the suprascapular nerve at the spinoglenoid notch. The natural history of infraspinatus atrophy in volleyball players. Am J Sports Med 1998;26(6):759-763. 5. Zehetgruber H, Noske H, Lang T, Wurnig C. Suprascapular nerve entrapment. A meta-analysis. Int Orthop 2002;26(6):339-343. 6. Arriaza R, Ballesteros J, Lopez-Vidriero E. Suprascapular neuropathy as a cause of swimmer's shoulder: results after arthroscopic treatment in 4 patients. Am J Sports Med 2013;41(4):887-893. 7. Shah AA, Butler RB, Sung SY, Wells JH, Higgins LD, Warner JJ. Clinical outcomes of suprascapular nerve decompression. J Shoulder Elbow Surg 2011;20(6):975-982. 8. Krarup C, Boeckstyns M, Ibsen A, Moldovan M, Archibald S. Remodeling of motor units after nerve regeneration studied by quantitative electromyography. Clin Neurophysiol 2016;127(2):1675-1682. 9. Hill LJ, Jelsing EJ, Terry MJ, Strommen JA. Evaluation, treatment, and outcomes of suprascapular neuropathy: a 5-year review. PM R 2014; 6(9):774-780. 10. Westerheide KJ, Dopirak RM, Karzel RP, Snyder SJ. Suprascapular nerve palsy secondary to spinoglenoid cysts: results of arthroscopic treatment. Arthroscopy 2006;22(7):721-727. 11. Lafosse L, Tomasi A, Corbett S, Baier G, Willems K, Gobezie R. Arthroscopic release of suprascapular nerve entrapment at the suprascapular notch: technique and preliminary results. Arthroscopy 2007;23(1):34-42. 12. Fernandes MR, Fernandes RJ. Indirect arthroscopic decompression of spinoglenoid cyst with suprascapular neuropathy: report of two cases and literature review. Rev Bras Ortop 2010;45(3):306-311.Additional supporting information may be found in the online version of this article.

Proximal fibular nerve conduction studies to tibialis anterior: Optimal E2 (reference electrode) placement

“…These data extend the finding from the previous studies, 7,16 each of 10 control subjects, to patients with abnormal results as well as larger numbers of controls across a broad range of amplitudes. Our conclusion was the same, that the medial knee is the preferred E2 site for fibular NCS to TA.…”

“…A number of AE2 positions were selected following a small pilot study (unpublished) on the assumption that the ideal E2 should contribute the smallest level of activity to the E1‐E2 montage. These included some of the sites studied in the Escorcio‐Bezzera study 16 . Montages are listed in Supporting Information Figure S1 and comprised: TA‐Tibia, TA‐Knee, TA‐ CL, Knee‐ CL, Tibia‐ CL, Ankle‐ CL, Toe‐CL.…”

“…In addition, the CMAP recorded with the conventional belly‐tendon montage (TA‐Tibia) was compared with the novel TA‐Knee montage, as recommended from our unpublished data, and also the study of Escorcio‐Bezzera 16 . The influence of montage was also assessed at the two standard stimulation sites by calculating popliteal:fibular (Pop:Fib) amplitude ratios and latency differences between the fibular neck and popliteal fossa sites.…”

“…Conventional fibular nerve conduction techniques to TA have mostly used a belly tendon montage with E2 placed over the mid‐tibia or low tibia/ankle with the implicit assumption that these sites are isoelectric 12‐15 . Recent reports assessed several alternative E2 (AE2) sites in fibular nerve studies to TA and concluded that the medial knee was the best AE2 site, 7,16 although numbers were small in each study (n = 10).…”

Optimal reference electrode placement for accessory and axillary nerve conduction studies

“…This assumption has been challenged even in distal muscles, and the effect of an “active reference” has been explored in various papers. Investigations of the median, ulnar, peroneal, and tibial nerves have shown variation in CMAP parameters with use of different E2 electrode sites …”