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

Background Several E2 (reference electrode) positions are described for fibular (peroneal) nerve conduction studies to tibialis anterior (TA). Methods This study compared the contribution of different E2 sites to the TA motor response, using remote referential recordings and different bipolar montages. Results The medial knee contributes minimal electrical activity to the bipolar TA recordings, whereas tibial, ankle, and toe references resulted in very similar, moderate amplitude contributions consistent with far field potentials. These observations were very similar in controls and in patients with lower leg symptoms and signs. Conclusions Standard montages using distal leg or foot E2 sites result in lower amplitudes with distortion arising from the E2 electrode, compared with the TA-Knee montage. Optimal measurement of the TA motor response is achieved using a medial knee reference, without compromising measures of fibular nerve conduction across the knee.