Comparison between the C5 or C6-Cz electrode assembly and C3 or C4-Cz assembly for transcranial electric motor activation of muscular response of the contralateral facial nerve

Abstract

We concluded that the C5 or C6-Cz assembly was similar to C3 or C4-Cz in obtaining a multisynaptic response in the contralateral mentalis muscle, although it required less intensive stimulation than the C3 or C4- Cz assembly.

Three montages for Transcranial Electric Stimulation in predicting the early post-surgery outcome of the facial nerve functioning

“…With regard to the feasibility, we tried to obtain Cb-MEPs from FCC5h/FCC6h-Mz with the lowest voltage possible. In our sample, the mean voltage used was about 180 V, very similar to that used for C5/C6-Cz stimulation, but significantly lower than that used for C3/C4-Cz stimulation, in the work comparing different stimulation sites most similar to ours (Verst et al, 2012). Furthermore, the voltage used by Fukuda et al, in a study assessing facial nerve outcome with C3/C4-Cz stimulation performed in 2008, was higher than ours.…”

“…Most of the groups usually perform TES with electrodes placed in C3-C4/C4-C3 or C3/C4-Cz (Zhou and Kelly, 2001; Akagami et al, 2005; Dong et al, 2005, Deletis et al, 2009b, Deletis et al, 2011), or in a similar way (Goto et al, 2010). On the other hand, Cb-MEPs of similar amplitude can be obtained (with even lower stimulus voltage) with C5/C6-Cz montage (Verst et al, 2012; Verst et al, 2013).…”

“…To date, a general agreement of the usefulness of Cb-MEPs has been achieved, considering that it is able to determine the facial nerve outcome with a good accuracy (Akagami et al, 2005, Dong et al, 2005, Fukuda et al, 2008; Morota et al, 2010), despite some limitations due to the challenging interpretation if a response arises from peripheral or central stimulation (Tellez et al, 2016). C3/C4-Cz TES montage is the most diffuse to determine Cb-MEPs, although the São Paulo group (Verst et al, 2012; Verst et al, 2013) proposed the C5/C6-Cz stimulation, with similar effectiveness, and even in Dong et al, 2005, TES montages alternative to C3/C4-Cz were used. Hence, the debate moves progressively from demonstrating the usefulness of Cb-MEPs to finding the best technical specifications and procedures to limit pitfalls and increase the diagnostic yield of the technique.…”

“…Although C3/C4-Cz is a widely used montage, C3/C4 are generally considered skull points centred on the sensory-motor hand areas (Shibasaki H., 2008; Goto et al, 2010; Holmes et al, 2019); on the contrary, the C5/C6-Cz montage was only used by a single group (Verst et al, 2012; Verst et al, 2013), and confirmative studies are needed before its extensive use in the daily routine, even considering that the Authors did not assess the Cb-MEP results with the post-surgical outcome of the facial nerves. Moreover, during neuronavigation, it is common to see that C5 and C6 ideally project in areas lying just behind the precentral gyrus, in the somatosensory areas, due to the peculiar inclination of the Rolandic sulcus.…”

Schwannoma of the Intermediate Nerve: A Rare Type of Cerebellopontine Angle Tumor

“…Somatosensory evoked potentials after right and left median and tibial nerves stimulation resulted in normal N20 and P40 potentials. Motor evoked potentials for corticobulbar tract used C6-Cz assembly 10 and recordings were realized in muscles of the V, VI, VII, IX, X, XI and XII nerves. Consistent muscle potentials were obtained for V, VII, IX and X nerves, which remained unchanged throughout the procedure.…”