Intra-Rater Reliability and Validity of Neuro-Mobinavigation: A Mobile App and Laser-Guided System of Motor HotSpot Localization

Abstract

Background: Optimal transcranial magnetic stimulation (TMS) efficacy depends on precise coil placement and orientation, as even minor deviations can significantly change the excitation evoked when stimulating the primary motor cortex (M1). To compare the intra-rater reliability of a novel method for consistent TMS coil orientation over a predetermined hotspot in M1, and to benchmark its accuracy against non-navigated method. New method: A three-step method was employed. First, a laser-guided-system stabilized head position. Second, a mobile-app monitored coil tilt and orientation. Finally, coil position was marked on participant’s head cap for visual reference for both methods. Twenty-nine healthy-participants underwent six TMS blocks of 20 pulses each. Six experimental blocks, alternating between non-navigated-TMS and Neuro-Mobinavigated-TMS, to investigate the parameters of motor evoked potential (MEP). The experimental blocks were quasi-randomized with a five-minute interval. Results and comparison with existing method(s): The novel method demonstrated excellent intra-rater reliability (ICC = 0.95, 95 % CI: 0.90–0.97) compared to moderate intra-rater reliability of the non-navigated TMS (ICC = 0.73, 95 % CI: 0.57–0.85) for MEP peak amplitude. Repeated measures ANOVA for novel-method showed consistent peak amplitude across three blocks (p = 0.078), non-navigated TMS exhibited significant variations (p < 0.0001). Wilcoxon signed rank test revealed significantly higher mean peak amplitudes for the novel method (1.02 ± 0.74) compared to non-navigated TMS (0.78 ± 0.61) (p < 0.001), small effect size (r = 0.35). Conclusions: Neuro-Mobinavigation is superior to non-navigated method and provides a reliable and cost-effective alternative for MEP studies where gold standard neuronavigation is not available.