Fig. 5

Effects of migration of the stimulating lead along the rostral-caudal and medial-lateral axes on the ECAP component in ESR. A X-ray images showcasing the caudal-rostral movement of the stimulation lead. Circular markers located left of the lower lead indicate stimulating contacts 7 (yellow, anodic) and 8 (red, cathodic). Contact 11 (yellow square) located on the second lead indicates the recording channel that was used for the reported ECAP quantifications. B ECAP latency calculated for stimulation lead in rostral and caudal position for all subjects (n = 4). The histogram shows the distribution of the latency measured at both locations. The bar plot indicates there was a significant increase (p < 0.001) in latency as the stimulation-recording distance increased. C Example median ESR waveforms from channel 11 are plotted overlain on 300 raw traces at 4.8 mA of stimulation for both the caudal and rostral position revealing changes in ECAP component latency. D From rostral to caudal shift in the stimulating lead, the normalized ECAP magnitude (AUC) decreased for all but one subject. E X-ray images illustrate stimulation lead shifted more laterally. Circular markers located left of the lower lead indicate stimulating contacts 7 (yellow, anodic) and 8 (red, cathodic). Contact 11 (yellow square) located on the second lead indicates the recording channel that was used for the reported ECAP quantifications. F Example median ESR waveforms are plotted overlain on 300 raw traces at 80% motor threshold for both medial and lateral configurations from channel 11. G ECAP component latencies were compared for medial and lateral electrode positions (n = 4 subjects). Shifting the stimulation lead along the medial-lateral axis showed no significant effect on ECAP latency. H ECAP magnitudes showed variable subject-specific changes with medial-lateral lead migration