Fig. 5
From: The role of spinal cord neuroanatomy in the variances of epidural spinal recordings
Evoked ESRs are responsive to the anatomical location of the stimulating cathode. Representative data from subject S3. Waveforms were represented as 300 individual recorded traces with an overlaid median trace. A Cathodic ‘off-disc’ stimulation resulted in observable EMG bleed-through for recorded ESRs compared to the ‘on-disc’ stimulation. B Intramuscular EMG recordings of the intercostal muscles via surgical placement of needle electrodes through the intercostal muscles (IM) and C through the skin (IMS) show preference for evoked muscle contraction when cathode was located ‘on-disc’. Cathodic ‘on-disc’ stimulation produced a delayed motor response at the maximum stimulation amplitude, 9.0 mA, for intramuscular EMG (IMS) recordings, as indicated by a black arrow (bottom). D Dose-response curves (calculated as root-mean-square, RMS) for collected ESRs, shown as (1) ECAP and (2) EMG components, and (3) intramuscular EMG (IM) recordings show a distinct relationship to cathode placement with respect to the intervertebral disc