Figure 1: Recording subdural strip electrode. a- Right median SSEPs phase reversal technique. Referential and bipolar recordings, with the recording strip placed with contact 1 most posterior in the anterior-posterior axis. The referential montage shows a phase reversal at the level of CS: contacts 4 is located postcentrally and contact 5 precentrally. In the bipolar montage, notice the phase reversal at contact 4, pointing towards the most electronegative region, the parietal somatosensory cortex. b- Subdural 8 contact strip electrode placed directly on the cortical surface. Label A shows the extension cable, with contact 8 being the closest. Label B shows a “flag” on the cortical surface, marking eloquent cortex. Label C shows the sterile subdermal needle electrode placed at the margin of the surgical field and connected to the cathode.