To record cortical SSEPs during intraoperative monitoring of cervical spinal cord surgery, where should electrodes be placed?

For recording cortical somatosensory evoked potentials (SSEPs) during cervical spinal cord surgery, placing electrodes 2 cm posterior to C3 and C4 is appropriate because this positioning targets the areas of the brain that are involved in somatosensory processing relevant to the cervical region.

C3 and C4 correspond to specific locations on the scalp according to the 10-20 EEG electrode placement system, which is standardized for monitoring electrical activities of the brain. The clinical rationale behind placing the electrodes posterior to these points is aimed at capturing the electrical signals that arise from sensory stimuli affecting the upper limbs or cervical spine, allowing for effective monitoring of the neural pathways involved.

This positioning helps in adequately capturing the SSEPs as they traverse the sensory pathways to the cortex. By locating the electrodes slightly posterior, there's a better chance to record the responses from the postcentral gyrus, which is where the somatosensory cortex resides, and is crucial for evaluating the integrity of the sensory pathways during surgical procedures on the spinal cord.