Microsurgical technique for concurrent cervical corpectomy and ventral phrenic nerve access in the rat

The phrenic nerve is useful to record as a motor output in studies investigating neural control of respiration. It may be accessed via dorsal or ventral microsurgical approaches. Since such studies frequently involve concurrent access to the spinal cord, the two approaches may be alternatively used, each with its own set of advantages and disadvantages. The dorsal approach permits easier exposure of the spinal cord via laminectomy, but, compared to the ventral approach, phrenic nerve access proves more challenging, and concurrent surgical access to the full complement of respiratory-related nerves (i.e., glossopharyngeal, vagus, recurrent laryngeal, hypoglossal nerves) and cervical sympathetic nerve in the neck is limited. The ventral approach achieves more direct access to the phrenic and respiratory-related nerves, but ventral access to the spinal cord via corpectomy requires much greater diligence and vigilance. Ventral spinal cord access, however, facilitates neuronal (e.g., phrenic motoneuron and interneuron) recordings in the ventral horn of the spinal cord, given greater proximity to the ventral compared to the dorsal surface of the spinal cord providing more leeway in recording pipette insertion point and trajectory. Additionally, ventral access to the cervical spinal cord proves useful across a broad range of studies investigating normal spinal cord physiology as well as spinal cord injury. We detail the microsurgical technique of concurrent ventral phrenic nerve dissection and cervical corpectomy in adult rats.