Spinal Cord Transection and Electrode Implantation Procedures and Post-surgical Animal Care

A partial laminectomy was performed to expose the T8–T9 spinal cord, and then a complete spinal cord transection to include the dura was performed with microscissors. Two surgeons verified the completeness of the transection by lifting the cut ends of the spinal cord with fine forceps and passing a glass probe through the lesion site. Gel foam was inserted into the gap created by the transection as a coagulant and to separate the cut ends of the spinal cord. For epidural electrode implantation, partial laminectomies were performed to expose the spinal cord levels L2 and S1. Two Teflon-coated stainless steel wires from the head connector were passed under the spinous processes and above the dura mater of the remaining vertebrae between the partial laminectomy sites. After a small portion (∼1-mm notch) of the Teflon coating was removed and the conductor was exposed on the surface facing the spinal cord, the electrodes were sutured to the dura mater at the midline of the spinal cord above and below the electrode sites with 8.0 Ethilon suture (Ethicon, New Brunswick, NJ, United States). Two common ground (indifferent EMG and ES) wires (∼1 cm of the Teflon removed distally) were inserted subcutaneously in the mid-back region on the right side (EMG) and midline (ES) close to the tail. All wires (for both EMG and ES) were coiled in the back region to provide stress relief. All incision areas were irrigated liberally with warm, sterile saline. All surgical sites were closed in layers with 5.0 Vicryl (Ethicon, New Brunswick, NJ, United States) for all muscle and connective tissue layers and for the skin incisions in the hind-limbs and 5.0 Ethilon for the back skin incision. Buprenex (0.01–0.05 mg/kg s every 8–12 h) was used to provide analgesia. Analgesics were initiated before completion of the surgery and continued for a minimum of 2 days. The rats were allowed to recover fully from anesthesia in an incubator. The rats were housed individually in cages that had ample CareFresh bedding, and the bladders of the spinal rats were expressed manually three times daily for the first 2 weeks after surgery and two times daily thereafter. The hind-limbs of the spinal rats were moved passively through a full range of motion once per day to maintain joint mobility. All of these procedures have been described in detail previously (Courtine et al., 2009).