Prophylactic thoracolumbar disk fenestration (Proceedings)

Surgical fenestration of the intervertebral space provides a means of prophylaxis on disk disease. If protrusion exists, surgical removal of the nucleus remaining in the intervertebral area will eliminate the pressure causing the protrusion. At the same time, if all other disks that are potential problems (T9-T10 to L5-L6) are fenestrated, complete prophylactics against future disk protrusions is achieved. The material already extruded into the canal cannot be removed by disk fenestration alone; however, fenestration is encouraged for the removal of other degenerated disks that are potential problems in order that vigorous physical therapy, such as hydrotherapy and cart walking, can be prescribed without fear of causing another protrusion or even extrusion. Ventral fenestration facilitates access to all the potentially offending disks with a minimum amount of surgical trauma. Ten disks are fenestrated (T9-T10 to L5-L6). The thoracic disks are exposed through a left tenth intercostal thoracic approach and the lumbar disks through a paracostal abdominal incision.

Surgical Procedure

The patient is preoperatively medicated with corticosteroids (Dexamethasone 1 mg/lb.) and antibiotics. The patient is placed in right lateral recumbency, and the left lateral side is clipped and prepared aseptically. The skin incision is made over the thirteenth rib from the dorsal to the ventral midline. The subcutaneous tissue is then dissected, the incision is slid caudally, and a paracostal incision is made into the abdomen. The left kidney is located and is reflected ventrally with the peritoneum. Frazier laminectomy retractors are then positioned and the abdominal viscera are packed off with a laparotomy pad. This retroperitoneal abdominal exposure affords access to the L1-L2 through L5-L6 intervertebral spaces. The iliopsoas muscle is then hooked with a muscle retractor and is retracted away from the ventral midline. The ventral intervertebral prominences can be palpated. The lateral transverse processes are then identified and are numbered for orientation. Medial to the first transverse process is the T13-L1 intervertebral space. This space is not easily exposed from the abdominal approach and thus fenestrated from the thorax. The remaining intervertebral spaces (L1-L2 to L5-L6) are fenestrated. The ventral longitudinal ligament and ventral annular fibers are cut with a scalpel. The nucleus pulposus is then removed with a Miltex oral B tartar scraper. An inward, upward, and outward motion is used to clear the intervertebral space of as much nucleus as possible. Once this maneuver has been completed, the retractors are removed, and the muscle layers are individually sutured with 2-0 PDS suture material. The skin incision is then slid in the cranial direction, and an incision is made into the thorax between the tenth and eleventh ribs. The Frazier laminectomy retractors are placed, and resuscitation is instituted. The T9-T10 through T13-L1 intervertebral spaces are located and dissected free of pleura; the sympathetic trunk and intercostal vessels are carefully avoided. When the dissection is complete, the disks are fenestrated in the same manner as already described. The thorax, latissimus dorsi muscle, and skin are closed in the routine manner.

Postoperative

The animal is monitored closely during the anesthetic recovery period. Antibiotics are given, the bladder is kept evacuated, and intensive physical therapy is instituted. Physical therapy includes hydrotherapy and cart walking.