Tubular Endoscopic Thoracic Decompressive Laminectomy

34 Tubular Endoscopic Thoracic Decompressive Laminectomy

Ryan Khanna and Zachary A. Smith

34.1 Introduction

Spinal surgeons are choosing to perform more and more cases using endoscopic instruments due to the advantages offered by minimally invasive approaches. Advances in technology have allowed the incorporation of these techniques in thoracic decompression. While the procedure is still evolving, there are indications for the use of endoscopes in thoracic decompression (Video 34.1).

34.2 Choice of Patient

34.2.1 Indications

• Symptomatic compression of the thoracic spinal cord (Fig. 34.1)

• Epidural hematoma and infection

• Thoracic epidural tumors

• Degenerative compression: ossified ligamentum flavum, synovial cysts (Fig. 34.2)

34.2.2 Contraindications

• Instability of the spinal column

• Any procedure requiring fusion of thoracic vertebrae

• Scoliosis

• Significant postlaminectomy scar (relative)

• Previous instrumentation at operative level

34.3 Technique

34.3.1 Position and Anesthesia

General anesthesia (propofol and remifentanil) is used, along with monitoring of somatosensory and motor evoked potentials. The patient is placed in the prone position, with the head secured in a Mayfield three-point fixation holder.

Surgical levels are identified and marked using lateral fluoroscopy and counting cephalad from the sacrum. Levels are confirmed with anteroposterior fluoroscopy by counting thoracic ribs. The authors commonly employ preoperative fiducial markers (Fig. 34.3). It is their experience that a fiducial marker placed at the level of the pedicle aids in minimizing operative time, decreases radiation exposure during the operation, and additionally adds safety in the correct localization of the surgical level. In particular, this is helpful in single-level cases in patients with poorly defined radiographic anatomy.

Skin infiltration is accomplished with a mixture of lidocaine and bupivacaine injected at the incision site.

34.3.2 Skin Entry

The skin entry point is incised 2.0 cm lateral to the midline in a rostral-caudal direction, for 20 to 24 mm.

Fig. 34.1 Thoracic MRI demonstrates multilevel degenerative changes of the thoracic spine, superimposed upon prominent dorsal epidural fat. The changes are overall most pronounced at T10–T11, where there is a severe spinal canal stenosis as well as mild to moderate (right greater than left) bilateral neural foraminal stenosis. There is associated cord compression and focal, abnormal, hyperintense T2 signal within the thoracic spinal cord, centered on the T10–T11 level. (a) Midline sagittal cut; (b) sagittal cut on the right side.

Fig. 34.2 Thoracic CT demonstrates heterotopic bone consistent with the potential ossification of the ligamentum flavum and hypertrophy of the facet. The bone is causing symptomatic compression of the spinal cord.

Fig. 34.3 Axial CT shows preoperatively placed fiducial, which facilitated docking and minimally invasive techniques intraoperatively. Interventional radiology placed the fiducial on the day before surgery.