Surgical Techniques in Percutaneous Endoscopic Thoracic Diskectomy

30 Surgical Techniques in Percutaneous Endoscopic Thoracic Diskectomy

Gun Choi, Akarawit Asawasaksakul, and Alfonso García

30.1 Introduction

In the era before MRI, symptomatic thoracic disk herniation was a rare condition in spinal surgery, representing only 1% of all disk herniations.1,2 In the MRI era, thoracic disk herniation can be detected much more easily than in the past, but the treatment is very difficult, since a transthoracic or extrapleural approach may be required.

Recently, with the development of endoscopic spine procedures and instruments, thoracic diskectomy is possible via a percutaneous endoscopic technique,³ but the procedure is technically demanding. Two methods are now available:

1. Percutaneous endoscopic thoracic diskectomy (PETD)

2. Percutaneous endoscopic thoracic annuloplasty using real-time CT guidance with laser-assisted spinal endoscopy (PETA with LASE)

This chapter focuses on PETD (Video 30.1).

30.2 Indications for PETD

• Thoracic paramedian or foraminal soft disk herniation

• In an upper thoracic level, diffuse bulging soft disk herniation

• Pain with no response to conservative treatment

30.3 Contraindications to PETD

• Calcified disk

• Ossification of posterior longitudinal ligament (OPLL)

• Central disk herniation

• Major compression or neurologic deficit

• Abnormal vasculature

30.4 Special Instruments and Preoperative Planning

The operating room setup and instrumentation needed to perform PETD are shown in Fig. 30.1 and Fig. 30.2. CT and MRI are mandatory for preoperative planning, not only to determine if the patient is a candidate for a percutaneous thoracic procedure but also to plan the needle trajectory. Axial MRI or CT is used to calculate the needle’s skin entry point (Fig. 30.3).

30.5 Position and Anesthesia

• The patient is positioned prone on a radiolucent operating table, with the affected side facing the surgeon. The arms are positioned above the patient.

• Local anesthesia using 1% lidocaine, together with conscious sedation with propofol and fentanyl, allows continuous feedback from the patient during the entire procedure to avoid any damage to neural structures.

Fig. 30.1 (a) Endoscopic set, (b) CT scanner, (c) Ho-YAG laser, (d) endoscope (KESS, Richard Wolf Medical Instruments Corporation, Vernon Hills, IL), dilators, and forceps.

Fig. 30.2 Instruments needed to perform a percutaneous endoscopic thoracic diskectomy. Need to explain details of each instrument.

Fig. 30.3 Measurements done on an axial CT scan to determine the skin entry point.

• Level and landmark marking are done under C-arm imaging. The lateral coordinates of the skin entry point are determined by extrapolating a line from the midpedicular annulus to the lateral margin of the facet and extending up to the skin’s surface.

30.6 Needle Insertion Technique

• The appropriate operative level must be precisely located using lateral and anteroposterior (AP) fluoroscopy, counting the level from the sacrum or C1.

• The procedure requires continuous or intermittent CT guidance. CT guidance is more precise but not necessary.

• Because the thoracic disks are more concave than the lumbar disks, lumbar fluoroscopic landmarks cannot be used for thoracic disks. Because of the concavity, thoracic disk herniations can only be approached through the foraminal region.

• The skin entry point is determined based on an imaginary line projected toward the skin from the target area (between the rib and facet). Usually 5 to 6 cm lateral to midline is the point calculated on axial CT scan or MRI.

• Direction of the needle should be parallel to the end plate at the corresponding level.

• The safest route for passing the needle into the thoracic disk is between the rib head and the thoracic facet (Fig. 30.4).