Thoracoscopic Surgery for Thoracic Spinal Tumors

Published on 02/04/2015 by admin

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Chapter 32 Thoracoscopic Surgery for Thoracic Spinal Tumors

Ung-Kyu Chang, Se-Hoon Kim, Daniel H. Kim

INTRODUCTION

For the surgery of thoracic spinal tumors, open thoracotomy is usually performed. However, morbidity associated with conventional open thoracotomy often limits the application of anterior approaches to the thoracic spine. Most of the vertebral body tumors of the thoracic spine involve the anterior column, and these tumors require rib removal and parietal pleura opening, which can cause the complications, such as post-thoracotomy syndromes and intercostal neuralgia.¹ Open thoracotomy also requires extensive exposures with incisions measuring up to 20 cm. In recent years minimally invasive open microscopic approaches using special retractors have been developed that can minimize the size of the operative access to 6–10 cm. These “mini-approaches” are quite feasible in surgery on the upper and mid-thoracic spine. The limited working space available through small incisions may block the microscopic view and result in difficult manipulation of instruments. However, video assisted thoracic surgery (VATS) using four portals in the chest wall permits surgery that is as effective as the open approaches, and it provides a better view than the microscopic approach. Unlike the open approaches, the surgeon’s operative view is not obscured by hands or operative instruments, and high morbidity associated with open procedures can be avoided. Biomechanically, the VATS approach, like any other anterior approach to the spine for reconstruction, significantly increases the axial load-bearing capabilities of the spine.²

INDICATIONS

• Vertebral body tumor affecting anterior column only (primary or metastatic)

• Neurogenic tumors in the thoracic spine (schwannoma, neurofibroma)

• Dumbbell tumor with large intrathoracic component

• Tumors of nerve origin arising from segmental intercostal nerve

CONTRAINDICATIONS

• Significant previous cardiopulmonary disease with restricted cardiopulmonary function

• Acute post-traumatic lung failure

• Significant disturbances of hemostasis

THORACOSCOPIC CORPECTOMY AND STABILIZATION

ENDOSCOPIC INSTRUMENTS

The following instruments are necessary to perform endoscopy-assisted anterior approaches to the thoracic spine.

• Routine surgical set for skin incision and preparation of the intercostal space

• Instruments for removal of bone graft from the iliac crest

• Video-endoscopy

• Instruments for thoracoscopic dissection of the prevertebral anatomic structures as well as for resection of bone and ligaments, osteotomes, hooks for dissection, hook probes, sharp and blunt rongeurs, Kerrison rongeurs, curettes, graft holder, reamers, monopolar and bipolar probes

• Disposable instruments, lung retractor, clip applicator

POSITIONING

The patient is placed in a stable lateral decubitus position and fixed with a four-point-support at the symphysis, sacrum, and scapula, as well as with arm rests (Fig. 32-1). A left-sided position is preferred for the treatment of lesions from T4 to T8. A right-sided position is preferred for the approach to the thoracolumbar junction (T9–L3). The upper arm should be abducted and elevated to prevent disturbing the placement and manipulation of the endoscope.

Fig. 32-1 Position and level confirmation. The patient is placed in a stable lateral decubitus position and fixed with a four-point support.

Both monitors are placed at the lower end of the operating table on opposite sides to enable free vision for the surgeon, as well as for the assistant. The surgeon and camera operator stand behind the patient. The C-arm is approached between the surgeon and the camera operator. The assistant as well as the C-arm monitor are placed on the opposite side.

LOCALIZATION

The target area is projected onto the skin level under fluoroscopic control. The borders of the lesion vertebra are marked on the skin, indicating the line of the anterior and posterior edges as well as the endplates of the affected segments (Fig. 32-2). The working channel is centered over the target vertebra (12.5 mm).

Fig. 32-2 Localization for the lesion. The target area is projected onto the skin under fluoroscopic control. The borders of the lesion vertebra are marked on the skin.

The optical channel (10 mm) is placed between two and three intercostal spaces cranial to the target vertebra in the spinal axis for lesions of the thoracolumbar junction. For lesions of the middle and upper thoracic spine, the optical channel is placed caudal to the target vertebra. The portals for suction/irrigation (5 mm) and retractor (10 mm) are placed approximately 5–10 cm anterior to the working and optical channels. The portal for the lung retractor should be placed as far as possible ventrally to prevent instruments coming into conflict.

PLACEMENT OF PORTALS

Through a 1.5-cm skin incision above the intercostal space, small Langenbeck hooks are inserted (Fig. 32-3) The muscles of the thoracic wall are crossed in a blunt, muscle-splitting technique, and the intercostal space is opened by blunt dissection, thus exposing the pleura and creating an opening to enter the thoracic cavity. The 10-mm trocar is inserted and one-lung ventilation is started. The 30-degree scope is inserted at a flat angle in the direction of the second trocar. Perforation of the thoracic wall to insert the second, third, and fourth trocars is performed under visual control through the scope, and the other trocars are inserted as shown (Fig. 32-4).

Fig. 32-3 Locations of the portals for T9 lesion. The optic channel is located in the caudal side. The retractor and suction instrument are located on the ventral side.

Fig. 32-4 The portal is seen from the endoscopic channel. Perforation of the thoracic wall with the third trocar is performed under visual control through the scope.

PREVERTEBRAL DISSECTION

The target area can now be exposed with the help of a fan-retractor inserted through the anterior port. The retractor sweeps away lung tissue and holds down the insertion of the diaphragm on the spine. The anterior border of the vertebral body and disc, as well as the course of the aorta, is palpated with a blunt probe (Fig. 32-5).

Fig. 32-5 The greater vessels are palpated with a blunt probe.

The parietal pleura is widely incised with a hook diathermy electrode (Fig. 32-6). The incision starts from the anterior border of the vertebral body, continuing to the rib head and to the proximal rib segment. The incision line should be in the disc level, and care should be taken to not injure the segmental vessels that are located in the mid-portion of the vertebral body.