Thoracic MIS Retropleural Access



Fig. 16.1
(a) Patient placed in a 90o true lateral decubitus position with pre-operative surgical marking of ribs and index level. (b) Fluoroscopic X-Ray image of the vertebrae is obtained with the patient is secured to the bed with two inch silk tape and straps





16.5.3 Surgical Approach


The C-arm is adjusted for a true lateral view and a radiopaque marker is placed above the disk space of interest. For single-level fusions, a 4–5-cm incision is marked at the level of the disk space. For two-level fusions or a single-level corpectomy, an incision is marked along the midvertebra between the two disk spaces of interest. The skin is incised and the underlying muscles are bluntly dissected to expose the rib overlying the target interspace(s). It is prudent to make the incision over an underlying rib to prevent plunging into the intercostal space. Approximately 4 cm of the rib are dissected from their muscular attachments as well as the parietal pleura and resected with a rongeur or a bone scalpel. Care must be taken to avoid injury to the pleura, intercostal vessels, and nerves on the caudal surface of the ribs.

A finger is inserted into the retropleural space hugging the posterior chest wall, and the lung is swept anteriorly with a sponge stick until the lateral vertebral column is exposed. Appropriately sized retractor blades are chosen and placed onto the correct target disk space under direct visualization. The position of the retractor can be confirmed with an AP fluoroscopic image. The authors use the SynFrame retractor system (DePuy Synthes, Raynham, MA) which employs a table-mounted ring directly above the incision attached to articulated retractor blade holders. Three blades are typically used: one for anterior retraction of the lung and two for rostral and caudal retraction (Fig. 16.2)

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Fig. 16.2
(a) Synframe retractor system (Depuy Synthes, Raynham, MA) which employs a table mounted ring directly above the incision attached to articulated retractor blade holders. (b) Visualization of thoracic plate through Synframe retractor system. (c) Antero-posterior X-ray image of the T8 cage and plate after corpectomy
. Alternatively, the table-mounted retractors used for lateral retroperitoneal lumbar access may be used in the thoracic spine in similar fashion (Fig. 16.3).

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Fig. 16.3
(a) Table mounted retractors used for lateral retroperitoneal lumbar access used in the thoracic spine. (b) Magnified view of retractor system intra-operatively. (c) Antero-posterior X-ray image of the cage placement after corpectomy

Once the exposure is complete and the self-retaining retractor is in place, fluoroscopy is used to confirm that the correct level has been exposed. From the lateral view, the disk spaces are elevated compared to the vertebral bodies. The disk space can be palpated with a Penfield dissector for confirmation and the surgeon may commence the diskectomy. For a corpectomy, a diskectomy is performed above and below before the removal of the vertebral body. The segmental artery courses in an anteromedial to posterolateral direction at the mid-position of the vertebral body. This vessel should be dissected, clipped, and cauterized with bipolar electrocautery before sectioning. As the segmental artery arises directly off of the descending aorta, it is critical to section the vessel at least 2 cm distal to the aorta. If the artery is cut too close to the aorta and was not sufficiently clipped or cauterized, it may retract and bleed profusely from aortic back pressure. The anterior border of the vertebral body can be palpated with a Penfield dissector. The neural foramen provides a useful landmark for the posterior border. The rostral/caudal boundaries have been defined by the diskectomies, and the surgeon may commence with the corpectomy.

Once the main procedure is complete, the pleural surface is inspected thoroughly. If the pleura is compromised or there is significant residual bleeding, a 10-French chest tube is placed in the wound and tunneled subcutaneously over several ribs from the incision. The retractor blades are carefully removed allowing the lung to expand to the posterior chest wall. The muscles overlying the rib resection are re-approximated with 0-Vicryl interrupted sutures, and the rest of the incision is closed in standard fashion.


16.5.4 Postoperative Care


If a chest tube is in place, it is connected to a reservoir on water seal or −20 cm of H2O depending on the severity of the pleural injury. All patients undergo a postoperative chest X-ray shortly after the arrival to the postanesthesia care unit. If a chest tube was placed or a pneumothorax is discovered on the postoperative chest X-ray, a follow-up X-ray is performed on postoperative day 2 for surveillance. The chest tube is weaned and removed as tolerated.

Patients are encouraged to sit in a chair and ambulate on the first postoperative day. All patients have sequential compression devices and are started on heparin prophylaxis for prevention of deep vein thrombosis.



16.6 Outcomes Using a Minimally Invasive Anterolateral Approach


Two studies reporting outcomes and complications of MIS retropleural access are available for review at the time this chapter was written. In 2011, Karikari et al. reported their series of 22 patients who underwent MIS thoracic and thoracolumbar lateral interbody fusions for a variety of pathologies using the MaXcess retractor (NuVasive, San Diego, CA) [19]. They report a 95.5 % successful fusion rate among 47 levels treated with three complications, none of which involved neural, vascular, or pulmonary injuries. In another study, Meredith et al. reported a series of 18 patients who underwent MIS lateral thoracic and thoracolumbar interbody fusions with the MaXcess retractor with only one patient failing to fuse [20]. Seven non-pulmonary complications occurred in six patients with none involving neural elements or vessels. Although large-scale studies are required for further evaluation, these early reports show that the MIS anterolateral approach can be used to treat a variety of thoracic pathologies safely with high rates of successful fusion.

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Sep 23, 2017 | Posted by in NEUROLOGY | Comments Off on Thoracic MIS Retropleural Access

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