Lateral Extracavitary Approach

Summary of Key Points

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The lateral extracavitary approach (LECA) can be used for surgical treatment of spinal tumors, disc herniations, fractures, and infections, enabling access to both the ventral and dorsal elements of the thoracolumbar spine.
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In contrast to transthoracic or dorsal approaches, the advantage of the LECA is that it provides both lateral exposure and visualization of ventral structures, while avoiding entrance into the pleural or abdominal cavities.
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Disadvantages to the approach include the possibility of insufficient ventral exposure that could limit adequate decompression and lead to increased risk of pleural and vascular injuries; blood loss is also a significant concern and would limit this approach in certain patients.
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The average complication rate of the LECA is 17% (based on published rates of retrospective studies).
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Lesions that do not cross midline can be adequately treated with the more minimal exposure of the costotransversectomy; the LECA may also be difficult for operations between T2 and T4, due to the presence of the scapula and associated musculature.

The lateral extracavitary approach (LECA) can be used in the thoracolumbar spine to access both the ventral and dorsal elements of the spinal column. Through this approach, discectomy, spondylectomy, fusion, and deformity reduction may be accomplished. In addition, other approaches, including transpedicular decompression and laminectomy, can be added to allow a 360-degree decompression/reconstruction through one incision. The LECA was first used as a derivation of lateral costotransversectomy in the treatment of tuberculous spondylitis (Pott disease) by Capener in 1933 and was first reported by Seldon in 1935. It was also described in 1960 by Hulme, who advocated it as an alternative to laminectomy for ventral thoracic disc herniations and thoracolumbar fractures. Throughout the 1950s and 1960, the technically simple laminectomy remained the most common approach to the thoracic spine. There remained, however, a high incidence of poor surgical outcomes that were attributed to inadequate exposure of ventral elements and the requirement of direct manipulation of the thoracic spinal cord and its extradural vasculature. Larson and associates, in 1976, refined and popularized the LECA, reporting significant neurologic improvement in 46 of 62 patients. It has since been applied to traumatic lesions, thoracic disc herniations, tumors, and other pathologic conditions ( Figs. 49-1 to 49-5 ). The LECA has been modified to be used via minimally invasive systems for deformity correction and thoracic disc herniation.

This approach can be applied to ventral spinal lesions located in the thoracic and lumbar spine and, if necessary, can be performed in a bilateral fashion for more extensive pathology. It has a distinct advantage of providing lateral exposure without entering the pleural or abdominal cavity (as opposed to the transthoracic or retroperitoneal approaches) and offers superior visualization of ventral structures compared to costotransversectomy and dorsal approaches. In addition to decompression and the removal of pathology, ventrolateral instrumentation can be accomplished through the LECA without requiring additional instrumentation placed dorsally through a second incision.

Surgical Preparation

Before undertaking any surgical procedure, a careful history and physical examination are essential, along with proper diagnostic imaging. For lesions that can be approached via the LECA, imaging should consist of plain radiographs, magnetic resonance imaging (MRI), and possibly computed tomography (CT). MRI is most useful for disc surgery and tumors, and CT is often obtained to evaluate fractures, understand the bony anatomy, and assess the size and orientation of the pedicles if transpedicular instrumentation is planned for augmentation. The importance of plain radiographs in preoperative evaluation cannot be overstated because it is vitally important to understand with certainty the true number of ribs that the patient has before undertaking the LECA. Overall spinal alignment is also important and best assessed with plain radiographs. Preoperative angiography should be considered when the lesion is located between T7 and L2, as the artery of Adamkiewicz is located at the pathologic level in 20% of cases. When treating tumors, characterizing the vascular supply to the tumor and spinal cord is particularly important, and angiography with embolization (just before surgery, if possible) should be performed to prevent excessive blood loss.

Operative Technique

Following the induction of general anesthesia, the patient should have a Foley catheter placed and appropriate preoperative antibiotics administered. The Jackson table provides optimal padding and available positioning for the LECA, and all pressure points should be checked after positioning. The patient should be safely secured to the table at all points because the bed will be rotated later in the case. For discectomy or fractures, the use of intraoperative monitoring may not be essential; for deformity correction and tumor cases, such monitoring may provide an additional measure of safety. The use of intraoperative monitoring remains controversial, and it is largely used as per personal preference. Following induction and proper positioning, the next step is appropriate fluoroscopic localization of the lesion. This is critical because the exposure provides a direct view of specific vertebrae, and extending the exposure more than one level in either direction can be difficult. It is imperative to have a clear understanding of the bony anatomy on radiograph before surgery to aid in localization. The typical anatomy of the rib and thoracic spine interface is also an important fact to keep in mind. In most patients a rib abuts the disc space in the thoracic spine, and this rib typically corresponds to the caudal vertebrae at the segment. For example, at T7, the rib typically articulates with the T6-7 disc space. This anatomy holds true down to the T10-11 space. The 11th and 12th ribs typically articulate with the corresponding vertebral bodies below the disc spaces. It is generally advisable to count ribs in the thoracic spine from above and below and to compare this count with preoperative radiographs for confirmation.

Once the location has been confirmed and marked, attention is given to planning the incision. Various shapes have been used ( Fig. 49-6 ), but the hockey stick–type incision is generally performed. The incision should usually extend from at least one segment cranial to the pathology to one segment caudal to it, with the caudal limb angling out toward the pathologic side with attention paid to the need for approaching the dorsal elements or placing instrumentation.