Laminotomy, Laminectomy, Laminoplasty, and Foraminotomy

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Chapter 53 Laminotomy, Laminectomy, Laminoplasty, and Foraminotomy

Thoracic and lumbar laminotomy and laminectomy are two of the more commonly performed spine procedures. They have changed little since the 1930s but have been refined with the advent of magnification and microtechnique, microinstrumentation, and power tools. These advances, along with use of perioperative antibiotics and better neurodiagnostic tests, have reduced the incidence of complications of these procedures.

The surgical management of thoracic and lumbar laminectomy, laminotomy, laminoplasty, and foraminotomy may be divided into four strategies and components: (1) positioning, (2) exposure of the spine, (3) decompression, and (4) wound closure. Important perioperative aspects include prophylactic antibiotics, which should be administered within 1 hour prior to surgery to reduce risk of infection, and mechanical prophylaxis measures, such as pneumatic compressive stockings, which should be utilized to reduce the risk of deep venous thrombosis.

Positioning

Positioning for thoracic and lumbar decompressive surgery is dictated by the level of the spine being operated upon. Exposure of the upper thoracic spine requires that the patient be prone with the neck moderately flexed, the arms at the side, and the shoulders depressed (Fig. 53-1). Middle and lower thoracic spine exposure requires that the patient be prone, with the arms either at the side or abducted at the shoulders and flexed at the elbows (Fig. 53-2). We recommend that head tongs, such as Gardner-Wells tongs, be used to allow the head to hang freely, thereby avoiding external pressure on the eyes and reducing intraocular pressure. In addition, we prefer that the head of the bed be elevated to reduce facial swelling, which can contribute to airway edema (see Fig. 53-2B). Lumbar exposure may be facilitated in either the prone position, kneeling position (Fig. 53-3), knee-chest position, or lateral decubitus position. The important common feature of all of these positions is the absence of abdominal compression, reducing intra-abdominal pressure and epidural bleeding. It is important to limit hip and knee flexion to approximately 90 degrees or slightly greater to avoid hyperflexion of the knees, which can result in calf swelling and possible compartment syndrome (see Fig. 53-3C). The prone and kneeling position, as compared with the lateral decubitus position, allows complete exposure of the dorsal elements from the cranium to the sacrum. It allows the surgical assistant to have an adequate view of the vertebral column and allows at least four hands to be available to help with the procedure. Surgeries are currently rarely done in the lateral decubitus position. There are, however, potential disadvantages of the prone position. These include restriction of thoracic expansion, compression of the abdominal viscera (producing increased venous pressure in the epidural venous plexus), and the potential for ocular and peripheral nerve compression. These disadvantages can be obviated by use of a Jackson operating table with Gardner-Wells skull traction, as was noted earlier in the chapter (see Fig. 53-2B). This setup allows the abdomen to hang freely, thereby eliminating abdominal compression, and suspends the head, thereby eliminating the potential for ocular pressure and facial abrasions.

To position for upper thoracic procedures (T1-5), the head is placed in three-point fixation using Mayfield tongs (see Fig 53-1) to provide stability to the lower cervical and upper thoracic spine. Ophthalmic ointment is applied to the eyes, which are taped shut prior to prone positioning. If head tongs are not employed, plastic goggles may be utilized to minimize the risk of pressure on the eyes. Compression stockings and serial venous compression devices should be placed on the patient’s legs to reduce the likelihood of deep venous thrombosis and possible pulmonary embolus. In turning the patient to the prone position, care is taken to prevent twisting the neck. The patient is log-rolled onto soft bolsters that extend from the shoulders to the pelvis, allowing the weight to be carried at these four points and allowing the chest to expand and the abdomen to be free from compression. The skeletal head holder is positioned so that the cervical spine is mildly flexed (“military position”). All bony prominences, particularly the elbows, are padded, and the arms are tucked to the side. Exposure can be facilitated by using 3-inch-wide adhesive tape to depress the shoulders by extending the tape from the tip of one shoulder to the opposite side of the table in a crisscross fashion, ensuring that the cross occurs at the thoracolumbar region and does not involve the upper thoracic region. Care must be exercised to avoid extreme shoulder depression, which can produce a traction injury to the brachial plexus. The operative table is then tilted in a mild, reverse Trendelenburg position to elevate the head in relation to the feet and to place the upper thoracic vertebrae parallel to the floor (see Figs. 53-1 and 53-2B).

Positioning for exposure of the lower thoracic spine is identical to that for the upper thoracic spine except that the arms may be either left at the side or abducted to 90 degrees at the shoulder with the elbows flexed 90 degrees. It is important to check the patient’s shoulder motion preoperatively to be sure that the shoulders are capable of 90 degrees of abduction. In addition, care must be exercised to avoid shoulder abduction beyond 90 degrees, which can result in a painful shoulder postoperatively.

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