Unilateral Tubular Over-the-Top Cervical Laminectomy for Cervical Stenosis

19 Unilateral Tubular Over-the-Top Cervical Laminectomy for Cervical Stenosis

Robert Nicholas Hernandez, Sergio Soriano-Solis, and José-Antonio Soriano-Sánchez

Summary

Unilateral Tubular Over-the-Top Cervical Laminectomy for Cervical Stenosis addresses the technical aspects of performing a minimally invasive cervical laminectomy for central cervical stenosis via tubular retractor. This chapter discusses indications and contraindications, preoperative planning, the surgical technique formatted into an easy-to-understand technique, and postoperative care. In addition, tips and tricks to facilitate safe and efficient performance of the technique as well as complication avoidance are discussed.

Keywords: cervical laminectomy minimally invasive laminectomy minimally invasive spine surgery technique tubular retractor

19.1 Introduction

The association between cervical spondylosis and spinal cord compression with myelopathy was first described in 1952 by Brain,1 now termed as cervical spondylotic myelopathy (CSM). CSM refers to impaired function of the spinal cord caused by degenerative changes of the anatomy within the cervical spine. The original treatment was open laminectomy, but associated complications included the development of cervical kyphosis, gross instability, infection, postlaminectomy membrane formation, and neurological deterioration.² This led to the development of other surgical options including anterior and posterior approaches.³ Although improvements have been made, postoperative axial neck pain is still a common patient complaint with open techniques.⁴ With the advancements of minimally invasive spine surgery (MISS) in the past two decades,⁵ minimally invasive techniques and approaches to spine have been developed and continue to evolve. The concept of achieving bilateral spinal decompression via a unilateral approach was first applied to open lumbar surgery in 1997.⁶ Minimally invasive unilateral laminotomy for bilateral decompression (ULBD) using tubular retractors was introduced for the treatment of lumbar spinal stenosis in 2002.⁷^,⁸^,⁹ Since then, the concept of ULBD has become a key surgical principle of MISS, with its application recently extending to all levels of the spinal column including the treatment of CSM.¹⁰^,¹¹^,¹²^,¹³^,¹⁴^,¹⁵ Potential advantages of a minimally invasive laminectomy compared with open laminectomy include less blood loss, less muscle disruption, and bony removal which may in return result in decreased rates of postlaminectomy kyphosis or secondary fusion, less postoperative pain, infection, and shorter recovery and hospital stay. However, concerns and risks exist, most importantly the risk of intraoperative injury to the dura, spinal cord, and nerves.

This chapter provides a detailed description of the step-by-step microsurgical technique for the performance of the minimally invasive cervical laminectomy via a unilateral approach for bilateral decompression.

19.2 Indications

The main indication for this technique is single- or multilevel CSM with or without accompanying radiculopathy. This procedure is particularly useful for patients with a posterior compression vector (e.g., ligamentum flavum [LF] hypertrophy and/or buckling). As with most MISS decompression procedures, this technique can be particularly beneficial for obese and/or elderly patients in whom open surgery may carry greater than acceptable surgical risk.¹⁶^,¹⁷

19.3 Contraindications

The contraindications for MIS cervical laminectomy include those for open laminectomy:

•Fixed cervical kyphosis.

•Gross cervical instability.

•Severe medical comorbidities with unacceptable risk for surgery.

Relative contraindications for MIS cervical laminectomy include:

•Flexible cervical kyphosis.

•Prior posterior cervical surgery at the index level with scar tissue/fibrosis.

•Predominantly anterior spinal cord compression. Patients with adequate cervical lordosis may undergo MIS cervical laminectomy with good outcome if the surgeon is confident that the spinal cord will adequately fall posterior, away from the anterior compression.

19.4 Preoperative Planning

19.4.1 Target (Patient Selection)

Radiographic evaluation should include magnetic resonance imaging and flexion/extension radiographs (Fig. 19.1), and a computed tomography (CT) scan should be obtained for any patient with suspected ossification of the posterior longitudinal ligament. Assessment of the cervical spinal alignment and lordosis, identification of the level of stenosis, and detection of accompanying foraminal stenosis with nerve root involvement are necessary. Radiographic findings should be correlated to the clinical findings on history and physical examination.

Fig. 19.1 Preoperative sagittal (a) and axial (b) T2-weighted magnetic resonance imaging demonstrating severe spinal stenosis at C4–C5 with significant posterior compression from ligamentum flavum hypertrophy and buckling.

19.4.2 Technology

The instruments required to perform this procedure include:

•Tubular retractor system with multiple dilators of increasing diameter, a rigid holding arm, and a table clamp. We use a 15- to 18-mm tubular retractor to perform the laminectomy.

•Bayoneted 45- and 90-degree 2-, 3-, and 4-mm kerrison rongeurs.

•Bayoneted 2- and 3-mm kerrison rongeurs.

•Bayoneted ball-tip probe or blunt nerve hook.

•Angled surgical drill with a 15-cm curved drill shaft: we prefer a 3-mm fluted side-cutting matchstick drill bit with blunt tip.

•Operative microscope.

•Size 12 and 9 metal suction tips.

•Extended monopolar electrocautery.

•Extended bayoneted bipolar electrocautery.

•Fluoroscopy or computer-assisted navigation.

•Hemostatic agents: Thrombin Gelfoam, Surgiflo, Cottonoids, etc.

19.5 Surgical Steps

19.5.1 Patient Positioning

Step 1: Patient Positioning

The patient is positioned in the prone position on a radiolucent table with the head immobilized in a 3-pin skull clamp attached to the operating table. The neck is neutral or slightly flexed to unshingle the cervical laminae (Fig. 19.2). Intraoperative neuromonitoring (IOM) can be utilized and may be especially helpful and reassuring in the beginning of the learning curve. Countertraction of the shoulders with tape is applied to facilitate fluoroscopy.

Fig. 19.2 Photograph demonstrating the patient positioning.

19.5.2 Incision

Step 2: Incision

Lateral fluoroscopy or navigation is used to identify the incision site. A metal instrument or spinal needle should be aimed at the disc space of interest. Keep the instrument perpendicular to the floor so that the working angle will also be perpendicular to the floor. Once the target facet joint and disc space has been identified, local anesthetic with epinephrine is injected into the skin 2-cm off midline. A linear 2.5-cm incision is then made (Fig. 19.3a).

Fig. 19.3 (a) Photograph demonstrating the incision. (b) Intraoperative photograph after the muscular dissection has been completed demonstrating the access corridor to the cervical spine.

19.5.3 Technique (Video 19.1)

Step 3: Approach

Video 19.1 MIS tubular cervical laminectomy.

Monopolar electrocautery or sharp dissection is continued until the fascia is identified. The fascia is incised sharply in a linear manner so as to facilitate closure at the conclusion of the procedure. Care should be taken to avoid incising the underlying musculature to avoid bleeding. Using a Metzenbaum scissor or blunt clamp, a corridor through the cervical musculature to the cervical lamina is created (Fig. 19.3b). This blunt dissection helps limit the amount of muscular bleeding, which can be significant in the cervical spine. Bipolar electrocautery is used to control bleeding.

Step 4: Serial Dilation and Tubular Retractor Placement

Under direct visualization through the created muscular corridor, the first tubular dilator is placed directly onto the cervical lamina. Dilators of increasing size are then passed over one another to dilate the corridor through the soft tissue (Fig. 19.4a). The surgeon should keep gentle downward pressure on the first dilator to keep it on the lamina. Care should be taken to avoid slipping of the dilator into the interlaminar space. Once the last dilator is passed, the surgeon can measure the depth and pass the appropriate sized tubular retractor onto the lamina and secure it in place with the table attachment (Fig. 19.4b). Lateral fluoroscopic images are obtained to confirm the correct level has been targeted (Fig. 19.4c, d).

Fig. 19.4 Intraoperative photographs showing serial dilation and tubular retractor placement (a, b) and confirmation of the correct level with lateral X-ray (c, d).

Only gold members can continue reading. Log In or Register to continue