Expansive Open-Door Laminoplasty for Multilevel Cervical Canal Stenosis

In the past, total laminectomy without fusion was the standard method of decompression in cases of multilevel compressive myelopathy in the cervical spine. ¹^, ²^, ³ It has been shown, however, that significant frequency of the postoperative kyphotic deformity or recurrent canal stenosis from scar formation occurs by performing wide laminectomy. ⁴^, ⁵^, ⁶^, ⁷^, ⁸^, ⁹^, ¹⁰ To reduce these complications, various laminoplasty methods have been developed. ⁸^, ¹¹^, ¹²^, ¹³ More recently, attention has been paid to preservation of the posterior tension band as a supporting element for maintenance of long-term postoperative cervical alignment. ¹⁴^, ¹⁵^, ¹⁶ Newer laminoplasty techniques have increased in complexity. In addition, axial symptoms, such as nuchal stiffness or shoulder pain, after the previously reported laminoplasty techniques have not been addressed because paravertebral muscles are extensively stripped bilaterally from the spinolaminar bony tissue, resulting in weakness and atrophy.

We have developed a simple procedure for expansive open-door laminoplasty using titanium miniplates alone and other devices via a unilateral approach under an operating microscope. This simple laminoplasty technique preserves the contralateral paravertebral muscles, as well as the posterior tension band via unilateral approach, and may provide a more satisfactory outcome.

16.2 Patient Selection

This procedure is best performed in patients with myelopathy attributable to multilevel stenosis secondary to either ossification of the posterior longitudinal ligament (OPLL) or multilevel cervical spondylosis. Preoperative kyphosis and intractable neck pain are relative contraindications to this procedure.

16.3 Operative Procedure (See ▶ Fig. 16.1, ▶ Fig. 16.2)

The patient is placed in a prone position with the head fixed on Mayfield clamp in the neutral position. Motor evoked potential (MEP) and somatosensory evoked potential (SEP) monitoring is routinely used in patients with myelopathy to avoid compromise caused by the neck position during the surgical procedure. After a 5- to 8-cm posterior midline skin incision, unilateral paravertebral fasciae and muscles of the prominent side of myelopathy are dissected at the necessary levels usually from C3 to C6. The base of the spinous process is transected using a surgical saw with a right-angled blade while preserving the posterior tension band, including the nuchal, supraspinous, and interspinous ligaments and the spinous process. The contralateral paravertebral muscles are dissected subosteally from the laminae and lateral mass without detaching from the spinous process. Multiple muscle attachments at the C2 spinous process are mostly preserved. Partial dome-shaped laminotomy can be performed at the adjacent C2 for additional posterior decompression by undercutting C2 lamina using the drill and ultrasonic bone curets (Sonopet, Stryker, Kalamazoo, Michigan) when canal stenosis is prominent at C2 by OPLL. C7 partial laminectomy is also performed before making gutter without dissection of the attachment of trapezius muscle at the C7 spinous process. By using high-speed drills with diamond burs of 3- to 4-mm in diameter, a narrow gutter along the laminoarticular line is made completely on one side and incompletely on the other hinge side, leaving a thin inner cortex. The ultrasonic bone curets are effectively used to make complete gutter while protecting epidural veins and nerve roots. The laminae are then carefully opened in a unilateral open-door fashion for expanding the spinal canal; the ligamentum flavum is sectioned at the gutter and usually at C2–3 and C6–7. During all procedures, MEP and SEP monitoring is used to avoid neurologic deterioration. Bleeding from the epidural venous plexus can be managed easily by using a bipolar coagulator and by placing a piece of Surgicel (Codman, California). Titanium miniplates are fixed with 4-mm screws over the opened lamina and the lateral mass in a lazy S-shaped manner at each level. Recently, we used two types of titanium devices made for open-door laminoplasty instead of the titanium miniplates for craniofacial surgery. The first is the Centerpiece (Medtronic Sofamore Danek, Fridley, Minnesota), and the second one is the Laminoplasty Basket (Ammtec, Japan). Both can be easily attached to the open side gutter (see ▶ Fig. 16.3). The Laminoplasty Basket has the basket shape cage at the open side gutter, which can be filled with bone chips and artificial bone to get the 360-degree fusion. Bone chips are then placed over the hinge-side lateral gutter. After expansive laminoplasty is performed, the paravertebral fasciae, the subcutaneous tissue, and the skin are sutured. Patients are immobilized in a collar for 1 week after the operation.

Fig. 16.1 Schematic drawings for expansive laminoplasty using Laminoplasty Baskey alone via the unilateral approach of the cervical spine. (a-c) Posterior view. (d) Axial view. (a) Splitting of the spinous process at the base. (b) Exposure of bilateral laminae. (c, d) Fixation with Laminoplasty Basket and closure of the wound.

Fig. 16.2 Neuroimaging of the cervical spine obtained in a 60-year-old man with a transient quadriparesis after a minor head injury, demonstrating multilevel cord compression with cervical spondylotic change at C3. (a) Preoperative MRI T2WI sagittal, (b) postoperative MRI T2WI sagittal, (c, d) postoperative CT axial images, (e) postoperative CT sagittal image