Laminotomy

Introduction

Direct decompression of the spinal cord through laminectomy and removal of ligaments has been a traditionally common treatment for central canal stenosis. During laminectomy, there is a successive removal of dorsal sources of stenosis such as the laminae, ligamentum flavum, and facet joint hypertrophy. One iatrogenic consideration of laminectomy is the destabilization of the spine resulting in spondylolisthesis or hypermobility of spinal segments. Additionally, traditional approaches to laminectomy may lead to ischemic damage in the surrounding musculature and poor vascularization of the bone and facet, contributing to the future progression of degeneration. To improve postoperative stability of the spine while allowing for adequate decompression, less invasive surgical methods have been developed, such as facet sparing laminectomy and laminotomy. In a laminotomy procedure, a caudal part of the lamina is removed unilaterally and is used as a surgical window to decompress the foramen, central canal, and lateral recesses bilaterally. This technique has been shown to have less destabilization than laminectomy in both porcine and human models and to result in comparable clinical improvements to other decompressive techniques.

In this chapter, we describe a method of laminotomy that has been described as a tubular unilateral approach for bilateral decompression. This technique utilizes a tubular retractor as a working portal that docks onto the posterior elements of the target segment to allow for partial removal of the lamina. After a caudal part of the lamina is removed, the tubular retractor is tilted as needed for visualization. A high-speed spinal drill is used to remove the inner parts of the lamina while the ligamentum flavum remains intact for dural protection. The tube is tilted more to perform removal of medial facet and achieve at first foraminotomy of the contralateral side. The ligamentum flavum is removed piecemeal from contralateral to ipsilateral under direct visualization of the dura, while the retractor is straightened. Finally, the ipsilateral foramen and medial facet are visualized, and the foramen is decompressed.

Indications

Indications of laminotomy for the treatment of patients with claudication and radiculopathy with:

1.

Have undergone and failed an intensive nonoperative treatment that includes medication optimization, activity modification, and active physical therapy for treatment of symptoms.
2.

Moderate to severe central and/or lateral recess spinal stenosis due to hypertrophy of ligaments or lamina or/and facets.

Relevant contraindications

Laminotomy is contraindicated in any of the following scenarios:

1.

Unstable spinal anatomy due to spondylolisthesis, lateral listhesis, or scoliosis.
2.

Axial back pain relating to instability or degenerative disc disease is a relative contraindication.

Preoperative considerations

Preoperatively, the patient is induced and placed in the prone position on a Jackson table. The area around the targeted levels is prepared and the draping is performed prior to surgery. Intraoperatively, 1% lidocaine with epinephrine and 0.25% Marcaine plain mixed 1:1 is injected at the skin where the incision will be made.

The side of the approach is usually the side with major symptoms or stenosis.

Postoperative care

The patient is usually discharged on the same day with pain medication and muscle relaxants.

Complications

Complications of laminotomy include:

1.

Violation of the thecal sac and nerve roots can result in iatrogenic damage to nerves and cerebrospinal fluid leak.
- a.
  
  This risk can be minimized by ensuring there is no adhesion of the dura to the ligamentum flavum and removing the ligamentum flavum after contralateral decompression.
- b.
  
  Durotomy should be repaired, if possible, directly with 4-0 Nurolon sutures. Hydrogel dural sealant (DuraSeal) may be sufficient to close the dura in smaller cases.
2.

Postoperative hematoma manifesting in progressively worsening neurological symptoms.
- a.
  
  Emergent MRI should be performed to rule out hematoma, and emergency decompression may be necessary.
3.

Infection of the surgical site requiring antibiotics.
4.

Postoperative iatrogenic instability requiring fusion.

Laminotomy

Equipment

The method of laminotomy described is performed through a tubular retractor system ( Fig. 8.1 ) that provides the surgeon an operative corridor. A surgical microscope is used for visualization during laminotomy ( Fig. 8.2 ).

Anatomy

The facet hypertrophy and ligamentum flavum/laminar hypertrophy are the targets for decompression during laminoplasty ( Fig. 8.3 ).

Setup

Patient is placed in the prone position on a Wilson frame or a flat Jackson table and appropriately draped, while the flex arm is assembled to provide access to the desired spinal level ( Fig. 8.4 ).