Discectomy: A surgical approach

Introduction

Lumbar disc herniation (LDH) is the one of the most common diagnoses in spine practice for patients with lower back pain and radiculopathy, with an estimated prevalence of 2%–3%. Disc herniation occurs when the nucleus pulposus is displaced through the annulus fibrosus, which can cause compression and irritation of the nerve roots and spinal cord. Lumbar discectomy, a surgery in which the nervous tissue is directly decompressed through removal of extruded disc, is the most common neurosurgical procedure in the United States. Though historically performed through an open, muscle stripping approach, the procedure has been modified using minimally invasive principles since the introduction of the operating microscope. Microdiscectomy has become the prevalent method of treatment for LDH due to the reduced soft tissue damage from the smaller approach window, while providing comparable patient outcomes. ^,

We describe a method of microdiscectomy which accesses the extruded disc utilizing a unilateral approach with a tubular retractor system that provides the surgical window. This approach minimizes iatrogenic muscle splitting while providing adequate visualization of relevant nervous anatomy and tissue. After the tubular retractor has been placed, laminotomy is performed to allow access to the disc. Medial facetectomy and foraminotomy is also oftentimes performed during this procedure to ensure adequate decompression of the nerve root in the foramen and lateral recess.

One divergence in the practice of minimally invasive discectomy is the choice to use a surgical microscope or endoscope for visualization during the procedure. Microscopy is our preferred method because it allows for a three-dimensional view of the operation and the use of both hands during discectomy, whereas endoscopy often needs one hand to stabilize the endoscope.

Indications

Indications of discectomy include:

1.

Lower back pain or radiculopathy with evidence of nerve root irritation or neurological deficits.
2.

Have undergone and failed intensive nonoperative treatment that includes medication optimization, activity modification, and active physical therapy for treatment of symptoms. In the case of progressive neurological deficit, there is no need for conservative therapy.
3.

MRI evidence of moderate to severe central canal and/or lateral recess spinal stenosis related to disc herniation.

Relevant contraindications

Microdiscectomy can be contraindicated in any of the following scenarios:

1.

Presence of unstable spinal anatomy due to spondylolisthesis, lateral listhesis, or scoliosis.
2.

Presence of concurrent pathology such as tumor or infection.
3.

Revision cases with extensive surgical scarring, which increases the risk of surgery dramatically.

Preoperative considerations

Preoperatively, the patient is induced and placed in the prone position on a Jackson table. The area around the patient’s targeted surgical level 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.

Postoperative care

The surgery can be performed in an outpatient setting, and the patient is usually discharged the same day. The patient is discharged with pain medication and muscle relaxants.

Complications

Complications of microdiscectomy 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 as 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.