Laser Discectomy

Updated: Aug 30, 2017
  • Author: Jasvinder Chawla, MD, MBA; Chief Editor: Erik D Schraga, MD  more...
  • Print
Overview

Background

Chronic low back pain is one of the major chronic debilitating conditions involving tremendous loss of money, work, and quality time. Lasers are used in different fields of medicine and confer unique advantages. In the treatment of lumbar disc disease, they are useful and advantageous.

Laser discectomy is an outpatient procedure with one-step insertion of a needle into the disc space. Disc material is not removed; instead, nucleus pulposus is burned by the laser. Laser discectomy is minimally invasive, cost-effective, and free of postoperative pain syndromes, and it is becoming more widely used at various centers.

The rapid acceptance of minimally invasive surgery in the United States has occurred largely without statistical proof of its superiority over traditional methods. All members of the healthcare field now see the need for valid outcome studies supporting the efficacy of new treatment techniques. Percutaneous laser disc decompression (PLDD) will gain wide acceptance only if it is demonstrated statistically to be a safe and effective alternative treatment for lumbar disc herniation.

Epiduroscopic laser neural decompression is considered an effective treatment alternative for chronic refractory low-back or lower-extremity pain, including lumbar disc herniation, lumbar spinal stenosis, and failed back surgery syndrome that cannot be alleviated with existing noninvasive conservative treatment. [1]

PLDD performed with computed tomographic (CT) and fluoroscopic guidance appears to be a safe and cost-effective treatment for herniated intervertebral discs and is being used with increasing frequency. [2] It is minimally invasive, can be performed in an outpatient setting, requires no general anesthesia, results in no scarring or spinal instability, shortens the rehabilitation time, is repeatable, and does not preclude open surgery should that become necessary.

Various laser wavelengths have been used, but no consensus exists regarding which is most efficacious. [3] Good candidates for this procedure have a classic clinical syndrome and neuroimaging evidence.

In cases of ruptured posterior longitudinal ligament (ie, epidural leak of contrast medium in discography), PLDD is not indicated. Indications for the operation first of all depend on the clinical symptoms, but the success of the operation depends on the discographic findings.

Laser-assisted posterior cervical foraminotomy with discectomy is an efficacious surgical option for treating lateral cervical disc herniation. The pinpoint accuracy of the laser scalpel facilitates sophisticated decompression within a limited surgical field and may reduce the risk of intraoperative bleeding and neural damage. [4]

Next:

Indications

This minimally invasive technique can be performed in patients who need surgical intervention for disc herniation (see the image below) with leg pain from radiculopathy. Patient selection and, especially, disc morphology are the two most important factors determining the choice of the technique.

Disc herniation classification. A: Normal disc ana Disc herniation classification. A: Normal disc anatomy demonstrating nucleus pulposus (NP) and annular margin (AM). B: Disc protrusion, with NP penetrating asymmetrically through annular fibers but confined within the AM. C: Disc extrusion with NP extending beyond the AM. D: Disc sequestration, with nuclear fragment separated from extruded disc.

Exclusion criteria include stenosis or facet hypertrophy and disc fragment, though a review from Knight et al described its use in foraminoplasty. [5]  Relative contraindications are progressive neurologic deficit, involvement in workers' compensation cases, and previous surgery at the same disc level.

In general, the herniation must have continuity with the parent disc; rupture of the annulus is not a contraindication. All patients must be considered on an individual basis.

Criteria for inclusion are undergoing continuing change. Although the optimal candidate, as previously described, is one who has an untreated single-level herniation with limited migration or sequestration of free fragments, a study from Ahn et al showed the procedure to be effective for recurrent disc herniations in some selected cases. [6]  What is unacceptable now may, with modifications, become acceptable in the future. At this stage in the development of PLDD, it is advisable not to adopt a fixed position.

Previous
Next:

Technical Considerations

The aim of PLDD is to vaporize a small portion of the nucleus pulposus of an intervertebral disc, thereby reducing the volume of a diseased disc and the pressure within it.

A small amount of tissue is excised from the center or nuclear part of the disc, which is believed to exert an effect on a noncontiguous portion of nucleus that is protruding through the annulus fibrosus and abutting an exiting nerve root. First described by Hijikata in relation to the percutaneous discectomy method, the central cavity created by the laser is believed to allow the nuclear protrusion to move back within the disc. [7]  A small change in disc nucleus volume can exert disproportionately large changes on the disc.

Yonezawa et al first demonstrated significant alterations in intradiscal pressure in response to vertical load after neodymium (Nd):yttrium-aluminum-garnet (YAG) laser treatment. [8] Their study also reported the equivalence of laser to aggressive manual curettage. Choy and Altman reported a greater than 50% reduction of intradiscal pressure in response to load following treatment with 1000 J of Nd:YAG laser energy. [9]  Prodoehl et al reported similar results using 1200 J from the holmium (Ho):YAG laser.

No specimen is available to weigh after laser discectomy; therefore, the amount of disc removed can only be approximated. By calculating the geometry of the laser tract, Choy and Altman estimated that 1000 J of Nd:YAG laser energy vaporized 98.52 mg of disc. [9]  Lane et al, who compared the effectiveness of 1200 J each of carbon dioxide, argon, and Ho:YAG laser energy, reported that Ho:YAG was superior, ablating 2.4 g of disc tissue.

By comparison, a clinical trial of automated percutaneous discectomy reported removal of 2-7 g of disc tissue with a suction cutting device. Quigley's group compared an automated device, Nd:YAG laser, and Ho:YAG laser and clearly demonstrated the superiority of the automated device in removing the greatest mass of tissue. [10]

Previous
Next:

Outcomes

Laser discectomy has been used for many years; however, there is a paucity of randomized clinical trials. On the basis of US Preventive Services Task Force criteria, the indicated level of evidence for percutaneous lumbar laser disc decompression is limited for short- and long-term relief.

Reviews by Singh et al and Manchikanti et al revealed limited evidence for percutaneous lumbar laser disc decompression. Automated percutaneous mechanical lumbar discectomy may provide appropriate relief in properly selected patients with contained lumbar disc herniation. [11, 12]

The most extensive experience in the literature was published by Choy and Ascher, who used an Nd:YAG laser. [13]  They observed 333 patients for a mean duration of 26 months. The success rate was 78.4% (as measured by a good or fair response) according to MacNab.

Siebert reported on his first 100 patients treated with Nd:YAG. [14]  The success rate was 78% at mean follow-up point of 17 months.

Davis reported an 85% success rate with the potassium titanyl phosphate (KTP) laser, with success rate defined as minimal discomfort and the ability to return to gainful employment (follow-up duration was not specified). [15]

Yeung reported preliminary assessment of more than 1000 patients whose herniated lumbar discs were treated with KTP laser. The reported success rate (good or excellent results) was 84%. No specifics were supplied. [16]

Sherk et al used a Ho:YAG laser in a comparison of laser discectomy and conservative treatment. [17, 18]  No differences were noted between treated and control groups. They concluded that laser discectomy is a safe procedure that appears to be effective in relieving symptoms in some patients. The author uses a Ho:YAG laser, with a success rate of approximately 80% (comparable to those of other investigators).

In another study from India by Agarwal, Ho:LADD (laser-assisted disc decompression) is a very cost-effective and minimally invasive procedure with patient mobilization immediately after the surgery. [19]

According to Kramer, the best clinical results were found in discographic stages 7 and 8. [20]  In cases of epidural leak of contrast medium and in cases of total degeneration, the clinical results were significantly poor (stages 6 and 9).

The literature includes more than 20 well-documented cases of erectile dysfunction caused by spinal cord disc herniation. PLDD is a minimally invasive procedure that that can be used to treat such herniation.

Singh et al reviewed 38 research reports published between 1986 and 2005 for intradiscal disease therapy classification, surgical intervention, and treatment outcomes (neurologic status, pain scores, and ambulation). Their results revealed that the surgical literature on the management of intradiscal disease continues to be limited, and arthrodesis continues to be the primary treatment modality in most patients. [21]  Newer treatment options, including laser discectomy, have shown promising results with regard to symptomatic relief and early return to function.

Provocative discography is recommended prior to the percutaneous lumbar disc decompression. Besides discectomy, laser has been used by Knight et al for endoscopic foraminoplasty as well. [5]

Ishiwata et al performed a study on magnetic resonance imaging (MRI)-guided percutaneous laser disc decompression for lumbar disc herniation. They suggested that the middle zone in the targeted disk space seems to be a favorable target to obtain better clinical outcomes. [22]

In a Cochrane database review by Gibson et al, microdiscectomy yielded results broadly comparable to those of open discectomy. [23]  Surgical discectomy for carefully selected patients with sciatica due to lumbar disc prolapse provides faster relief from the acute attack than conservative management. The evidence on other minimally invasive techniques remains unclear (with the exception of chemonucleolysis using chymopapain, which is no longer widely available).

In a study done in the Netherlands by Schenk et al on routine management of lumbar disc herniation, minimally invasive techniques were expected to be less effective, with higher recurrence rates but less postoperative low back pain. [24]  Most surgeons allowed early mobilization but appeared to give conservative advice in resumption of work.

Brouwer et al performed a randomized, controlled trial comparing PLDD with conventional treatment for lumbar disc herniation. [25]  In terms of the primary outcome (Roland-Morris Disability Questionnaire), they found a strategy of PLDD, followed by surgery if needed, to be noninferior to surgery at 1 year.

Previous