What Is Minimally Invasive Spine Surgery

Minimally Invasive Spine Surgery

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What Is Minimally Invasive Spine Surgery?

In essence, minimally invasive spine surgery is the performance of surgery through small incision, usually with the aid of microscopes or endoscopic visualization (i.e., very small devices or cameras designed for viewing internal portions of the body).

Why Is Minimally Invasive Spine Surgery Needed?

Minimally invasive spine surgery has developed out of the desire to effectively treat disorders of the spinal discs with minimal muscle related injury, and with rapid recovery.

Traditionally, surgical approaches to the spine have necessitated prolonged recovery time. For example, prior to the use of the operating room microscope a large incision was used to visualize the herniated lumbar disc. In order to perform this procedure, large sections of the back muscles are moved away from their spinal attachments.

First, this surgical approach (i.e., dissecting the muscles) produces the majority of the perioperative pain and delays return to full activity. The degree of the perioperative pain necessitates the use of significant pain medication with their inherent side effects. Also, the degree of the perioperative pain delays return to normal daily activities and nonphysical work.

Second, the dissection of the paraspinal muscles from their normal anatomic points of attachment results in a healing by scarring of these muscles. The various layers of the individual muscle scar to one another losing their independent function.

In addition, it has been found that this type of dissection sometimes results in the loss of innervation (i.e., the supply of nerve stimulation) of the muscles with subsequent wasting away. A permanent weakness of the back muscles results. This weakness itself may be symptomatic (as a back fatigue-type pain) and/or limit the patient's function - particularly in those who perform physical work.

Clearly, with such significant muscle injury associated with surgical approaches to the spine, the need existed for the development of less invasive surgical techniques. It was envisioned that minimally invasive techniques would offer several advantages including: -Reduced surgical complications - Reduced surgical blood loss - Reduced use of post-op narcotic pain medicines - Reduced length of hospital stay - Increased speed of functional return to daily activities

History of Minimally Invasive Disc Surgery

In 1964—Lyman Smith, an orthopedic surgeon in Chicago, was the first to inject, percutaneously, chymopapain into a patient with sciatica with the purpose of hydrolyzing the mucoprotein of the herniated nucleus pulposus.

In 1975 Hijikata performed a percutaneous nucleotomy by inserting a 7-mm diameter tube down to the annulus fibrosis and, then, using specially designed forceps removed disc material.

In 1977-78 Yasargil, Caspar and Williams pioneered the use of the operating microscope and microsurgical techniques for treating lumbar disc disease.

In 1983 Kambin began developing what eventually would be a modified arthroscopic approach to lumbar discectomy using a working sheath with a 6.5 mm outer diameter and coring instruments and forceps designed for a 5 mm inner access.

Onik and subsequently Maroon and Onik described and published their early results with automated percutaneous discectomy using a guillotine like 2 mm probe inserted fluoroscopically into the disc space.

In 1987 Choy and Asher described laser discectomy and subsequently laser energy has been used percutaneously for disc ablation.

In 1993 Mayer and Brock discussed the use of the endoscope for percutaneous discectomy. Subsequently Smith and Foley designed instrumentation and endoscopic equipment to perform a micro-endoscopic approach to lumbar disc removal.

In 2000, intradiscal electrothermal energy as well as newly designed lasers are being advocated for percutaneous thermal annuloplasty in patients with low back pain.

Summary of Microscopic Approach

In 1965-66 Gazi Yasargil spent 14 months with R. Peardon Donaghy at the University of Vermont developing the microsurgical instrumentation and techniques that would revolutionize the surgical approach to many neurosurgical diseases. Upon returning to Zurich 1n 1967, he applied his knowledge and microsurgical skills to reduce the morbidity and improve the outcome in patients with aneurysms, arteriovenous malformations, various neoplasms—and herniated lumbar discs.

The first publication of the microsurgical discectomy procedure was in 1977 in the journal, Advances in Neurosurgery. It was Williams, a Las Vegas neurosurgeon and consultant to many of the casinos employing female dancers, that popularized the technique in the United States. He supported his hypothesis that surgical scars could be minimized and performers could return to dancing quicker through techniques he described in his 532 reported patients. Subsequently Goald and Ebeling, et al, Wilson and Harbaugh, Maroon and Abla and many others have confirmed the ability to reduce incision size, blood loss and morbidity with the microsurgical technique. Success rates of microdiscectomy range from 88% to 98.5% in various series.

Because of the small incision, the diminished trauma to lumbar musculature, the easier identification of deep seated structures, the minimal traumatic manipulation of neural structures and the direct view into the disc with magnification and coaxial illumination, for the most part, this resistance has faded and the great majority of neurosurgeons now use magnification if not the operating microscope in performing lumbar disc surgery.

Dr. Maroon now have personally operated on over 2,500 microdiscectomies patients. After investigating and using almost all percutaneous and standard operative techniques, Dr. Maroon believes that the microsurgical approach for lumbar discectomy remains the gold standard against which all other procedures must compare.

Our surgical approach is similar, with a few modifications, to that described by Yasargil, Caspar and Williams. Patients are placed in the lateral decubitus position, slightly flexed with the affected side up and the surgeon is seated. X-ray is used to confirm the correct interspace. Prophylactic intravenous antibiotics are given in one dose at least 30 minutes prior to the skin incision. A 15-25 mm skin incision is made.

The operating microscope with a 300-mm objective is then brought into use. A low profile, high speed drill is used to drill a small window in the bone. Free fragments and attached disc material are removed and pressure is released from the nerve root. And the bony opening which the nerve pasts is also enlarged. Steri strips and a band-aid are applied to the wound.

Patients are urged to ambulate immediately and are discharged within 23 hours, either the same day or the following morning in 95% of the cases. Our results have not significantly changed since our earlier report. The average operating time is less than one hour. Approximately 90% of patients obtain good to excellent pain relief. Complications such as dural tears, nerve root injury and discitis are under 1.5%. Long term reoperations at the same level are under 5%. No transfusions, great vessel or retroperitoneal injuries or mortality has occurred in over 2,500 operations.

To reduce scarring we preserve, as much as possible, the epidural fat and ligamentum flavum over the nerve root. If it is necessary to do a more extensive dissection, ADCON-L® is used in the epidural space.

Conclusion and Comparisons

When one compares the surgical outcome and overall experience with microsurgical discectomy with percutaneous techniques such as chemonucleolysis, automated percutaneous lumbar discectomy, modified nucleotomy and transforaminal endoscopic techniques the microsurgical approach appears to be superior in most areas. Obviously, laser discectomy has no place with extruded or sequestered fragments and none of the other techniques deal with lateral recess or foraminal stenosis, hypertrophy of the ligamentum flavum or osteophytes that occasionally are encountered unawares.

A valid comparison can be drawn between the micro-endoscopic technique and the strict microsurgical method. Proponents of MED assert that the primary differences with the microsurgical approach are 1) a smaller skin incision, 2) a muscle splitting rather than a subperiosteal approach to the lamina, 3) less postoperative pain, 4) faster hospital discharge and 5) a quicker return to employment. Once exposure through the tubular endoscopic system is obtained, the endoscopic technique for ligamentum flavum removal, discectomy and foraminotomy are the same as that used in the microsurgical approach.

With the microsurgical approach described above virtually the same size surgical incision is made, 15-20 mm, and the same surgical technique is used for discectomy. The primary difference, therefore, is a subperiosteal dissection versus a muscle splitting dissection which, in our opinion, is minor. Dr. Maroon, and others, have demonstrated the incision size, hospital stay and results are at least equivalent to that reported with the MED system. The return to work interval is also comparable. Recently, Dr. Maroon (Team Neurosurgeon for the Pittsburgh Steelers) returned an NFL defensive end to football in one month after microsurgery for an extruded fragment.

Dr. Maroon and his Associates have spent the last 25 years investigating and reporting on minimally invasive approaches to the lumbar disc. They believe there still are indications for APLD, disc ablation with lasers, endoscopic techniques and nucleotomy in very carefully selected patients. Despite the relative ease of performance in some cases, however, none of these methods have found their place in the hands of the majority of surgeons due either to the paucity of long term results, the potential and real complication rate or the learning curve in acquiring the technical skills. With the tremendous advances in neuro imaging, better understanding of the pathophysiology of disc disease and the innovations in technological development, pursuit of unique and minimally invasive ways to treat lumbar disc disease must continue. Nevertheless, in the year 2000 microsurgical discectomy remains the procedure of choice for the majority of patients requiring surgery and continues to be the standard against which all other procedures must be measured.

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Last Updated: January 1, 2008