Minimally Invasive Surgery a Viable Option for Patients with Herniated Lumbar Disks

An estimated 12 million Americans suffer from degenerative disk disease, with over one million patients undergoing surgery each year. A herniated disk is a fragment of the disk nucleus which is pushed out of the annulus into the spinal canal, through a tear or rupture. Disks that become herniated are usually in an early stage of degeneration. The spinal canal has limited space, which becomes inadequate for the spinal nerve when a disk fragment herniates into the space. Due to this displacement, the disk presses on spinal nerves and often produces pain, which may be severe.

In the past, the standard surgical treatment for herniated lumbar intervertebral disks was open microscopic diskectomy. However, in recent years, minimally invasive techniques such as microendoscopic diskectomy (MED) have been developed, allowing diskectomy to be performed through smaller incisions with less tissue disruption. While these techniques are less invasive, few studies have been performed that objectively delineate patient outcome after MED.

Researchers recently studied the use of minimally invasive procedures to treat herniated lumbar intervertebral disks. The results of this study, Objective Clinical Outcome Following Microendoscopic Diskectomy (MED) for Lumbar Herniated Intervertebral Disks Using SF-36, Visual Analog Scale, and Oswestry Disability Index, was presented by Kurt Eichholz, MD, 5:00 to 5:10 p.m. on Tuesday, April 24, 2006, during the 74th Annual Meeting of the American Association of Neurological Surgeons in San Francisco. Co-authors are Dae-Hyun Kim, MD, John O'Toole, MD, John Song, MD, Sean Christie, MD, PhD, and Melody Hrubes, BS, and Richard G. Fessler, MD, PhD.

Between September, 2002 and February, 2005, 114 patients with classic symptoms of lumbar radiculopathy underwent MED for lumbar disk herniations. The majority of the procedures were performed on an outpatient basis using general anesthesia. The average operative time was 109 minutes, and mean blood loss was 38 mL. The approximate hospital stay was 10.2 hours, compared to the longer stay that is common after standard open diskectomy.

Data were collected prospectively. Eighty-seven patients were available for follow-up, on average, for 16.5 months. The remaining patients were lost to follow-up due to change in address or phone number. Outcomes were measured using the Visual Analog Scale (VAS), the Oswestry Disability Index (ODI), and the Short Form-36 (SF-36) questionnaires to quantify outcome. These assessments were performed preoperatively, at 6 weeks, 4.5 months, 10.5 months, and 18 months postoperatively.

Patients showed improvement in preoperative scores for all three outcome scales. The following outcomes were noted:

• VAS: patients showed an improvement in low back pain (3.9 preop vs. 2.1 postop); leg pain (right leg: 3.2 preop vs. 1.2 postop, left leg: 3.4 preop vs. 2.2 postop).

• ODI: patients showed an improvement from 40.5 preop to 19.1 at follow-up.

• SF-36: scores improved in all subscales (physical function subscale: 37.1 preop vs. 66.1 at follow-up; role-physical functioning: 11.9 preop vs. 52.5 at follow-up; bodily pain: 22.3 preop vs. 60.2 at follow-up).

"In conclusion, minimally invasive MED for lumbar disk herniations is a safe and effective treatment. This new technique provides the benefit of shorter operative time, decreased blood loss, and shorter length of hospital stay," stated Dr. Fessler. The objective outcomes utilized all delineate improvement in symptoms after minimally invasive MED. "The outcomes for this minimally invasive approach are comparable to published outcomes for standard diskectomy," added Dr. Fessler.

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