- Mission Hospital Regional Medical Center, Mission Viejo, CA, USA
Mission Hospital Regional Medical Center, Mission Viejo, CA, USA
DOI:10.4103/2152-7806.94294Copyright: © 2012 Palmer S. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
How to cite this article: Palmer S, Davison L. Minimally invasive surgical treatment of lumbar spinal stenosis: Two-year follow-up in 54 patients. Surg Neurol Int 24-Mar-2012;3:41
How to cite this URL: Palmer S, Davison L. Minimally invasive surgical treatment of lumbar spinal stenosis: Two-year follow-up in 54 patients. Surg Neurol Int 24-Mar-2012;3:41. Available from: http://sni.wpengine.com/surgicalint_articles/minimally-invasive-surgical-treatment-of-lumbar-spinal-stenosis-two-year-follow-up-in-54-patients/
Objective:Minimally invasive surgery has seen increasing application in the treatment of spinal disorders. Treatment of degenerative spinal stenosis, with or without spondylolisthesis, with minimally invasive technique preserves stabilizing ligaments, bone, and muscle. Satisfactory results can be achieved without the need for fusion in most cases.
Methods:Fifty-four consecutive patients underwent bilateral decompressions from a unilateral approach for spinal stenosis using METRx instrumentation. Visual Analog Scale (VAS) pain scores were recorded preoperatively and patients were interviewed, in person or by phone, by our office nurse practitioner (LD) to assess postoperative VAS scores, and patient satisfaction with the clinical results 21-39 months postoperatively (median 27 months).
Results:Fifty-four patients underwent decompression at 77 levels (L4/5 = 43, L3/4 = 22, L5/S1 = 8, L1/2 = 4, L2/3 = 4), (single = 35, double = 16, triple = 2, quadruple = 1). There were 39 females and 15 males. The average age was 67 years. The average operative time was 78 minutes and the average blood loss was 37 ml per level. Twenty-seven patients had preoperative degenerative spondylolisthesis (Grade 1 = 26, Grade 2 = 1). Eight patients had discectomies and four had synovial cysts. Patient satisfaction was high. Use of pain medication for leg and back pain was low, and VAS scores improved by more than half. There were three dural tears. There were no deaths or infections. One patient with an unrecognized dural tear required re-exploration for repair of a pseudomeningocele and one patient required a lumbar fusion for pain associated with progression of her spondylolisthesis.
Conclusions:Minimally invasive bilateral decompression of acquired spinal stenosis from a unilateral approach can be successfully accomplished with reasonable operative times, minimal blood loss, and acceptable morbidity. Two-year outcomes in this series revealed high patient satisfaction and only one patient progressed to lumbar fusion.
Keywords: Lumbar spinal stenosis, minimally invasive surgery, spondylolisthesis
The initial description of the surgical treatment of spinal stenosis was given by Sacks and Fraenkel in 1900.[
Minimally invasive approaches to spinal surgery have been described utilizing chemical,[
The 54 consecutive patients who underwent bilateral METRx decompression from a unilateral approach for spinal stenosis, by a single surgeon, were included in this study. A total of 77 levels were decompressed. Procedures were done as out-patients or in-patients. All patients underwent the procedures under general anesthesia. Prospective Visual Analog Scale (VAS) pain scores were recorded preoperatively and at 2, 6, 12, 26, and 52 weeks postoperatively. Patients were interviewed, in person or by phone, by our office nurse practitioner (LD) to assess long-term VAS scores, and patient satisfaction was assessed utilizing a patient satisfaction questionnaire developed by PhDx (Albuquerque, NM, USA) at 21–39 months postoperatively (median 27 months).
The average age was 67 years (range 43–84 years) and there were 39 females and 15 males. Twenty-seven patients had degenerative spondylolisthesis (Grade 1 = 26, Grade 2 = 1). All patients were studied with preoperative magnetic resonance imaging (MRI) scans and lumbar X-rays with flexion/extension views [
Patients were prepared and positioned as for standard laminectomy. The procedure is a modification of the microendoscopic discectomy (MED) procedure previously described in detail by Foley and Smith.[
The working channel was then angled medially exposing the anterior aspect of the spinous process, which was then removed utilizing a power drill with a diamond burr [
Bupivacaine 0.25% with epinephrine 1:200,000 was infiltrated into the soft tissues prior to closure. The incision was closed in layers with Vicryl (Johnson and Johnson/Ethicon, Somerville, NJ, USA) followed by Steristrips (3M Corporation, St. Paul, MN, USA) and a bioocclusive dressing or, more recently, Dermabond (Johnson and Johnson, Somerville, NJ, USA) on the skin edge. The patients were encouraged to use ice postoperatively and were given only oral analgesics (usually hydrocodone). Patients with preoperative spondylolisthesis were placed in a chair back brace for 6 weeks as a precautionary measure whether or not they were stable to preoperative flexion/extension lateral radiographs. Physical therapy was begun at 6 weeks, and thereafter increased activities were encouraged.
A total of 77 levels were decompressed in the 54 patients. There were 35 single-level procedures, 16 two-level procedures, 2 three-level procedures, and 1 four-level procedure. The level of decompression was L4/5 in 43, L3/4 in 22, L5/S1 in 8, L1/2 in 4, and L2/3 in 4 patients. Eight patients had concomitant discectomies at the index level and one patient had a discectomy at a non-stenotic level. Five patients had an associated synovial cyst. Average operative time was 78 minutes per level and average estimated blood loss was 35 ml per level. There were three durotomies that were not primarily repaired but covered with gelfoam. These three patients were admitted for 48 hours of bed rest and did not have adverse consequences. One pseudomeningocele developed in a patient with an unrecognized dural tear. She required re-exploration for repair of the pseudomeningocele. There were no neurologic injuries and infections. One patient from the entire group of 54 patients went on to require fusion at 16 months postoperatively with a progressive spondylolisthesis.
VAS pain scores were followed prospectively at pre-op, 2, 6, 12, 26, and 52 weeks. The results were followed separately for back pain and for leg pain. The average preoperative VAS pain score was 6 for back pain and 8 for leg pain. The score decreased to 2 for back pain and 1 for leg pain at 2 weeks (n = 52), 2 for back pain and 1 for leg pain at 6 weeks (n = 52), 1 for back pain and 1 for leg pain at 12 weeks (n = 52), 3 for back pain and 3 for leg pain at 26 weeks (n = 27), and 3 for back pain and 4 for leg pain at 52 weeks (n = 22). VAS pain scores were also assessed at an average of 27 months postoperatively by phone interview and the average results were 3 for back pain and 2 for leg pain (n = 45) [
Patients′ use of analgesic medications was followed prospectively. Patients were queried as to their use of narcotics, non-narcotic analgesics, or no analgesics. Preoperatively 18 patients used narcotics, 20 patients used non-narcotic analgesics, and 14 used no analgesics (n = 52). The analgesic usage was 18 narcotic, 4 non-narcotic, and 30 none at 2 weeks (n = 52); 7 narcotic, 8 non-narcotic, and 38 none at 6 weeks (n = 52); 7 narcotic, 15 non-narcotic, and 30 none at 12 weeks (n = 52); 3 narcotic, 9 non-narcotic, and 15 none at 26 weeks (n = 27); and 4 narcotic, 4 non-narcotic, and 14 none at 52 weeks (n = 22) [
Analgesic usage was assessed at an average of 27 months postoperatively (range 22–39 months) by phone interview. It was assessed separately for back pain and for leg pain. Seventeen patients had no back pain, 10 patients had back pain but did not use analgesics, 2 patients had bad back pain but did not use analgesics, 1 patient used analgesics with complete relief of back pain, 9 patients used analgesics with moderate relief of back pain, 6 patients used analgesics with little relief of back pain, zero patients used analgesics with no relief of back pain [
Patient satisfaction with the care they received and the results of the surgery were also assessed by questionnaire at an average of 27 months postoperatively (range 22–39 months). Approximately 80% of patients thought it was definitely true or mostly true that they were pleased with the care they received and the results of the surgery. Thirty-seven of 44 patients thought it was definitely or mostly true and only 7 of 44 patients thought it was definitely or mostly false that, “All things considered, I would have the surgery again for the same condition” [
The goal of any surgical treatment of spinal stenosis is to decrease pain and increase the functional capacity of the patient while limiting surgery-related morbidity and mortality. Limiting the extent of surgical invasiveness with the preservation of preexisting spinal elements has been utilized to try and optimize the clinical benefit of surgery.[
We have previously demonstrated the feasibility of performing minimally invasive bilateral decompression for spinal stenosis from a unilateral approach.[
The biomechanics of the normal spine, as it relates to spinal stenosis and spondylolisthesis, have been extensively studied and previously reported. The salient work by Adams, Risannen, and Cusick will be reviewed here. Adams and Hutton showed that the tendency to anterolisthesis is resisted by multiple spinal elements. The facet joints have been shown to resist 33% of the shear forces, with the disk resisting 67%.[
Cusick et al. designed a biomechanical study of sequential sectioning of the posterior ligaments and facets using a two-motion segment model.[
Many authors have questioned the effectiveness of treating patients with spinal stenosis complicated by spondylolisthesis without the use of fusion.[
Lumbar spinal stenosis is not commonly a disease of younger patients. Surgery in an older patient is commonly complicated by multiple co-morbidities. It is particularly attractive to have a minimally invasive surgical treatment option for this older group. This allows for early consideration of surgical options without waiting for potentially irreversible neurological morbidity before entertaining fusion surgery. This also allows for an earlier return to an active lifestyle, often limited by the symptoms of lumbar spinal stenosis. Rehabilitation is quicker with minimally invasive surgery with the avoidance of the complications related to postoperative immobility of more extensive procedures. We utilized general anesthesia in all patients, but spinal or epidural anesthesia has been utilized successfully by others. The surgery can be performed with the patient as an in-patient or an out-patient depending on medical, social, and economic factors.
Minimally invasive bilateral decompression of acquired spinal stenosis from a unilateral approach can be successfully accomplished with reasonable operative times, minimal blood loss, and acceptable morbidity.
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