Spinal stenosis prevalence and association with symptoms: the Framingham Study

Study design A randomized, controlled, prospective multicenter trial comparing the outcomes of neurogenic intermittent claudication (NIC) patients treated with the interspinous process decompression system (X STOP) with patients treated nonoperatively. Objective To determine the safety and efficacy of the X STOP interspinous implant. Summary of background data Patients suffering from NIC secondary to lumbar spinal stenosis have been limited to a choice between nonoperative therapies and decompressive surgical procedures, with or without fusion. The X STOP was developed to provide an alternative therapeutic treatment. METHODS.: 191 patients were treated, 100 in the X STOP group and 91 in the control group. The primary outcomes measure was the Zurich Claudication Questionnaire, a patient-completed, validated instrument for NIC. Results At every follow-up visit, X STOP patients had significantly better outcomes in each domain of the Zurich Claudication Questionnaire. At 2 years, the X STOP patients improved by 45.4% over the mean baseline Symptom Severity score compared with 7.4% in the control group; the mean improvement in the Physical Function domain was 44.3% in the X STOP group and -0.4% in the control group. In the X STOP group, 73.1% patients were satisfied with their treatment compared with 35.9% of control patients. Conclusions The X STOP provides a conservative yet effective treatment for patients suffering from lumbar spinal stenosis. In the continuum of treatment options, the X STOP offers an attractive alternative to both conservative care and decompressive surgery.

A multicenter, prospective, randomized trial evaluating the X STOP interspinous process decompression system for the treatment of neurogenic intermittent claudication: two-year follow-up results.

Patients suffering from neurogenic intermittent claudication secondary to lumbar spinal stenosis have historically been limited to a choice between a decompressive laminectomy with or without fusion or a regimen of non-operative therapies. The X STOP Interspinous Process Distraction System (St. Francis Medical Technologies, Concord, Calif.), a new interspinous implant for patients whose symptoms are exacerbated in extension and relieved in flexion, has been available in Europe since June 2002. This study reports the results from a prospective, randomized trial of the X STOP conducted at nine centers in the U.S. Two hundred patients were enrolled in the study and 191 were treated; 100 received the X STOP and 91 received non-operative therapy (NON OP) as a control. The Zurich Claudication Questionnaire (ZCQ) was the primary outcomes measurement. Validated for lumbar spinal stenosis patients, the ZCQ measures physical function, symptom severity, and patient satisfaction. Patients completed the ZCQ upon enrollment and at follow-up periods of 6 weeks, 6 months, and 1 year. Using the ZCQ criteria, at 6 weeks the success rate was 52% for X STOP patients and 10% for NON OP patients. At 6 months, the success rates were 52 and 9%, respectively, and at 1 year, 59 and 12%. The results of this prospective study indicate that the X STOP offers a significant improvement over non-operative therapies at 1 year with a success rate comparable to published reports for decompressive laminectomy, but with considerably lower morbidity.

A prospective randomized multi-center study for the treatment of lumbar spinal stenosis with the X STOP interspinous implant: 1-year results

Study design A cadaveric study was done to analyze the dimensional changes in the spinal canal and intervertebral foramen of the lumber spine with flexion and extension movements. Objectives To investigate the relationship between flexion and extension movements and morphologic changes in the spinal canal and the intervertebral foramen. Summary of background data Previous studies have reported that the dimensions of the spinal canal and the intervertebral foramen may change significantly with motion. The purpose of this study was to assess the quantitative changes in the spinal canal and the intervertebral foramen with segmental flexion-extension movements. Methods Nineteen fresh cadaveric spines yielding 25 motion segments were used. The lumbar motion segments were frozen and then imaged in axial and sagittal projections by a computed tomography scanner. They were thawed then, and the motion segments were loaded to 5.7 Nm in flexion (13 motion segments) and in extension (12 motion segments) specimens. While in flexion or extension, the specimens again were frozen and imaged by computed tomography scan. The frozen specimens than were sliced using a cryomicrotome in the sagittal plane to study the dimensions of the intervertebral foramen. Eighteen other fresh cadaveric spines were sliced sagittally for study in the neutral position. Results The axial computed tomography scans showed that extension significantly decreased the canal area, midsagittal diameter, and subarticular sagittal diameter, whereas flexion had the opposite effects. The sagittal computed tomography scans showed that extension decreased all the foraminal dimensions significantly, whereas flexion increased all the foraminal dimensions significantly. The translational changes were associated with the bulging of the disc and the presence of traction spurs. The cryomicrotome sections showed the cross-sectional area of the foramen to be 12% greater for the flexion group and 15% smaller for the extension group than the cross-sectional area of the neutral group. Nerve root compression in the foramen was found to be 21.0% in neutral, 15.4% in flexion, and 33.3% in extension groups. Conclusions The study supports the concept of dynamic spinal stenosis. In addition to static anatomic changes, careful dynamic studies may be required to evaluate better the central canal and the foramen.

Anatomic changes of the spinal canal and intervertebral foramen associated with flexion-extension movement.

Study design The spinal canal and neural foramina dimensions of cadaver lumbar spines were quantified during flexion and extension using magnetic resonance imaging before and after placement of an interspinous process implant. Objective To quantify the effect of the implant on the dimensions of the spinal canal and neural foramina during flexion and extension. Summary of the background data Lumbar neurogenic intermittent claudication symptoms are typically exacerbated during extension and relieved during flexion. It is understood that the dimensions of the spinal canal and neural foramen increase in flexion and decrease in extension. The authors hypothesized that an interspinous process implant would significantly prevent narrowing of the canal and foramina in extension and have no significant effect in flexion. Methods Eight L2-L5 specimens were positioned to 15 degrees of flexion and 15 degrees of extension using a positioning frame. Each specimen was magnetic resonance imaged with and without an interspinous implant (X STOP) placed between the L3-L4 spinous processes. Canal and foramina dimensions were compared between the intact and implanted specimens using a repeated measures analysis of variance with a level of significance of 0.05. Results In extension, the implant significantly increased the canal area by 18% (231-273 mm), the subarticular diameter by 50% (2.5-3.7 mm), the canal diameter by 10% (17.8-19.5 mm), the foraminal area by 25% (106-133 mm), and the foraminal width by 41% (3.4-4.8 mm). Conclusions The results of this study show that the X STOP interspinous process implant prevents narrowing of the spinal canal and foramina in extension.

The treatment mechanism of an interspinous process implant for lumbar neurogenic intermittent claudication

Computerized axial tomography (CAT) in cases of stenosis of the lumbar bony vertebral canal may demonstrate features of diagnostic significance in the shape of the canal and the bony structures surrounding it. The distinguishing features are the measurements. Standardized measurements of the midsagittal diameters at the cephalad and caudad borders of the laminas of the vertebral canal are proposed as a means of furthering both surgical and comparative studies. Identification of these borders in CAT scans is described, as is the procedure for taking measurements. One or two interlaminar, transarticular CAT scans are also made. In these scans, the midsagittal diameters cannot be measured because the ligamentum flavum forms the posterior wall in the midline. The scans may, however, demonstrate narrow lateral recesses and deformities of the articular processes and joint spaces. Errors in measurement of midsagittal diameters result from the inability of CT body scanners to show the angle between axial sections and the anterior vertebral canal wall, and from the partial volume phenomenon. The diameters are then too large. Errors in the angle of axial sections also lead to distortion in reconstructions of sagittal sections of the vertebral canal from the soft material obtained from axial sections. New precision designs are described. The principal indication for the intrathecal injection of water-soluble contrast media in CAT scanning is the determination of the thickness of the ligamentum flavum. Apart from its value in distinguishing various forms of stenosis, CAT scanning may also reveal inadequacies in surgical decompression.

The significance and principles of computerized axial tomography in idiopathic developmental stenosis of the bony lumbar vertebral canal.

The fallacies of the term stenosis are discussed. Propositions for a more precise definition of the stenotic conditions are given, based on the distinction between transport stenosis and compressive stenosis and their different properties. Uncertainties in the present nomenclature of the various for

Fallacies of the Present Definition, Nomenclature, and Classification of the Stenoses of the Lumbar Vertebral Canal

Three patients with complete lumbar spondyloptosis and 8 patients with fourth-degree spondylolisthesis suffering from radicular signs and symptoms are reported. There were 8 female and 3 male patients in the study. A high incidence of neurogenic intermittent claudication was noted in this condition. Decompressive laminectomy and foraminectomy were performed on all patients followed by transabdominal console fusion. Length of follow-up varied from 3 to 17 years, with a mean value of 13.5 years, and results are reported. Radicular signs and symptoms had completely subsided in all cases. Nine of 11 patients are free from signs and symptoms and 2 suffer from residual pain, although less severe than before surgery. All 3 males fathered children after surgery, which is in contrast to the opinion that anterior lumbosacrial fusion is followed by infertility in males. Special attention was given to individuality of remodeling of the lumbosacral junction over the course of time. Solid fusion was obtained in 10 of the 11 patients, while the console fusion collapsed because of failure to follow instructions after surgery in 1 patient.

The treatment of lumbar spondyloptosis or impending lumbar spondyloptosis accompanied by neurologic deficit and/or neurogenic intermittent claudication.

Henk Verbiest

Papers

The significance and principles of computerized axial tomography in idiopathic developmental stenosis of the bony lumbar vertebral canal.

Fallacies of the Present Definition, Nomenclature, and Classification of the Stenoses of the Lumbar Vertebral Canal

The treatment of lumbar spondyloptosis or impending lumbar spondyloptosis accompanied by neurologic deficit and/or neurogenic intermittent claudication.