Westesson, Per-Lennart, M.D. Phd, DDS

Sidhu, Ravinder, M.D.

Hiwatashi, Akio, M.D.

Piekut, Diane, PhD.

DeGuzman, Ramon, M.D.

Lee, Ryan, M.D.

Purpose:
To compare height gains and cement leakage in vertebroplasty and kyphoplasty in a cadaver model.

Methods and Materials:
We harvested 80 vertebral bodies from donated cadavers, created compression fractures and treated half of the fractures with vertebroplasty and the other half with kyphoplasty in a random fashion. The results were evaluated by measuring the height of the vertebral bodies on sagittally reformatted CT scans obtained before and after creation of fractures and after treatment. The amount of cement leakage was quantified on axial CT scans.

Results:
At the time of this submission we have treated four treated vertebral bodies; 2 with vertebroplasty and 2 with kyphoplasty. Both methods increased the vertebral body height (vertebroplasty 1.9 mm, kyphoplasty 3.3 mm). There was no significant difference in the amount of cement leakage. At the time of presentation we will have the results of the complete study.

Conclusion:
Both vertebroplasty and kyphoplasty can increase the height of fractured vertebral bodies. At the time of presentation we will have the result of a large series and will have a more definite comparison of the two techniques.

Watanabe, Lisa, M.D.
Georgy, Bassem, M.D.

Introduction:
Syringes, stylets, and cement delivery devices are commonly used methods of applying cement into the spine during vertebroplasty. We attempt to qualitatively measure the amount of pressure that can be generated by these devices and compare the strength of the delivery devices in terms of working time.

Methods and Materials:
Testing was performed on multiple commercial devices including those made by Cook, Arthrocare-Parallax, Cardinal Health, Spinal Specialties, and BMDI as well as with 1 cc luer lock syringes. Pressure testing was performed with a water pressure meter in psi. Cement delivery working time was measured using unchilled Stryker Howmedica methy lmethacrylate cement. The mixtures were prepared using Stryker Mix-It devices according to manufacturer’s guidelines. No additional barium or antibiotic added to the cement. The syringes and delivery devices were then attached to 11 gauge 4 cm length bone trocars and tested for length of working time.

Results:
Between 800 and 1400 psi of pressure can be generated by hand injection through 1 cc syringes. Only 300-500 psi was generated by hand injection using 3 cc syringes. Significant physical strength was required to generate the higher end pressures in all cases except for BMDI. BMDI reached its pre-set pressure limit (1300 psi) with little physical effort.

The working times of the delivery devices was between 8-12 minutes. Unscrewing and leaking of connections were the main causes of device failure at high pressures. Device bursting occurred at levels of extremely high applied force that would likely not occur within the clinical realm. The 1cc syrin ges were unusable after 6 minutes, although the cement could still be pushed through the needles using stylets. Significantly greater thermal reaction was noted in the larger volume devices compared to the smaller syringes suggesting that the setting time may be affected by the volume of cement within a dispenser.

Conclusions:
All of the methods currently used for cement application in the spine have been shown to have advantages and disadvantages. The actual working time of the cement (as used in the study) is longer with the delivery devices than with the syringes. This may be due to the continuous pressure that can be applied with the devices. The working time of the syringes and devices would be prolonged with cement chilling. Further testing with different cement preparations is in progress.

Solsberg, Murray, M.D.

Purpose:
The purpose of this study was to evaluate the long-term outcome of patients treated percutaneously for synovial cysts of the lumbar facets.

Methods and Materials:
38 patients with synovial cysts of the lumbar facet joints treated at our facility between 1999 and 2003 were contacted by telephone in November and December 2003. The patient’s current pain level, limitations of daily activities and additional surgical and conservative treatments were recorded. These patients were treated with a standardized technique under fluoroscopic guidance. The standard technique was to first enter the facet joint with a 22-gauge spinal needle and aspirate any fluid. After arthrography confirmed that a cyst was present the joint was anesthetized with 2 % Xylocaine. The joint capsule then was distended until there was loss of resistance indicating cyst or capsule rupture. Then, Depo-Medrol 40 mg was instilled into the joint. Pre and post procedure visual pain analog diagrams and scores were completed and the values recorded. We also contacted each patient at 48 hours post procedure and noted the pain level. The demographics and pain responses were then analyzed. The chart, MRI and fluoroscopic images were also reviewed and the size and location of the facet cyst was noted.

Results:
26 women and 12 men were treated. The average age at time of treatment was 59 years. The average pain level prior to the procedure was 6/10 and immediate post-procedure was 1/10. The average time of follow-up was 20 months (range 3- 42 months). Twenty (53%) patients had no back pain or radiculopathy. In four (11 %) patients the radiculopathy was resolved but they stil l had mild (pain level < 4/10) low back pain. Six (16%) patients reported no improvement in their pain post-procedure but were still managed conservatively (without surgery) with pain levels all less than 4/10. Eight (21 %) patients had little or only short term improvement after the procedure and needed surgery. One patient had persistent pain and radiculopathy even after surgery.

Conclusions:
Radiculopathy was successfully treated in 64 % of our patients. No patients reported significant worsening of symptoms after treatment. The majority of patients at our facility with synovial cysts of the lumbar spine were successfully managed with conservative therapy.

Solsberg, Murray, M.D.

Purpose:
Percutaneous techniques are effective in the conservative management of patients with radiculopathy and a synovial cyst of the facet joint. The purpose of this study was to compare the outcome of patients with and without spinal stenosis and/or spondylolisthesis treated with fluoroscopically guided synovial cyst rupture.

Methods and Materials:
38 patients with synovial cysts of the lumbar facet joints treated at our facility between 1999 and 2003 were contacted by telephone in November and December 2003. The patient’s current pain level, limitations of daily activities and additional surgical and conservative treatments were recorded. Immediate pre and post procedure vis ual pain analog diagrams and scores were completed at the time of the procedure also. We also contacted each patient at 48 hours post procedure and noted the pain level. The demographics and pain responses were then analyzed. The chart, MRI and fluoroscopic images were also reviewed and the size and location of the facet cyst was noted. The spinal canal was measured on a workstation. Spinal stenosis was graded as: Normal (AP dimension >12mm cross sectional area > 100 mm2), Mild Relative (ap dimension>12 mm, cross sectional area >100, triangular shape of central canal, no thecal sac compression), Moderate Relative (thecal sac is effaced but cross sectional area > 100 mm2), and Absolute Severe (cross sectional area <100 mm2 and thecal sac compressed ap dimension less than 11 mm) spinal stenosis. Spondylisthesis was measured.

Results:
The average time of follow-up was 20 months (range 3-42). 20 patients had no residual back pain or radiculopathy. Only one patient in this group had severe spinal stenosis (Area = 75 mm2). Two patients in this group had spondylolisthesis >2 mm (2 and 7 mm respectively). In four other patients, the radiculopathy was resolved but they still had back pain. In this group one patient had severe stenosis (70 mm2 area) and no patient had spondylolisthesis over 2 mm. Six patients had no improvement post procedure and one patient had spinal stenosis (75 mm2) but none of the patients in this group underwent surgery. Eight patients had no improvement and had surgery. In the surgical group, four patients had spinal stenosis (50, 70, 75, 85 mm2 respectively) and three patients had spondylolisthesis (4, 6, 7 mm respectively). Probability of distribution for the surgical group versus the successfully treated radiculopathy group were significantly different (p <.05 (p=.00862)Fisher’s exact test) for spinal stenosis but not for (p >.05 (p=.09)) spondylolisthesis.

Conclusions:
In our study, patients without spinal stenosis had better pain relief after percutaneous facet therapy. Patients with severe spinal stenosis and a synovial cyst frequently required surgery. There was no significant difference between the surgical and conservative therapy group in the incidence of spondylolisthesis but this patient group was small. Patients with spinal stenosis contemplating percutaneous therapy of a synovial cyst should be counseled about realistic expected outcomes.

Sara-Lavi E, Bowen BC, Sklar EM, Quencer RM

Background and Purpose:
Several published studies have described the MR imaging findings which occur with variable frequency in cases of Spinal Dural Arteriovenous Fistula (SDAVF). While hyperintensity within the center of the cord on T2-weighted images has been reported as the most consistently observed finding, 1 it is not specific. Saraf-Lavi and colleagues2 showed that the observation of flow voids on T2-weighted fast-spin-echo images, and serpentine enhancement on postcontrast T1-weighted images, for a length exceeding three vertebral levels were each strongly associated with the presence of dural AVF, yet these findings are not always evident, or may be spurious and due to CSF pulsation artifacts. A recent study3 suggested that peripheral spinal cord hypointensity on T2-weighted images may be a reliable sign of venous hypertensive myelopathy and in particular of SDAVF. The purpose of this study is to evaluate the accuracy of this sign in predicting SDAVF.

Methods:
Gradient-echo axial images of 21 subjects with surgically proven DAVF (diagnosed with x-ray digital subtraction angiography, DSA) and 9 control subjects, who had normal DSA, were retrospectively reviewed by 2 experienced neuroradiologists blinded to the final diagnosis. The control group included subjects with abnormal cord signal intensity. The reviewers were asked to indicate “yes” or “no” in response to the question, “Is peripheral spinal cord hypointensity present?” Sensitivity, specificity, positive and negative predictive values were calculated. The level of agreement between the reviewers was also calculated.

Results:
Peripheral spinal cord hypointensity was observed in 9 of 20 patients with proven SDAVF, and in 2 of 9 control subjects. Sensitivity, specificity, and accuracy, as well as positive and negative predictive values, for each reviewer are presented in Table 1.

Kappa value was 0.71 representing good agreement between the reviewers beyond chance.

Conclusion:
The finding on T2-weighted images of peripheral spinal cord hypointensity in association with SDAVF has been attributed to slow flow of blood containing deoxyhemoglobin within a distended spinal cord capillary and venous system.3 Quencer4 has questioned whether the finding represent a real pathologic alteration or a visual phenomenon produced by the sandwiching of the peripheral cord between two hyperintense regions, the frequently observed hyperintensity of the central cord in SDAVF and the hyperintensity of the CSF surrounding the cord. Whatever the basis for the finding, our results indicate that the majority of patients with SDAVF are unlikely to exhibit peripheral cord hypointensity – as evidenced by the very low sensitivity in our study. Interestingly, peripheral cord hypointensity was observed in the control group. We conclude that peripheral cord hyperintensity is not a highly reliable sign of SDAVF. Based on the results for PPV, though, we suggest that when the sign is present, a more meticulous search should be instituted for other signs that are more strongly associated with the presence of SDAVF.

Reference:

1. 1. Gilbertson JR, Miller GM, Goldman MS, et al. Spinal dural arteriovenous fistulas: MR and myelographic findings. AJNR Am J Neuroradiol 1995;16:2049-2057
2. 2. Saraf-Lavi E, Bowen BC, Quencer RM, et al. Detection of spinal dural arteriovenous fistula with MR imaging and angiography: Sensitivity, specificity, and prediction of vertebral level. AJNR Am J Neuroradiol 2002;23:858-867
3. 3. Hurst RW, Grossman RI. Peripheral spinal cord hypointensity on T2-weighted MR images: a reliable imaging sign of venous hypertensive myelopathy. AJNR Am J Neuroradiol 2000;21:781-786
4. 4. Quencer RM. Is peripheral spinal cord hypointensity a sign of venous hypertensive myelopathy? AJNR Am J Neuroradiol 2000;21:617

Romero, Miriam, M.D., Sattenberg, Ronald, M.D., Wong, Alexis,M.D., Hinz, Brian, R.T., Rafal, Richard, M.D., Bettmann, Michael, M.D.

Purpose:
There has been much debate and literature on the significance of the lumbar disk high intensity zone (HIZ) on MRI imaging. Does this imaging finding have a clinical correlate with lower back pain?, What is the pathological correalte?, Is it worthy of reporting in examination interpretation, or will it lead to confusion?. These are some of the questions which need to be settled, or at least brought to a level of awareness.

Material and Methods:
A systematic review of the radiological literature was performed. Studies on the lumbar disk HIZ were compiled, and the findings are compared and contrasted.

Many authors are in agreement on the significance of the HIZ, however, there still is some controversy on its significance.

Results and Conclusions:
The lumbar disk high signal intensity zone (HIZ) on MRI has been assessed relative to low back pain, and although it can often be correlated with low back pain, its utility is somewhat controversial due to its relatively low sensitivity and specificity. This will be presented in the exhibit.

Although, there is still some debate over the significance of the lumbar disk HIZ, the presentation of the data will enable the observer to formulate his/ her own opinion, or at least to appreciate the controversy.

Similarly, the imaging finding of the HIZ will be demonstrated in the exhibit. The pathological correlate of the HIZ will also be discussed.

Gepstein, Reuven, M.D.

Purpose:
The current report is intended to describe the author’s initial experience with a novel vertebral body reconstruction device named the SKy Bone Expander. The implant is percutaneously inserted through the pedicle(s) and remotely expanded within the vertebral body resulting in vertebral height augmentation and void creation. Bone cement is then injected into the created void through the implant core, encasing the implant and forging the reconstructed vertebra. The device permits radiologists experienced with spine procedures to carry the procedure.

Material and Methods:
The SKy Bone Expander system (Disc-o-tech Ltd., Israel) is a polymer tube that following axial p ressure applied using a specifically designed delivery system, radially expands, causing endplate jacking and hence reconstruction of the compression fracture. This concept enables percutaneous positioning of the implant in its reduced form through the pedicle under local or general anesthesia, thus promoting minimal invasiveness. When adequate endplate augmentation has been achieved the device is contracted and removed. Cement injection into the created void follows. Twenty patients (mean age 62.5) have been treated using this system. Acute fractures were treated using a unilateral approach and chronic fractures were treated using a bilateral approach. Post-operative clinical evaluations were performed one week and one month post-op.

Results:
The preoperative average vertebral body compression height (A/P%) was 58.0%(±18%) of the pre-fracture height, improving to 81.8%(±12%) post-op. Average kyphosis angle decreased from 17.20 to 8.150. All patients reported signific ant pain relief. No complications occurred in the series.

Conclusion:
Kyphoplasty using the SKy Bone Expander system was found to be an effective and safe mode of treatment of vertebral compression fractures at the author’s hands. The device enables maximal control of the expansion stage and location, and is far more rapid to deploy than other comparable methods currently available. Additionally, a unilateral approach in the treatment of acute fractures proved to achieve adequate cement void permeation. It has also been found that the implant is exceptionally capable of correcting chronic fractures as well.

Gepstein, Reuven, M.D.
David, Rami, M.D.
Mirovsky, Igaal, M.D.
Pekarsky, Ilya, M.D.
Boriani, Stefano, M.D.
Folman, Yoram, M.D.

Purpose:
The current study was intended to assess the efficacy of a novel vertebral body reconstruction device, the B-Twin VBR. The implant is percutaneously inserted through the pedicle(s) and remotely expanded within the vertebral body resulting in vertebral height augmentation and void creation. Bone cement is then injected into the created void through the implant core, encasing the implant and forging the reconstructed vertebra. The device permits radiologists experienced with spine operations to carry the procedure.

Material and Methods:
An institutional review board approved level I randomized trial. The B-Twin VBR implant (Disc-o-tech Ltd., Israel) is a titanium tube that following axial pressure applied using a specifically designed delivery system, radially expands by projecting fins toward the upper and lower endplates, causing their jacking up and hence reconstruction of the compression fracture. This concept enables percutaneous positioning of the implant in its reduced form through the pedicle under local or general anesthesia, thus promoting minimal invasiveness. Twenty patients (mean age 61.8) participated in the study. Acute fractures were treated using a unilateral approach and chronic fractures were treated using a bilateral approach. Post-operative clinical evaluations were performed one week, one month, three months and in three month increments later on.

Results:
The preoperative average vertebral body compression height (A/P%) was 61.6%(±16%) of the pre-fracture height, improving to 79.1%(±14%) post-op. Average kyphosis angle decreased from 15.10 to 8.90. All patients reported significant pain relief; VAS scores ha d decreased from 8.3 to 2.2. Other than clinically insignificant minor cement extravasations in four patients, no complications occurred in the series.

Conclusion:
Kyphoplasty using the B-Twin VBR implant was found to be an effective and safe mode of treatment of vertebral compression fractures. Additionally, a unilateral approach in the treatment of acute fractures proved to achieve adequate cement void permeation. It has also been found that the implant is capable of correcting chronic fractures as well.

Georgy, Bassem, M.D.
James, Brandy, MA

Purpose:
To investigate the role of using coblation technology (Low-energy radiofrequency wave that removes tissue from the treatment area via a molecular dissociation process that converts the tissue into gases which exit the treatment site) to create a tissue void cavity before performing Vertebroplasty in treatment of vertebral malignant compression fractures.

Material and Methods:
Six vertebral bodies in 6 patients (4 males and 2 females) with mean age of 56 years and different metastatic lesions were included in the study after obtaining the appropriate consents. Cases included lesions with destruction of the posterior vertebral wall (two cases) vertebral and paraspinal exten sion (2 cases) and epidural tumor extension (two cases). 11G needles were used first to access the malignant lesions using a transpedicular approach under fluoroscopy guidance. A special coblation device (Arthrocare Sunnyvale, CA) was introduced through the needle and tissue coblation was performed to create a cavity by tissue destruction. The needle was then repositioned and bone cement was injected under fluoroscopy.

Results:
Adequate amount of cement was injected in every case. Post procedure imaging showed no evidence of extravasation of cement outside the presumed vertebral boundaries. All patients experienced marked pain relief. Coblation does not rely on heat energy to remove tissue, so thermal damage and tissue necrosis was avoided.

Conclusion:
The concept of creating a cavity by tissue destruction before injecting bone cement into a malignant vertebral lesion may help to reduce complication rate, in particular extravasation of cement into the spinal canal. Fur ther experience is needed to confirm this finding.