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P100. Disc replacement versus fusion: comparision of patient self-assessments
170S
Proceedings of the NASS 18th Annual Meeting / The Spine Journal 3 (2003) 67S–171S
RESULTS: Two hundred and thirteen patients, aged 18–89 (mean 59), 107 male and 106 female, operated by 10 surgeons for various conditions. A total of 387 levels were operated on. EMG recordings were technically successful in 212 patients. Successful SSEP recordings were obtained in 203 patients (95.8%). Spontaneous intraoperative EMG activation was seen in 165 (77.5%). Significant SSEP changes defined as a decrease of 50% or more in amplitude were seen in 14 patients (6.6%). Fourteen patients had new neurological symptoms or exacerbation of their previous symptoms on follow up (mean 1.8 months). All of those had intraoperative EMG activation but only 4 had significant SSEP changes. The sensitivity of EMG to identify patients with new neurological deficit or exacerbation of preexisting neurological deficits after thoracolumbar surgery was 100% with a specificity of 24.1%. The sensitivity of SSEP to identify patients with new neurological deficits or exacerbation of preexisting neurological deficits after thoracolumbar surgery was 28.6% with a specificity of 95.0%. DISCUSSION: In our review of 11 papers focusing on intraoperative EMG monitoring only 9 cases are described where a correlation is given between the EMG activation and new postoperative neurological deficits, each study reporting from one or two patients. In the present study we describe 14 patients with new neurological deficits. The results of this study show a good outcome with only 6.6% with new neurological symptoms or exacerbation of preexisting symptoms many of which are high risk patients undergoing extensive thoracolumbar procedures. Intraoperative EMG activation was very common and occurred in all patients that had new neurological symptoms underlining its sensitivity for intraoperative manipulation of neural structures which we have found helpful for avoiding neurological injury. SSEP is not as sensitive but up almost one third of patients with SSEP changes will have new postoperative neurological deficit. CONCLUSIONS: Intraoperative EMG activation during thoracolumbar surgery is very common and correlates well to the intraoperative manipulation of neural structures. It has a high sensitivity but low specificity for the detection of new postoperative neurological deficits or exacerbation of new neurological deficits. Significant SSEP changes are uncommon and have a lower sensitivity but higher specificity than EMG for the detection of new postoperative neurological deficits. DISCLOSURES: No disclosures. CONFLICT OF INTEREST: No conflicts. doi: 10.1016/S1529-9430(03)00398-X
P100. Disc replacement versus fusion: comparision of patient self-assessments Hyun Bae, MD1, L.E.A. Kanim, MA1, Parveen Sra, MPH1, Rick Delamarter, MD2, Michael Kropf, MD2; 1Spine Institute at Saint John’s Health Center, Santa Monica, CA, USA; 2Saint John’s Health Center, Santa Monica, CA, USA HYPOTHESIS: Disc replacement is intended to reduce pain via removal of the diseased disc while restoring height and physiologic motion at the affected level. The physiologic advantage of disc replacement to fusion is that it may also preserve motion and prevent degeneration at adjacent levels. As clinicians, patients outcomes still remain the primary interest. Patient self-assessments of pain and disability are presented from the prospective, randomized study of disc replacement (PRODISC) versus circumferential fusion for one and two level degenerative disc disease conducted at our center. METHODS: Patients meeting inclusion criteria pain completed preoperative self-assessments, Oswestry Low Back Disability Questionnaire and overall pain on Visual Analog Scale (VAS). Randomization was performed using 2 to 1 ratio of disc replacement to fusion, stratified by number of diseased levels. Questionnaires were completed postoperatively at 6 weeks, 3 and 6 months. Changes in pain from preoperative values as a function of treatment were evaluated using repeated measures mixed design ANOVA.
Table 1 Results
VAS (10 cm scale) Disc replacement Fusion Oswestry (100 pt. scale) Disc replacement Fusion
Pre-op
6 wk
3 mo
6 mo
average 7.45 7.44 average 30.86 30.56
average 2.96 4.33 average 20.75 24.11
average 3.39 5.60 average 18.11 29.00
average 2.00 6.33 average 15.86 29.33
RESULTS: Data from the first 38 randomized patients (29 PRODISC and 9 fusion) were analyzed. There were 18 patients with 1-level and 20 patients with 2-level procedures performed. Controlling for number of levels operated, there was a statistically significant decrease in pain from preoperative values associated to treatment (6 months: VAS [F⫽6.56 , p⬍0.04] and Oswestry [F⫽6.20, p⬍0.04], Table 1). DISCUSSION: Disc replacement patients reported greater improvement in pain and function from preoperative values on both the VAS and Oswestry questionnaires than did fusion patients. This difference was most remarkable at 6 months when fusion patients would be expected to have had benefit from some bony union. CONCLUSIONS: Postoperative results indicate consistently significantly less pain and disability following surgery for patients who underwent disc replacement compared to those treated by a fusion procedure. These results are promising. Longer follow-up is necessary to fully evaluate the apparently continuing advantage of disc replacement for the treatment of degenerative disc disease. DISCLOSURES: Device or drug: PRODISC. Status: investigational. CONFLICT OF INTEREST: No conflicts. doi: 10.1016/S1529-9430(03)00399-1
P105. Posterior atlantoaxial stabilization: a new alternative to C1-2 transarticular screws Carl Lauryssen1, John Stokes, MD2, J. Patrick Johnson, MD1; 1 Cedars-Sinai Institute for Spinal Disorders, Los Angeles, CA, USA; 2 Neurosurgical Associates of Austin, Austin, TX, USA HYPOTHESIS: Surgical treatment of atlantoaxial instability has evolved from posterior wiring techniques with 60–90% fusion rates later modified with the Magerl C1-2 transarticular screw technique and fusion rates of 90–100%. The C1-2 screw procedure is technically demanding and requires precise surgical and radiographic knowledge of vertebral artery anatomy. METHODS: A standard posterior C1-2 exposure is performed, and cross table lateral fluoroscopy is used to guide and confirm screw trajectories. The C2 pedicle screw entry point is identified and drilled with angles of 15 degrees medially and 25 degrees cephalad that is stopped short of the C2 transverse foramen The C1 lateral mass screw is placed beneath the arch of C1 in the midposition of the lateral mass and angled 10 degrees medial and cephalad toward the anterior arch of C1. Posterior rods are contoured and connected to the polyaxial screw heads and a cross-connector is applied. The C1-2 joint is prepared as the fusion site. RESULTS: This technique has been used in 30 cases of atlantoaxial instability and there have been no C2 nerve root or vertebral artery injuries. No construct failures have been observed during the current follow-up over 2 years. DISCUSSION: C1 lateral mass and C2 pedicle screw fixation is an alternative atlantoaxial fusion technique that is less demanding than C1-2 transarticular screw placement. Laminectomy or fracture of the posterior elements does not preclude this technique. We feel this procedure will replace the C1-2 transarticular screw procedure and may significantly reduce the risk of vertebral artery injury.
Proceedings of the NASS 18th Annual Meeting / The Spine Journal 3 (2003) 67S–171S
RESULTS: Two hundred and thirteen patients, aged 18–89 (mean 59), 107 male and 106 female, operated by 10 surgeons for various conditions. A total of 387 levels were operated on. EMG recordings were technically successful in 212 patients. Successful SSEP recordings were obtained in 203 patients (95.8%). Spontaneous intraoperative EMG activation was seen in 165 (77.5%). Significant SSEP changes defined as a decrease of 50% or more in amplitude were seen in 14 patients (6.6%). Fourteen patients had new neurological symptoms or exacerbation of their previous symptoms on follow up (mean 1.8 months). All of those had intraoperative EMG activation but only 4 had significant SSEP changes. The sensitivity of EMG to identify patients with new neurological deficit or exacerbation of preexisting neurological deficits after thoracolumbar surgery was 100% with a specificity of 24.1%. The sensitivity of SSEP to identify patients with new neurological deficits or exacerbation of preexisting neurological deficits after thoracolumbar surgery was 28.6% with a specificity of 95.0%. DISCUSSION: In our review of 11 papers focusing on intraoperative EMG monitoring only 9 cases are described where a correlation is given between the EMG activation and new postoperative neurological deficits, each study reporting from one or two patients. In the present study we describe 14 patients with new neurological deficits. The results of this study show a good outcome with only 6.6% with new neurological symptoms or exacerbation of preexisting symptoms many of which are high risk patients undergoing extensive thoracolumbar procedures. Intraoperative EMG activation was very common and occurred in all patients that had new neurological symptoms underlining its sensitivity for intraoperative manipulation of neural structures which we have found helpful for avoiding neurological injury. SSEP is not as sensitive but up almost one third of patients with SSEP changes will have new postoperative neurological deficit. CONCLUSIONS: Intraoperative EMG activation during thoracolumbar surgery is very common and correlates well to the intraoperative manipulation of neural structures. It has a high sensitivity but low specificity for the detection of new postoperative neurological deficits or exacerbation of new neurological deficits. Significant SSEP changes are uncommon and have a lower sensitivity but higher specificity than EMG for the detection of new postoperative neurological deficits. DISCLOSURES: No disclosures. CONFLICT OF INTEREST: No conflicts. doi: 10.1016/S1529-9430(03)00398-X
P100. Disc replacement versus fusion: comparision of patient self-assessments Hyun Bae, MD1, L.E.A. Kanim, MA1, Parveen Sra, MPH1, Rick Delamarter, MD2, Michael Kropf, MD2; 1Spine Institute at Saint John’s Health Center, Santa Monica, CA, USA; 2Saint John’s Health Center, Santa Monica, CA, USA HYPOTHESIS: Disc replacement is intended to reduce pain via removal of the diseased disc while restoring height and physiologic motion at the affected level. The physiologic advantage of disc replacement to fusion is that it may also preserve motion and prevent degeneration at adjacent levels. As clinicians, patients outcomes still remain the primary interest. Patient self-assessments of pain and disability are presented from the prospective, randomized study of disc replacement (PRODISC) versus circumferential fusion for one and two level degenerative disc disease conducted at our center. METHODS: Patients meeting inclusion criteria pain completed preoperative self-assessments, Oswestry Low Back Disability Questionnaire and overall pain on Visual Analog Scale (VAS). Randomization was performed using 2 to 1 ratio of disc replacement to fusion, stratified by number of diseased levels. Questionnaires were completed postoperatively at 6 weeks, 3 and 6 months. Changes in pain from preoperative values as a function of treatment were evaluated using repeated measures mixed design ANOVA.
Table 1 Results
VAS (10 cm scale) Disc replacement Fusion Oswestry (100 pt. scale) Disc replacement Fusion
Pre-op
6 wk
3 mo
6 mo
average 7.45 7.44 average 30.86 30.56
average 2.96 4.33 average 20.75 24.11
average 3.39 5.60 average 18.11 29.00
average 2.00 6.33 average 15.86 29.33
RESULTS: Data from the first 38 randomized patients (29 PRODISC and 9 fusion) were analyzed. There were 18 patients with 1-level and 20 patients with 2-level procedures performed. Controlling for number of levels operated, there was a statistically significant decrease in pain from preoperative values associated to treatment (6 months: VAS [F⫽6.56 , p⬍0.04] and Oswestry [F⫽6.20, p⬍0.04], Table 1). DISCUSSION: Disc replacement patients reported greater improvement in pain and function from preoperative values on both the VAS and Oswestry questionnaires than did fusion patients. This difference was most remarkable at 6 months when fusion patients would be expected to have had benefit from some bony union. CONCLUSIONS: Postoperative results indicate consistently significantly less pain and disability following surgery for patients who underwent disc replacement compared to those treated by a fusion procedure. These results are promising. Longer follow-up is necessary to fully evaluate the apparently continuing advantage of disc replacement for the treatment of degenerative disc disease. DISCLOSURES: Device or drug: PRODISC. Status: investigational. CONFLICT OF INTEREST: No conflicts. doi: 10.1016/S1529-9430(03)00399-1
P105. Posterior atlantoaxial stabilization: a new alternative to C1-2 transarticular screws Carl Lauryssen1, John Stokes, MD2, J. Patrick Johnson, MD1; 1 Cedars-Sinai Institute for Spinal Disorders, Los Angeles, CA, USA; 2 Neurosurgical Associates of Austin, Austin, TX, USA HYPOTHESIS: Surgical treatment of atlantoaxial instability has evolved from posterior wiring techniques with 60–90% fusion rates later modified with the Magerl C1-2 transarticular screw technique and fusion rates of 90–100%. The C1-2 screw procedure is technically demanding and requires precise surgical and radiographic knowledge of vertebral artery anatomy. METHODS: A standard posterior C1-2 exposure is performed, and cross table lateral fluoroscopy is used to guide and confirm screw trajectories. The C2 pedicle screw entry point is identified and drilled with angles of 15 degrees medially and 25 degrees cephalad that is stopped short of the C2 transverse foramen The C1 lateral mass screw is placed beneath the arch of C1 in the midposition of the lateral mass and angled 10 degrees medial and cephalad toward the anterior arch of C1. Posterior rods are contoured and connected to the polyaxial screw heads and a cross-connector is applied. The C1-2 joint is prepared as the fusion site. RESULTS: This technique has been used in 30 cases of atlantoaxial instability and there have been no C2 nerve root or vertebral artery injuries. No construct failures have been observed during the current follow-up over 2 years. DISCUSSION: C1 lateral mass and C2 pedicle screw fixation is an alternative atlantoaxial fusion technique that is less demanding than C1-2 transarticular screw placement. Laminectomy or fracture of the posterior elements does not preclude this technique. We feel this procedure will replace the C1-2 transarticular screw procedure and may significantly reduce the risk of vertebral artery injury.