Use of a postoperative lumbar corset after lumbar spinal arthrodesis for degenerative conditions of the spine. A prospective randomized trial.

BACKGROUND: Lumbosacral corsets and braces have been used to treat a variety of spinal disorders. Although their use after lumbar arthrodesis for degenerative conditions has been reported, there is a lack of evidence on which to base guidelines on their use. The purpose of this study was to evaluate the effect of a postoperative corset on the outcome of lumbar arthrodesis. METHODS: A prospective randomized trial was performed in which patients who wore a postoperative lumbar corset for eight weeks full-time after a posterior lumbar arthrodesis for a degenerative spinal condition were compared with those who did not use a corset after such an operation. Ninety patients were randomized to one of the two treatments. A history was recorded and patients were assessed with a physical examination, radiographs, and functional outcome questionnaires (the Dallas Pain Questionnaire [DPQ] and the Short Form-36 [SF-36]) preoperatively and at one year and two years following the surgery. The primary outcome measure of the study was the DPQ, a disease-specific patient-derived functional measure of the spine, and secondary end points included the SF-36 scores, complications, rates of fusion as determined radiographically, and reoperation rates. RESULTS: Follow-up analysis was performed for seventy-two patients, thirty-seven randomized to the brace (experimental) group and thirty-five randomized to the control group. Regardless of the treatment method, the patients had substantial improvement in the disease-specific and general health measures by two years postoperatively. At two years, there was no difference in the DPQ category scores (the primary outcome parameter) of the two treatment groups. There was also no difference in the mean SF-36 component scores at two years. Postoperative complications occurred in 22% and 23% of patients in the experimental and control groups, respectively, and a subsequent lumbar spinal operation was performed in 19% and 14%, respectively. Seven patients (five in the experimental group and two in the control group) with radiographic evidence of nonunion underwent revision surgery. CONCLUSIONS: This study does not indicate a significant advantage or disadvantage to the use of a postoperative lumbar corset following spinal arthrodesis for degenerative conditions of the lumbar spine. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions to Authors for a complete description of levels of evidence.

Impact of smoking on the outcome of anterior cervical arthrodesis with interbody or strut-grafting.

BACKGROUND: An increased rate of pseudarthrosis has been documented following posterolateral lumbar spine grafting in patients who smoke. This same relationship has been assumed for anterior cervical interbody grafting, but to our knowledge it has never been proven. This study compared the long-term radiographic and clinical results of smokers and nonsmokers who had undergone arthrodesis with autogenous bone graft following multi-level anterior cervical decompression for the treatment of cervical radiculopathy or myelopathy, or both. METHODS: One hundred and ninety patients were followed clinically and radiographically for at least two years (range, two to fifteen years). Fifty-nine of the patients had corpectomy with strut-grafting, and 131 patients had multiple discectomies and interbody grafting. Fifty-five of the 190 patients had a history of active cigarette-smoking; fifteen of the fifty-five had corpectomy with strut-grafting, and forty had multilevel discectomies and interbody grafting. Internal fixation was not used in any patient. The reconstruction techniques and postoperative bracing regimen were similar between smokers and nonsmokers. Osseous union was judged on dynamic lateral radiographs made at least two years following surgery, and clinical outcomes were judged on the basis of pain level, medication usage, and daily activity level. RESULTS: Of the forty smokers who had undergone multilevel interbody grafting, twenty had a solid fusion at all levels, whereas sixty-nine of the ninety-one nonsmokers had solid fusion at all levels (p < 0.02; chi-square test). This difference was especially pronounced among patients who had had a two-level interbody grafting procedure (p < 0.002; chi-square test). With the numbers available, there was no difference in the rate of fusion between smokers (fourteen of fifteen) and nonsmokers (forty-one of forty-four) who had undergone corpectomy and strut-grafting, as 93% of both groups had a solid union. In addition, clinical outcomes were significantly worse among smokers when compared with nonsmokers (p < 0.03; rank-sum analysis). CONCLUSIONS: Smoking had a significant negative impact on healing and clinical recovery after multilevel anterior cervical decompression and fusion with autogenous interbody graft for radiculopathy or myelopathy. Since smoking had no apparent effect upon the healing of autogenous iliac-crest or fibular strut grafts, subtotal corpectomy and autogenous strut-grafting should be considered when a multilevel anterior cervical decompression and fusion is performed in patients who are unable or unwilling to stop smoking prior to surgical treatment.

Fungal infections of the spine. Report of eleven patients with long-term follow-up.

BACKGROUND: Fungal infections of the spine are noncaseating, acid-fast-negative infections that occur primarily as opportunistic infections in immunocompromised patients. We analyzed eleven patients with spinal osteomyelitis caused by a fungus, and we developed suggestions for treatment. METHODS: All patients with a fungal infection of the spine treated by the authors over a sixteen-year period at three teaching institutions were evaluated. There was a total of eleven patients. Medical records and roentgenograms were available for every patient. Long-term follow-up of the nine surviving patients was performed by direct examination by the authors or by the patient's primary physician. RESULTS: For ten of the eleven patients, the average delay in the diagnosis was ninety-nine days. Nine patients were immunocompromised secondary to diabetes mellitus, corticosteroid use, chemotherapy for a tumor, or malnutrition. The sources of the spinal infections included direct implantation from trauma (one patient), hematogenous spread (four patients), and local extension (two patients). The infection followed elective spine surgery in three patients, and the cause was unknown in one. Paralysis secondary to the spine infection developed in eight patients. Ten patients were treated with surgical debridement. All eleven patients were treated with systemic antifungal medications for a minimum of six weeks. One patient died of generalized sepsis at thirty-three days, and another patient died of gastrointestinal hemorrhage at five months. After an average of 6.3 years of follow-up, the infection had resolved in all nine surviving patients. CONCLUSIONS: Treatment of fungal spondylitis is often delayed because of difficulty with the diagnosis. Delay in the diagnosis led to poorer results in terms of neurologic recovery in our study. Performing fungal cultures whenever a spinal infection is suspected might hasten the diagnosis. Patients should be given a guarded prognosis and informed of the many possible complications of the disease.

Diagnosing basilar invagination in the rheumatoid patient. The reliability of radiographic criteria.

BACKGROUND: Basilar invagination can be difficult to diagnose with plain radiography in patients with rheumatoid arthritis. Although numerous radiographic criteria have been described, few studies have addressed the reliability of these parameters in the rheumatoid population. The purpose of the present study was to validate and compare the most widely accepted plain radiographic criteria for basilar invagination in this patient population. METHODS: Cervical radiographs of 131 rheumatoid patients were examined. Of these patients, sixty-seven (twenty-nine with basilar invagination and thirty-eight without it) were also evaluated with tomograms, magnetic resonance imaging, and/or sagittally reconstructed computed tomography scans to detect the presence of basilar invagination. Three observers who were blinded with regard to the diagnosis independently scored each radiograph as positive, negative, or indeterminate according to the established criteria for invagination proposed by Clark et al., McRae and Barnum, Chamberlain, McGregor, Redlund-Johnell and Pettersson, Ranawat et al., Fischgold and Metzger, and Wackenheim. Interobserver and intraobserver variability, sensitivity, specificity, total percentage of correct results, and negative and positive predictive values were determined for each criterion as well as for various combinations of the criteria. RESULTS: No single test had a sensitivity and a negative predictive value of greater than 90% as well as a reasonable specificity and a reasonable positive predictive value. The combination of the Clark station, the Redlund-Johnell criterion, and the Ranawat criterion, scored as positive for basilar invagination if any of the three were positive, proved to be better than any single criterion; the sensitivity of the combined criteria was 94%, and the negative predictive value was 91%. CONCLUSIONS: A screening test for basilar invagination should have a high sensitivity and a high negative predictive value, so that the disease will not be missed, and yet be specific, so that the disease will not be overdiagnosed. Our data suggest that none of the widely utilized plain radiographic criteria meet these goals. We recommend that measurements be made according to the methods described by Clark et al., Redlund-Johnell et al., and Ranawat et al. and, if any of these suggests basilar invagination, tomography or magnetic resonance imaging should be performed. Since approximately 6% of the cases of basilar invagination in rheumatoid patients would still be missed with this approach, tomography or magnetic resonance imaging should be performed on a rheumatoid patient whenever plain radiographs leave any doubt about the diagnosis of basilar invagination.

Tortuous course of the vertebral artery and anterior cervical decompression: a cadaveric and clinical case study.

STUDY DESIGN: Both the cadaveric and clinical examples of anomalous vertebral artery courses are described. The incidence of this anomaly in the general population and recognition, complications, and treatment options for these patients when undergoing anterior cervical decompression are discussed. OBJECTIVES: Cadaveric study: In this study vertebral artery's course through the cervical spine in the adult population was analyzed. The relation between an abnormal vertebral artery course and surgical landmarks are described. Clinical study: Complications and alternative treatment methods for decompression in patients with the anomaly are described. SUMMARY OF BACKGROUND DATA: The incidence of anomalous vertebral artery course is low, but failure to recognize a medially located vertebral artery may result in a life-threatening iatrogenic injury during decompression. Neither the relation between the vertebral arteries and the surgical landmarks nor the guidelines for decompression in the face of a tortuous vertebral artery have been well described. METHODS: Transverse foramens of the cervical spine were measured in 222 cadaveric spines. The measurements were taken describing the relation between transverse foramens and other surgical landmarks. Three patients with anomalies were identified in clinical practice. The complications and treatment options are identified in these patients. RESULTS: In the cadaveric specimens, a 2.7% incidence of tortuous vertebral artery course was identified. In these abnormal specimens, the transverse foramen was located an average of 0.14 mm medial to the joint of Luschka. In one patient, the abnormal course of the vertebral artery was recognized after laceration of the artery during a routine corpectomy. Anomalies in the other two patients were recognized before surgery, and the patients underwent modified anterior decompression by combining a discectomy at the anomalous level with a corpectomy at other levels. Vertebral artery ectasia is identifiable on axial magnetic resonance or computed tomographic images. CONCLUSIONS: Aberrant vertebral artery is rare. Preoperative recognition and appropriate modification of anterior decompression can yield excellent clinical results without risking significant complications.

Results of surgery for spinal stenosis adjacent to previous lumbar fusion.

The literature provides little data to guide surgical management of spinal stenosis adjacent to previous lumbar fusion. Thirty-three consecutive patients who had surgical decompression for spinal stenosis at the lumbar segments adjacent to a previous lumbar fusion were studied. The mean interval between fusion and the adjacent segment surgery was 94 months. Of the 33 patients, 26 were followed for 3-14 years (mean: 5 years) after adjacent segment surgery and were clinically evaluated and independently completed an outcome questionnaire. Of the 26 patients, 15 rated their outcome as completely satisfactory, 6 were neutral toward the surgery, and 5 considered their surgery a failure. The surgery was generally effective at improving or relieving lower extremity neurogenic claudication. The strongest independent predictive factor of patient dissatisfaction was ongoing postoperative low back pain (r = 0.7, p = 0.001). A higher back pain score at follow-up was associated with continued narcotic use (p = 0.001) and decreased ability to perform activities of daily living (p = 0.05). Six patients required further lumbar surgery during the follow-up period. This study provides the longest published follow-up data of surgical results for symptomatic spinal stenosis adjacent to a previously asymptomatic lumbar fusion.

Iatrogenic lumbar spondylolisthesis: treatment by anterior fibular and iliac arthrodesis.

A retrospective independent radiographic and chart review was undertaken for 17 patients who underwent a unique anterior salvage procedure for iatrogenic and progressive postoperative spondylolisthesis. This one-stage anterior transabdominal discectomy, reduction, stabilization, and arthrodesis was first performed in 1979. Of the 17 patients, all complained of leg pain, 14 of back pain, 11 had neurogenic claudication, and 2 were bedridden preoperatively because of their pain. Of the 17 patients, 7 had no neurologic deficits, 2 had cauda equina syndrome, and the remaining 8 had motor root deficits. The average number of posterior operations before our salvage procedure was 1.8, with a range of 1 to 3. Eight patients had an average of 1.6 attempts at posterior arthrodesis, with a range of 1 to 3 procedures. Two patients had a grade I spondylolisthesis, 11 a grade II, and 4 a grade III. Follow-up was available for 16 patients from 2 years and 3 months to 11 years and 5 months after the index operation (mean, 6 years and 5 months). One patient with severe cardiovascular disease died perioperatively. This anterior procedure was able to restore spinal stability and decompress the neural elements in 13 of 16 patients. Eleven obtained a solid arthrodesis. Three patients required further spinal surgery: two posterior fusions for symptomatic nonunions and one posterior foraminotomy for persistent foraminal stenosis. No patient deteriorated neurologically, the two with cauda equina syndrome recovered, and all but one patient with motor root deficits recovered fully. At latest follow-up, there were six excellent, seven good, and three fair results. There were no poor results. Although technically difficult and troubled by complications, the relative historical merits and principles of this unique anterior salvage procedure probably warrant further consideration, especially in light of evolving anterior surgical technologies.

Cervical disc herniation in a patient with congenital insensitivity to pain: a case report.

STUDY DESIGN: A case report of a patient with a known diagnosis of congenital insensitivity to pain who developed a herniated cervical disc. OBJECTIVES: To study the clinical manifestations of cervical radiculopathy in a patient with congenital insensitivity to pain and the long-term outcome after surgical treatment. SUMMARY OF BACKGROUND DATA: There have been no reports in the English literature documenting such a patient. METHODS: Retrospective case report and long-term clinical and radiographic follow-up. RESULTS: This patient with a known diagnosis of congenital insensitivity to pain had neurologic motor weakness with "neck and shoulder pain." Clear radicular pattern could not be elicited. The patient underwent a successful anterior discectomy and fusion with long-term clinical and radiographic results. CONCLUSION: Patients with congenital insensitivity to pain who develop a cervical disc herniation may present with atypical symptoms not manifesting in the classic radicular pattern. Higher index of suspicion by the clinician must be practiced to make the appropriate diagnosis. Successful surgical outcome may be achieved in these patients.

Anterior cervical corpectomy in patients previously managed with a laminectomy: short-term complications.

BACKGROUND: The purpose of this study was to evaluate the complications of anterior cervical corpectomy and arthrodesis in patients who had had a previous cervical laminectomy. The results of previous studies have suggested that these patients can be managed with anterior decompression and an arthrodesis with either plate fixation or immobilization in a halo vest. However, no studies that we are aware of have specifically focused on the complications of these types of procedures. METHODS: The records and radiographs of eighteen patients who had been managed with a one to four-level corpectomy with strut-grafting were retrospectively reviewed. The reviews were independently performed by the three of us who were not involved in the original operation. The interval between the laminectomy and the corpectomy ranged from one month to twenty-two years (mean, eight years). RESULTS: Eleven of the eighteen patients sustained a total of sixteen complications during the follow-up period, which averaged 2.7 years (range, seven months to six years and four months), and nine of the eleven had graft-related complications. Five grafts extruded or collapsed, or both. There were four reoperations. Immobilization in a halo vest did not prevent extrusions, as three of the four extrusions occurred while the patient wore a halo vest. Four patients had a pseudarthrosis. In three patients, the kyphosis increased by 10 degrees or more from the immediate preoperative period to the most recent follow-up evaluation. Two patients had respiratory distress that necessitated reintubation, one patient had a small dural tear, and one had transient dysphagia. CONCLUSIONS: Our data suggest that anterior cervical corpectomy without instrumentation in a patient who has had a previous laminectomy is associated with a great risk of graft-related complications despite the use of a halo vest. This previously unreported finding is relevant in that it contradicts the recommendation previously made by Zdeblick and the senior one of us, who advocated postoperative immobilization in a halo vest for these patients. Anterior cervical corpectomy should be performed with caution and knowledge of the potential complications in a patient who has had a previous laminectomy.

Radiculopathy and myelopathy at segments adjacent to the site of a previous anterior cervical arthrodesis.

BACKGROUND: We studied the incidence, prevalence, and radiographic progression of symptomatic adjacent-segment disease, which we defined as the development of new radiculopathy or myelopathy referable to a motion segment adjacent to the site of a previous anterior arthrodesis of the cervical spine. METHODS: A consecutive series of 374 patients who had a total of 409 anterior cervical arthrodeses for the treatment of cervical spondylosis with radiculopathy or myelopathy, or both, were followed for a maximum of twenty-one years after the operation. The annual incidence of symptomatic adjacent-segment disease was defined as the percentage of patients who had been disease-free at the start of a given year of follow-up in whom new disease developed during that year. The prevalence was defined as the percentage of all patients in whom symptomatic adjacent-segment disease developed within a given period of follow-up. The natural history of the disease was predicted with use of a Kaplan-Meier survivorship analysis. The hypothesis that new disease at an adjacent level is more likely to develop following a multilevel arthrodesis than it is following a single-level arthrodesis was tested with logistic regression. RESULTS: Symptomatic adjacent-segment disease occurred at a relatively constant incidence of 2.9 percent per year (range, 0.0 to 4.8 percent per year) during the ten years after the operation. Survivorship analysis predicted that 25.6 percent of the patients (95 percent confidence interval, 20 to 32 percent) who had an anterior cervical arthrodesis would have new disease at an adjacent level within ten years after the operation. There were highly significant differences among the motion segments with regard to the likelihood of symptomatic adjacent-segment disease (p<0.0001); the greatest risk was at the interspaces between the fifth and sixth and between the sixth and seventh cervical vertebrae. Contrary to our hypothesis, we found that the risk of new disease at an adjacent level was significantly lower following a multilevel arthrodesis than it was following a single-level arthrodesis (p<0.001). More than two-thirds of all patients in whom the new disease developed had failure of nonoperative management and needed additional operative procedures. CONCLUSIONS: Symptomatic adjacent-segment disease may affect more than one-fourth of all patients within ten years after an anterior cervical arthrodesis. A single-level arthrodesis involving the fifth or sixth cervical vertebra and preexisting radiographic evidence of degeneration at adjacent levels appear to be the greatest risk factors for new disease. Therefore, we believe that all degenerated segments causing radiculopathy or myelopathy should be included in an anterior cervical arthrodesis. Although our findings suggest that symptomatic adjacent-segment disease is the result of progressive spondylosis, patients should be informed of the substantial possibility that new disease will develop at an adjacent level over the long term.

Anterior cervical decompression and arthrodesis for the treatment of cervical spondylotic myelopathy. Two to seventeen-year follow-up.

We reviewed the cases of 108 patients with cervical spondylotic myelopathy who had been managed with anterior decompression and arthrodesis at our institution. Operative treatment consisted of anterior discectomy, partial corpectomy, or subtotal corpectomy at one level or more, followed by placement of autogenous bone graft from the iliac crest or the fibula. At the latest follow-up examination, thirty-eight of the eighty-two patients who had had a preoperative gait abnormality had a normal gait, thirty-three had an improvement in gait, six had no change, four had improvement and later deterioration, and one had a worse gait abnormality. Of the eighty-seven patients who had had a preoperative motor deficit, fifty-four had complete recovery; twenty-six, partial recovery; six, no change; and one had a worse deficit. The average grade according to the system of Nurick improved from 2.4 preoperatively to 1.2 (range, 0.0 to 5.0) postoperatively. A pseudarthrosis developed in sixteen patients, thirteen of whom had had a multilevel discectomy. Only one of thirty-eight arthrodeses that had been performed with use of a fibular strut graft was followed by a non-union. An unsatisfactory outcome with respect to pain was significantly associated with pseudarthrosis (p < 0.001). The development of complications other than non-union was associated with a history of one previous operative procedure or more (p = 0.005). Recurrent myelopathy was rare, but when it occurred it was associated with a pseudarthrosis or stenosis at a new level. The strongest predictive factor for recovery from myelopathy was the severity of the myelopathy before the operative intervention--that is, better preoperative neurological function was associated with a better neurological outcome. Anterior decompression and arthrodesis with autogenous bone-grafting can be performed safely, and is associated with a high rate of neurological recovery, functional improvement, and pain relief, in patients who have cervical spondylotic myelopathy.

Dural tears secondary to operations on the lumbar spine. Management and results after a two-year-minimum follow-up of eighty-eight patients.

We reviewed the results of acute management of patients who had sustained a dural tear during an operation on the lumbar spine, and we attempted to determine the long-term sequelae of this complication. In the five years from July 1989 to July 1994, 641 consecutive patients had a decompression of the lumbar spine, performed by the senior one of us; of these patients, eighty-eight (14 percent) sustained a dural tear, which was repaired during the operation. The duration of follow-up ranged from two to eight years (average, 4.3 years). Postoperative management consisted of closed suction wound drainage for an average of 2.1 days and bed rest for an average of 2.9 days. Of the eighty-eight procedures that resulted in a dural tear, forty-five were revisions; these revisions were performed after an average of 2.2 previous operations on the lumbar spine, all of which resulted in a scar adherent to the dura. Only eight patients had headaches related to the spinal procedure and photophobia in the postoperative period; these symptoms resolved in all but two patients, both of whom had had a revision operation. Each of the two patients had symptoms of a persistent leak of spinal fluid and needed a reoperation for repair. Overall, seventy-six patients had a good or excellent result and twelve had a poor or satisfactory result with some residual back pain. One patient had arachnoiditis, and another had symptoms of viral meningitis one month postoperatively. A dural tear that occurs during an operation on the lumbar spine can be treated successfully with primary repair followed by bed rest. Such a tear does not appear to have any long-term deleterious effects or to increase the risk of postoperative infection, neural damage, or arachnoiditis. Closed suction wound drainage does not seem to aggravate the leak and can be used safely in the presence of a dural repair.

Three-level anterior cervical discectomy and fusion: radiographic and clinical results.

STUDY DESIGN: A retrospective study of 16 patients who underwent the modified Robinson anterior cervical discectomy and fusion at three operative levels. OBJECTIVES: To provide long-term follow-up data on the surgical success and patient outcome of three-level anterior cervical discectomies and fusions. SUMMARY OF BACKGROUND DATA: The success of arthrodesis for anterior cervical fusion depends on several factors, including the number of surgical levels. To the authors' knowledge, there are no long-term follow-up reports to describe the arthrodesis rate and outcome for patients having specifically three-level discectomy and fusion procedures. METHODS: Sixteen patients, with an average age of 59 years, were followed for an average of 37 months. All had an anterior discectomy, burring of the endplates, and placement of an autogenous tricortical iliac crest graft at three levels. All patients had follow-up office visits with examinations and radiographs. Radiographic union, postoperative pain relief, and neurologic recovery were evaluated. RESULTS: Only 9 (56%) of the 16 patients went on to achieve solid arthrodesis at all three levels. Of the seven patients with pseudarthrosis, two had severe pain and required revision; two had moderate pain and three no pain. Of the nine with the solid fusion, three had mild pain and six no pain, a statistically significant difference in comparing the two outcomes (P < 0.01). All patients with preoperative motor deficit recovered, but two patients in whom a pseudarthrosis had developed had limited improvement in function until the nonunion was surgically repaired. CONCLUSIONS: A three-level modified Robinson cervical discectomy and fusion results in an unacceptably high rate of pseudarthrosis. Although not all pseudarthroses are painful, these data suggest that those with a successful fusion have a better outcome. It is recommended that these patients undergo additional or alternative measures to achieve arthrodesis consistently.

The success of anterior cervical arthrodesis adjacent to a previous fusion.

STUDY DESIGN: A retrospective review of all patients surgically treated for adjacent segment disease of the cervical spine over a 20-year period. OBJECTIVES: To determine the clinical and radiographic success of discectomy with interbody grafting and corpectomy with strut grafting in the treatment of adjacent segment disease of the cervical spine. SUMMARY OF BACKGROUND DATA: Up to 25% of all patients undergoing anterior cervical fusion have new disease due to degeneration of an adjacent segment within 10 years. The success of surgical treatment in these patients with adjacent segment disease has not been reported. METHODS: Thirty-eight patients were surgically treated for adjacent segment disease by discectomy with interbody grafting or corpectomy with strut grafting. Arthrodesis was evaluated by flexion-extension lateral radiographs and clinical outcomes were assessed using Robinson's criteria at least 2 years after surgery. Fusion rates were compared by Fisher's exact test, and outcomes were compared by rank-sum analysis. RESULTS: The rate of arthrodesis was significantly lower in the 24 patients treated by discectomy with interbody grafting at one or more levels (63%) than in the 14 patients treated by corpectomy with strut grafting (100%; P = 0.01). Clinical outcomes were similar for the corpectomy and discectomy groups (P = 0.55). There was a trend toward better outcomes in patients who achieved a solid arthrodesis (P = 0.13). CONCLUSIONS: Achieving fusion is more difficult when anterior cervical arthrodesis is performed adjacent to a prior fusion. Strut grafting resulted in a significantly higher rate of arthrodesis than interbody grafting.

Anterior cervical pseudarthrosis. Natural history and treatment.

STUDY DESIGN: A retrospective study of long-term clinical outcomes in 48 patients with pseudarthroses after anterior cervical discectomy and fusion. OBJECTIVES: To determine the natural history, risk factors, and treatment outcomes in a large population with documented pseudarthrosis after anterior cervical discectomy and fusion. SUMMARY OF BACKGROUND DATA: Recent reports suggest that pseudarthrosis after anterior cervical discectomy and fusion adversely affects clinical outcome. Little data regarding cervical pseudarthroses have been published, and conclusions have been drawn from reports with small patient populations and short-term follow-up periods. METHODS: Forty-eight patients with radiographically documented pseudarthrosis after anterior cervical discectomy and fusion were studied. Patients were examined and radiographs made at regular intervals (mean follow-up, 66 months). Clinical results were based on patients' assessment of pain, prescription drug use, activity level and Odom's criteria. Clinical outcomes in patients who underwent surgical repair of the pseudarthrosis are reported. RESULTS: Of the 48 patients, 32 (67%) with pseudarthroses were symptomatic at latest follow-up or at the time of further surgery. Of the 32 patients, 9 had a symptom-free period of at least 2 years after the anterior cervical discectomy and fusion before redeveloping cervical symptoms after a traumatic episode. Of 48 patients with pseudarthroses, 16 (33%) remained asymptomatic at a mean of 5.1 years after anterior cervical discectomy and fusion. A younger age at the time of anterior cervical discectomy and fusion increased the likelihood of the pseudarthrosis becoming symptomatic. After multiple level anterior cervical discectomy and fusion, the caudal-most operated level accounted for 82% of the pseudarthroses. Sixteen patients had an anterior repair of the pseudarthrosis, and fusion was achieved in 14. Six patients underwent posterior pseudarthrosis repair, and all healed. In patients in whom fusion was achieved with a second cervical operation, the results were excellent in 19 and good in 1. CONCLUSION: A pseudarthrosis after anterior cervical discectomy and fusion is frequently associated with a poor clinical outcome. Surgical repair of the pseudarthrosis with an anterior or posterior approach seems to have a high likelihood of a successful clinical outcome.

Viscoelastic relaxation and regional blood flow response to spinal cord compression and decompression.

STUDY DESIGN: To better understand the relationships between primary mechanical factors of spinal cord trauma and secondary mechanisms of injury, this study evaluated regional blood flow and somatosensory evoked potential function in an in vivo canine model with controlled velocity spinal cord displacement and real-time piston-spinal cord interface pressure feedback. OBJECTIVES: To determine the effect of regional spinal cord blood flow and viscoelastic cord relaxation on recovery of neural conduction, with and without spinal cord decompression. SUMMARY OF BACKGROUND DATA: The relative contribution of mechanical and vascular factors on spinal cord injury remains undefined. METHODS: Twelve beagles were anesthetized and underwent T13 laminectomy. A constant velocity spinal cord compression was applied using a hydraulic loading piston with a subminiature pressure transducer rigidly attached to the spinal column. Spinal cord displacement was stopped when somatosensory evoked potential amplitudes decreased by 50% (maximum compression). Six animals were decompressed 5 minutes after maximum compression and were compared with six animals who had spinal cord displacement maintained for 3 hours and were not decompressed. Regional spinal cord blood flow was measured with a fluorescent microsphere technique. RESULTS: At maximum compression, regional spinal cord blood flow at the injury site fell from 19.0 +/- 1.3 mL/100 g/min to 12.6 +/- 1.0 mL/100 g/min, whereas piston-spinal cord interface pressure was 30.5 +/- 1.8 kPa, and cord displacement measured 2.1 +/- 0.1 mm (mean +/- SE). Five minutes after the piston translation was stopped, the spinal cord interface pressure had dissipated 51%, whereas the somatosensory evoked potential amplitudes continued to decrease to 16% of baseline. In the sustained compression group, cord interface pressure relaxed to 13% of maximum within 90 minutes; however, no recovery of somatosensory evoked potential function occurred, and regional spinal cord blood flow remained significantly lower than baseline at 30 and 180 minutes after maximum compression. In the six animals that underwent spinal cord decompression, somatosensory evoked potential function and regional spinal cord blood flow recovered to baseline 30 minutes after maximum compression. CONCLUSIONS: Despite rapid cord relaxation of more than 50% within 5 minutes after maximum compression, somatosensory evoked potential conduction recovered only with early decompression. Spinal cord decompression was associated with an early recovery of regional spinal cord blood flow and somatosensory evoked potential recovery. By 3 hours, spinal cord blood flow was similar in both the compressed and decompressed groups, despite that somatosensory evoked potential recovery occurred only in the decompressed group.

Failed anterior cervical discectomy and arthrodesis. Analysis and treatment of thirty-five patients.

Thirty-five patients were managed operatively after failure of an anterior cervical discectomy and arthrodesis. Failure was classified as the absence of fusion without deformity but with neck pain or radiculopathy, or both; the absence of fusion after anterior or posterior dislodgment of the graft; or kyphosis due to collapse of the graft or to an unrecognized posterior soft-tissue injury. Twenty-three patients had failure of the arthrodesis without deformity (with neck pain only, neck and arm pain, radiculopathy, or myelopathy). Four patients had dislodgment of the graft; in two of them the graft migrated anteriorly after a multilevel Robinson arthrodesis, and in two it migrated posteriorly after a Cloward arthrodesis. Eight patients had a failure because of a kyphotic deformity. Five of them had had a Cloward arthrodesis; one, a discectomy; and two, a Robinson arthrodesis. Six had received allograft bone. Operative treatment of the pseudarthrosis consisted of repeat resection of the disc space in the area of the failed arthrodesis followed by repeat anterior Robinson arthrodesis with decompression of the nerve root if the patient had radiculopathy. It consisted of anterior corpectomy or vertebral-body resection and strut-grafting with reduction of the deformity if the patient had migration of the graft and kyphosis. The reoperations were performed four months to fourteen years (average, thirty-two months) after the initial operation. The duration of follow-up after the second operation averaged forty-four months (range, twenty-four to 216 months). The result was excellent for twenty-nine patients, good for one, fair for four, and poor for one. We concluded that, in patients who have persistent symptoms after an anterior cervical arthrodesis, an excellent result can be achieved with repeat anterior decompression and autogenous bone-grafting.

Early time-dependent decompression for spinal cord injury: vascular mechanisms of recovery.

Although surgical decompression is often advocated for acute spinal cord injury, the timing and efficacy of early treatment have not been clinically proven. Our objectives were to determine the importance of early spinal cord decompression on recovery of evoked potential conduction under precision loading conditions and to determine if regional vascular mechanisms could be linked to electrophysiologic recovery. Twenty-one mature beagles were anesthetized and mechanically ventilated to maintain normal respiratory and acid-base balance. Somatosensory-evoked potentials from the upper and lower extremities were measured at regular intervals. The spinal cord at T-13 was loaded dorsally under precision loading conditions until evoked potential amplitudes had been reduced by 50%. At this functional endpoint, spinal cord displacement was maintained for either 30 (n = 7), 60 (n = 8), or 180 min (n = 6). Spinal cord decompression was followed by a 3-h monitoring period. Regional spinal cord blood flow was measured with fluorescent microspheres at baseline (following laminectomy) immediately after stopping dynamic cord compression, 5, 15, and 180 min after decompression. Within 5 min after stopping dynamic compression, evoked potential signals were absent in all dogs. We observed somatosensory-evoked potential recovery in 6 of 7 dogs in the 30-min compression group, 5 of 8 dogs in the 60-min compression group, and 0 of 6 dogs in the 180-min compression group. Recovery in the 30- and 60-min groups varied significantly from the 180-min group (p < 0.05). Regional spinal cord blood flow at baseline, 21.4+/-2.2 ml/100/g/min (combined group mean +/- SE) decreased to 4.1+/-0.7 ml/100 g/min after stopping dynamic compression. Reperfusion flows after decompression were inversely related to duration of compression. Of the 7 dogs in the 30 min compression group, 5 min after decompression the blood flow was 49.1+/-3.1 ml/100 g/min, which was greater than two times baseline. In the 180-min compression group early post-decompression blood flow, 19.8+/-6.2 ml/100 g/min, was not significantly different than baseline. Of the 8 dogs in the 60-min compression group, 5 who recovered evoked potential conduction revealed a lower spinal cord blood flow sampled immediately after stopping dynamic compression, 2.1+/-0.4 ml/100 g/min, compared to the 3 who did not recover where blood flow was 8.4+/-2.1 ml/100 g/min (p < 0.05). Reperfusion flows measured as the interval change in blood flow between the time dynamic compression was stopped to 5, 15, or 180 min after decompression, were significantly greater in those dogs that recovered evoked potential function (p < 0.05). Three hours after decompression, spinal cord blood flow in the 3 dogs in the 60-min compression group with no recovery, 11.1+/-2.1 ml/100 g/min, was significantly less than the spinal cord blood flow of the recovered group (n = 5), 20.5+/-2.2 ml/100 g/min. These data illustrate the importance of early time-dependent events following precision dynamic spinal cord loading and sustained compression conditions. Spinal cord decompression performed within 1 h of evoked potential loss resulted in significant electrophysiologic recovery after 3 h of monitoring. This study showed that the degree of early reperfusion hyperemia after decompression was inversely proportional to the duration of spinal cord compression and proportional to electrophysiologic recovery. Residual blood flow during the sustained compression period was significantly higher in those dogs that did not recover evoked potential function after decompression suggesting a reperfusion injury. These results indicate that, after precise dynamic spinal cord loading to a point of functional conduction deficit (50% decline in evoked potential amplitude), a critical time period exists where intervention in the form of early spinal cord decompression can lead to effective recovery of electrophysiologic function in the 1- to 3-h post-decompression p