Efficacy of magnetic resonance imaging in the evaluation of posterior cervical spine fractures

STUDY DESIGN

A retrospective study using two independent, blinded musculoskeletal radiologists to evaluate the sensitivity, specificity, and predictive value of cervical spine magnetic resonance imaging in detecting posterior element fractures of the cervical spine.

OBJECTIVE

To evaluate the sensitivity, specificity, and predictive value of magnetic resonance imaging, using computed tomographic scanning as the gold standard, in the diagnosis of posterior element cervical spine fractures.

SUMMARY OF BACKGROUND DATA

Few investigators have evaluated the accuracy of magnetic resonance imaging in the determination of cervical spine fractures.

METHODS

From January 1994 through June 1996, 75 cervical spine fractures in 32 patients were confirmed by computed tomography. Two musculoskeletal radiologists who were blinded to the clinical history and presence or absence of cervical injury among the study population, independently evaluated each cervical magnetic resonance image recording the presence or absence of soft tissue or bony injury.

RESULTS

The overall sensitivity and specificity rates for the diagnosis of a posterior element fracture by magnetic resonance imaging was 11.5% and 97.0%, respectively. The positive predictive value for this group was 83%, and the negative predictive value was 46%. In reference to anterior fractures, the sensitivity was 36.7% and the specificity 98%. Positive and negative predictive values were 91.2% and 64%, respectively.

CONCLUSIONS

Magnetic resonance imaging was not effective in recognizing bony injury to the cervical spine and in particular was not as sensitive or as specific as computed tomography in identifying cervical spinal fractures. Computed tomography remains the study of choice for the detection and precise classification of bony injuries to the cervical region, especially when plain radiographs are difficult to evaluate. Magnetic resonance imaging, although not as effective as computed tomography in defining specific bony disorders, remains the gold standard in the evaluation of spinal cord injury, occult vascular injury, and intervertebral disc disruption (hyperextension injury), including herniation and other soft tissue disorders (hematoma, ligament tear).

Transpedicle screw fixation of the cervical spine

The use of posterior cervical spine fixation has become increasingly popular in recent years. Dissatisfaction with lateral mass fixation, especially at the cervicothoracic junction, has led spine surgeons to use cervical pedicle screw fixation for reconstruction in numerous cervical spine disorders. The biomechanical advantage of a three-column fixation device implanted to secure an unstable cervical spine has proven to be a valuable tool in the spine surgeon's armamentarium. Successful placement of a pedicle screw in the cervical spine requires a sufficient three-dimensional understanding of pedicle morphology to allow accurate identification of the ideal screw axis. Variability in cadaveric based morphometric measurements used to guide the surgeon in the placement of a pedicle screw has raised legitimate concerns as to whether transpedicle fixation can be applied without significant neurovascular complications. The emergence of computer assisted image guidance systems may be implemented in the operative protocol to improve the accurate placement of a pedicle screw. The indications for placement of a pedicle screw in the cervical spine are beginning to evolve. Only surgeons experienced in transpedicle screw fixation and surgery of the cervical spine should perform this method of instrumentation.

Postlaminectomy kyphosis

Postlaminectomy kyphosis is a rare but potentially catastrophic complication of laminectomy performed to treat cervical myelopathy. The best strategy for prevention is awareness of the sagittal plane before surgery in patients with cervical spondylotic myelopathy. An understanding of the biomechanical forces placed on the cervical spine, the normal structures contributing to stability and the underlying pathologic process helps in the prevention and ultimate treatment of postlaminectomy kyphosis. This is a review of the risk factors, biomechanics, work-up, and surgical treatment of postlaminectomy kyphosis.

Anterior junctional plate in the cervical spine

STUDY DESIGN

This study introduces a useful plating technique for complex reconstructions of the anterior cervical spine.

OBJECTIVE

To provide a short-segment-buttressing technique for the stabilization of long anterior fusion constructs in the cervical spine while avoiding the potential morbidity and risks associated with long-segment anterior cervical plating.

SUMMARY OF BACKGROUND DATA

Anterior fibular or iliac crest strut grafts are at risk of dislodging when used after multisegment (> 3 vertebrae) corpectomy in various spinal disorders. Long-segment anterior cervical plates have been used to reduce the incidence of graft displacement and migration but have been shown to increase risk for early failure because of screw dislodgement.

METHODS

Eleven patients with cervical myelopathy underwent a multilevel (average 3.36 levels) corpectomy followed by the placement of a fibular or iliac crest strut graft. An anterior short-segment locking or buttress plate was then placed in the vertebral body, either inferior or superior to the seated graft, depending on the ease of insertion and quality of the host bone. Posterior segmental fixation was performed in all patients during the same procedure. The average follow-up was 30.8 months (range, 25-36 months).

RESULTS

No incidence of plate or graft migration (anteroposterior plane) or dislodgement was reported in this series. One graft fracture occurred secondary to the placement of a intragraft screw through an anterior junctional plate. No patients experienced clinical morbidity related to the junctional plate. Neurovascular complications and wound complications were not encountered in any of these patients. All had an improvement in their neurologic symptoms, and 10 of the 11 patients had fusion documented on plain radiographs.

CONCLUSIONS

The use of a junctional plate anteriorly along with posterior segmental fixation and fusion may prevent or decrease the incidence of graft and internal fixation dislodgement after a long-segment cervical reconstruction procedure.

Cervical degenerative disease: rationale for selecting the appropriate fusion technique (Anterior, posterior, and 360 degree)

Many options exist for those treating cervical disc herniation, spondylosis, and deformity. This article examines the options for cervical degenerative fusions, the appropriate choice of technique (anterior, posterior, or combined anterior/posterior techniques), as well as bone graft and instrumentation choices.

The changing nature of admissions to a spinal cord injury center: violence on the rise

The purpose of this study was to analyze changing etiologies for admission to a spinal cord injury center. This study was designed to retrospectively analyze the etiology of admissions to a spinal cord injury center during a 15-year period, specifically gunshot versus nongunshot wound injuries. Gunshot wounds are a well-recognized cause of spinal cord injury. In some centers, up to 52% of admissions are due to this, and these trends are believed to be increasing. All patients with spinal cord injury admitted to our center between 1979 and 1993 were analyzed. Frequencies of specific etiologies were determined and then comparisons were made between gunshot wound and nongunshot wound groups. Factors analyzed included age, male/female ratio, ethnic make-up, marital status, employment status, level of injury, and neurologic status. One thousand eight hundred seventeen patients were included. Overall, gunshot wound spinal cord injuries compromised 16.9% of injuries. A clear trend of increasing numbers of admissions was seen between 1984 and 1993 because of this. Gunshot wounds and nongunshot wounds differed dramatically in terms of age, ethnic make-up, marital status, employment status, and neurologic status. Cost attributed to treating gunshot wound injuries at our center for 1993 was 5.4 million dollars. Gunshot wounds as a cause of spinal cord injury are increasing at an alarming rate. The demographics of the gunshot wounds and nongunshot wound spine cord injuries differ significantly.

Foraminal pressure changes during intervertebral distraction simulating anterior cervical discectomy

Distraction of the disc space over baseline height has been shown to increase foraminal size. The purpose of this procedure is to determine pressure changes, with disc space distraction simulating an anterior cervical discectomy and fusion (ACDF). An analysis of pressure changes during disc space distraction at C5-C6 was performed. Data were analyzed for maximal pressure observed and for pressure change with prolonged distraction. Five cadaveric specimens underwent a discectomy at the C5-C6 level. Distraction of the disc space was performed and pressure measurements were obtained from within the foramen. Measurements were made for maximal pressure with an intact posterior longitudinal ligament (PLL), divided PLL, and with the nerve root removed from within the foramen. Pressures were also recorded with prolonged distraction until a steady state was achieved. Incremental distraction of +2, +4, and +6 mm resulted in pressure increases within the foramen. Sectioning of the PLL did not affect these increases. Removal of the nerve root from the foramen resulted in pressure increases; however, these were not significantly different from baseline. Prolonged distraction produced an initial increase and a gradual return toward baseline. Final pressures still differed significantly from baseline. Increase intraforaminal pressures can be seen with increasing disc space distraction such as occurs during an ACDF. This suggests that either the foramen narrows in at least one dimension and/or soft-tissue attachments to the nerve produce a tensile force in the nerve as they tighten. The pressure increases relax over time.

Use of cervicothoracic junction pedicle screws for reconstruction of complex cervical spine pathology

STUDY DESIGN

A retrospective review of 21 patients in which cervical pedicle screw fixation was used at C7 with or without upper thoracic pedicle screw fixation.

OBJECTIVE

To evaluate the use of pedicle screw placement in the lower cervical spine.

SUMMARY OF BACKGROUND DATA

The use of posterior cervical spine fixation, including lateral mass fixation, has become increasingly popular in recent years. However, lateral mass fixation at C7 is often hindered by lack of substantial high quality bone. The end level of long cervical spine constructs is frequently C7 or T1. Dissatisfaction with lateral mass fixation at C7 and T1 led the authors to use lower cervical pedicle screw fixation for several cervical spine disorders.

METHODS

Twenty-one patients who had undergone cervical pedicle screw fixation at C7 were reviewed retrospectively. There were 12 males and 9 females, with an average age of 52 years. All pedicle screws were placed, after direct palpation of the pedicle, with a right angle nerve hook after laminoforaminotomy at C7.

RESULTS

There were no neurologic complications related to pedicle screw placement, and no patient was symptomatically worse after the operation. Six patients with root pathology improved. Of 14 patients with cervical myelopathy, 12 improved at least one Nurick grade, and 2 had no improvement. There were no failures of fixation or complications related to pedicle fixation at a minimum of 1 year follow-up.

CONCLUSION

Pedicle screws in C7 placed with laminoforaminotomy and palpation technique appears to be safe and efficacious. Excellent fixation can be achieved.

Neurologic deterioration after cervical spinal cord injury

Neurologic deterioration after cervical spinal cord injury (SCI) at a regional spinal cord center was examined. This study examined the incidence of neurologic deterioration as well as associated risk factors in our patient population. Up to 5.8% of cervical SCI patients have been noted to deteriorate neurologically after admission. Risk factors have been early surgery, halo application, traction, and Stryker frame rotation. All cervical SCI patients admitted between 1978 and 1993 who had neurologic deterioration were studied for characteristics of their event, operative status, risk factors, mortality, and neurologic return at 1 year postinjury. Patients were divided into minor and major groups based on the degree of neurologic loss. Nineteen of 1,031 patients were identified as neurologically deteriorated (1.84%). There were 8 major and 11 minor group patients. The average time from injury to deterioration was 3.95 days. Of 10 patients undergoing surgery at < or =5 days, 8 deteriorated postoperatively. Potential risk factors were ankylosing spondylitis (three patients), sepsis (four patients), and intubation (four patients). Neurologic recovery at 1 year showed that 11 of 12 patients were improved. Neurologic deterioration occurred in 1.84% of our patients. Deteriorations were associated with surgery at <5 days after injury, ankylosing spondylitis, sepsis, and intubation.

Accuracy of SPECT scanning in diagnosing pseudoarthrosis: a prospective study

The present study attempted to analyze the efficacy of single photon emission computed tomography (SPECT) in diagnosing pseudoarthrosis after fusion using surgical exploration as the gold standard. This study examined the SPECT scans of 38 patients before they underwent surgical exploration of their fusion mass for suspected pseudoarthrosis or in conjunction with instrumentation removal. Surgical findings were compared with the radiologists' findings to determine the efficacy of SPECT in diagnosing pseudoarthrosis. Radiographic determination of pseudoarthrosis has been difficult after attempted fusion of the spine. Multiple radiographic modalities have been touted as accurate depicters of the failure of spinal fusion. However, no method has been found to be highly accurate in the clinical setting. Thirty-eight patients (mean age = 42.8, 21 males/17 females, 35 of 38 with instrumentation) underwent SPECT scans before surgical exploration of their fusion mass for suspected pseudoarthrosis or in conjunction with instrumentation removal as part of this prospective study. The average interval from their fusion procedure until their SPECT scan was 23.9 months (range, 9-120 months). All surgical findings were recorded with regard to solidity of the fusion and the level of the possible pseudoarthrosis. All SPECT scans were read at a time after surgery by an independent nuclear radiologist who had not read their SPECT scans before surgery and who did not know the results of exploration. Results of the radiologist's reading were then compared with surgical exploration findings, and sensitivity and specificity was calculated. There were 24 solid fusions and 14 pseudoarthroses. SPECT scans correctly identified 7 of the 14 pseudoarthroses and 14 of the 24 solid fusions. This represents a sensitivity of 0.50 and a specificity of 0.58. SPECT scanning correctly diagnosed the one solid fusion and two pseudoarthrosis patients in the three patients who had no instrumentation. This study demonstrates that SPECT scanning alone is inaccurate in diagnosing pseudoarthrosis when using surgical exploration as the gold standard. Given recent pressures for cost containment, we cannot recommend SPECT scanning as a routine modality for use in the diagnosis of pseudoarthrosis. We cannot define the accuracy of SPECT scanning used together with computed tomography scans, plain films, or other radiographic modalities in the diagnosis of pseudoarthrosis.

Variation in surgical opinion regarding management of selected cervical spine injuries. A preliminary study

STUDY DESIGN

The opinions of orthopedic surgeons and neurosurgeons were compared regarding appropriate management of selected cervical injuries and the timing of stabilization.

OBJECTIVE

To determine whether there is consistency of opinion regarding the management of cervical trauma.

SUMMARY OF BACKGROUND DATA

Numerous forms of management for cervical trauma exist, but there are few consistent recommendations. No previous study has been done to determine uniformity of preferences of the surgeons who manage these injuries.

METHODS

Thirty-one orthopedic surgeons and neurosurgeons were given a brief clinical situation and pertinent radiographic studies of five selected cervical injuries. Management options included halo and nonhalo orthoses, traction, and various forms of anterior and/or posterior procedures. The surgeons rated, in whole numbers from 1 to 10, their opinions on the appropriateness of each technique. Each surgeon was given a case of a "generic" cervical injury, in which stabilization was required and for which preoperative alignment was adequate in traction. They gave opinions on the timing of stabilization, with a choice of four time frames. Four neurologic situations were rated, ranging from intact to complete cord injury.

RESULTS

Of 46 possible responses to the five test cases regarding appropriateness, 18 ranged from 1 to 10, the largest possible variation. Only 2 had a range of 5 or less, implying better consensus among tested surgeons. Mean values ranged from 1.9 to 9.5. Agreementamong respondents regarding appropriateness was slight with a range of kappa statistics from 0.09 to 0.14. Of 16 possible responses regarding timing, 14 were within a range of 8 or higher. Within 24 to 72 hours was the generally preferred time frame, with all possible responses showing a range of 3 or 4. Results of a multiple analysis of variance showed no significant differences among respondents.

CONCLUSION

There is a large variety of opinion regarding appropriateness of specific operative and nonoperative management procedures and surgical timing among the surgeons polled who manage cervical trauma. This implies that there is no widely accepted standard management procedure for many of these injuries.

Long-term evaluation of vertebral artery injuries following cervical spine trauma using magnetic resonance angiography

STUDY DESIGN

A prospective study to determine the long-term outcome of traumatically induced vertebral artery injuries. Magnetic resonance angiography was performed at the time of cervical injury and at a follow-up office visit.

OBJECTIVE

To determine the long-term outcome in terms of arterial flow competency of traumatically induced vertebral artery injuries.

SUMMARY OF BACKGROUND DATA

Vertebral artery injury associated with cervical spine trauma has been well documented; however its healing or nonhealing potential has not been elucidated.

METHODS

During the 7-month period from July 1993 to January 1994, all patients admitted to the authors' institution with cervical spine injuries underwent magnetic resonance imaging and magnetic resonance angiography of the cervical spine to determine the patency of their vertebral arteries. Magnetic resonance angiography was performed at the time of injury and at a follow-up office visit. Twelve of 61 patients were found to have a lack of signal flow within one of their vertebral vessels during this study period.

RESULTS

Eighty-three percent of the patients (five of six) who were available for follow-up observation in this study did not manifest flow reconstitution of their vertebral arteries after an average 25.8-month follow-up period.

CONCLUSIONS

According to these data, most patients with vertebral artery injuries after nonpenetrating cervical spine trauma do not reconstitute flow in the injured vertebral arteries. This lack of flow must be considered if future surgery in this region of the cervical spine is contemplated.

The benefits of early decompression in cervical spinal cord injury

Decompression and stabilization have been shown to improve neurologic outcome in cases of cervical spine trauma with proven compression of the spinal cord. This paper reviews experimental and clinical research to clarify the benefits of early surgery for cervical spinal cord injury. The direct clinical benefit of early surgery is a theoretic improvement in neurologic recovery over that of delayed surgery. Additional benefits of early surgery include the clinical advantages of a decreased length of hospitalization and its associated complications and a decreased time to rehabilitation and mobilization. Proper, timely surgical intervention can better the physiologic environment so as to allow for maximum neurologic improvement.

Magnetic resonance imaging analysis of lumbar disc changes below scoliosis fusions. A prospective study

STUDY DESIGN

The authors of this prospective study examined the preoperative and 3-year postoperative magnetic resonance images of 14 patients undergoing anterior and posterior fusion and/or posterior fusion only for scoliosis. All magnetic resonance images were ready by two independent neuroradiologists, who were blinded to the purposes of the study, for the presence of disc narrowing, signal decrease on T2, or herniated nucleus pulposus before and after surgery. Particular attention was paid to the disc changes at the level directly below the end vertebral level of the fusion and two levels below the fusion in the lumbosacral spine existing before surgical intervention.

OBJECTIVES

To evaluate the potential for disc degeneration distal to long scoliosis fusions with end fusion levels in the mid to lower lumbar spine.

SUMMARY OF BACKGROUND DATA

The determination of end levels of fusion for contructs presently used to manage adult scoliotic deformity has been evaluated in terms of correction of curvature and late decompensation in coronal and sagittal plane balance after fusion. However, the natural history of the caudal, free-motion segments in terms of degeneration and/or correlation with pain has not yet been addressed.

METHODS

Fourteen patients undergoing scoliosis fusion underwent magnetic resonance imaging before surgery and approximately 3 years after surgery. The scans were reviewed by two independent neuroradiologists who looked at three degenerative indices at the disc below the area of scoliosis fusion. The authors analyzed rates of change of the three degenerative indices in the pre- and postoperative magnetic resonance images and created associations between the observed changes on the magnetic resonance images and the clinical outcomes of pain, the presence or absence of solid fusion, and the need for repeat surgery.

RESULTS

Estimates of the rates of change of the three degenerative indices one or two levels below the fusion were as follow: the chance of disc narrowing, .2-34%; the chance of a decreasing signal on T2, 5-54%, with a 23% incidence among this group; and the chance of herniated nucleus pulposus, 0-34%. There was a significant correlation between the presence of back and/or leg pain and the signal decrease one level below the fusion (P = .04).

CONCLUSIONS

If these results are corroborated in a larger sample size, surgeons who manage deformity may have to consider altering fusion levels at the time of fusion based on magnetic resonance imaging predictors. The present data may help to inform patients about the risk of developing junctional degenerative changes and potential symptoms from these changes below scoliosis fusions.

Relationship of total hip arthroplasty outcomes to other orthopaedic procedures

The Medical Outcomes Study Short Form-36 was used preoperatively and 2 years postoperatively to compare patients' self reported assessment of health and function between 151 patients who had primary total hip replacement and 49 patients who had total hip revision, 149 patients who had primary total knee replacements, 41 patients who had lumbar laminectomy, and 43 patients who had scoliosis surgery. Primary total hip arthroplasty and lumbar laminectomy posted equivalent followup scores. Primary total hip arthroplasty showed significant improvements in physical function and health perception when compared with revision total hip arthroplasty; all other health parameters were similar. Primary total hip arthroplasty showed significantly better followup scores and greater improvement in scores in four of nine categories of the SF-36 when compared with primary total knee arthroplasty (despite identical scores preoperatively). Despite a higher level of assessed health preoperatively, patients who had scoliosis surgery compared least favorably with patients who had primary total hip arthroplasty at 2 years followup. In terms of patient self assessment of health and function, primary total hip arthroplasty and lumbar laminectomy for radiculopathy gave the best results.

Steroids and gunshot wounds to the spine

OBJECTIVE

The second National Acute Spinal Cord Injury Study demonstrated that there were neurological benefits from "spinal cord injury" doses of methylprednisolone for blunt spinal cord injuries. In this review, we examined the relative risk/benefit ratio of intravenously treating spinal gunshot wound victims with steroids.

METHODS

A retrospective review was conducted of 254 consecutive patients who were treated between 1979 and 1994 for gunshot wounds to the spine (C1-L1) and a spinal cord injury. Three subgroups were established based on the administration of the steroids methylprednisolone (National Acute Spinal Cord Injury Study 2 protocol), dexamethasone (initial dose, 10-100 mg), and no steroids. All patients who received steroids were initially treated at another hospital and then transferred. No patients received steroids at our institution. The data analyzed included neurological outcome and infectious and noninfectious complications.

RESULTS

No statistically significant neurological benefits were demonstrable from the use of steroids (methylprednisolone, dexamethasone). Infectious complications were increased in both groups receiving steroids (not statistically significant). Gastrointestinal complications were significantly increased in the dexamethasone group (P = 0.021), and pancreatitis was significantly increased in the methylprednisolone group (P = 0.040). The mean duration of follow-up was 56.3 months.

CONCLUSION

In this retrospective, nonrandomized review, no neurological benefits were detectable from intravenously administered steroids after a gunshot wound to the spine. Both infectious and noninfectious complication rates were higher in the groups receiving steroids. Patients who sustain a spinal cord injury secondary to a gunshot wound to the spine should not be treated with steroids until the efficacy of such treatment is proven in a controlled study.

An in vivo analysis of the dimensional changes of the neuroforamen after anterior cervical diskectomy and fusion: a radiologic investigation

Eighteen patients (11 men, 7 women; average age, 45.5 years) who underwent anterior cervical diskectomy and fusion (ACDF) for the treatment of radiculopathy had preoperative and immediate postoperative computed tomography (CT) scans to measure pre- and postoperative foraminal heights and foraminal areas, preoperative disk space height, and postoperative graft height. The mean foraminal height preoperatively was 0.851 cm; postoperatively, it was 1.01 cm, with a mean percentage increase of 20% (-8.8 to 56.8%). Mean preoperative foraminal area was 37.53 mm2, increasing to a mean of 49.04 mm2 postoperatively with a mean percentage increase of 33% (range, -1.5 to 76.9%). No significant correlations between graft height and change in maximal foraminal height or foraminal area or between changes in foraminal height or area and postoperative symptom relief were found. Although significant increases in foraminal dimensions were seen radiographically after ACDF, these increases were variable and not strongly related to graft height. In addition, the increases in foraminal dimensions were not related to the short-term clinical results of ACDF. This study fails to support the hypothesis that the reliable results of ACDF can be ascribed primarily to indirect decompression of the uncovertebral foramen by disk-space distraction.

Vertebral artery occlusion associated with cervical spine trauma. A prospective analysis

STUDY DESIGN

Radiographs and charts of 61 patients sustaining cervical spine trauma were studied prospectively to determine the incidence of vertebral artery injuries and possible correlative factors. Statistical analysis was conducted using chi-square testing of a two-way classification system.

OBJECTIVES

To elucidate the incidence of vertebral artery injuries associated with cervical spine trauma, and to determine the value of various factors in predicting the existence of a vertebral artery injury.

SUMMARY OF BACKGROUND DATA

During a 7-month period, 61 patients (41 male patients, 20 female; average age, 40.3 years) with cervical spine trauma were studied.

METHODS

All patients admitted to the authors' hospital with cervical spine injuries underwent magnetic resonance imaging and magnetic resonance angiography of their cervical spine. All magnetic resonance angiographies were examined for vertebral artery injury. Data on demographics and the injury were recorded.

RESULTS

Complete disruption of blood flow through the vertebral artery was demonstrated by magnetic resonance angiography in 12 of the 61 patients (19.7%). Ten of the 12 patients (83%) had either flexion distraction or flexion compression injuries. Age, sex, mechanism of injury, neurologic impairment, and associated injuries were not statistically significant in predicting the presence of a vertebral vessel occlusion.

CONCLUSION

The findings in this study may support the need for vertebral vessel evaluation in selective patients, particularly those with flexion injuries and with neurologic symptoms consistent with vertebral artery insufficiency syndrome that do not correlate with the presenting bone and soft-tissue injuries.

Surgical anatomy of the vertebral arteries

STUDY DESIGN

This study compared direct measurements of the distances between the vertebral arteries in the cervical spines of human cadaver specimens with data obtained from axial computed tomography images of these specimens.

OBJECTIVE

To determine whether the information obtained from a computed tomography scan can be used reliably to predict the true anatomic location of the vertebral arteries and, in so doing, provide accurate guidelines for the lateral extent of anterior cervical decompressive procedures.

SUMMARY OF BACKGROUND DATA

Iatrogenic vertebral artery injury during anterior cervical surgery is uncommon, potentially catastrophic, and avoidable.

METHODS

The means and standard deviation of measurements of the location of the cervical segment of the vertebral arteries obtained with high-precision, digital calipers by direct gross anatomic dissection of 16 adult (eight male, eight female) cadaver specimens were recorded. These measurements were compared with computed tomography scan data obtained on the same specimens.

RESULTS

The mean distances between the vertebral arteries progressively increased from C3 to C6. Computed tomography scan measurements of the distance between the cervical foramina transversaria were consistently smaller than direct measurements of the gross specimens. At C6, the computed tomography scan data were significantly less than the gross anatomic data.

CONCLUSIONS

According to these data, computed tomography scan measurements may be used safely and accurately to plan the lateral extent of anterior cervical decompressive surgical procedures. Although the data obtained from the gross anatomic dissections may serve as guidelines to assist the surgeon, the authors recommend a careful review of the preoperative computed tomography scan on an individual case-by-case basis as the safest method to plan for anterior cervical surgery.

Prenatal detection of fetal anomalies in pregnancies complicated by insulin-dependent diabetes mellitus

OBJECTIVES

We evaluated the clinical utility of a comprehensive program of prenatal diagnostic testing for congenital anomalies in pregnancies complicated by insulin-dependent diabetes mellitus.

STUDY DESIGN

Data were retrospectively analyzed from 289 diabetic women and their newborns from August 1987 to July 1993. Our protocol included initial hemoglobin A1 and maternal serum alpha-fetoprotein determinations and comprehensive fetal ultrasonography inclusive of a standard four-chamber view of the heart and detailed multiimage fetal echocardiography.

RESULTS

Anomalies were identified in 29 of 289 (10%) fetuses and neonates: 12 cardiac only, 14 noncardiac, and 3 combined. In 21 of the 29 (72%) neonates the anomalies were detected prenatally. Twelve of 15 (80%) cardiac and 10 of 17 (59%) noncardiac lesions were identified prenatally. Cardiac lesions, especially of the cardiac septum and great vessels, accounted for 50% of all fetal defects. Malformations of the neuroaxis, skeleton, and genitourinary system were also detected. There were six neonatal deaths and four therapeutic pregnancy terminations associated with congenital anomalies. Although the hemoglobin A1 level was statistically significantly increased in 22 mothers of anomalous fetuses (p = 0.017), the actual difference between affected and nonaffected pregnancies was not clinically meaningful and much overlap occurred. Although 96% of women with a normal hemoglobin A1 level were delivered of normal infants, only 14% of those with an elevated value had a malformed fetus. Similarly, although 89% of gravid women with a normal maternal serum alpha-fetoprotein level were delivered of nonaffected fetuses, only 7.3% of patients with an elevated value had a malformed fetus. For the detection of cardiac defects, the sensitivity of the four-chamber view compared with detailed multiimage fetal echocardiography was 33% and 92%, respectively.

CONCLUSIONS

This study demonstrates the utility of a comprehensive program to detect fetal anomalies in pregnancies complicated by diabetes mellitus.

Health outcome assessment before and after lumbar laminectomy for radiculopathy

STUDY DESIGN

Forty-one patients undergoing lumbar laminectomy for radiculopathy resulting from herniated discs assessed their health status using a generic health outcome instrument (Medical Outcomes Study Short Form 36) before surgery and at an average of 2 years after surgery.

OBJECTIVES

To assess whether lumbar laminectomy for herniated nucleus pulposus is a useful intervention when patients evaluate their own perception of health.

SUMMARY OF BACKGROUND DATA

The medical Outcomes Study Short Form 36 has been used in multiple studies assessing various medical conditions. It is brief, generic, and reliable. Although surgical treatment for radiculopathy by lumbar laminectomy has been shown to be successful using specific criteria for patient selection and an algorithmic approach, the authors are not aware of any study using a patient-based health outcome assessment to evaluate the results of this type of surgery.

METHODS

Forty-one patients (82% completed follow-up evaluation; average follow-up period, 2.08 years) completed Medical Outcomes Study Short Form 36 before and after surgery. Scores from before and after surgery were compared.

RESULTS

Statistically significant improvements (P < 0.01) were seen in eight of the nine health scores comparing scores from before and after surgery at follow-up evaluation. These included physical function, social function, role function resulting from physical limitations, role function resulting from emotional limitations, mental health, vitality, pain, and perceived health change. No significant change was seen in the patients' health perception after surgery.

CONCLUSIONS

This study shows that the patients' self-reported health outcomes after lumbar laminectomy correlate with the excellent results previously seen using physician-driven outcome measures in an appropriately selected population with radiculopathy. The excellent results shown here did not deteriorate with age (> 40 years compared with < 40 years) or with complications after surgery.

Health outcome assessment before and after adult deformity surgery. A prospective study

STUDY DESIGN

Fifty-five patients undergoing surgery for adult spinal deformity assessed their health status using a generic health outcome instrument before surgery and at an average of 2 years after surgery.

OBJECTIVE

To assess whether adult spinal deformity surgery is a useful intervention when patients evaluate their own perception of health. The Medical Outcomes Survey Short Form-36, a validated generic health outcome assessment form, was used to measure patient's health status.

SUMMARY OF BACKGROUND DATA

Surgery for adult scoliosis is technically demanding. No study that we are aware of uses a generic health outcome instrument in a prospective manner to compare patients' perception of their health after adult scoliosis surgery. The Medical Outcomes Survey Short Form-36 has been validated in multiple studies assessing other medical conditions and was found to be reliable, comprehensive, brief, and generic.

METHODS

Sixty-eight adult patients undergoing surgery for adult spinal deformity were prospectively enrolled. Fifty-five patients were available to complete the Medical Outcomes Surgery Short Form-36 after surgery. The scores of the health profile were compared before and after surgery. The results of patients younger than 40 years were compared with those of patients older than 40 years. The results of patients younger than 40 years were compared with those of patients older than 40 years. The results of patients fused to more caudal end vertebral levels ((L4, L5)5) were compared with those who were fused to more cranial end vertebral levels. The results of patients without complications after surgery were compared with those of patients with complications after surgery.

RESULTS

Average follow-up period was 22.5 months (minimum 12 months) in 82% of 68 patients. Statistically significant improvements were seen in postoperative scores for physical function, social function, bodily pain, and perceived health change. We found no significant differences in self-reported health function parameters related to age ( > 40 vs. < 40), end vertebral level of fusion, or presence of complications after surgery.

CONCLUSIONS

Applying a generic health outcome instrument to adult spinal deformity surgery shows that adult scoliosis surgery significantly improves patient self-reported health assessment and function. Beneficial results do not appear to deteriorate with age or more caudal end vertebral levels of fusion. Future studies combining disease-specific outcomes analysis and generic health surveys to assess end results of adult spinal deformity surgery will be useful.

Interleukin-1 beta regulates the inducible cyclooxygenase in amnion-derived WISH cells

The purpose of this study was to determine the mechanism of enhanced prostaglandin synthesis in amnion-derived WISH cell cultures when stimulated by interleukin-1 beta (IL-1 beta). Confluent monolayer cultures of WISH cells were incubated with human recombinant IL-1 beta (0.001-10 ng/ml) for 0-24 hours, while control cells received medium alone. PGE2 production was measured by specific radioimmunoassay. IL-1 beta enhanced the production of PGE2 in a dose- and time-dependent manner with enhanced production detectable by 2 h following exposure. Immunoblot analysis using isoform-specific antibodies showed that the inducible cyclooxygenase enzyme, i.e., COX-2, was expressed by 2 h in IL-1 treated cells, while the constitutive COX-1 remained unaltered in its expression. Northern blot analysis demonstrated that COX-2 mRNA expression was not detected in untreated cells, but became evident after a 30-min exposure to IL-1 beta (10 ng/ml). COX-1 mRNA was detected under basal conditions and did not increase significantly following IL-1 beta treatment. The close parallel between the kinetics of COX-2 mRNA and protein expression and PGE2 accumulation in the medium, as well as the constitutive, unregulated nature of the COX-1 isoform, indicates that cytokine-driven PGE2 formation in WISH cells may be mediated by de novo expression of the novel COX-2 enzyme.