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R D Guyer

Publications and source records attributed to R D Guyer.

At least 19 recordsLinked to original sources
PubMed2000

The relation between cervical discographic pain responses and radiographic images.

OBJECTIVE: The purpose of this study was to investigate the relation between cervical discographic pain responses and radiographic images. DESIGN: Records were reviewed for a series of patients who had undergone cervical discography. SETTING: All patients were being treated at a spine specialty clinic. PATIENTS: A total of 269 discs were studied in 161 discographic procedures in patients with neck, shoulder, or arm pain. All patients underwent other diagnostic procedures before discography, including magnetic resonance imaging, computed tomography (CT), and CT/myelography. INTERVENTIONS: During the injection of contrast in each disc evaluated, the patient was asked if any pain was felt, and if so, was it similar or dissimilar to the pain typically experienced. OUTCOME MEASURES: Results were determined by analyzing the pain responses during disc injection with respect to imaged pathology seen on the axial CT discographic image of the disc. Results were further analyzed based on patient age. RESULTS: There was a significant relation between the radiographic image of the disc and the results of clinical pain provocation (p < 0.01; chi2). Among the 35 discs appearing as normal, clinical pain was provoked in only 14.3%. Among the 234 discs appearing as abnormal, clinical pain was provoked in 77.8%. The mean age of the patients with painless radiographically abnormal discs was significantly greater than that of the patients in the other subgroups of the study population. CONCLUSIONS: There was good agreement between the radiographic appearance of the disc and the pain provocation results. Discs that were painless but disrupted were found among older patients. Among such patients, discography may be particularly helpful in differentiating clinically significant abnormalities from those associated with aging.

Adult↗
PubMed1999

A double-blind study of capacitively coupled electrical stimulation as an adjunct to lumbar spinal fusions.

STUDY DESIGN: A randomized double-blind prospective comparison with a placebo control. This report of the results is the first in an ongoing study. OBJECTIVES: To evaluate the effect of noninvasive capacitively coupled electrical stimulation on the success rate of lumbar spine fusion surgery, and to compare active with placebo stimulators as adjuncts to contemporary fusion techniques. SUMMARY OF BACKGROUND DATA: Previous studies have established the effectiveness of direct current and electromagnetic field stimulation as adjuncts for some forms of spinal fusion. None of the previous placebo-controlled studies on external bone stimulation included posterolateral fusion techniques, and most were conducted with prior generations of internal fixation hardware. METHODS: The investigation was conducted by 28 U.S. surgeons. Patients with a primary diagnosis of degenerative disc disease with or without other degenerative changes were selected. The study protocol defined success as a clinical outcome rated as excellent or good and a fusion documented as solid by both the investigator and the blinded independent radiologist. Disagreements on radiographic success were resolved by a second blinded independent reviewer. RESULTS: For the 179 patients who completed treatment and evaluation, the overall protocol success rate (both clinical and radiographic results rated as successes) was 84.7% for the active patients and 64.9% for the placebo patients. This difference is highly significant according to the Yates corrected chi-square test (P = 0.0043). Best improvements in patient outcomes (20% or greater success rate) occurred when active stimulation was used in conjunction with posterolateral fusion (P = 0.006) and when internal fixation also was incorporated (P = 0.013). DISCUSSION: This study was consistent in that active stimulation improved results for each stratification, although some strata had insufficient numbers of patients for the results to have statistical significance. Improved success rates when capacitively coupled stimulation is added to internal fixation are hypothesized to result from overcoming the biochemical effects of stress shielding. CONCLUSIONS: Capacitively coupled stimulation is an effective adjunct to primary spine fusion, especially for patients with posterolateral fusion and those with internal fixation.

Adult↗
PubMed1997

Endoscopic techniques in spinal surgery.

Minimally invasive techniques are becoming more widespread in the surgical subspecialties. Standard open surgical procedures are being modified to become less invasive, with the hopes of decreased recovery time, lessened morbidity, and ultimately, cost savings. Improvements in technology have allowed the surgeon to peer into body cavities and create potential spaces such as the retroperitoneum and the neuroforaminal space without the need for traditional extensile surgical approach. Improved fiberoptics, light sources, and the advent of the 3-chip camera and the 3-dimensional camera have resulted in improvements in visualization of the structures surrounding the spine. Although the goals of endoscopic surgery are to maintain or improve visualization and minimize the approach related trauma, procedures must also prove efficacious and safe with at least equivalent results compared with their open surgical counterpart. Not all procedures may be applicable to minimally invasive approaches and just because a procedure can be done does not mean that it should be done. Laparoscopic and thoracoscopic spine procedures also depend on the partnership of the spine surgeon with the thoracic or general surgeon with endoscopic experience to ensure patient safety. Proficiency in minimally invasive spinal techniques takes devotion and does not occur after taking minicourses. Practice with cadaver and in vivo models, preceptorship and proctorship training, and ultimately the teaching of these techniques in residency and spinal fellowship programs will undoubtedly lead to favorable outcomes and reduced medical expenditure. Preliminary results are encouraging for endoscopic spinal surgery, but further testing of these new techniques against conventional open procedures will be important in documenting not only the efficacy of the procedure, but also its value in patient satisfaction and cost.

Adult↗
PubMed1997

Complications of cervical discography: findings in a large series.

The use of cervical discography remains controversial. Recently in a small patient group, a high complication rate was reported. The purpose of this study was to determine the incidence of complications associated with cervical discography. Data from 161 cervical discography procedures, involving 269 disc injections, were recorded. There were four complications; thus the complication rate was 2.48% based on the number of procedures and 1.49% based on the number of disc injections. The complications were two cases of discitis, one postinjection hematoma, and one patient developed significant headache pain after the disc injection. Reports of high complication rates associated with cervical discography and serious outcomes from them should serve as a warning that the procedure does have associated risks, and great care is warranted. However, based on the results of our study, discography is not an inherently unsafe procedure. It can be accomplished with few complications when performed in sterile conditions by those well experienced with cervical disc injections.

Adult↗
PubMed1996

A controlled biochemical and immunohistochemical study of human synovial-type (group II) phospholipase A2 and inflammatory cells in macroscopically normal, degenerated, and herniated human lumbar disc tissues.

STUDY DESIGN: Group II phospholipase A2 enzyme activity was studied biochemically and immunohistochemically in tissue samples from disc prolapses, degenerated discs, and macroscopically normal discs. In parallel, phospholipase A2 and inflammatory cells were studied by indirect immunocytochemistry. OBJECTIVES: To compare phospholipase A2 activity in normal discs and abnormal discs by an identical assay for phospholipases A2, and to compare the occurrence of inflammatory cells with phospholipase A2 activity and immunoreactivity. SUMMARY OF BACKGROUND DATA: It has been suggested that a high phospholipase A2 enzyme activity in herniated disc tissue could be significant in abnormal states such as sciatica and discogenic pain. No comparison between healthy disc tissue and samples of abnormal discs (degenerated or herniated) has been carried out. In particular, an identical assay for phospholipase A2 for such tissue samples, supported by immunohistochemical staining data, has never been applied in parallel to normal and abnormal disc tissue, and neither have such results been compared with the demonstration of inflammatory cells. METHODS: Group II phospholipase A2 enzyme activity was determined, in parallel, using an identical assay for tissue samples from 11 macroscopically normal discs, 33 disc herniations, and six discs showing degeneration by discography. For determination of phospholipase A2 enzyme activity, a radioassay using 1-palmitoyl-2-(1-14C)linoleoyl-L-3-phosphatidylethanolamine as the phospholipid substrate was used. Total tissue DNA as an estimate of total tissue cell number was measured in parallel with phospholipase A2 activity. All tissue samples also were studied by indirect immunocytochemistry, locating phospholipase A2 and T and B lymphocytes. RESULTS: Neither degenerated nor herniated disc tissue samples demonstrated a higher phospholipase A2 activity than control disc tissue samples. Average phospholipase A2 activity was actually higher in the control samples than in herniated disc samples (Mann-Whitney test, P < 0.001), possibly a result of a higher total DNA (P < 0.005). The observed level of phospholipase A2 activity was lower than that of inflammatory human synovial fluid. Neither was there marked immunoreactivity for phospholipase A2, which was observed in chondrocytes in areas of cartilage and occasional disc cells, supporting the biochemical results. Lymphocytes were more numerous only in herniated disc samples (15%), and their presence showed little overlap with phospholipase A2 immunoreactivity. CONCLUSIONS: Synovial-type (Group II) phospholipase A2 enzyme activity is not particularly high in disc tissue and does not appear to be higher in herniated or degenerated discs than control disc tissue. Immunoreactivity to phospholipase A2 is seen only occasionally and is strong only when cartilage tissue is present. Neither are inflammatory lymphocytes commonly observed.

Adult↗
PubMed1996

Discographic pain report. Influence of psychological factors.

STUDY DESIGN: The possibility of a relationship between discographic pain responses and Minnesota Multiphasic Personality inventory scores was investigated. OBJECTIVES: To determine if patients with elevated Minnesota Multiphasic Personality Inventory scale scores were more likely to report pain on the injection of a nondisrupted disc than were patients without such high scores. SUMMARY OF BACKGROUND DATA: In general, injection into disrupted discs provokes pain, whereas injection into nondisrupted discs does not. However, discordant results are sometimes obtained and create a more difficult diagnostic challenge. METHODS: The primary study group was composed of 72 patients who underwent computed tomography/discography at the three lowest lumbar levels for diagnostic purposes and completed the Minnesota Multiphasic Personality Inventory. RESULTS: The mean scores on the Minnesota Multiphasic Personality Inventory hypochondriasis and hysteria scales were significantly greater for patients reporting reproduction of clinical pain than for patients not reporting pain on injection of a nondisrupted disc (hypochondriasis: 77.2 vs. 68.6, P < 0.01; hysteria: 74.5 vs. 68.3, P < 0.05). The scores on the depression scale followed a similar trend (68.6 vs. 63.6, P < 0.15). Multivariate analysis, adjusting the means for possible confounding effects of age, symptom duration, and sex, did not alter the results. CONCLUSIONS: Discographic pain reports are not only related to anatomic abnormalities, but are influenced by personality as assessed by the Minnesota Multiphasic Personality Inventory. Patients with elevated scores on the hypochondriasis, hysteria, and depression scales may tend to overreport pain during discographic injection. Among such patients, even those with a concordant computed tomography/discographic image, selection of therapeutic modalities should be made with caution.

Adult↗
PubMed1996

Laparoscopic fusion of the lumbar spine in a multicenter series of the first 34 consecutive patients.

The purpose of this study was to describe the development of the laparoscopic technique for anterior lumbar fusion and to evaluate the clinical results of a first case series of patients. The in vivo porcine model was used first to develop the technique of transperitoneal laparoscopic interbody fusion. Afterwards, operative time, blood loss, perioperative complications and length of stay were recorded for the first 34 patients who underwent laparoscopic fusion of L4-5 or L5-S1 at two medical centers in 1994. Laparoscopic lumbar fusion was successful in 30 of 34 patients. Four patients early in the series successfully were converted to an open procedure because of poor visualization (two cases) or iliac venous injury (two cases). Transfusion was required in one patient; average blood loss was 128 ml. Operative time averaged 218 min, hospitalization 3.67 days. Laparoscopic fusion is feasible and has minimal complications when a skilled laparoscopic surgeon is present for exposure. Minimal excisional trauma associated with this technique should result in decreased hospitalization and earlier recovery compared with standard open techniques. Preliminary results indicate an earlier discharge and return to work (3 weeks) than that expected for standard open techniques.

Adult↗
PubMed1995

Lumbar discography. Position statement from the North American Spine Society Diagnostic and Therapeutic Committee.

STUDY DESIGN: A comprehensive review of the literature dealing with lumbar discography was conducted. OBJECTIVE: The purpose of the review was to generate a position statement addressing criticisms of lumbar discography, identify indications for its use, and describe a technique for its performance. SUMMARY OF BACKGROUND DATA: Lumbar discography remains a controversial diagnostic procedure. There are concerns about its safety and clinical value, although others support its use in specific applications. METHODS: Articles dealing with lumbar discography were reviewed and summarized in this report. RESULTS: Most of the recent literature supports the use of discography in select patients. Although not to be taken lightly, many of the serious and high complication rates were reported before 1970 and have decreased since because of improvement in injection technique, imaging, and contrast materials. CONCLUSIONS: Most of the current literature supports the use of discography in select situations. Particular applications include patients with persistent pain in whom disc abnormality is suspect, but noninvasive tests have not provided sufficient diagnostic information or the images need to be correlated with clinical symptoms. Another application is assessment of discs in patients in whom fusion is being considered. Discography's role in such cases is to determine if discs within the proposed fusion segment are symptomatic and if the adjacent discs are normal. Discography appears to be helpful in patients who have previously undergone surgery but continue to experience significant pain. In such cases, it can be used to differentiate between postoperative scar and recurrent disc herniation and to investigate the condition of a disc within, or adjacent to, a fused spinal segment to better delineate the source of symptoms. When minimally invasive discectomy is being considered, discography can be used to confirm a contained disc herniation, which is generally an indication for such surgical procedures. Lumbar discography should be performed by those well experienced with the procedure and in sterile conditions with a double needle technique and fluoroscopic imaging for proper needle placement. Information assessed and recorded should include the volume of contrast injected, pain response with particular emphasis on its location and similarity to clinical symptoms, and the pattern of dye distribution. Frequently, discography is followed by axial computed tomography scanning to obtain more information about the condition of the disc.

Humans↗
PubMed1995

Radiographic assessment for patients with low back pain.

Guidelines for radiographs of the lumbar spine are established. In general, radiographs are not believed to be necessary for a first episode of low back pain present for less than 7 weeks. Exceptions to this include various medical or physical findings, which are listed. In general, anteroposterior and lateral views only should be done initially. Indications for other views are discussed.

Humans↗
PubMed1995

Magnetic resonance imaging. Use in patients with low back or radicular pain.

With the current emphasis on cost containment, it is important to order the single best diagnostic test when clinical uncertainties must be resolved. Magnetic resonance imaging is currently the optimal imaging modality to provide the maximum amount of information when evaluating patients with suspected spinal disorders. A comprehensive magnetic resonance imaging study is needed along with a subspecialty interpretation to provide the greatest amount of useful clinical information.

Humans↗
PubMed1995

Early changes in bone mineral density above a combined anteroposterior L4-S1 lumbar spinal fusion. A clinical investigation.

STUDY DESIGN: Fifteen patients meeting rigid study entrance criteria for undergoing a combined anteroposterior L4-S1 spinal fusion as a first time operation were included in the study. Bone mineral density changes at adjacent segments (L3 and L2) were assessed by scanning patients in the anteroposterior and lateral projections before surgery and 3 and 6 months after surgery. OBJECTIVES: To prospectively evaluate changes in bone mineral density at adjacent segments after lumbar spinal fusion and postoperative bracing. SUMMARY OF BACKGROUND DATA: The majority of studies investigating changes in bone mineral density after spinal fusion have been performed in canines. Although such work has provided valuable insight, its application to humans is questionable because the loading mechanics are so different. METHODS: Bone mineral density was assessed noninvasively by dual energy x-ray absorptiometry in the lateral and anteroposterior projections. Data were analyzed with special edge detection software. RESULTS: In the lateral projection at L3, one level above the fusion, the preoperative bone mineral density was 0.91 +/- 0.24 (mean +/- standard deviation in g/cm2). This decreased significantly at 3 months to 0.82 +/- 0.24 and remained reduced at 6 months (0.80 +/- 0.21). This reflected a loss of primarily trabecular bone. In the anteroposterior projection at L2, there was a significant loss at 3- and 6-month follow-up (1.24 +/- 0.15 to 1.19 +/- 0.15 and 1.19 +/- 0.14). This may reflect changes at either or both of the anterior and posterior columns. CONCLUSION: Significant decreases in bone mineral density were noted above fused lumbar segments. This may have been related to immobilization or altered mechanics associated with arthrodesis. Trabecular bone of the axial skeleton is most responsive to change, compared with cortical bone, because of the higher metabolic activity. This may explain the reduction of bone mineral density at L3. Changes at L2 may have been related to altered loads at the anterior or posterior columns and should be further investigated.

Adult↗
PubMed1995

The association between pain drawings and computed tomographic/discographic pain responses.

STUDY DESIGN: Pain drawings were scored and their relationship to discographic pain responses was investigated. OBJECTIVES: The purpose of this study was to determine if there was a relationship between patients indicating pain in nonanatomic patterns on pain drawings (possibly suggestive of a tendency to overreport pain) and discographic pain responses, and in particular, if patients with abnormal drawings were more likely to provide false-positive discographic pain reports. SUMMARY OF BACKGROUND DATA: Patients with abnormal pain drawings have been found to have elevated scores on the hysteria and hypochondriasis scales of the Minnesota Multiphasic Personality Inventory. Elevations on these same two scales have been related to discordant discographic pain reports. METHODS: Pain drawings were completed by 170 patients the day of, but before computed tomography/discography. The drawings were scored as described by Ransford et al and classified as normal or abnormal. The number of levels at which a patient reported pain and the incidence of false-positive computed tomographic/discographic pain reports were compared for the two pain drawing groups. RESULTS: Patients with abnormal drawings reported pain at more levels than patients with normal ones. When dealing specifically with false-positive pain reports (pain reproduction on the injection of a nondisrupted disc), among the 105 patients in the normal group, only 13 (12.3%) reported false-positive pain. This was significantly less than the 50.0% (18 of 36) reporting false-positive pain in the abnormal group. The overall accuracy of pain drawings in differentiating patients with false-positive pain reports was 78.0% (110 of 141). CONCLUSIONS: There is a relationship between pain drawings and discographic pain responses. Pain drawings can help identify patients who may be likely to report pain on injection of a nondisrupted disc. While it was not totally sensitive to this occurrence, it can help identify at least some of the patients in whom pain responses should be interpreted cautiously.

Adult↗
PubMed1995

Intradiscal pressure measurements above an instrumented fusion. A cadaveric study.

STUDY DESIGN: An in vitro study to determine the intradiscal pressure changes during flexion in levels above a simulated fusion was performed. OBJECTIVES: To determine if intradiscal pressure increases more during flexion in discs above an instrumented spinal segment compared to an uninstrumented segment. SUMMARY OF BACKGROUND DATA: The progressive degeneration of intervertebral discs adjacent to a fused or fixed segment is a phenomenon that is noted but poorly understood. Intuitively, the degeneration appears to be a function of altered biomechanics of the motion segments in the spine. METHODS: Two intervertebral disc levels were evaluated, L3-L4 and L4-L5 from each of six fresh frozen cadaver spines. Pressure measurements were taken with the spine uninstrumented, with bilateral pedicle screw-rod instrumentation from L5 to S1, and with bilateral pedicle screw-rod instrumentation from L4 to S1. Pressure measurements were accomplished with Millar Mikro-Tip pressure transducers. The transducers were placed within the nucleus pulposus of L3-L4 and L4-L5 intervertebral discs. Pressure data were recorded by computer data acquisition. The pressure data were compared by intervertebral level and by the effects of added instrumentation. RESULTS: In general, the addition of instrumentation significantly affected the intradiscal pressure in the levels above a simulated fusion. The intradiscal pressure increased as the amount of levels involved in the simulated fusion increased. The intradiscal pressure increased as flexion motion increased. A greater increase was seen at the L4-L5 level than the L3-L4 level. When L5-S1 fixation was added, the intradiscal pressure increased. When L4-S1 fixation was added, the intradiscal pressure further increased. CONCLUSION: This study demonstrated increasing intradiscal pressures during flexion.

Aged↗
PubMed1995

Biomechanical comparison of anterior instrumentation for the cervical spine.

Metal fixation has been advocated to achieve immediate local stabilization during anterior cervical fusion surgery. Screw loosening, screw backout, and breakage of screws or plates remain clinical complications that warrant concern. This study examined the biomechanical characteristics of a prototype anterior cervical plating system with unique screw and plate geometries in comparison to a fixation system currently used clinically. Compared with a standard screw design, a taper screw design resulted in increased ultimate strength and fatigue life. The addition of a locking pin hole in the tapered screw made the screw's fatigue life comparable to the standard design. Pullout strength was comparable in all screw designs. The prototype fixation system had higher strength in pure compression and compression with bending than the comparative system, while also demonstrating improved fatigue characteristics. The tensile bending stiffness of the prototype was double that of the comparative system and within the anatomical range of cervical vertebrae, the bending moment was greater. Torsional yield strength was greater than the reported breaking strength of cervical disc in situ for both systems. The unique designs of the screw and plate geometry resulted in an anterior cervical plate fixation system that is stronger with decreased risk of fatigue failure than a currently used system. Clinical evaluation in patients requiring immediate stabilization is warranted.

Biomechanical Phenomena↗
PubMed1994

Laser disc decompression. The importance of proper patient selection.

STUDY DESIGN: The value of adherence to selection criteria for laser disc decompression (LDD) was evaluated. A total of 204 patients who underwent LDDs were identified. Follow-up information could be obtained for 164 (80.8%) patients. Results were compared based on the selection criteria. SUMMARY OF BACKGROUND DATA: Laser disc decompression is a relatively new procedure. Few reports concerning outcome of LDD exist; and none deal specifically with patient selection. OBJECTIVE: This study compared the results of LDD performed among patients who met appropriate selection criteria with those who did not. Also, the value of discography in patient selection for LDD was investigated. METHODS: Two independent reviewers extracted data from patient charts. From this information, each patient was assigned to one of three groups: 1) those who met all selection criteria for LDD (leg pain, positive physical examination finding such motor, sensory, or reflex deficits, and/or straight leg raise, contained disc herniation confirmed by discography); 2) those who did not meet the selection criteria (had a normal physical examination, the presence of stenosis, spondylolisthesis, extruded disc fragment, leakage of discographic dye from the outer annulus, multiple prior lumbar surgeries); or 3) those who could not be assigned to either of the first two groups for reasons such as discography not being performed or inadequate physical examination data recorded in the chart. At 1 year follow-up, each patient was sent a questionnaire assessing outcome. Successful outcome was defined to be no subsequent lumbar surgery, the patient felt that LDD had helped, and if the patient was working before symptom onset, he was able to work at the time of follow-up. RESULTS: Among the 41 patients who met all selection criteria, the success rate was 70.7% (29/41); among patients who did not meet all the criteria, the success rate was only 28.6% (12/42); significantly less than in the first group (P < 0.005). Among patients who could not be assigned definitively to either of the first two groups, the success rate was 55.6% (45/81). Also, the success rate among patients with discographic confirmation of a contained disc herniation was significantly greater than among those who either did not have discography performed or extravasation of contrast was noted (70.7% vs. 44.4%, P < 0.035). CONCLUSIONS: These results emphasize the importance of strict adherence to appropriate selection criteria to obtain satisfactory results from LDD.

Adult↗
PubMed1994

Reported pain during lumbar discography as a function of anular ruptures and disc degeneration. A re-analysis of 833 discograms.

STUDY DESIGN: This re-analysis was based on 833 computed tomography/discograms collected from 306 candidates for back surgery. OBJECTIVES: The goal was to test the hypothesis that outer anular ruptures are the main determinant of the pain of discography. SUMMARY OF BACKGROUND DATA: Previous analyses indicated univariate associations of pain with disc degeneration and anular ruptures. METHODS: If present, pain was classified as "exact", "similar", or "dissimilar" reproduction of the previously experienced pain. For each disc, ruptures and degeneration were separately evaluated by a four-point scale. Multiple logistic regression with random effects was used in the analysis. RESULTS: Outer anular ruptures were the only predictor of the responses "similar" and "exact". General disc degeneration was the only predictor of the response "dissimilar". There was no effect modification due to gender, age, and spinal level. CONCLUSIONS: During discography, the outer anulus appears to be the origin of pain reproduction.

Adult↗
PubMed1993

The relationship of facet tropism to degenerative disc disease.

The role of facet tropism (asymmetry) in the pathogenesis of degenerative disc disease is unknown, and several conflicting reports have been published. We studied this association using CT/discography performed at 324 lumbar levels (108 patients). The stage of disc degeneration as well as the patient's pain response upon discographic injection were scored using a standardized protocol. The facet angles were measured directly from the axial CT/discographic images and defined, in each case, as the angle formed by the facet orientation with respect to the midsagittal plane. The facet tropism angle was defined as the difference between the left and right facet angles at each disc level. The mean and standard deviation (SD) of the tropism angles were calculated. From this calculation, each pair of facet joints was classified as symmetric (within 1 SD of the mean), moderately asymmetric (between 1 and 2 SD), or severely asymmetric (beyond 2 SD of the mean). There were no differences in degree of disc degeneration or pain response with respect to the facet tropism. The total facet angle was also studied. The total facet angle was greater at the more caudal levels. The total angle size was not associated, however, with disc degeneration or pain provocation. These findings do not support the hypothesis that there is an association between facet tropism and degenerative lumbar disc disease.

Adult↗