摘要:

Study DesignThe authors present the results of an anatomic study of the human occiput to delineate appropriate screw placement sites.ObjectivesOccipital bone morphologic characteristics were evaluated to determine whether significant variability exists and to determine the position of greatest bone thickness for safe and effective internal fixation.Summary of Background DataNew instrumentation and techniques for occipital fixation are being developed in response to concerns about occipital bone variability. Thirty cadaveric occiputs were evaluated to determine if such variability exists and the location of greatest bone thickness. Radial thickness, occipital locations, and gender differences, were determined.MethodsTwenty-six skulls were sectioned sagittally to determine the contributions of the inner, middle, and outer tables to overall occipital thickness. The angle required to gain maximal cortical purchase was determined. Mean values and variance were analyzed statistically to determine variability and thickness. Data was plotted in three dimensions. Variability in morphologic features was minimal.ResultsThe internal occipital protuberance-external occipital protuberance was thickest at 17.55 mm (SD = 3.18 mm) and was consistently located on the superior nuchal line 43° from the horizontal skull base line. Bone thickness decreased radially from the central internal occipital protuberance position. Bone thickness above the superior nuchal line exceeded that below by 2.74 mm (P< 0.05) vertically and at the oblique positions (P< 0.05). Bone to the right of the midline was only 1 mm thicker than that to the left. Gender differences were minimal. The inner table contributed only 10% to overall occipital thickness. As occipital thickness decreased, the optimal purchase angle increased.ConclusionsUnicortical purchase at and above the superior nuchal line is warranted with a low risk of intracranial venous penetration. Internal fixation devices developed in response to occipital bone variability should be considered with respect to occipital bone thickness distributions. Attention to cervical morphologic characteristics should result in higher success rates in occipitocervical arthrodesis.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study DesignThe authors measured the thickness and quality of occipital bone regions to determine screw placement during occipitocervical fusion and described the projection of the posterior dural venous sinuses.ObjectiveThis study provides anatomic data relevant to areas of screw placement into the occiput during occipitocervical fixation.Summary of Background DataFew reports exist regarding the morphometrics of the occipital bone and intracranial structures relevant to occipitocervical fusion.MethodThe thickness of the posterior inferior occipital bone was measured relative to a 10 × 5 cm grid. Sections were evaluated grossly and histologically. The projections of the posterior dural venous sinuses were determined by direct measurements.ResultsThe maximum thickness of the occipital bone, which ranged from 11.5 to 15.1 mm in males and from 9.7 to 12.0 mm in females, was at the level of the external occipital protuberance. The occipital bone was thicker than 8 mm in an area extending laterally from the external occipital protuberance for 23 mm and consisted of dense cortical bone with little or no diploic bone. The projection of most of the torcula on the external surface of the occipital bone was located superior to the center of the external occipital protuberance (mean, 12.6 mm superior and 4.7 mm inferior to external occipital protuberance), whereas that of the transverse sinus was distributed more evenly above and below the external occipital protuberance (mean, 7.3 mm superior and 6.5 mm inferior).ConclusionsScrews that are 8-mm long may be inserted in the region of the superior nuchal line (Level 0) extending 2 cm laterally from the center of the external occipital protuberance, 1 cm from the midline at a level 1 cm inferior to the external occipital protuberance (Level 1), and 0.5 cm from the midline at a level 2 cm inferior to the external occipital protuberance (Level 2). The major dural venous sinuses are situated immediately beneath the thickest regions of the occiput and are at risk of penetrative injury during screw placement.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study DesignThis study ascertained the effects of discectomy on prostaglandin synthesis.ObjectivesThe purpose of these novel experiments was to measure the levels of two prostaglandins in lumbar epidural fluid obtained from an area subjected to discectomy. For comparison, lumbar epidural fluid from a site not disturbed by discectomy and fluid from a subcutaneous site were analyzed for the prostaglandins.Summary of Background DataPrevious studies have shown that nuclear material obtained from degenerative discs manifests an extraordinarily high level of phospholipase A2activity. Others have hypothesized that the known inflammatory effects of phospholipase A2are due to the release of arachidonic acid, which is converted to various eicosanoids, including several algesic prostaglandins (PGI2and PGE2). No previous study has continuously measured prostaglandin levels in epidural fluid or assessed the effect of discectomy on prostaglandin production.MethodsAn ultrafiltrate of lumbar epidural fluid of dogs was obtained from indwelling catheters located adjacent to spinal areas that were and were not subjected to discectomy as well as from subcutaneous tissue. The fluid was collected daily for 14 days and analyzed for PGE2and 6-keto PGF1α(the stable metabolite of PGI2) by radioimmunoassay.ResultsThe concentration of 6-keto PGF1αand PGE2in fluid collected during the first 24 hours was significantly higher in the area of discectomy than in the epidural region that was not subjected to discectomy and significantly higher than in fluid obtained from the subcutaneous site. The high level of these prostaglandins at the discectomy site fell rapidly, so that by the end of 48 hours the differences in values between spinal fluid from the discectomy and nondiscectomy regions were not statistically significant. The concentration of the prostaglandins in epidural fluid decreased with time and became minimal within the second week.ConclusionThe removal of normal discs is accompanied for 24 hours by a marked rise in the synthesis of two prostaglandins known to produce pain. Because the concentration of prostaglandins in epidural fluid decreased rapidly thereafter, the initial surge obtained appears to be associated more with chemical factors such as phospholipase A2than with wound healing.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study DesignThe authors developed a diagnostic double-blindfolded survey using placebo-controlled local anesthetic blocks.ObjectiveTo determine the prevalence of cervical zygapophysial joint pain among patients with chronic neck pain (more than 3 months' duration) after whiplash injury.Summary of Background DataThe prevalence of cervical zygapophysial joint pain after whiplash has been studied by means of comparative local anesthetic blocks. The concern is that such blocks may be compromised by placebo responses and that prevalence estimates based on such blocks may exaggerate the importance of this condition.MethodsSixty-eight consecutive patients referred for chronic neck pain after whiplash were studied. Patients with dominant headache were first screened with the use of comparative blocks of the C2-C3 zygapophysial joint. Patients who had positive responses concluded investigations. Those who did not experience pain relief together with the patients with dominant neck pain proceeded to undergo placebo-controlled local anesthetic blocks. Two different local anesthetics and a placebo injection of normal saline were administered in random order and under double-blindfolded conditions. A positive diagnosis was made if the patient's pain was completely and reproducibly relieved by each local anesthetic but not by the placebo injection.ResultsAmong patients with dominant headache, comparative blocks revealed that the prevalence of C2-C3 zygapophysial joint pain was 50%. Among those without C2-C3 zygapophysial joint pain, placebo-controlled blocks revealed the prevalence of lower cervical zygapophysial joint pain to be 49%. Overall, the prevalence of cervical zygapophysial joint pain (C2-C3 or below) was 60% (95% confidence interval, 46%, 73%).ConclusionCervical zygapophysial joint pain is common among patients with chronic neck pain after whiplash. This nosologic entity has survived challenge with placebo-controlled, diagnostic investigations and has proven to be of major clinical importance.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study DesignCervical spine manipulation and mobilization were reviewed in an analysis of the literature from 1966 to the present.ObjectivesTo assess the evidence for the efficacy and complications of cervical spine manipulation and mobilization for the treatment of neck pain and headache.Summary of Background DataAlthough recent research has demonstrated the efficacy of spinal manipulation for some patients with low back pain, little is known about its efficacy for neck pain and headache.MethodsA structured search of four computerized bibliographic data bases was performed to identify articles on the efficacy and complications of cervical spine manual therapy. Data were summarized, and randomized controlled trials were critically appraised for study quality. The confidence profile method of meta-analysis was used to estimate the effect of spinal manipulation on patients' pain status.ResultsTwo of three randomized controlled trials showed a short-term benefit for cervical mobilization for acute neck pain. The combination of three of the randomized controlled trials comparing spinal manipulation with other therapies for patients with subacute or chronic neck pain showed an improvement on a 100-mm visual analogue scale of pain at 3 weeks of 12.6 mm (95% confidence interval, -0.15, 25.5) for manipulation compared with muscle relaxants or usual medical care. The highest quality randomized controlled trial demonstrated that spinal manipulation provided short-term relief for patients with tension-type headache. The complication rate for cervical spine manipulation is estimated to be between 5 and 10 per 10 million manipulations.ConclusionsCervical spine manipulation and mobilization probably provide at least short-term benefits for some patients with neck pain and headaches. Although the complication rate of manipulation is small, the potential for adverse outcomes must be considered because of the possibility of permanent impairment or death.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study DesignThe sensitivity of plain radiographs for diagnosing traumatic atlanto-occipital dislocation and its association with craniocervical junction subarachnoid hemorrhage was examined in a retrospective review of seven patients.ObjectiveThe purpose of this study was to demonstrate the frequency of nondiagnostic plain radiographs and the common association of craniocervical junction subarachnoid hemorrhage in the context of reported cases of atlanto-occipital dislocation to facilitate better recognition of this injury. The use of sagittal reconstructions of computed tomography or sagittal magnetic resonance imaging for diagnosis was evaluated.Summary of Background DataAlthough traumatic atlanto-occipital dislocation is a common cause of motor vehicle fatalities, survival has been more common in the last 16 years. However, the diagnosis was missed on lateral cervical radiographs in 38% of children and 59% of adults; fewer than half were diagnosed subsequently with plain radiography. Moreover, the diagnosis of traumatic atlanto-occipital dislocation often was not considered, because more than half of the survivors had no neurologic abnormality or unilateral deficit. Consequently, more than one third of initially undiagnosed patients experienced neurologic deterioration due to inadequate cervical immobilization. Additional radiographic studies allowing diagnosis were prompted by the neurologic worsening.MethodsThe authors reviewed seven patients treated with traumatic atlanto-occipital dislocation during a 14-year period. Emergency department records were compared with reexamination of initial cervical radiographs to determine the success in diagnosis by means of published methods. The frequency of craniocervical junction subarachnoid hemorrhage on computed tomography was determined, and the use of sagittal imaging for subsequent diagnosis was evaluated.ResultsIn the emergency department, only one patient's condition was diagnosed as atlanto-occipital dislocation. Review of the initial radiographs identified an additional four patients for whom atlanto-occipital dislocation could be diagnosed. Sagittal computed tomography reconstruction or sagittal magnetic resonance imaging identified the remaining two. All but one patient had craniocervical junction subarachnoid hemorrhage. A review of reported cases revealed a common association of craniocervical junction subarachnoid hemorrhage with traumatic atlanto-occipital dislocation but not with traumatic head injury.ConclusionsThe diagnosis of traumatic atlanto-occipital dislocation is often missed in the emergency department, and current methods for evaluating the integrity of the atlanto-occipital joint on cervical radiographs fail to identify all patients with this injury. Although infratentorial subarachnoid hemorrhage is uncommon in traumatic head injury, craniocervical junction subarachnoid hemorrhage is often associated with atlanto-occipital dislocation and should raise the suspicion of severe craniocervical ligamentous injury. Sagittal computed tomography reconstructions or sagittal magnetic resonance imaging can allow for the diagnosis when plain radiography is inconclusive.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study DesignThis paper describes the background and factors that led to the development and implementation of the Maine Lumbar Spine Study, a prospective cohort study of patients undergoing surgical and non-surgical treatment of herniated lumbar disc with sciatica and symptomatic spinal stenosis.ObjectivesTo define the factors leading to the study and the methods of designing and implementing a community-based effectiveness study to evaluate the outcomes of herniated lumbar intervertebral disc and spinal stenosis.Summary of Background DataVariations in the utilization of surgery for these conditions and physicians' uncertainty regarding the best way to manage them resulted in support of a community-based study of the effectiveness of treatment alternatives.MethodsA prospective cohort design was used. Methods of patient enrollment, data collection, management, and analysis are described. An innovative method of ascertaining the representativeness of the enrolledversusnonenrolled patient population is presented.ResultsThe importance of developing community-based networks of physicians is discussed.ConclusionsThese networks play an important role in analyzing practice pattern variations and in stimulating and participating in effectiveness research. Because effectiveness studies must be conducted at the community level, mechanisms must be developed with which to support and implement these efforts.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study DesignThe Maine Lumbar Spine Study is a prospective cohort study of patients recruited from the practices of orthopedic surgeons, neurosurgeons, and occupational medicine physicians throughout Maine.ObjectiveTo assess 1-year outcomes of patients with sciatica believed to be due to a herniated lumbar disc treated surgically or nonsurgically.Summary of Background DataLumbar spine surgery rates vary by geographic region and may reflect uncertainty about optimal clinical use.MethodsEligible consenting patients participated in a baseline interview performed by study personnel and then were mailed follow-up questionnaires at 3, 6, and 12 months. Clinical data were obtained from a physician questionnaire. Outcomes included patient-reported symptoms of leg and back pain, functional status, disability, quality of life, and satisfaction with care.ResultsFive hundred seven patients with sciatica, 275 treated surgically and 232 treated nonsurgically initially, were enrolled. Surgically treated patients, on average, had more severe symptoms and had more severe physical and imaging findings than nonsurgically treated patients at entry. Although few surgically treated patients had mild symptoms and few nonsurgically treated patients had severe symptoms, about half in each treatment group had symptoms that fell into a moderate category. At the 1-year evaluation, improvement in symptoms, functional status, and disability were found in both treatment groups. However, surgically treated patients reported significantly greater improvement. For the predominant symptom, either back or leg pain, 71% of surgically treated and 43% of nonsurgically treated patients reported definite improvement (P< 0.001). This effect was even greater after adjustment for differences between treatment groups at entry (relative odds of definite improvement, 4.3;P< 0.001). For patients with moderate symptoms and abnormal physical examination findings, surgical treatment also resulted in greater improvement than nonsurgical treatment. However, there was little difference in the employment or workers' compensation status of patients treated surgicallyversusnonsurgically (5%vs.7% unemployed at 1-year follow-up if employed at entry [P= 0.68]; 46%vs.55% receiving workers' compensation at 1-year follow-up if receiving it at entry [P= 0.30] for surgical and nonsurgical management, respectively). For patients with mild symptoms, the benefits of surgical and nonsurgical treatment were similar.ConclusionsAlthough surgically treated patients were on average more symptomatic at entry, there was substantial overlap in symptoms between surgically treated and nonsurgically treated patients. Surgically treated patients with sciatica reported substantially greater improvement at 1-year follow-up. However, employment and compensation outcomes were similar between the two treatment groups, and surgery appeared to provide little advantage for the subset of patients with mild symptoms. These results should be interpreted cautiously, because surgical treatment was not assigned randomly. Long-term follow-up will determine if these differences persist.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study DesignA prospective cohort study of patients with lumbar spinal stenosis recruited from the practices of orthopedic surgeons and neurosurgeons throughout Maine.ObjectiveTo assess 1-year outcomes of patients with lumbar spinal stenosis treated surgically or nonsurgically.Summary of Background DataNo randomized trials and few nonexperimental studies have compared surgical and nonsurgical treatment of patients with lumbar spinal stenosis. The authors' goal was to assess 1-year outcomes of patients with lumbar spinal stenosis treated surgically or nonsurgically.MethodsEligible, consenting patients participated in baseline interviews and were then mailed follow-up questionnaires at 3, 6, and 12 months. Clinical data were obtained from a physician questionnaire. Outcomes included patient-reported symptoms of leg and back pain, functional status, disability, and satisfaction with care.ResultsOne hundred forty-eight patients with lumbar spinal stenosis were enrolled, of whom 81 were treated surgically and 67 treated nonsurgically. On average, patients in the surgical group had more severe imaging findings and symptoms and worse functional status than patients in the nonsurgical group at entry. Few patients with mild symptoms were treated surgically, and few patients with severe symptoms were treated nonsurgically. However, of the patients with moderate symptoms, a similar percent were treated surgically or nonsurgically. One year after study entry, 28% of nonsurgically and 55% of surgically treated patients reported definite improvement in their predominant symptoms (P= 0.003). For patients with moderate symptoms, outcomes for surgically treated patients were also improved compared with those of nonsurgically treated patients. Surgicla treatment remained a significant determinant of 1-year outcome, even after adjustment for differences between treatment groups at entry (P= 0.05). The maximal benefit of surgery was observed by the time of the first follow-up evaluation, which was at 3 months. Although few nonsurgically treated patients experienced a worsening of their condition, there was little improvement in symptoms and functional status compared with study entry.ConclusionsAt a 1-year evaluation of patient-reported outcomes, patients with severe lumbar spinal stenosis who were treated surgically had greater improvement than patients treated nonsurgically. Comparisons of outcomes by treatment received must be made cautiously because of differences in baseline characteristics. A determination of whether the outcomes observed persist requires long-term follow-up.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study DesignOne hundred fifteen of 120 patients with β-thalassemia followed in the thalassemia unit were studied for the presence of scoliosis. Forty-nine of these patients were reevaluated 1 year later.ObjectivesTo determine the frequency and the course of scoliosis in β-thalassemia and to compare the findings with those of patients with idiopathic scoliosis.Summary and Background DataThere is only one report indicating increased frequency of scoliosis in a limited number of patients with thalassemia. In this study, the authors assessed the frequency of scoliosis in a large sample of patients and followed the evolution of this spinal deformity.MethodsPatients with β-thalassemia aged 3-35 years were examined clinically and radiologically for scoliosis. Forty-nine of them were reexamined 1 year later for determination of the evolution of scoliosis.ResultsLateral curves of at least 5° Cobb were found in 77 patients (67%), with a male-to-female ratio of 0.9. Scoliosis of at least 10° was found in 21.7% of the male and 20% of the female patients with thalassemia. The ratio was 1.18 for curves of at least 10° and 0.77 for curves of a smaller magnitude. The most common curve pattern was the left lumbar (35.1%), followed by the double-curve pattern (16.9%). Forty-nine randomly selected patients (42.6%) of the 115 included in the study were reexamined 1 year later. Seven male and 7 female patients (total, 28.6%) showed a progression of at least 5°. Six patients (12.2%) experienced spontaneous improvement of less than 6°. The pattern and the evolution of scoliosis observed in patients with β-thalassemia differ from those found in Greek children with idiopathic scoliosis.ConclusionsThe findings of this study show that the incidence, evolution, and etiology of scoliosis in β-thalassemia differ from those of idiopathic scoliosis, indicating that the spinal deformities in patients with β-thalassemia represents a distinct type of scoliosis. Longer follow-up is needed to investigate the natural history of this type of scoliosis.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID