ISSN:0362-2436    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

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

ISSN:0362-2436    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Study Design.A rat tail model was used to test the hypothesis that angulation and asymmetric axial compressive loading would lead to vertebral wedging because of asymmetric longitudinal growth in the physes.Objectives.To study the effect of angulation and asymmetric loading on the progression of spinal curvature in a rat tail model.Summary of Background Data.Large idiopathic scoliotic curves in children with significant growth remaining are the curves most likely to progress. The mechanism of progression of skeletal deformities is thought to be controlled by the Hueter-Volkmann law, whereby additional axial compression decelerates growth, and reduced axial compression accelerates growth. It has been hypothesized that spinal curvature leads to asymmetric loading transversely along the vertebral growth plate, causing progressive vertebral wedging by means of a vicious cycle.Methods.Two 32-mm diameter external ring fixators were glued to 0.7-mm pins that had been inserted percutaneously through the eighth and 10th caudal vertebra of 10 6-week-old Sprague-Dawley rats. Calibrated springs and 15° wedges, mounted on stainless steel threaded rods passing through holes distributed around the rings, imposed a 30° Cobb angle and axially compressed the instrumented vertebrae. Fluorochrome labels and radiographs were used to document the progression of vertebral wedging.Results.The wedging initially was entirely in the intervertebral discs, but by 6 weeks the wedging of the discs and vertebrae were approximately equal. Fluorochrome labeling confirmed that the vertebral wedging resulted from asymmetric growth in the physes.Conclusions.This study shows that vertebrae, when asymmetrically loaded, become wedged. This is consistent with the concept of mechanically provoked progression of scoliotic deformities according to the Hueter-Volkmann law.

ISSN:0362-2436    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Study Design.The effect of intraperitoneal injection of 5-hydroxytryptophan (5-HTP)versuscontrol in pinealectomized chickens.Objective.To find if the serotonin may have some role in the cause or treatment of idiopathic scoliosis.Summary of Background Data.One of the causes of idiopathic scoliosis is thought to be the disruption of postural reflex. Serotonin has been proposed to have a crucial role in maintaining normal postural muscle tone or postural equilibrium.Method.Forty pinealectomized chickens served as controls, and an additional 40 pinealectomized chickens received daily intraperitoneal injections of 5-hydroxy-tryptophan, a precursor of serotonin, which can pass through the blood-brain barrier. Spine radiographs were examined to measure the scoliotic deformity.Results.Scoliosis developed in all 40 pinealectomized chickens (control), whereas only 28 chickens in the 5-hydroxytryptophan-treated group (6 in severe, 22 in mild) had scoliosis developed. The remaining 12 chickens grew up with normal spines. Most chickens with mild scoliosis did not have curve progression but continued to have wedged vertebrae.Conclusion.Serotonin deficit secondary to a defect of melatonin may have disturbed postural muscle tone or postural equilibrium resulting in scoliosis in pinealectomized chicken. Prevention from the development of scoliosis or its progression in chickens treated with 5-hydroxytryptophan suggests that serotonin may have potential therapeutic value.

ISSN:0362-2436    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Study Design.The authors studied 319 patients with adolescent idiopathic scoliosis treated at the same institution with either a Boston brace or a Charleston bending brace.Objectives.To determine if both orthoses are equally effective in stopping curve progression and preventing the need for surgical correction.Summary of Background Data.Early reports suggest that the Charleston brace may be comparable to the Boston brace in its effectiveness and that both braces positively influence the natural history of idiopathic scoliosis.Methods.Skeletally immature (Risser 0, 1, or 2) patients with idiopathic scoliosis who were 10 years old or older at the time of brace prescription, had curves from 25° to 45°, and had no prior treatment were studied retrospectively. All measurements were collected by a single observer, and all patients were followed up to skeletal maturity.Results.The Boston brace is more effective than the Charleston brace, both in preventing curve progression and in avoiding the need for surgery. These findings were most notable for patients with curves of 36°-45°, in whom 83% of the those treated with a Charleston brace had curve progression of more than 5°, compared with 43% of those treated with the Boston brace (p < 0.0001).Conclusion.When given the choice between these two orthoses in the treatment of adolescent idiopathic scoliosis, the authors recommend use of the Boston brace. The Charleston brace should be considered only in the treatment of smaller single thoracolumbar or single lumbar curves.

ISSN:0362-2436    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Study Design.A retrospective review of a series of 12 children who underwent suboccipital foraminotomy and duroplasty for Chiari I malformation.Objective.To assess the effects of this surgery on associated syringomyelia and scoliosis.Summary of Background Data.Suboccipital foraminotomy for the treatment of syringomyelia associated with Chiari I malformation was greatly stimulated by Gardner's hydrodynamic theory, and its results proved to be encouraging. However, several authors reported improvement or stabilization of associated scoliosis after this surgery.Methods.A retrospective review was conducted on 12 patients who underwent suboccipital foraminotomy for Chiari I malformation associated with syringomyelia. Neurologic impairment, extent of syringomyelia, and severity of associated spinal deformity were assessed preoperatively and at a 4.5-year average follow-up (range, 2.1-12 years). Anomaly of superficial abdominal reflexes was found in all cases, and para or tetraparesis in three cases. Syringomyelia was of variable localization and extent. Scoliosis was present in 7 cases (greater than 40° in 5 cases).Results.Diminution or complete disappearance of syringomyelia was observed in 11 cases, 3 months to 1 year after surgery. Superficial abdominal reflexes anomaly improved in four cases. Minimal neurologic deficit persisted in one case. Scoliosis improved in one case, remained unchanged in one case, and progressed in the five cases with preoperative severe deformity, requiring instrumentation and fusion.Conclusions.Improvement of syringomyelia and neurologic deficit, observed with suboccipital foraminotomy, supports the theory that abnormal hydrodynamics of the cerebral spinal fluid is most likely to cause these deficits.

ISSN:0362-2436    

出版商:OVID    

年代:1997

数据来源: OVID

ISSN:0362-2436    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Study Design.A retrospective review of 3450 spinal surgeries was performed.Objectives.To review ophthalmic complications and their etiologies, as well as treatments and outcomes, in patients who have undergone spinal surgery.Summary of Background Data.Ophthalmic complications after major spinal reconstructive surgery are rare and have not been adequately addressed in the orthopedic literature.Methods.In a series of 3450 spinal surgeries at three institutions, the authors identified seven patients (incidence = 0.20%) whose postoperative course was complicated by loss of visual acuity. These perioperative ophthalmic complications included posterior optic nerve ischemia, occipital lobe infarcts, and central retinal vein thrombosis. Operative time, estimated blood loss, and medical history of peripheral vascular, cardiovascular, or ophthalmic disease were obtained from the charts, as were follow-up data.Results.Three patients recovered completely, and one had partial return of visual function. In the remaining three patients, significant visual loss persisted.Conclusions.The risk of ophthalmic complications with spinal surgery has not been fully appreciated. Because ophthalmic complications in spinal surgery may be reversed with prompt recognition and intervention, it is important for clinicians to be aware of their possible occurrence.

ISSN:0362-2436    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Study Design.Thirty-seven patients who experienced visual loss after spine surgery were identified through a survey of the members of the Scoliosis Research Society and a review of the recent literature.Objectives.Records were reviewed in an attempt to identify preoperative and intraoperative risk factors and to assess the likelihood of recovery.Summary of Background Data.Postoperative blindness after spine surgery has been documented in case reports or small series. The authors report the largest group of such cases to date and the first to allow conclusions regarding risk and prognosis.Methods.Letters were sent to members of the Scoliosis Research Society requesting copies of medical records concerning patients who experienced postoperative visual deficits after spine surgery. An additional 10 well-documented recent cases were identified from published reports.Results.Patients with visual loss had a mean age of 46.5 years. Surgery included instrumented posterior fusion in 92% of the cases, with an average operative time of 410 minutes and blood loss of 3500 mL. Most cases had significant intraoperative hypotension, with a mean drop in systolic blood pressure from 130 to 77 mm Hg. However, comparison with a matched group of patients with no visual symptoms showed no differences in the hematocrit or blood pressure values. Visual loss occurred because of ischemic optic neuropathy, retinal artery occlusion, or cerebral ischemia. Eleven cases were bilateral, and 15 patients had complete blindness in at least one eye. Most deficits were permanent.Conclusions.The authors conclude that blindness after spine surgery is more common than has been recognized previously. Most cases are associated with complex instrumented fusions.

ISSN:0362-2436    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Study Design.This study evaluated the different forms of treatment of camptomelic dysplasia, a rare form of short-limbed dwarfism.Objectives.To determine the most efficacious form of management of spinal deformities in camptomelic dysplasia.Summary of Background Data.The literature on treatment of spinal deformities in camptomelic dysplasia is sparse. One report advocates aggressive surgical treatment to prevent curve progression and prevent already compromised respiratory function.Methods.Eight patients with camptomelic dysplasia and progressive spinal deformity underwent a retrospective chart and radiographic review by an independent observer. Follow-up averaged 3 years and 9 months.Results.Five of eight patients initially were treated with bracing and six of eight patients eventually required surgery. Average initial kyphosis was 114° and scoliosis 61°, compared with 99° kyphosis and 52° scoliosis at follow-up. Complications included pseudarthrosis (50%) and neurologic problems (33%).Conclusions.The authors advocate anterior/posterior uninstrumented fusion and halo cast immobilization postoperatively to prevent curve progression and avoid the potentially fatal sequelae associated with this disorder.

ISSN:0362-2436    

出版商:OVID    

年代:1997

数据来源: OVID