ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study DesignThe cervical spine of the healthy Japanese children aged between 1 year and 18 years was radiographically examined.ObjectivesTo examine the correlation between growth of the cervical vertebral body and the facet joint and the development of the cervical lordosis and intervertebral motion.Summary of Background DataAlthough the growth of body height and facet angle have been well documented, their correlation with curvature or mobility has not been elucidated.MethodsWe evaluated plain lateral radiographs of 180 boys and 180 girls regarding diameters and central heights of the cervical vertebra, the anterior and posterior vertebral height ratio, body height index, the facet joint angles, and tilting and sliding motions. Cervical length as the summation of the central height from C3 to C7 and the cervical lordosis angle (C3-C7 angle) were also measured.ResultsThe mean C3-C7 angle and body height index gradually decreased until 9 years of age and then increased. The C3-C7 angle showed a significant correlation with cervical length, body height index, and facet joint angles before 9 years of age, and with cervical length and body height index after 9 years of age but not with facet joint angles. Facet joint angle decreased until 10 years of age and remained almost unchanged thereafter. Total sliding showed a significant age-related decrease and showed a significant correlation with facet joint angle.ConclusionAlthough the lordosis angle showed a significant correlation with the other values, cervical length, body height index, and facet joint angle, the determinants of the lordosis could not be elucidate in the present study. As for the mobility of the cervical spine, changes of tilting motion were small, whereas changes of sliding motion were restricted by the change of orientation of the facet joints.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study DesignThis 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.ObjectiveTo 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 DataIatrogenic vertebral artery injury during anterior cervical surgery is uncommon, potentially catastrophic, and avoidable.MethodsThe 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.ResultsThe 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.ConclusionsAccording 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.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study DesignLaminectomy was performed on cats to destroy the posterior epidural ligament. Evoked potentials and spinal cord blood flows quantified the spinal cord function before and after cervical flexion.ObjectivesThis work describes a relationship between the loss of the posterior epidural ligaments and cervical spinal cord injury.Summary of Background DataThe posterior epidural ligaments of the human cervical spine have been recently described. These ligaments theoretically prevent injury to the spinal cord by resisting collapse of the dura during cervical flexion.MethodsThe animals were divided into three experimental groups: 1) control: no laminectomy and standard position, 2) flexion control: no laminectomy and known imposed flexion, 3) laminectomy (C3-C7) and flexion. Motor-evoked potentials and evoked spinal cord potentials were recorded to quantify the spinal cord functions. Radioactive microspheres were used to quantify ischemia in the spinal cord.ResultsControl subjects showed blood flows of 36 mL/100 g/min (C3-C4) to 46 mL/100 g/min (C7-C8). Flexion control subjects did not experience significant reductions in blood flows or substantial changes in evoked potentials. The laminectomy plus flexion group experienced reduced blood flows and substantial motor-evoked potentials and slight evoked spinal cord potential changes with 50°, 60°, and 70° flexion. Blood flow reduction was greater in the anterior half of the C7-C8 segments compared with the posterior half at 60° flexion. Evoked spinal cord potentials were less vulnerable than motor-evoked potentials.ConclusionThe role of the posterior cervical epidural ligaments is to anchor the posterior dura mater to the ligamentum flavum. Loss of the ligaments allows anterior displacement of the posterior dura mater in flexion. Abnormal distribution of or lack of the cervical posterior epidural ligaments may lead to flexion myelopathy.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study DesignThis study analyzedin vitroexperiments of ectopic firing evoked by mechanical compression or hypoxia of canine lumbar dorsal roots with dorsal root ganglia using anin vitromodel.ObjectivesThe results were correlated to understand the pathophysiology of radiculopathy, which manifests abnormal sensation and pain.Summary of Background DataIt has been speculated that blood flow in the nerve root and mechanical compression play major roles in the production of radiculopathy symptoms. However, no precise experimental studies have been conducted on the relationship between these factors and the development of ectopic firing.MethodsCanine lumbar dorsal roots with dorsal root ganglia were immersed in an oxygenated artificial cerebrospinal fluid, and activity of the nerve root was recorded using bipolar platinum electrodes. Using this model, the effects of quantitative mechanical compression and hypoxia on the ectopic firing were analyzed.ResultsWhen compression was applied, mechanical thresholds for eliciting firing were much lower in dorsal root ganglia than in dorsal roots, and the firing lasted for a longer period in dorsal root ganglia. Under hypoxia, dorsal root ganglia showed firing, and their thresholds from mechanical stimuli decreased significantly. In dorsal roots, impulse propagation was not affected, whereas firing was seen under the hypoxic condition.ConclusionDorsal root ganglia are highly sensitive to mechanical compression and hypoxia and closely related to abnormal sensations and pain in radiculopathy.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study DesignThis study investigated the effects of hypoxia and glucose on motor functions of spinal cord, monitoring ventral root motor-evoked potential in thein vitrocervical cord preparations.ObjectiveTo study ischemia-induced changes in ventral root motor-evoked potential of spinal cord.Summary of Background DataPrevious studies demonstrated ischemic changes caused by local circulatory impairment might be a major pathophysiologic basis of neuron damage in cord compression.MethodsVentral root motor-evoked potential elicited by stimulation of ventrolateral funiculus was recorded from the ventral root in the isolated spinal cord preparations obtained from a newborn rat. The preparations were exposed to artificial cerebrospinal fluid equilibrated with severe or mild hypoxia for 90 minutes. Inhibitory and excitatory neurotransmitter antagonists were added to artificial cerebrospinal fluid to investigate synaptic transmission. The artificial cerebrospinal fluids containing various concentrations of glucose were used to study the glucose's effects.ResultsVentral root motor-evoked potential consisted of the early and late components, which were excitatory transsynaptic potentials. The amplitudes were increased in the early phase of severe hypoxia and declined in the prolonged exposure. In mild hypoxia, there was a sustained increase of the amplitudes. The application of inhibitory neurotransmitter antagonists abolished the augmentation of the amplitudes in the early phase of severe hypoxia. Hypoxia without glucose accelerated hypoxic change.ConclusionInhibitory synaptic transmission was depressed preferentially in the early phase of severe hypoxia or in mild hypoxia. Excitatory and inhibitory transmissions were suppressed in prolonged severe hypoxia. Glucose deficiency aggravated hypoxic inhibition of synaptic transmissions.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study DesignThis study was designed to evaluate whether allografts of intervertebral disc materials produce hyperalgesia in the rat and whether an immune response, pH, or chemicals correlate with the induced hyperalgesia.ObjectiveTo elucidate the pathomechanisms of radicular pain secondary to lumbar disc herniation.Summary of Background DataIt has been reported that a low pH, an autoimmune reaction, or chemical radiculitis is likely responsible for radicular pain associated with lumbar disc herniation. In animal studies, it has been shown that hyperalgesia (an increased sensitivity to painful stimuli) involves activation of phospholipase A2and nitric oxide synthase.MethodsFat, nucleus pulposus, and anulus fibrosus were allografted into the epidural space at L6 in the rat. Withdrawal response thresholds to mechanical stimuli and withdrawal response latencies to thermal stimuli on the tail and pH in the applied tissues were measured after surgery. Interleukin-1, phospholipase A2, and nitric oxide synthase were examined in the applied tissues using immunohistochemistry, nicotineamide adenine dinucleotide phosphate-diaphorase histochemistry, andin situhybridization.ResultsAllografted fat did not produce hyperalgesia. Allografts of nucleus pulposus and nucleus pulposus plus anulus fibrosis showed evidence of mechanical and thermal hyperalgesia, respectively. There were no observed changes in pH over time. Although interleukin-1 was demonstrated in all applied tissues, phospholipase A2was only observed around the applied nucleus pulposus and nucleus pulposus plus anulus fibrosus. Nitric oxide synthase was only markedly increased around the applied tissues.ConclusionThe nucleus pulposus and anulus fibrosus produce different forms of hyperalgesia (mechanicalvs.thermal) associated with different and distinct immunohistochemical changes. It is possible that radicular pain of a lumbar disc herniation results from chemicals, such as phospholiapse A2and nitric oxide.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study DesignThe biomechanical stability of six different methods of cervical spine stabilization, three using multistrand cables, were evaluated in a bovine model.ObjectivesTo quantify and compare thein vitrobiomechanical properties of multistrand cables used for posterior cervical wiring to standard cervical fixation techniques.Summary of Background DataFixation of the posterior cervical spine with monofilament stainless steel wire is a proven technique for stabilization of the cervical spine. Recently, multistrand braided cables have been used as a substitute for monofilament stainless steel wires. These cables, made of stainless steel, titanium, or polyethylene, are reported to be stronger, more flexible, and fatigue resistant than are monofilament wire based on mechanical testing. However, noin vitrobiomechanical studies have been performed testing a standard posterior cervical wiring technique using multistrand cables.MethodsThirty-six fresh frozen cervical calf spines consistent in size and age were mounted and fixed rigidly to isolate the C4-C5 motion segment. Six different reconstruction techniques were evaluated for Rogers' posterior cervical wiring technique using: 1) 20-guage stainless steel monofilament wire, 2) stainless steel cable, 3) titanium cable, 4) polyethylene cables, 5) anterior locking plate construct with interbody graft, and 6) posterior plate construct. Six cervical spines were included in each group (n = 6), with each specimen statically evaluated under three stability conditions: 1) intact, 2) reconstructed, and 3) postfatigue. The instability model created before the reconstruction consisted of a distractive flexion Stage 3 injury at C4-C5. Nondestructive static biomechanical testing, performed on an material testing machine (MTS 858 Bionix test system, Minneapolis, MN), included axial compression, axial rotation, flexion-extension, and lateral bending. After reconstruction and static analysis, the specimens were fatigued for 1500 cycles and then statically retested. Data analysis included normalization of the reconstructed and postfatigue data to the intact condition. The calculated static parameters included operative functional unit stiffness and range of motion.ResultsPosterior cervical reconstruction with stainless steel monofilament wire proved inadequate under fatigue testing. Two of the six specimens failed with fatigue, and this construct permitted the greatest degree of flexion-extension motion after fatigue in comparison with all other constructs (P< 0.05). There were no significant differences in flexural stiffness or range of motion between stainless steel, titanium, or polyethylene cable constructs before or after fatigue testing. The posterior cervical plate constructs were the stiffest constructs under flexion, extension, and lateral bending modes, before and after fatigue testing (P< 0.05).ConclusionsMultistrand cables were superior to monofilament wire with fatigue testing using anin vitrocalf cervical spine model. There were no failures or detectable differences in elongation after fatigue testing between the stainless steel, titanium, and polyethylene cables, as shown by the flexion-extension range of motion. The posterior cervical plate construct offered the greatest stability compared with all other constructs.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID