Discrimination of spinal fracture with various bone mineral measurements

For several different bone mineral measurements and various skeletal sites, we compared capability to discriminate between women in various age decades with and without spinal fracture, and attempted to identify the most effective cutoff level in discrimination of spinal fracture. The subjects were 88 women aged 50–59 years (including 32 with fracture), 95 women aged 60–69 years (including 54 with fracture), and 34 women aged 70–79 years (including 18 with fracture). Spinal trabecular and cortical bone mineral density (BMD) were measured using quantitative computed tomography (CT), and spinal, radial (ultra-distal, 10% distal and 33% distal), and calcaneal BMD were measured by dual X-ray absorptiometry. These BMD values were obtained in each subject on the same day. Three statistical techniques—Student's t-test, the logistic regression analysis, and the receiver operating characteristics (ROC) analysis— were applied and accuracy was calculated using the various cutoff values. The capability to discriminate between women with and those without fracture using these BMD values was different among the three age groups. In women aged 50–59 and 60–69 years, all measurements showed good capabilities for discriminating women with fracture. In women aged 70–79 years, these measurements showed lower capability than in those aged 50–59 and 60–69 years, but among them, the calcaneal and ultradistal radial BMD showed relatively good capability. The 10% and 33% distal radial BMD values were not useful in the detection of the high risk women with fracture. The cutoff BMD values for discrimination of women with fracture varied according to the sites and methods of measurement. For each specific age group, the most suitable measurement methods and the appropriate skeletal sites should be considered, and the effective cutoff values to discriminate those with fracture may differ according to the measurement methods, the skeletal sites examined, and age. Received: 5 February 1996 / Accepted: 18 June 1996     

Dynamic gadolinium-enhanced MRI in the detection of spinal arteriovenous malformations

Arteriovenous fistulae and malformations (AVFs and AVMs) of the spinal cord are rare, potentially treatable causes of progressive disability. Although a variety of MRI abnormalities has been described, the diagnosis rests on the findings on selective spinal angiography.Collecting T2^*-weighted MR images during the passage of a gadolinium bolus gives information about perfusion and blood volume. We carried out dynamic MRI in seven patients with vascular abnormalities (5 dural AVFs, 1 intramedullary AVM, 1 cryptic angioma) and in two patients without an AVM. High resolution T1- and T2-weighted sagittal images of the whole spinal cord were first obtained using a multiarray receiver coil. Sagittal radiofrequency spoilt gradient echo images (GE34/25, flip angle 10⁰) were then obtained during bolus injection of gadolinium-DTPA. Abnormalities were seen in all seven patients with AVFs or AVMs. In the patient with an intramedullary AVM and four of the five with dural AVFs transient signal reduction was seen within the perimedullary venous plexus during passage of the bolus. The findings correlated well with those from selective spinal angiography. We conclude that dynamic MRI offers a useful adjunct to angiography and may localise an arteriovenous shunt when conventional MRI fails to do so. In combination with high-resolution imaging of the entire spinal cord the technique may make myelography redundant; it is simple, well tolerated and can be carried out without significant time penalty.     

Use of gadolinium chelates in MR imaging of the spine

Spinal disease can be divided into intramedullary, extramedullary-intradural, and extradural compartments. In the cord (intramedullary compartment), gadolinium chelates are useful to diagnose primary and metastatic tumors, inflammation, and demyelination, and to evaluate syringomyelia when a Chiari I malformation is not present. In the extra-medulullary-intradural compartment, gadolinium chelates are useful for the diagnosis of drop metastases, meningiomas, and schwannomas. In the extradural compartment, gadolinium chelates are most useful to distinguish recurrent disc herniation from epidural fibrosis in the postoperative back and may be useful to diagnosis the soft tissue component of osseous metastases.     

Scintigraphic visualization of intrathecal liposome biodistribution

Background: Liposomes containing local anaesthetics have been administered intrathecally and in the epidural space. Poor attention has been given to the pharmacokinetics of liposomes as drug carriers. Therefore, we observed the biodistribution of liposomes after intrathecal injection in rats by scintigraphic imaging during 24 h.
Methods: We administered ⁹⁹Tc-labeled multilamellar (MLV) and small unilamellar vesicles (SUV) of defined size and volume dispersities into the cerebrospinal fluid at the lumbar level. Those vesicles were free of contamination by radiolabeled colloids as visualized by light and electron microscopy and of neurotoxic products from phosphatidylcholine hydrolysis and peroxidation, both during the preparation process and after 24 h incubation in cerebrospinal fluid at 37°C in vitro.
Results: SUV immediately diffused from the lumbar site of injection to the head and were cleared between 1 and 24 h after injection. MLV were cleared more slowly from the spinal space and appeared in the head region 1 h after injection where they accumulated up to 24 h. These differences were explained in terms of vesicle sizes and volumes. SUV with 0.05 μm diameters were rapidly absorbed into the blood through the arachnoid granulations. In contrast, particles larger than the upper size limit of the arachnoid granulations permeability (±8 μm) could accumulate in the head with a slow elimination rate.
Conclusion: This difference in clearance from the intrathecal space outlines the importance of defining the size of the liposomes, the distribution of a tracer or a drug inside the liposomal preparation, the chemical stability and the absence of toxic degradation products of liposome formulations before clinical use.     

脊髓萎缩（附2例报告）

本文报告了两例脊髓萎缩，并结合文献复习讨论了该病的好发部位、病因、临床表现、诊断和治疗。脊髓萎缩的病因多为继发性，也可为特发性。根据临床表现结合脊髓ＣＴ造影及ＭＲＩ检查，可以明确诊断。     

节段性不稳定在颈椎病性脊髓病发病中的作用

复习１００例颈椎病性脊髓病患者的临床资料，并以正常成人４９例作为对照，在颈椎侧位及伸、屈位Ｘ线片上测量椎管中矢径、椎体中矢径、功能Ⅰ径、功能Ⅱ径，颈伸位时椎体后滑距离，椎体后缘骨刺。将颈椎管中矢径比值小于０．７５作为发育性椎管狭窄的判断标准，中矢径比值小于０．７５为椎管狭窄组（Ａ组），其余为非狭窄组（Ｂ组），将正常成人组定为Ｃ组。对所测数据进行统计学处理。用ＪＯＡ法对脊髓病患者（Ａ、Ｂ组）的颈脊髓功能做出评估。结果显示：Ａ、Ｂ组中节段性不稳定（ｓｅｇｍｅｎｔａｌｉｎｓｔａｂｉｌｉｔｙ，ＳＩ）发生率明显高于正常人，但不稳定程度（颈椎后滑）无明显差异。脊髓病损程度Ａ组重于Ｂ组，在Ａ组中与滑移程度正相关。Ａ组功能Ⅰ径＜Ⅱ径，Ｂ组功能Ⅰ径＞Ⅱ径，提示节段性不稳定合并发育性椎管狭窄时具有致病作用。颈伸位时椎体后滑使功能Ⅰ径小于１２ｍｍ为脊髓受压的临界标准。     

Bone mineral status in paraplegic patients who do or do not perform standing

Bone mineral density (BMD) was assessed by dual-photon X-ray absorptiometry at the lumbar spine (L3, L4), the proximal femur and the femoral shaft, and by single-photon absorptiometry at the forearm in 53 patients with complete traumatic paraplegia of at least 1 year's duration and in age- and sex-matched healthy controls. The patients did (n=38) or did not (n=15) regularly perform passive weightbearing standing with the aid of a standing device. Compared with the controls, the BMD of paraplegic patients was preserved in the lumbar spine and was markedly decreased in the proximal femur (33%) and the femoral shaft (25%). When considering all patients performing standing, they had a better-preserved BMD at the femoral shaft (p=0.009), but not at the proximal femur, than patients not performing standing. BMD at the lumbar spine (L3,L4) was marginally higher in the standing group (significant only for L3;p=0.040). A subgroup of patients performing standing with use of long leg braces had a significantly higher BMD at the proximal femur than patients using a standing frame or a standing wheelchair (p=0.030). The present results suggest that passive mechanical loading can have a beneficial effect on the preservation of bone mass in osteoporosis found in paraplegics.     

Differential effects of substance P on serotonin-modulated spinal nociceptive reflexes

Recent immunohistochemical studies indicate the presence of a bulbospinal substance P (SP) system, as well as a bulbospinal serotonin (5-HT) system, involved in spinal pain transmission. Although electrophysiological studies indicate that SP may modulate the effects of 5-HT on post-synaptic spinal nociceptive neurons, the functional relationship between SP and 5-HT on “pain behavior” remains obscure. To bridge this gap between mechanism and behavior, the purpose of the present study was to determine specific postsynaptic behavioral effects of SP and 5-HT on local spinal nociceptive reflexes in spinally transected animals. Administration of the 5-HT agonists 5-methoxydi-methyltryptamine (5-MeODMT) (0, 0.5, 1.5, 2.0 mg/kg) and quipazine (0, 5, 10, 20 mg/kg) 2 days after transection significantly expanded the receptive field (RF) areas of three spinal reflexes, as previously reported. Intrathecal administration of SP alone (0, 0.25, 2.5, 7.5 ng) also resulted in hyperalgesia, indicated by a significant expansion of the RF areas of all three nociceptive reflexes. However, administration of SP, in animals pretreated with 5-HT agonists, decreased the 5-HT-induced expansion of RF size. Therefore, SP had opposite effects on spinal nociceptive reflexes depending on whether or not the animal was pretreated with 5-HT agonists, i.e., hyperalgesia in the absence of 5-HT agonists, and analgesia in the presence of 5-HT agonists. The two effects of SP on local spinal reflexes may be related to the anatomical organization of the two spinal SP systems: 1) SP released from primary afferents facilitates nociceptive reflexes, and 2) SP associated with the descending bulbospinal system interacts with the descending bulbospinal 5-HT system and inhibits nociceptive reflexes. The present results help explain contradictory literature regarding the effect of SP on spinal nociceptive reflexes.     

尼卡地平控制性降压对家犬脊髓血流的影响

目的　观察尼卡地平控制性降压对家犬脊髓血流的影响。方法　成年杂种犬 6只 ,体重 12 5～ 16kg ,以 2 5 %硫喷妥钠麻醉。股动脉置管监测MAP。以尼卡地平 8μg·kg 1·min 1持续静脉注射控制性降压。以激光多普勒血流仪测定脊髓血流 (SCBF)。结果　降压前MAP为 (12 5 7±10 6 )mmHg ,降压后为 (72 0± 11 2 )mmHg ,平均下降 4 2 8%。降压前SCBF为 (9 80± 1 0 5 )v ,降压后为 (8 0 4± 0 96 )v ,降低幅度为 18%。结论　尼卡地平控制性降压对SCBF影响较小 ,可安全用于脊髓手术。