Intervertebral disc degeneration

Summary Disc degeneration in the human spine is a complex phenomenon characterised by biochemical change in the nucleus pulposus and inner annulus and the formation of clefts and fissures radiating from the central area of the disc towards the periphery. In addition, and probably independent of these phenomena, discrete defects in the outer annular attachement are seen which are likely to be due to mechanical stress and failure. The presence of stress tears in disc tissue and their failure to heal can initiate or accelerate the degeneration of the central component of the intervertebral disc. We postulate that discogenic pain may be linked to damage to the outer portion of the annulus fibrosus. Although it would seem logical to assume that discs with sustained high intradiscal pressure would be more prone to pain referred in the outer annular layers because of higher tensile strain, analysis of prospective studies has failed to confirm a relationship between typical pain reproduction at discography and high pressure values. It is concluded that, at present, the only consistent morphological changes present in patients with pain reproduction at discography are the presence of various annular defects involving the outer layers. Whether nerve ingrowth during attempts at repair of these defects is a consistent feature remains to be established.     

腰椎间盘MRI高信号区的组织病理学特点和临床意义

目的研究椎间盘源性下腰痛患者腰椎间盘纤维环后方MRI高信号区的组织病理学特征及其临床意义。方法对52例经保守治疗无效、CT片显示无腰椎间盘突出的下腰痛患者行腰椎MR检查及腰椎间盘造影术。男39例,女13例;平均年龄38.8岁。选择纤维环后方出现高信号区的部分病例行腰椎后路椎间盘切除、椎体间融合、椎弓根螺钉内固定术,术中收集包括高信号区部位的椎间盘。对标本行矢状面连续组织学切片,光镜下观察高信号区椎间盘组织的组织病理学结构,并分析其临床意义。结果在行腰椎间盘造影的52例142个椎间盘中,17例17个椎间盘显示高信号区,且在椎间盘造影过程中全部呈现2或3级的纤维环破裂和疼痛复制反应。敏感性和特异性均为100%。高信号区与纤维环破裂程度分级呈正相关,说明纤维环破裂程度分级越高,越易出现高信号区(R=0.462,P<0.01)。共收集11例患者11个椎间盘,组织学研究发现对应高信号区的椎间盘组织表现为沿纤维环裂隙形成的不同程度的血管化肉芽组织,有成熟的瘢痕化胶原组织。结论症状性下腰痛患者的腰椎MRI上有椎间盘高信号区,可以作为椎间盘源性下腰痛诊断的重要征象。     

Roentgenographic evaluation of ossification and calcification of the lumbar spinal canal after intradiscal betamethasone injection

There have been reports of lumbar spinal canal ossification and calcification after triamcinolone intradiscal injection therapy. Our objective was to observe the roentgenographic changes after betamethasone intradiscal injection therapy for lumbar disc diseases. The subjects were 183 patients (498 discs; 130 men and 53 women) who underwent discography and betamethasone intradiscal injection therapy and were followed for a mean of 5 years and 7 months. Ossification and calcification appeared de novo (three patients, three discs) or enlarged (four patients, five discs) in the outer layer of the posterior annulus fibrosus or posterior longitudinal ligament in eight discs among seven patients (3.8%). The incidence and degree of ossification and calcification in our patients were significantly lower than those reported in previous studies, and a long time elapsed before ossification and calcification appeared or enlarged. Intradiscal injection of betamethasone did not appear to confer any incremental relative risk for lumbar spinal canal ossification and calcification based on review of follow-up roentgenographs.     

In vitro measurement of pressure differences using manometry at various injection speeds during discography.

BACKGROUND CONTEXT: Lumbar discography has been widely used to evaluate discogenic low back pain. Anecdotal evidence suggests that pain reproduction during discography is more closely correlated with peak dynamic pressure than with static postinjection pressure. Although there can be a significant difference between dynamic and static pressures, to date most discographic evaluations use static pressure recorded postinjection (which is stable and easily measured). The use of readings taken after injection, rather than readings of maximum dynamic peak pressure recorded during injection, appear to increase false positives in lumbar discography. High-speed intradiscal injections also appear to have potentially confounding effects that may increase the rate of false-positive responses during lumbar discography. To date there has been no study for the evaluation of peak dynamic intradiscal pressures or for differentiating dynamic from static pressures in the nucleus pulposus (NP) in response to various speeds of intradiscal injection. PURPOSE: The goal of this study was to obtain additional data on potential confounding factors that could affect discographic results by assessment of pressures within the NP during discography at various injection speeds. The purpose of data collection was to more precisely evaluate pressure differences between dynamic and static pressure within the NP, evident during discography. STUDY DESIGN: In vitro laboratory study. SAMPLES: A total of 82 trials were performed on intervening discs of 82 porcine cadaver lumbar spines. METHODS: Dynamic and static intradiscal pressures were measured with manometry, using two pressure sensors simultaneously during intradiscal injection of contrast media at various speeds. The tip of a 25-gauge needle was placed in the center of the NP and connected with a pressure manometer, which recorded the pressure and therefore the speed of injection. A second pressure reading was obtained using a sensor tip connected to a transducer; the sensor tip was located separately in the same NP tissue. The needle and transducer locations were confirmed by fluoroscopy. OUTCOME MEASURES: At low controlled injection speeds (below 0.08 mL/s), the mean peak pressure difference in the NP was 4.06 (+/-1.52) psi. With high-speed injections of 0.08 mL/s or greater, the mean increased abruptly up to 14.52 (+/-4.11) psi (p<.05). The data indicate that injections applied slowly resulted in smaller differences in pressure within the NP, registered by both manometry and the needle sensor tip. Additional samples were taken using both devices to confirm this threshold level. RESULTS: With low injection speeds, especially those below 0.08 mL/s, differences between dynamic and static pressures on both pressure sensors were minor. These differences increased as injection speed became faster. However, at fast injection speeds of 0.08 mL/s and above, those differences were significantly higher. CONCLUSION: Dynamic and static intradiscal pressures are of similar value when measured by manometer and by needle sensor at slow injection speeds during discography. However, the pressure differences appeared to rapidly increase in response to incremental increases in injection speed. The data from these 82 samples suggest that uncontrolled high speeds of intradiscal injections are a potential confounding factor, which may increase false-positive responses during lumbar discography.     

椎间盘源性下腰痛的发病机制

目的探讨椎间盘源性下腰痛的发病机制。方法收集腰椎后路切除的17例椎间盘源性下腰痛患者的19个经腰椎间盘造影术证实的疼痛腰椎间盘;同时收集12个在MRI T2加权像上信号强度明显减弱、无腰痛症状的生理老化椎间盘和10个正常对照椎间盘,行组织学检查和P物质、神经丝蛋白和血管活性肠肽的免疫组织化学染色检查。结果椎间盘源性下腰痛患者的疼痛椎间盘在组织学上的显著特征表现为,一条从髓核至纤维环外层的血管化肉芽组织条带区,其间伴有1个或多个裂隙;肉芽组织条带区与椎间盘造影术后CT上显示的纤维环裂隙一致,肉芽组织之外的纤维环结构基本正常。生理老化椎间盘和正常对照椎间盘表现为与年龄相关的改变。免疫组织化学染色显示,疼痛椎间盘中P物质、神经丝蛋白和血管活性肠肽3种神经肽阳性神经纤维分布数量和比例,较正常对照椎间盘和生理老化椎间盘明显增多;神经纤维主要沿伴有裂隙的肉芽组织条带区分布;疼痛椎间盘髓核中可见P物质和神经丝蛋白的阳性神经纤维分布。结论椎间盘后方神经分布广泛的肉芽组织条带区是椎间盘造影术疼痛和椎间盘源性下腰痛的起源部位。肉芽组织条带可能起源于椎间盘的创伤修复过程。生理老化椎间盘和疼痛椎间盘的差异是后者形成组织学上的肉芽组织条带区。     

Effects of axial traction stress on solute transport and proteoglycan synthesis in the porcine intervertebral disc in vitro

Summary The effects of axial traction stress on intradiscal hydration, solute transport and proteoglycan synthesis were examined in 658 porcine coccygeal intervertebral discs in vitro. Measurements were performed in three tissue fractions: nucleus pulposus, inner and outer annulus fibrosus. At 0.80 MPa traction stress, the equilibrium hydration did not change in the nucleus pulposus. However, in the inner and outer annulus, the equilibrium hydration was reduced, and the change led to an increase of the effective fixed charge density. Diffusion of solute to the nucleus pulposus was significantly suppressed at 0.80 MPa traction stress. The fluid flow of the intervertebral disc tended to be suppressed during the creep recovery process after compression. The proteoglycan synthesis rate in the outer annulus was markedly suppressed by traction stress of 0.80 MPa for 4 h, but not that in the nucleus pulposus. These results suggest that a prolonged excessive axial traction stress induces a decrease in tissue hydration in the annulus fibrosus, and this may lead to an increase in the fractional volume of solid in the matrix and tissue osmotic pressure, resulting in diffusion inhibition of solute and suppression of proteoglycan synthesis. Thus, prolonged and excessive spinal traction may accelerate disc degeneration.Presented at the annual meeting of the International Society for the Study of the Lumbar Spine, May 12–16, 1991, Heidelberg, Germany     

Experimental disc degeneration due to endplate injury

The aim of this study was to create an experimental model of disc degeneration that closely mimicked human disc degeneration. In six domestic pigs, an L4 cranial endplate perforation into the nucleus pulposus was made. Three months postoperatively, compressive testing was performed on the L2-L4 motion segments, and intradiscal pressure was measured in the intervening discs. Histochemical and morphologic examinations were made on the excised degenerated and adjacent discs. A significant reduction in water content was observed in the outer anterior annulus of the degenerated disc. In the nucleus, the proteoglycan content was significantly reduced, as well as the cellularity, although not significantly. The nucleus lost its gel-like structure and was discolored, and there was delamination of annular layers. Intradiscal pressure in the nucleus was significantly lower in the degenerated disc. In conclusion, experimental degeneration of the intervertebral disc induced by endplate penetration resembled human disc degeneration, as exemplified by biochemical and structural changes.     

The pathogenesis and clinical significance of a high-intensity zone (HIZ) of lumbar intervertebral disc on MR imaging in the patient with discogenic low back pain

Recently, the presence of a high-intensity zone (HIZ) within the posterior annulus seen on T2-weighted MRI has aroused great interest and even controversy among many investigators, particularly on whether the HIZ was closely associated with a concordant pain response on awake discography. The study attempted to interpret the correlation between the presence of the HIZ on MRI and awake discography, as well as its characteristic pathology. Fifty two patients with low back pain without disc herniation underwent MRI and discography successively. Each disc with HIZ was correlated for an association between the presence of a HIZ and the grading of annular disruption and a concordant pain response. Eleven specimens of lumbar intervertebral discs which contain HIZ in the posterior annulus from 11 patients with discogenic low back pain were harvested for histologic examination to interpret the histologic basis of a nociceptive response during posterior lumbar interbody fusion (PLIF). The study found that in all of 142 discograms in 52 patients, 17 presented HIZ. All 17 discs with HIZ showed painful reproduction and abnormal morphology with annular tears extending either well into or through the outer third of the annulus fibrosus. The consecutive sagittal slices through the HIZ lesion showed that a notable histologic feature of the formation of vascularized granulation tissue in the outer region of the annulus fibrosus. The current study suggests that the HIZ of the lumbar disc on MRI in the patient with low back pain could be considered as a reliable marker of painful outer anular disruption.     

The pathogenesis of discogenic low back pain

Discogenic low back pain is a common cause of disability, but its pathogenesis is poorly understood. We collected 19 specimens of lumbar intervertebral discs from 17 patients with discogenic low back pain during posterior lumbar interbody fusion, 12 from physiologically ageing discs and ten from normal control discs. We investigated the histological features and assessed the immunoreactive activity of neurofilament (NF200) and neuropeptides such as substance P (SP) and vasoactive-intestinal peptide (VIP) in the nerve fibres. The distinct histological characteristic of the painful disc was the formation of a zone of vascularised granulation tissue from the nucleus pulposus to the outer part of the annulus fibrosus along the edges of the fissures. SP-, NF- and VIP-immunoreactive nerve fibres in the painful discs were more extensive than in the control discs. Growth of nerves deep into the annulus fibrosus and nucleus pulposus was observed mainly along the zone of granulation tissue in the painful discs. This suggests that the zone of granulation tissue with extensive innervation along the tears in the posterior part of the painful disc may be responsible for causing the pain of discography and of discogenic low back pain.     

Lumbar Intervertebral Disc Herniation Following Experimental Intradiscal Pressure Increase

Summary  An experimental biomechanical model of overload and rupture of the annulus fibrosus (AF) and lumbar disc herniation was achieved by increasing intradiscal pressure while keeping disc height constant in 69 motion segments at the L4–L5 level excised from cadaveric spines. The experiments were made on 53 specimens in neutral posture and on 16 specimens in flexion posture.  The values found for the rupture intradiscal pressure (RIP) ranged from 750 to 1300 kPa for neutral posture and the maximum RIP in anterior flexion was 1177 kPa.  The degree of disc degeneration was assessed by vertebral transcorporeal discography (previous to experiment) and by sectioning the intervertebral disc after the experiment.  The herniated lumbar intervertebral disc model by intradiscal pressure increase makes possible these assertions: –*The correlation between the degree of AF degeneration and the RIP is significant: the maximum RIP corresponds to a nondegenerated AF and the less RIP can tear only a degenerated AF; so disc herniation only occurs to discs with torn AF. –*AF breaking is more often paramedian, left or right. The place of AF breaking was paramedian in 70.3% cases, median in 9.45% cases and posterolateral in 20.25% cases.     

Mechanical analysis of the lumbar vertebrae in a three-dimensional finite element method model in which intradiscal pressure in the nucleus pulposus was used to establish the model

We established a three-dimensional finite element method (FEM) model of the 4th and 5th vertebrae, using computed tomography (CT) images (2-mm slice thickness) of a healthy 29-year-old man. Because of the lack of specific data regarding the material characteristics of the nucleus pulposus of intervertebral discs, we used intradiscal pressure in the nucleus pulposus to establish the model. We referred to data from Nachemson and from Sato et al. regarding intradiscal pressure and to the methods of Shirazi-Adl for data for other material characteristics (see text for these references). The mid-position model bears a load of 294 N in the vertical direction, while the models of the flexed and extended positions bear loads of 15 N-m. In addition, a degenerative disc model without intradiscal pressure was created for the standing model. The use of these models allowed the investigation of von Mises stress on the vertebral endplates and the annulus fibrosus. We also examined von Mises stress on the facet joint in normal and degenerative disc models. There was increased von Mises stress on the vertebral endplate in the anterior, center portions. von Mises stress on the annulus fibrosus increased in the posterior portion, the entrance to the neural foramen, and the exit of the neural foramen. von Mises stress was greater during flexion in the posterior portion; in particular, increasing to about 1.6 times the level seen with other postures. No changes were observed in von Mises stress on the vertebral endplates or annulus fibrosus in the degenerative disc model, but von Mises stress on the facet joints was about 2.5 times that seen in the normal disc model. Received: June 28, 2001 / Accepted: October 27, 2001     

Stress in lumbar intervertebral discs during distraction: a cadaveric study

Background contextThe intervertebral disc is a common source of low back pain (LBP). Prospective studies suggest that treatments that intermittently distract the disc might be beneficial for chronic LBP. Although the potential exists for distraction therapies to affect the disc biomechanically, their effect on intradiscal stress is debated.PurposeTo determine if distraction alone, distraction combined with flexion, or distraction combined with extension can reduce nucleus pulposus pressure and posterior annulus compressive stress in cadaveric lumbar discs compared with simulated standing or lying.Study designLaboratory study using single cadaveric motion segments.Outcome measuresStrain gauge measures of nucleus pulposus pressure and compressive stress in the anterior and posterior annulus fibrosus.MethodsIntradiscal stress profilometry was performed on 15 motion segments during 5 simulated conditions: standing, lying, and 3 distracted conditions. Disc degeneration was graded by inspection from 1 (normal) to 4 (severe degeneration).ResultsAll distraction conditions markedly reduced nucleus pressure compared with either simulated standing or lying. There was no difference between distraction with flexion and distraction with extension in regard to posterior annulus compressive stress. Discs with little or no degeneration appeared to distribute compressive stress differently than those with moderate or severe degeneration.ConclusionsDistraction appears to predictably reduce nucleus pulposus pressure. The effect of distraction therapy on the distribution of compressive stress may be dependent in part on the health of the disc.     

Lovastatin prevents discography-associated degeneration and maintains the functional morphology of intervertebral discs

Background context

Discography is an important diagnostic approach to identify the painful discs. However, the benefit of discography, a procedure involving needle puncture and injection of the diagnostic agent into the intervertebral disc, is controversial and has been reported to be associated with accelerated degeneration.

Purpose

To investigate the effect of lovastatin on the prevention of degeneration caused by a discography simulation procedure in rat caudal discs.

Study design

In vivo study using rat caudal discs.

Methods

A single flexible 27-gauge needle puncture into rat caudal discs was performed under fluoroscopic monitoring. Different concentrations (0.1, 1, 5, and 10 μM) of lovastatin were prepared and injected into randomly chosen caudal discs. RNA expression of selected genes, histologic, and immunohistochemical staining were performed to evaluate the phenotypic effects of lovastatin on rat caudal discs.

Results

Simulation of the discography procedure by puncturing the rat caudal discs with a 27-gauge needle and injection of saline solution induced degenerative changes in the nucleus pulposus with minimal damage to the annulus fibrosus. Aggrecan, Type II collagen, and SOX9 expressions were upregulated, whereas Type I collagen expression was significantly suppressed in discs treated with 5 and 10 μM lovastatin. Discs treated with 5 and 10 μM lovastatin were subjected to alcian blue staining and immunohistochemistry that revealed higher levels of glycosaminoglycans and an increase in the number of cells producing S-100 proteins, Type II collagen, and bone morphogenetic protein-2 (BMP-2), respectively. The most effective phenotypic repair was observed in discs treated with 10 μM lovastatin.

Conclusions

Intradiscal administration of lovastatin solution upregulated the expressions of BMP-2 and SOX9 and promoted chondrogenesis of rat caudal discs after needle puncture and substance injection. Therefore, we suggest that lovastatin promotes disc repair and can be used as a potential therapeutic agent for biological repair of disc degeneration after the diagnostic discography procedure.     

Pathophysiology,diagnosis, and treatment of discogenic low back pain

Discogenic low back pain is a serious medical and social problem, and accounts for 26%-42% of the patients with chronic low back pain. Recent studies found that the pathologic features of discs obtained from the patients with discogenic low back pain were the formation of the zones of vascularized granulation tissue, with extensive innervation in fissures extending from the outer part of the annulus into the nucleus pulposus. Studies suggested that the degeneration of the painful disc might originate from the injury and subsequent repair of annulus fibrosus. Growth factors such as basic fibroblast growth factor, transforming growth factor β1, and connective tissue growth factor, macrophages and mast cells might play a key role in the repair of the injured annulus fibrosus and subsequent disc degeneration. Although there exist controversies about the role of discography as a diagnostic test, provocation discography still is the only available means by which to identify a painful disc. A recent study has classified discogenic low back pain into two types that were annular disruption-induced low back pain and internal endplate disruption-induced low back pain, which have been fully supported by clinical and theoretical bases. Current treatment options for discogenic back pain range from medicinal anti-inflammation strategy to invasive procedures including spine fusion and recently spinal arthroplasty. However, these treatments are limited to relieving symptoms, with no attempt to restore the disc’s structure. Recently, there has been a growing interest in developing strategies that aim to repair or regenerate the degenerated disc biologically.     

Effects of monopolar radiofrequency heating on intradiscal pressure in sheep.

BACKGROUND CONTEXT: No previous study has assessed the effect of monopolar radiofrequency (RF) heating on intradiscal pressure. PURPOSE: To determine the decrease in lumbar intradiscal pressure after monopolar RF heating. STUDY DESIGN/SETTING: Intradiscal pressure was measured in sheep lumbar discs treated with monopolar RF heating. METHODS: Two monopolar RF heat treatments at 90 degrees C were applied for 2 minutes each to lumbar intervertebral discs of sheep. Intradiscal pressure was measured in live sheep at 0, 7, 14, 21, and 28 days posttreatment. Pressure measurements were taken with a microtip pressure transducer. Electrodes were inserted but not activated in separate discs as a sham control. In vitro sheep spine of different age groups, loading conditions, and electrode orientations were similarly heat treated and intradiscal pressures were measured. RESULTS: Intradiscal pressure was significantly reduced 1 week after monopolar RF heating and remained stable through the 4-week observation period. The RF electrode orientation, the age, and the type of disc loading have significant effects on the amount of initial intradiscal pressure reduction. CONCLUSIONS: Monopolar RF heating can reduce intradiscal pressure in the lumbar spine of sheep.     

Comparison of discographic findings in asymptomatic subject discs and the negative discs of chronic LBP patients: can discography distinguish asymptomatic discs among morphologically abnormal discs?

BACKGROUND CONTEXT: Lumbar discography has been widely used for evaluating discogenic low back pain (LBP). Comparison of pain responses from suspected symptomatic discs with pain responses from asymptomatic negative discs is routine. However, the ability of discography to distinguish asymptomatic morphologically abnormal discs from those that are symptomatic has been understudied. In addition, the discographic characteristics of negative discs in patients with chronic discogenic LBP have not been reported. Criteria for negative morphologically abnormal discs may be valuable for excluding discs from further treatment and examination. PURPOSE: To determine if discography can distinguish asymptomatic discs among morphologically abnormal discs in patients with suspected chronic discogenic LBP and establish the standard characteristics of negative discs. STUDY DESIGN/SETTING: Prospective, experimental with control group. PATIENT SAMPLE: Fifty-five discs from a control group of 16 healthy volunteers without current back pain (11 men, 5 women, 32-61 years of age, mean age: 47 years) and 282 discs from a patient group of 90 LBP patients (59 men, 31 women, 20-70 years of age, mean age: 44.7 years) were recruited. METHODS: Discography was performed using a pressure-controlled manometric technique with an injection rate of 0.05 mL/s and a 3.5 mL restricted total volume. Concordance was rated as none/unfamiliar, or familiar. Pain was rated via a 0-10 numerical rating scale (NRS). The pressure and volume at which pain was evoked and NRS pain responses at 15, 30, and 50 psi were recorded. Annular disruption grade was rated during the procedure by computed tomography discography and fluoroscopic imaging. Negative discogram required no pain described by the participant as "familiar," with no pain responses >or=6/10 NRS at pressures 相似文献   

Neuropeptides in the human intervertebral disc

The innervation of the human intervertebral disc was investigated by immunochemical methods. Immunoreactivity to the general nerve marker protein gene product (PGP 9.5) was found in the outer annulus fibrosus of 11 of 12 discs removed during anterior arthrodesis for back pain. PGP 9.5-immunoreactive fibres ran between and across the collagenous lamellae, both in association with blood vessels and distant from them, and extended at least 3 mm into the disc. No innervation was observed in the nucleus pulposus. Fine fibres (< 1 μm in diameter) immunoreactive to calcitonin gene-related peptide and substance P (neuropeptides located in sensory and possibly nociceptive nerves) were identified in eight and four of the annuli fibrosi, respectively. Nerve fibres immunoreactive to vasoactive intestinal peptide and to the c-flanking peptide of neuropeptide Y were found in the majority of specimens of annulus fibrosus that were examined.     

Magnetic resonance discography in cadavers: tears of the annulus fibrosus

The purpose of this study was to investigate the diagnostic capabilities of magnetic resonance discography in the detection of tears of the annulus fibrosus, and to compare the findings with those derived from conventional magnetic resonance imaging. Twenty-four intervertebral discs from cadavers were examined with magnetic resonance imaging and magnetic resonance discography, and anatomic correlation was done. Forty-six annular tears were documented on anatomic inspection of the specimens. Magnetic resonance discography allowed significantly better observation of radial than transverse annular tears, and identification of radial tears was significantly better than that of concentric tears. With magnetic resonance discography, detectability of concentric tears was not significantly better than that of the transverse tears. No significant differences in the detection of different types of annular tears were appreciated on the magnetic resonance images obtained before discography. Magnetic resonance discography allowed direct diagnosis of radial, transverse, and concentric tears in 100%, 57%, and 21% of specimens, respectively. With magnetic resonance imaging, the diagnosis of radial, transverse, and concentric tears was possible in 67%, 71%, and 21% of specimens, respectively. Magnetic resonance discography does well in the evaluation of the clinically important radial tears of the annulus fibrosus, although not uniformly well in the identification of other types of annular tears.     

腰椎间盘MRI高信号区在诊断椎间盘源性下腰痛中的意义

目的:探讨腰椎间盘MRI高信号区(HIZ)在诊断椎间盘源性下腰痛中的作用。方法:对52例经保守治疗无效、CT影像上无腰椎间盘突出的下腰痛患者行腰椎MRI检查和腰椎间盘造影术,分析腰椎间盘MRI高信号区与腰椎间盘造影诱发的下腰痛之间的关系。结果:在行腰椎间盘造影的142个椎间盘中,共有38个椎间盘呈现疼痛复制反应,其中17个椎间盘显示高信号区。这17个有高信号区的椎间盘在椎间盘造影过程中全部呈现2～3级的纤维环破裂和疼痛复制反应。结论:无椎间盘突出的下腰痛患者在腰椎MRI上存在椎间盘内高信号区,可表明该椎间盘是产生腰痛的破裂椎间盘。     

Acute biomechanical and histological effects of intradiscal electrothermal therapy on human lumbar discs

STUDY DESIGN: Human cadaver lumbar spines were used to assess the acute effects of intradiscal electrothermal therapy in vitro. OBJECTIVE: To determine whether intradiscal electrothermal therapy produces acute changes in disc histology and motion segment stability. SUMMARY OF BACKGROUND DATA: Intradiscal electrothermal therapy has been introduced as an alternative for the treatment of discogenic low back pain. Several hypothesized mechanisms for the effect of intradiscal electrothermal therapy have been suggested including shrinkage of the nucleus or sealing of the anulus fibrosus by contraction of collagen fibers, and thermal ablation of sensitive nerve fibers in the outer anulus. METHODS: Intradiscal electrothermal therapy was performed with the Spinecath by Oratec on 19 fresh, frozen human lumbar cadaver specimens. In a separate study, eight specimens were tested biomechanically and instrumented to map the thermal distribution, whereas five specimens were tested only biomechanically, both before and after intradiscal electrothermal therapy. Six additional specimens were heated with intradiscal electrothermal therapy, and the resulting canal was backfilled with a silicone rubber compound to allow colocalization of the catheter and anular architecture. RESULTS: A consistent pattern of increased motion and decreased stiffness was observed. For the specimens in which only biomechanical measurements were taken, a 10% increase in the motion, on the average, at 5 Nm torque was observed after intradiscal electrothermal therapy. No apparent alteration of the anular architecture was observed around the catheter site in the intradiscal electrothermal therapy-treated discs. CONCLUSION: The data from this study suggest that the temperatures developed during intradiscal electrothermal therapy are insufficient to alter collagen architecture or stiffen the treated motion segment acutely.