Impact of lumbar pedicle screw positioning on screw stability - A biomechanical investigation

BackgroundScrew loosening is a major complication following spondylodesis. While several modifications increase screw stability, some, such as screw augmentation, are associated with potential complications; new techniques are needed to minimize the risk of screw loosening without increasing complication rates.Methods13 fresh-frozen human lumbar vertebral bodies (L1 to L5) were dissected. In group 1 (n = 7), pedicle screws were implanted conventionally, while in group 2 (n = 6), the screws were positioned divergent in the sagittal pathway. Screw stability was tested under cyclic axial load; one testing-cycle included 1000 repetitions. The first cycle started with a load of 100 N while the load was increased by +20 N in each following cycle until failure. Failure was defined by either a >5 mm movement of the screw heads or triggering of the switch-off threshold.FindingsAverage number of cycles until failure was increased in group 2 compared with group 1 (12,046 vs 9761 cycles), as was the average load to failure (Fmax 313 N vs 260 N). Overall, in group 2, the number of cycles until screw loosening or failure increased by 23% (p = 0.28), while the required force increased by 20% (p = 0.3). Statistically significant correlation between BMD and increased number of cycles completed as well as with increased load (p < 0.01) could be observed.InterpretationThe results demonstrate, that divergent screw-drift of pairs of screws in the sagittal plane tends to increase stability, especially in vertebral bodies with lower bone density. Moreover, we could demonstrate a correlation between BMD and stability of screw-fixation.     

胸椎椎弓根螺钉置入与经胸椎"椎弓根-肋骨间"途径置入的生物力学稳定性

尽管胸椎椎弓根螺钉固定现在已广泛地应用于脊柱外科,但应用在中段胸椎(T4,T7)时的安全性己引起关注.椎弓根根外通道的解剖学研究表明:①在此通道中置入螺钉由于和椎管的距离增加,从而降低了神经组织医源性损伤的风险.②椎弓根根外螺钉固定和标准的经椎弓根螺钉固定在生物力学稳定性方面的差别并不太大.③当胸椎椎弓根螺钉置入失败时,可以用椎弓根根外螺钉固定来补救.④补救后的固定螺钉拉拔力尚缺较精确的测量.     

下颈椎经椎弓根内固定的生物力学稳定性分析

经椎弓根固定是目前能提供三柱生物力学稳定性最可靠的脊柱后路内固定，具有很高的临床应用价值，但颈椎椎弓根毗邻结构复杂，螺钉置入风险很高，限制了其在临床的广泛应用。文章从颈椎椎弓根的形态，生物力学性能，椎弓根螺钉内固定技术和固定系统，手术导航，手术的适应证、禁忌证及并发症等不同研究侧面，总结国内外学者在以上相关领域，有关椎弓根固定在下颈椎疾病治疗方面的应用和进展，认为椎弓根固定虽然有很高风险，但通过术前精确测量椎弓根形态、术中结合各种新辅助技术、配合手感，下颈椎经椎弓根内固定的风险将降低，其在临床应用将越来越广泛。     

伤椎后路椎弓根螺钉置入并椎体内植骨重建胸腰椎椎体的高度

背景:后路短节段经椎弓根内固定器械可使骨折达到近似解剖复位效果,明显提高疗效,但远期随访矫形度数丢失、内固定失败等并发症较普遍.目的:探讨经伤椎椎弓根螺钉置入固定结合经椎弓根植骨治疗胸腰椎骨折的可行性.方法:对73例胸腰椎骨折应用椎弓根钉棒系统后路伤椎一侧椎弓根螺钉置入内固定,对侧经椎弓根通道采用自体骨和同种异体骨行椎体内植骨.结果与结论:73例随访6个月内均获骨性愈合,脊柱植骨融合率100%,无螺钉松动、折断.1例Frankel分级C级无变化,1例D级无变化,其余患者神经功能及腰背痛明显改善;置入后6个月损伤节段后凸平均Cobb角、伤椎椎体前缘高度、椎管前后径残留程度均较治疗前明显恢复.表明经伤椎椎弓根钉置入内固定结合经椎弓根植骨治疗骨折可获得满意复位,重建椎体高度,增强脊柱的抗压稳定性,减少内固定因应力过大造成的断钉、矫正丢失等并发症.     

Biomechanical analysis of the durability of a modified S1 vertebrae transpedicular screws insertion technique

BackgroundOne of the most important elements of the transpedicular screw implantation technique, which enables a strong screw-bone interface, is the precise choice of the site of screw insertion and the screw's trajectory. Due to the complex biomechanics of the lumbosacral interface and different shape of the sacrum, fixation of this segment remains a challenge for surgeons. Because of this, Kubaszewski et al. proposed a modified technique in which the entry point for screw insertion in the S1 vertebra is changed.MethodsSix human cadaver specimens of the S1 vertebrae were examined. Two transpedicular screws were inserted into the body of each examined vertebra using two implantation methods with different screw entry points and trajectories. The screws were subjected to cyclic preloading, followed by the pull-out test. The ultimate pull-out force, displacement, stiffness, and failure energy were measured.FindingsThe average pull-out force obtained for the standard method of implantation was 498 N (SD 201), whereas for the modified technique, it was 1308 N (SD 581). Displacement of the inserted screws in the new method was 36% higher than in the case of the standard method. This method is also characterized by the greater stiffness of the obtained interface and greater failure energy than the normally used technique.InterpretationThe obtained results demonstrate that the use of the new technique of implantation significantly increases the strength of the obtained screw-bone interface. It should also increase the success rate of the performed fixations and increase the safety of such fixations in clinical practice.     

经皮椎弓根螺钉内固定技术治疗胸腰段椎体骨折

目的对比经皮椎弓根螺钉内固定技术与传统后路切开复位椎弓根螺钉内固定治疗胸腰段椎体骨折的临床疗效。方法 40例胸腰段椎体骨折患者,20例采用经皮椎弓根螺钉内固定技术治疗(微创组),20例采用传统后路切开复位椎弓根螺钉内固定治疗(传统组)。比较两组患者的手术切口长度、手术时间、术中出血量、术后引流量、住院时间、术前及术后椎体前缘高度、后凸Cobb角、术前及术后7天、3个月的疼痛视觉模拟评分(VAS)。结果与传统组相比,微创组的手术切口长度明显缩短(P0.01),手术时间明显缩短(P0.05),术中出血量(P0.05)和术后引流量(P0.05)明显减少,住院时间明显缩短(P0.01)。两组患者术前VAS无差异,术后7天及3个月微创组VAS比传统组明显降低(P0.05)、各组内术后7天及3个月VAS均较术前明显降低(P0.05)。两组患者间术前、术后伤椎椎体前缘高度、后凸Cobb角度无显著性差异,各组内术前、术后伤椎椎体前缘高度均有明显恢复(P0.05)、后凸Cobb角度均有明显减小(P0.05)。结论经皮椎弓根螺钉内固定技术治疗胸腰段椎体骨折疗效确切,同时具有微创、住院时间短、术后疼痛轻等优点。     

三种置钉方法在下颈椎经椎弓根螺钉置入过程中的比较

背景：目前各种下颈椎椎弓根置钉方法的准确率报道不一,特别是国内常用的椎板部分切除置钉法、Abumi法、管道疏通法缺乏比较。目的：探讨下颈椎（C3-7）经椎弓根螺钉内固定的可行性,比较椎板部分切除置钉法、Abumi法、管道疏通法在置钉满意率、出血量、置钉时间、并发症等方面的差异。方法：选择60例需颈后路经椎弓根螺钉内固定治疗的下颈椎疾患病例,随机分成3组,各置入椎弓根螺钉80枚,分别采用椎板部分切除置钉法、Abumi法及管道疏通法。术中计算各方法置钉时间、出血量;出院前观察置钉满意率及在颈椎椎弓根四壁损伤例数的构成比;比较C3-7每一节段的椎弓根外侧壁损伤发生率。结果与结论：椎板部分切除组、Abumi组及管道疏通组置钉时间依次递减（P〈0.05）,置钉满意率依次递增（P〈0.05）。3组间置钉出血量及颈椎椎弓根四壁损伤例数的构成比差异无显著性意义（P〉0.05）,椎弓根损伤好发生于外壁。C4、C5节段外壁损伤发生率明显高于C3、C6、C7。提示管道疏通法在经颈后路椎弓根螺钉内固定常规置钉法中优势明显。     

三种置钉方法在下颈椎经椎弓根螺钉置入过程中的比较

背景:目前各种下颈椎椎弓根置钉方法的准确率报道不一,特别是国内常用的椎板部分切除置钉法、Abumi法、管道疏通法缺乏比较。目的:探讨下颈椎(C3~7)经椎弓根螺钉内固定的可行性,比较椎板部分切除置钉法、Abumi法、管道疏通法在置钉满意率、出血量、置钉时间、并发症等方面的差异。方法:选择60例需颈后路经椎弓根螺钉内固定治疗的下颈椎疾患病例,随机分成3组,各置入椎弓根螺钉80枚,分别采用椎板部分切除置钉法、Abumi法及管道疏通法。术中计算各方法置钉时间、出血量;出院前观察置钉满意率及在颈椎椎弓根四壁损伤例数的构成比;比较C3~7每一节段的椎弓根外侧壁损伤发生率。结果与结论:椎板部分切除组、Abumi组及管道疏通组置钉时间依次递减(P<0.05),置钉满意率依次递增(P<0.05)。3组间置钉出血量及颈椎椎弓根四壁损伤例数的构成比差异无显著性意义(P>0.05),椎弓根损伤好发生于外壁。C4、C5节段外壁损伤发生率明显高于C3、C6、C7。提示管道疏通法在经颈后路椎弓根螺钉内固定常规置钉法中优势明显。     

微创经伤椎椎弓根植骨附加伤椎椎弓根螺钉内固定治疗胸腰椎骨折

目的探讨应用微创经伤椎椎弓根植骨附加伤椎椎弓根螺钉内固定治疗胸腰椎骨折的疗效。方法 2006年1月至2010年4月,选择52例胸腰椎骨折患者分为微创经伤椎椎弓根植骨附加伤椎椎弓根螺钉内固定手术组(A组,27例)和传统开放跨伤椎四钉椎弓根钉内固定术+后外侧植骨融合术组(B组,25例)。比较两组围手术期相关指标、影像学指标、VAS疼痛评分等。结果 A组与B组手术时间、手术切口长度、术中出血量、术后引流量、住院日、术后3d伤口疼痛评分均有统计学差异(P<0.05),两组之间术前、术后的矢状面指数、Cobb’s角、椎体前缘高度均无统计学差异(P>0.05)。两组术后的矢状面指数、Cobb’s角、椎体前缘高度与同组术前比较,均有统计学差异(P<0.01)。取内固定后3个月,两组的矢状面指数、Cobb’s角、椎体前缘高度比较均有统计学差异(P<0.01)。A组术后1个月时VAS疼痛评分明显低于B组,术后1个月以后两组无统计学差异。结论微创经伤椎椎弓根植骨附加伤椎椎弓根螺钉内固定治疗胸腰椎骨折,安全、操作简便、疼痛轻、创伤小、恢复快、住院时间短,内固定失败率较低,伤椎高度恢复良好,利于维持后凸畸形的矫正效果。     

影像导航引导腰椎椎弓钉固定的围手术期护理

目的探讨影像导航引导腰椎椎弓钉固定治疗退行性腰椎病变患者的围手术期护理。方法通过总结65例影像导航引导腰椎椎弓钉固定治疗退行性腰椎病变手术患者的护理,介绍影像导航手术的方法、优点及围手术期护理的要点,包括心理护理、术前宣教、术后护理、并发症观察与功能锻炼要点。结果65例退行性腰椎病变患者共植入椎弓钉螺钉260枚,得到的植入物实际影像图与导航虚拟手术路径图重叠,椎弓钉完整在椎弓根内为96%,手术效果优良率93%,无螺钉松动断裂,无硬膜损伤及马尾神经牵拉损伤并发症。结论影像导航引导腰椎椎弓钉固定术是一种更加安全、有效的手术方法,辅助加强患者围手术期的护理和术后功能锻炼,可以极大提高手术的成功率和患者的恢复率。     

椎弓根钉棒系统治疗腰椎骨折32例

目的总结基层医院应用椎弓根钉棒系统治疗腰椎骨折32例的经验。方法采用椎弓根钉棒系统治疗32例腰椎骨折,随访、总结、分析手术疗效。结果32例患者术后随访6～28个月,脊柱生理弯曲、椎体前缘高度恢复理想,疗效满意。结论椎弓根钉棒系统结构简单、操作方便、复位确切、固定可靠,重建了脊柱的生理弯曲、椎体前缘高度恢复理想,是基层治疗腰椎骨折的较理想方法。     

经后路椎弓根钉置入内固定结合硫酸钙椎体成形治疗胸腰椎压缩性骨折的生物力学特征

背景:目前硫酸钙骨水泥用于胸腰椎压缩性骨折的生物力学研究仅限于骨折椎的单个椎体,未对脊柱压缩性骨折经后路椎弓根固定以及骨折椎体硫酸钙骨水泥成形后的脊柱单元进行生物力学分析,如作为一个整体进行分析更符合临床的实际情况.目的:分析经后路椎弓根螺钉置入内固定结合硫酸钙椎体成形术治疗胸腰椎压缩性骨折的生物力学性能.设计、时间及地点:对比观察,于2009-03在上海大学生物力学研究所完成.材料:采集15具新鲜成年小牛胸腰椎标本,制成T_(11)～L_1脊柱功能单位,将标本分成3组,即正常完整标本组、后路复位椎弓根钉固定组及椎弓根钉固定结合硫酸钙椎体成形组.方法:除正常完整标本组外,将其他两组标本制成T_(12)椎体屈曲压缩性骨折模型,分别采用后路复位椎弓根钉固定及后路复位椎弓根钉固定结合硫酸钙椎体成形术.主要观察指标:3组标本在WE-10型万能材料试验机上加载不同级别载荷,在轴向压缩、屈曲、伸展、侧屈4种状态下检测脊柱功能单位的载荷-应变关系、载荷-位移关系、强度、刚度及抗扭等生物力学性能,进行组间比较.结果:胸腰椎载荷-应变及载荷-位移关系呈线性变化,椎弓根钉固定结合硫酸钙椎体成形组的椎体和椎间盘平均应变比后路复位椎弓根钉固定组低14%和12%,比正常完整标本组的低21%和13%.3组标本位移比较,椎弓根钉固定结合硫酸钙椎体成形组位移分别比后路复位椎弓根钉固定组、正常完整标本组减少25%和37%.胸腰椎脊柱功能单位的椎体和椎间盘的强度,椎弓根钉固定结合硫酸钙椎体成形组比后路复位椎弓根钉固定组高14%和24%,比正常完整标本组高13%和20%.胸腰椎刚度方面,椎弓根钉固定结合硫酸钙椎体成形组比后路复位椎弓根钉固定组、正常完整标本组分别高44%和53%.胸腰椎脊柱功能单位最大抗扭强度方面,椎弓根钉固定结合硫酸钙椎体成形组分别比后路复位椎弓根钉固定组、正常完整标本组高18%和30%;扭转刚度方面,椎弓根钉固定结合硫酸钙椎体成形组分别比后路复位椎弓根钉固定组、正常完整标本组高30%和40%.以上数据差异均具有显著性意义(P<0.05).结论:经后路椎弓根螺钉置入内固定结合硫酸钙椎体成形术治疗胸腰椎压缩性骨折的生物力学性能是优越的,不但强度、刚度大,而且术后的胸腰椎体稳定,有利于减轻内植物的应力负荷,进而降低螺钉的松动、折断发生率及术后椎体高度的丢失.     

A biomechanical investigation of the retentive force of pedicle screw structures for different screw tulip designs

BackgroundPedicle screw based spinal fixation systems have been widely used for treating a variety of spinal diseases. The retentive force is an important factor that determines structural stability. The screw tulip design and the magnitude of nut tightening torque influence the retentive force. This study investigated the influences of varied tilt angles between the shaft-rod interface and varied nut tightening torques on the retentive force of the monoaxial, polyaxial, and uniplanar screws.MethodsThree types of tulip constructs were biomechanically tested. Two parameters that affect the retentive force include the tilt angle and the nut tightening torque. The retentive force was investigated by an axial gripping capacity test and axial torque gripping capacity test.FindingAmong all combinations of screw designs and tilt angles, the 12 Nm nut tightening torque offered a greater retentive force than the 8 Nm, except for monoaxial screws with a 0 degree tilt angle. For monoaxial screws, the retentive force was negatively correlated with increasing tilt angles. For polyaxial and uniplanar screws, the retentive forces remained constant with increasing tilt angles.InterpretationIn monoaxial screws, when the axis of the shaft isn't perpendicular to the axis of the rod, a gap is formed between the tulip-rod interface. This results in a decreased retentive force. In polyaxial and uniplanar screws, the contact surfaces were the same in different tilt angles, therefore, the retentive force remained constant, which was attributed to the adjustable tulips always being perpendicular to the axis of the rods.     

伤椎椎弓根置钉植骨治疗胸腰椎骨折的应用现状及进展

背景：经后路伤椎椎弓根置钉植骨的手术方式近年来被广泛运用于治疗胸腰椎骨折,既往对其可行性、有效性、安全性等方面都进行了大量的生物力学和临床研究,但仍然存在较多争议。目的：对经后路伤椎椎弓根置钉植骨治疗胸腰椎骨折的有效性和安全性研究现状及进展作一综述。方法：应用计算机检索维普和Pubmed数据库中1989年1月至2011年9月关于伤椎椎弓根置钉植骨治疗胸腰椎骨折的文章,在标题和摘要中以＂胸腰椎骨折,伤椎,固定,植骨＂或＂thoracolumbar fractures,injured vertebral,fixation,bonegraft＂为检索词进行检索。最终选择33篇文献进行综述。结果与结论：经后路伤椎椎弓根置钉植骨治疗胸腰椎骨折不仅为骨折愈合提供了更为坚稳的内固定,同时有助于骨折复位和后凸畸形的矫正,恢复和维持椎体高度,减少矫正率的丢失。但目前报道的手术疗效以回顾性分析居多,缺乏长期随访、系列的前瞻性分析和循证医学依据,并且对伤椎置钉的适应证、安全性和技术规范还存在较大争议,这些都有待进一步去研究和完善。     

植入椎弓根螺钉内固定胸腰椎骨折患者术后的矫正度丢失：植入体特征与临床技术的关系

目的:分析植入椎弓根螺钉内固定胸腰椎骨折患者术后矫正度丢失的原因及预防措施,指导临床实践。资料来源:应用计算机检索Medline1997-01/2005-07相关文章,检索词“thoracolumbar;pedicle screw;complication”,并限定文章语言种类为English。同时检索万方数据库1994-01/2006-07文献,检索词“胸腰椎;椎弓根螺钉;并发症”,限定文章语言种类为中文,。资料选择:文献纳入标准:①随机对照研究。②前后对照研究。③个案报道。排除标准:重复研究和综述类文献。资料提炼:共收集36篇文献,通过查找全文,重点引用文献30篇,排除6篇为重复研究和综述文献。30篇文献分别对胸腰椎骨折经椎弓根螺钉内固定后矫正度的丢失的原因和预防方法进行了分析。资料综合:预防术后矫正度丢失的措施:①增加椎弓根固定系统的稳定性,可通过增加螺钉的把持力和降低螺钉的应力负荷实现;重建前、中柱的骨缺损,通过经椎弓根椎体内植骨和经椎弓根椎体内注入骨水泥来实现。②正确的术后康复。避免术后过早负重,术后坚持佩戴支具,避免过早取除内固定;伴骨质疏松症者术前术后可采用药物、运动等疗法以改善骨密度。③认识导致术后矫正度丢失的原因。椎体骨缺损未及时修复;相邻间隙的椎间盘退变;内固定存在缺陷;严重椎体骨折;其他如术后过早去除内固定,术后过早负重或未佩带支具,严重骨质疏松。结论:植入椎弓根螺钉内固定后胸腰椎骨折患者矫正度的丢失主要包含伤椎的骨塌陷和相邻间隙的继发性狭窄两个方面。其原因可能是单一因素所致,但多数是多因素所致,预防术后矫正度丢失的主要措施是增加内固定的稳定性和重建伤椎前、中柱的骨缺损以及介入正确的术后康复。     

脱水程度不同的同种异体骨螺钉生物力学实验研究

目的研究不同脱水程度的同种异体骨螺钉生物力学。方法制作120根同种异体骨螺钉，按脱水程度分为A、B、C、D4组，进行生物力学参数测定。结果A组与对照组相比较生物力学参数无差异；B组与对照组相比较生物力学参数存在差异；C组与对照组相比较生物力学参数存在显著性差异。结论冻干8h（含水量5％）的同种异体骨螺钉，生物力学强度良好。     

Posterior pedicle screw fixation combined with transpedicular bone grafting for treatment of single-level thoracolumbar fractures with the aid of a vertebroplasty tool

ObjectiveThis study was performed to assess the efficacy of a novel tool to assist transpedicular bone grafting in short-segment pedicle screw fixation combined with pedicle fixation at the level of the fractured vertebra (six-screw fixation).MethodsWe retrospectively analyzed 80 patients (40 in the control group and 40 in the tool-aided group) with single-level thoracolumbar fractures. Patients in the control group underwent traditional six-screw fixation combined with transpedicular bone grafting. In the tool-aided group, we introduced a novel vertebroplasty tool to assist transpedicular bone grafting. Basic information and related indicators were recorded.ResultsThere were no significant differences in the patients’ baseline characteristics or surgical outcomes between the control group and tool-aided group. Both traditional surgery and tool-aided surgery restored the height of the fractured vertebrae and decreased the Cobb angle, visual analog scale score, and Oswestry Disability Index. However, tool-aided surgery more effectively restored the height of the fractured vertebrae and reduced the visual analog scale score and Oswestry Disability Index than did traditional surgery.ConclusionVertebroplasty tool-aided surgery facilitated more precise and successful grafting of bone into damaged vertebrae than did traditional surgery and therefore might be recommended for treating single-level thoracolumbar fractures.     

Experimental investigation of NIRS spatial sensitivity

Near infrared spectroscopy (NIRS) is regarded as a potential medical diagnostic technique for investigation of hemodynamic changes. However, uncertainties pertaining to the origin of NIRS signals have hampered its clinical interpretation. The uncertainities in NIRS measurements especially in case of living tissues are due to lack of rigorous combined theoretical-experimental studies resulting in clear understanding of the origin of NIRS signals. For their reliable interpretation it is important to understand the relationship between spatial changes in optical properties and corresponding changes in the NIRS signal. We investigated spatial sensitivity of near infrared optical measurements using an experimental approach. It uses a liquid optical phantom as tissue equivalent, which is explored under robot-control by a small, approximately point like perturbation of desired optical properties, and a NIRS instrument for trans-illumination/reflection measurements. The experimentally obtained sensitivity has been analyzed and compared with numerical simulations. In preliminary experiments we investigated the influence of various optical properties of the medium and of source/detector distances on the spatial sensitivity distribution. The acquired sensitivity maps can be used to define characteristic parameters. As an example, we used a 25% threshold to define a penetration depth measure which provides values in good accordance with published ones. To the best of our knowledge this is the first experimental study of NIRS spatial sensitivity. The presented method will allow in depth experimental investigation of the influence of various conditions pertaining to medium such as optical properties of tissue (scattering and absorption) and of the source/detector configuration.     

后外侧植骨椎弓根系统内固定同期病灶清除术治疗胸腰椎结核

目的探讨后外侧植骨椎弓根系统内固定同期病灶清除治疗胸腰椎结核的疗效。方法总结我科行后外侧植骨椎弓根系统内固定同期病灶清除治疗胸腰椎结核患者 48例 ,随访时间 1 5— 5 5年 ,平均 3 6年。内容包括植骨融合率、截瘫恢复情况和后凸畸形矫正状况。结果所有患者均显示骨性融合 ;38例合并截瘫的患者中 ,症状改善 35例 ;术后后凸畸形平均矫正 2 9 1° ,1 5— 5 5年后随访 ,后凸角度平均丢失 3 2°。结论后外侧植骨椎弓根系统内固定同期病灶清除可恢复脊柱的即刻稳定性 ,有利于骨融合 ,促进截瘫恢复和防止截瘫复发 ,矫正及预防后凸畸形     

Experimental investigation of the character of hypnosis

A backward masking paradigm was employed to test die hypothesis that high hypnotic susceptible Ss are able to process information at a faster rate than low susceptible Ss. The critical interstimulus interval was determined for 8 high and 8 low susceptible Ss. A t-test analysis of the critical interstimulus intervals showed a significant difference between high and low susceptible Ss with the high susceptible Ss showing a lower critical interstimulus interval. Mean critical interstimulus intervals for die high (76 milliseconds) and low (98 milliseconds) susceptible groups suggested that the high susceptible Ss were an average of 22 milliseconds faster at processing information. Results were interpreted as being consistent with, and providing support for attentional theories of hypnosis.