Effect of spinal manipulation on the development of history-dependent responsiveness of lumbar paraspinal muscle spindles in the cat

We determined whether spinal manipulation could prevent and/or reverse the decrease and increase in paraspinal muscle spindle responsiveness caused respectively by lengthening and shortening histories of the lumbar muscles. Single unit spindle activity from multifidus and longissimus muscles was recorded in the L₆ dorsal root in anesthetized cats. Muscle history was created and spinal manipulation delivered (thrust amplitude: 1.0mm, duration: 100ms) using a feedback-controlled motor attached to the L₆ spinous process. Muscle spindle discharge to a fixed vertebral position (static test) and to vertebral movement (dynamic test) was evaluated following the lengthening and shortening histories. For the static test, changes in muscle spindle responsiveness were significantly less when spinal manipulation followed muscle history (p<0.01), but not when spinal manipulation preceded it (p>0.05). For the dynamic test, spinal manipulation did not significantly affect the history-induced change in muscle spindle responsiveness. Spinal manipulation may partially reverse the effects of muscle history on muscle spindle signaling of vertebral position.     

Stimulation of chemosensitive afferents from multifidus muscle does not sensitize multifidus muscle spindles to vertebral loads in the lumbar spine of the cat.

STUDY DESIGN: Electrophysiologic recordings from muscle spindle afferents innervating the lumbar multifidus muscle of the cat while loading the L6 vertebra at its spinous process and while exposing the segmentally adjacent lumbar multifidus muscles to algesic and inflammatory mediators. OBJECTIVES: The purpose of this study was to investigate a possible mechanism underlying muscle spasm and pain in the lumbar spine. The hypothesis was tested that stimulation of chemosensitive afferents with receptive endings in the paraspinal muscle increases the discharge of paraspinal muscle spindle afferents during loading of a lumbar vertebra. The presence of such a phenomenon would provide a mechanism by which pain or inflammation could alter segmental lumbar biomechanics and contribute to lumbar spine dysfunction. SUMMARY OF BACKGROUND DATA: Muscle pain, tenderness, and altered muscle tone are often associated with musculoskeletal disorders. The literature suggests that stimulation of Group III and IV muscle afferents sensitive to algesic or inflammatory metabolites increases the stretch sensitivity of muscle spindles via a reflex pathway involving gamma-motoneurons. The reflex increase in muscle spindle activity, in turn, reflexly increases the excitability of alpha-motoneurons leading to enhanced muscle tone and the further accumulation of muscle metabolites and subsequent pain. Studies in the cervical spine support this hypothesis. It has not been investigated in the lumbar spine. METHODS: Single unit activity from muscle spindles in the L6 multifidus muscle were recorded from the cut peripheral end of the L6 dorsal root in alpha-chloralose-anesthetized cats and in decerebrate unanesthetized cats. The L6 vertebra was loaded at its spinous process using a force-feedback motor. Ramp and hold loads were delivered at 25%, 50%, 75%, and 100% body weight. Chemosensitive afferents in the L5 and L7 multifidus muscle were stimulated by bathing (subfascial injection) or infiltrating (intramuscular injection) the L5 and L7 multifidus muscles with bradykinin or capsaicin. RESULTS: Loading the L6 vertebra stimulated muscle spindles in the L6 multifidus muscle. Neither the saline volume control nor bradykinin nor capsaicin injected subfascially or intramuscularly affected the response of L6 multifidus muscle spindles to ramp and hold vertebral loads in the alpha-chloralose-anesthetized cat. In addition, neither saline nor bradykinin nor capsaicin injected intramuscularly affected the activity of L6 multifidus muscle spindles to ramp and hold vertebral loads in the unanesthetized decerebrate cat. CONCLUSIONS: These results indicate that stimulation of small diameter muscle afferents in a deep muscle of the lumbar spine does not sensitize muscle spindles to vertebral loads. These data do not support the hypothesis that fusimotor reflexes evoked by chemosensitive muscle afferents contribute to muscle spasm or to changes in muscle tone in the lumbar spine. In addition, the present results do not provide evidence for the pain-spasm-pain cycle in the lumbar spine.     

Time course for the development of muscle history in lumbar paraspinal muscle spindles arising from changes in vertebral position.

BACKGROUND CONTEXT: In neutral spinal postures with low loading moments, the lumbar spine is not inherently stable. Small compromises in paraspinal muscle activity may affect lumbar spinal biomechanics. Proprioceptive feedback from muscle spindles is considered important for control of muscle activity. Because skeletal muscle and muscle spindles are thixotropic, their length history changes their physical properties. The present study explores a mechanism that can affect the responsiveness of paraspinal muscle spindles in the lumbar spine. PURPOSE: This study has the following two aims: to extend our previous findings demonstrating the history-dependent effects of vertebral position on the responsiveness of lumbar paraspinal muscle spindles and to determine the time course for these effects. Based on previous studies, if a cross-bridge mechanism underlies these thixotropic effects, then the relationship between the magnitude of spindle discharge and the duration of the vertebral position will be one of exponential decay or growth. STUDY DESIGN/SETTING: A neurophysiological study using the lumbar spine in a feline model. METHODS: The discharge from individual muscle spindle afferents innervating lumbar paraspinal muscles in response to the duration and direction of vertebral position was obtained from teased filaments in the L(6) dorsal roots of 30 Nembutal-anesthetized cats. The L(6) vertebra was controlled using a displacement-controlled feedback motor and was held in each of three different conditioning positions for durations of 0, 0.5, 1, 1.5, and 2 seconds. Two of the conditioning positions stretched or shortened the lumbar muscles relative to an intermediate conditioning position. Conditioning positions for all cats ranged from 0.9 to 2.0mm dorsal- and ventralward relative to the intermediate position. These magnitudes were determined based on the displacement that loaded the L(6) vertebra to 50% to 60% of the cat's body weight. Conditioning was thought to simulate a motion segment's position that might be passively maintained because of fixation, external load, a prolonged posture, or structural change. After conditioning positions that stretched (hold-long) and shortened (hold-short) the spindle, the vertebra was repositioned identically and muscle spindle discharge at rest and to movement was compared with having conditioned at the intermediate position. RESULTS: Lumbar vertebral positions maintained for less than 2 seconds were capable of evoking different discharge rates from lumbar paraspinal muscle spindles despite the vertebra having been returned to an identical locations. Both resting spindle discharge and their responsiveness to movement were altered. Conditioning vertebral positions that stretched the spindles decreased spindle activity and positions that unloaded the spindles increased spindle activity on returning the vertebra to its identical original (intermediate) position. The magnitude of these effects increased as conditioning duration increased to 2 seconds. These effects developed with a time course following a first-order exponential reaching a maximal value after approximately 4 seconds of history. The time constant for a hold-short history was 2.6 seconds and for a hold-long history was approximately half of that at 1.1 seconds. CONCLUSIONS: Thixotropic contributions to the responsiveness of muscle spindles in the low back are caused by the rapid, spontaneous formation of stable crossbridges. These sensory alterations because of vertebral history would represent a proprioceptive input not necessarily representative of the current state of intersegmental positioning. As such, they would constitute a source of inaccurate sensory feedback. Examples are presented suggesting ways in which this novel finding may affect spinal physiology.     

Comparison of the effect of 3 different approaches to the lumbar spinal canal on postoperative paraspinal muscle damage

BACKGROUND: To assess the effect of 3 different surgical approaches on paraspinal muscle atrophy in patients undergoing lumbar back surgery, we compared their pre- and postoperative CT scans and their serum Hb, CRP, and CPK levels. METHODS: The study population consisted of 71 patients who had undergone lumbar back surgery with microscopic posterior decompression without fusion. We examined the effect on paraspinal muscle atrophy of 3 different approaches to the spinal canal. Group 1 (n = 19) underwent unilateral paraspinal dissection from the spinous process with cutting of the spinous process. In group 2 (n = 24), we used modified bilateral decompression via hemilaminectomy, and group 3 (n = 28) was treated by modified bilateral decompression via spinous process splitting. We measured the levels of CPK, Hb, and CRP preoperatively and on the first postoperative day, and compared the preoperative volume of the paraspinal muscle with the volume measured 1 year after the operation. RESULTS: Age, sex, operative time, and CRP and Hb levels were not statistically different among the 3 groups. The postoperative elevation of CPK was significantly lower in groups 2 and 3 than in group 1. Group 3 manifested a significantly lower degree of atrophic changes of the paraspinal muscle than groups 1 and 2. CONCLUSIONS: We found that among the 3 approaches evaluated, modified bilateral decompression via spinous process splitting is less invasive, facilitates preservation of the paraspinal muscle, and is a useful approach to posterior spinal elements resulting in decreased muscle damage.     

Spinal reflex excitability changes after cervical and lumbar spinal manipulation: a comparative study.

BACKGROUND CONTEXT: Spinal manipulation (SM) is a commonly employed nonoperative treatment modality in the management of patients with neck, low back or pelvic pain. One basic physiologic response to SM is a transient decrease in motoneuron activity as assessed using the Hoffmann reflex (H-reflex) technique. Previous research from our laboratory indicates that both SM with a high-velocity, low-amplitude thrust and mobilization without thrust produced a profound but transient attenuation of motoneuronal activity of the lumbosacral spine in asymptomatic subjects. To date, effects of cervical SM procedures on the excitability cervical motoneuron pools are unknown. PURPOSE: The objective of this research was to a gain a more complete understanding of the physiologic effects of SM procedures on motoneuron activity, by comparing the effects of regional SM on cervical and lumbar motoneuron pool excitability. STUDY DESIGN/SETTING: Maximal H-reflex amplitudes were recorded before and after SM in both the cervical and lumbar regions of asymptomatic subjects in two successive experimental sessions. PATIENT SAMPLE: Asymptomatic, young healthy volunteers were used in this study. OUTCOME MEASURES: Changes in flexor carpi radialis and gastrocnemius H-reflex amplitudes before and after SM procedures. METHODS: H-reflexes recorded form the tibial and median nerves were evaluated before and after lumbar and cervical SM, respectively. RESULTS: Both Lumbar and cervical SM produced a transient but significant attenuation of motoneuron excitability. The attenuation of the tibial nerve H-reflex amplitude was proportionately greater than that of the median nerve, which occurred after cervical SM. CONCLUSIONS: SM procedures lead to transient suppression of motoneuron excitability, as assessed by the H-reflex technique. Lumbar spine SM appears to lead to greater attenuation of motoneuron activity compared with that of the cervical region. Thus, these two distinct regions of the spine may possess different responsiveness levels to spinal manipulative therapy.     

Muscle spindles in the paraspinal musculature of patients with adolescent idiopathic scoliosis

Electromyographic studies have determined that muscle imbalance and asymmetry of stretch receptors in the paraspinal muscle of patients with idiopathic scoliosis may have a large role to play in the development and production of the deformity. This project consisted of a detailed histologic and histochemical analysis of the distribution of muscle spindles in paraspinal musculature of patients suffering from idiopathic scoliosis, using the reduced form of nicotinamide-adenine dinucleotide (NADH), adenosine triphosphatase (ATPase), and Tri-chrome stain techniques. Muscle biopsy samples were taken at operation for spinal instrumentation from each of 13 patients (mean age: 16.2 years; 3 males, 10 females) with all but one female exhibiting right thoracic curves. The samples were collected from two specific sites (superficial and deep) on both sides of the vertebral column at the level of the apex of the primary curve and two vertebral levels above and below the apex. From the results there appear to be few muscle spindles in the scoliotic muscle of this region. All of the patients from whom muscle samples were taken possessed at least one sample with a muscle spindle. However, each patient had very few samples which contained a minimum of one muscle spindle (mean: 20.3%; SD: 12.6). It is clear that further examination is necessary, particularly in the area of comparison with 'normal' standards when these standards become available.     

Neurophysiological effects of spinal manipulation.

BACKGROUND CONTEXT: Despite clinical evidence for the benefits of spinal manipulation and the apparent wide usage of it, the biological mechanisms underlying the effects of spinal manipulation are not known. Although this does not negate the clinical effects of spinal manipulation, it hinders acceptance by the wider scientific and health-care communities and hinders rational strategies for improving the delivery of spinal manipulation. PURPOSE: The purpose of this review article is to examine the neurophysiological basis for the effects of spinal manipulation. STUDY DESIGN: A review article discussing primarily basic science literature and clinically oriented basic science studies. METHODS: This review article draws primarily from the peer-reviewed literature available on Medline. Several textbook publications and reports are referenced. A theoretical model is presented describing the relationships between spinal manipulation, segmental biomechanics, the nervous system and end-organ physiology. Experimental data for these relationships are presented. RESULTS: Biomechanical changes caused by spinal manipulation are thought to have physiological consequences by means of their effects on the inflow of sensory information to the central nervous system. Muscle spindle afferents and Golgi tendon organ afferents are stimulated by spinal manipulation. Smaller-diameter sensory nerve fibers are likely activated, although this has not been demonstrated directly. Mechanical and chemical changes in the intervertebral foramen caused by a herniated intervertebral disc can affect the dorsal roots and dorsal root ganglia, but it is not known if spinal manipulation directly affects these changes. Individuals with herniated lumbar discs have shown clinical improvement in response to spinal manipulation. The phenomenon of central facilitation is known to increase the receptive field of central neurons, enabling either subthreshold or innocuous stimuli access to central pain pathways. Numerous studies show that spinal manipulation increases pain tolerance or its threshold. One mechanism underlying the effects of spinal manipulation may, therefore, be the manipulation's ability to alter central sensory processing by removing subthreshold mechanical or chemical stimuli from paraspinal tissues. Spinal manipulation is also thought to affect reflex neural outputs to both muscle and visceral organs. Substantial evidence demonstrates that spinal manipulation evokes paraspinal muscle reflexes and alters motoneuron excitability. The effects of spinal manipulation on these somatosomatic reflexes may be quite complex, producing excitatory and inhibitory effects. Whereas substantial information also shows that sensory input, especially noxious input, from paraspinal tissues can reflexively elicit sympathetic nerve activity, knowledge about spinal manipulation's effects on these reflexes and on end-organ function is more limited. CONCLUSIONS: A theoretical framework exists from which hypotheses about the neurophysiological effects of spinal manipulation can be developed. An experimental body of evidence exists indicating that spinal manipulation impacts primary afferent neurons from paraspinal tissues, the motor control system and pain processing. Experimental work in this area is warranted and should be encouraged to help better understand mechanisms underlying the therapeutic scope of spinal manipulation.     

Lumbar spinous process-splitting laminectomy for lumbar canal stenosis. Technical note

In conventional laminectomy for lumbar canal stenosis (LCS), intraoperative damage of posterior supporting structures can lead to irreversible atrophy of paraspinal muscles. In 2001, the authors developed a new procedure for lumbar laminectomy, the lumbar spinous process-splitting laminectomy (LSPSL). In this new procedure, the spinous process is split longitudinally in the middle and then divided at its base from the posterior arch, leaving the bilateral paraspinal muscles attached to the lateral aspects. Ample working space for laminectomy is obtained by retracting the split spinous process laterally together with its attached paraspinal muscles. After successfully decompressing nerve tissues, each half of the split spinous process is reapproximated using a strong suture. Thus, the supra- and interspinous ligaments are preserved, as is the spinous process, and damage to the paraspinal muscles is minimal. Eighteen patients with LCS underwent surgery in which this new technique was used. Twenty patients in whom conventional laminectomy was undertaken were chosen as controls. At 2 years, the clinical outcomes (as determined using the Japanese Orthopaedic Association [JOA] scores and recovery rate) and the rate of measured magnetic resonance imaging-documented paravertebral muscle atrophy were evaluated and compared between the two groups. The mean JOA score recovery rates were 67.6 and 59.2%, respectively, for patients treated with LSPSL and conventional laminectomy; the mean rates of paravertebral muscle atrophy were 5.3 and 23.9%, respectively (p = 0.0005). Preservation of posterior supporting structures and satisfactory recovery rate after 2 years indicated that this technique can be a useful alternative to conventional decompression surgery for lumbar canal stenosis.     

Effect of paraspinal muscle vibration on position sense of the lumbosacral spine.

STUDY DESIGN: A two-group experimental design with repeated measures on one factor was used. OBJECTIVES: To investigate the role of the muscle spindles of the paraspinal muscles in lumbosacral position sense of healthy individuals. SUMMARY OF BACKGROUND DATA: Muscle spindles are recognized to be important mediators for position and movement sense in peripheral joints, and they are very sensitive to mechanical vibration. However, little is known about their role in the control of lumbosacral spine positioning. METHODS: Twenty-five young individuals with no low back pain were assigned at random to an experimental or control group. Proprioceptive information of the multifidus muscle spindles was distorted in half of the trials in 16 individuals by manually applying vibration (70 Hz, 0.5 mm amplitude) for approximately 5 seconds. The control group (n = 9) only heard the vibrator noise during repositioning of the lumbosacral spine. Repositioning accuracy in the sitting position was estimated by calculating the mean absolute error, constant error, and variable error among six criteria and reproduction sacral tilt angles. RESULTS: Multifidus muscle vibration induced a significant muscle lengthening illusion through which the members of the experimental group undershot the target position (F(1,15) = 30.77, P < 0.0001). The position sense scores of the control group displayed no significant differences across trials (F(1,8) = 0.56, P > 0.05). CONCLUSIONS: The findings suggest that precise muscle spindle input of the paraspinal muscles is essential for accurate positioning of the pelvis and lumbosacral spine in a sitting posture.     

The role of paraspinal muscle spindles in lumbosacral position sense in individuals with and without low back pain

STUDY DESIGN: A two-group experimental design with repeated measures on one factor was used. OBJECTIVES: To investigate the role of paraspinal muscle spindles in lumbosacral position sense in individuals with and without low back pain. SUMMARY OF BACKGROUND DATA: Proprioceptive deficits have been identified in patients with low back pain. The underlying mechanisms, however, are not well documented. METHODS: Lumbosacral position sense was determined before, during, and after lumbar paraspinal muscle vibration in 23 young patients with low back pain and in 21 control subjects. Position sense was estimated by calculating the mean absolute error, constant error, and variable error between six criterion and reproduction sacral tilt angles. RESULTS: Repositioning accuracy was significantly lower in the patient group than in healthy individuals (absolute error difference between groups = 2.7 degrees, P < 0.0001). Multifidus muscle vibration induced a significant muscle-lengthening illusion that resulted in an undershooting of the target position in healthy individuals (constant error = -3.1 degrees, P < 0.0001). Conversely, the position sense scores of the patient group did not display an increase in negative directional error but a significant improvement in position sense during muscle vibration (P < 0.05). No significant differences in absolute error were found between the first and last trial in the healthy individuals (P >/= 0.05) and in the patient group (P > 0.05). CONCLUSIONS: Patients with low back pain have a less refined position sense than healthy individuals, possibly because of an altered paraspinal muscle spindle afference and central processing of this sensory input. Furthermore, muscle vibration can be an interesting expedient for improving proprioception and enhancing local muscle control.     

Spinous process-splitting open pedicle screw fusion provides favorable results in patients with low back discomfort and pain compared to conventional open pedicle screw fixation over 1?year after surgery

Introduction  

The conventional open pedicle screw fusion (PSF) requires an extensive detachment of the paraspinal muscle from the posterior aspect of the lumbar spine, which can cause muscle injury and subsequently lead to “approach-related morbidity”. The spinous process-splitting (SPS) approach for decompression, unilateral laminotomy for bilateral decompression, and the Wiltse approach for pedicle screw insertion are considered to be less invasive to the paraspinal musculature. We investigated whether SPS open PSF combined with the abovementioned techniques attenuates the paraspinal muscle damage and yields favorable clinical results, including alleviation in the low back discomfort, in comparison to the conventional open PSF.     

Electromyographic reflex responses to mechanical force, manually assisted spinal manipulative therapy.

STUDY DESIGN: Surface electromyographic reflex responses associated with mechanical force, manually assisted (MFMA) spinal manipulative therapy were analyzed in this prospective clinical investigation of 20 consecutive patients with low back pain. OBJECTIVES: To characterize and determine the magnitude of electromyographic reflex responses in human paraspinal muscles during high loading rate mechanical force, manually assisted spinal manipulative therapy of the thoracolumbar spine and sacroiliac joints. SUMMARY OF BACKGROUND DATA: Spinal manipulative therapy has been investigated for its effectiveness in the treatment of patients with low back pain, but its physiologic mechanisms are not well understood. Noteworthy is the fact that spinal manipulative therapy has been demonstrated to produce consistent reflex responses in the back musculature; however, no study has examined the extent of reflex responses in patients with low back pain. METHODS: Twenty patients (10 male and 10 female, mean age 43.0 years) underwent standard physical examination on presentation to an outpatient chiropractic clinic. After repeated isometric trunk extension strength tests, short duration (<5 msec), localized posteroanterior manipulative thrusts were delivered to the sacroiliac joints, and L5, L4, L2, T12, and T8 spinous processes and transverse processes. Surface, linear-enveloped electromyographic (sEMG) recordings were obtained from electrodes located bilaterally over the L5 and L3 erector spinae musculature. Force-time and sEMG time histories were recorded simultaneously to quantify the association between spinal manipulative therapy mechanical and electromyographic response. A total of 1600 sEMG recordings were analyzed from 20 spinal manipulative therapy treatments, and comparisons were made between segmental level, segmental contact point (spinous vs. transverse processes), and magnitude of the reflex response (peak-peak [p-p] ratio and relative mean sEMG). Positive sEMG responses were defined as >2.5 p-p baseline sEMG output (>3.5% relative mean sEMG output). SEMG threshold was further assessed for correlation of patient self-reported pain and disability. RESULTS: Consistent, but relatively localized, reflex responses occurred in response to the localized, brief duration MFMA thrusts delivered to the thoracolumbar spine and SI joints. The time to peak tension (sEMG magnitude) ranged from 50 to 200 msec, and the reflex response times ranged from 2 to 4 msec, the latter consistent with intraspinal conduction times. Overall, the 20 treatments produced systematic and significantly different L5 and L3 sEMG responses, particularly for thrusts delivered to the lumbosacral spine. Thrusts applied over the transverse processes produced more positive sEMG responses (25.4%) in comparison with thrusts applied over the spinous processes (20.6%). Left side thrusts and right side thrusts over the transverse processes elicited positive contralateral L5 and L3 sEMG responses. When the data were examined across both treatment level and electrode site (L5 or L3, L or R), 95% of patients showed positive sEMG response to MFMA thrusts. Patients with frequent to constant low back pain symptoms tended to have a more marked sEMG response in comparison with patients with occasional to intermittent low back pain. CONCLUSIONS: This is the first study demonstrating neuromuscular reflex responses associated with MFMA spinal manipulative therapy in patients with low back pain. Noteworthy was the finding that such mechanical stimulation of both the paraspinal musculature (transverse processes) and spinous processes produced consistent, generally localized sEMG responses. Identification of neuromuscular characteristics, together with a comprehensive assessment of patient clinical status, may provide for clarification of the significance of spinal manipulative therapy in eliciting putative conservative therapeutic benefits in patients with pain of musculoskeletal origin.     

Spinal reflex attenuation associated with spinal manipulation

STUDY DESIGN: This study evaluated the effect of lumbosacral spinal manipulation with thrust and spinal mobilization without thrust on the excitability of the alpha motoneuronal pool in human subjects without low back pain. OBJECTIVES: To investigate the effect of high velocity, low amplitude thrust, or mobilization without thrust on the excitability of the alpha motoneuron pool, and to elucidate potential mechanisms in which manual procedures may affect back muscle activity. SUMMARY OF BACKGROUND DATA: The physiologic mechanisms of spinal manipulation are largely unknown. It has been proposed that spinal manipulation may reduce back muscle electromyographic activity in patients with low back pain. Although positive outcomes of spinal manipulation intervention for low back pain have been reported in clinical trials, the mechanisms involved in the amelioration of symptoms are unknown. METHODS: In this study, 17 nonpatient human subjects were used to investigate the effect of spinal manipulation and mobilization on the amplitude of the tibial nerve Hoffmann reflex recorded from the gastrocnemius muscle. Reflexes were recorded before and after manual spinal procedures. RESULTS: Both spinal manipulation with thrust and mobilization without thrust significantly attenuated alpha motoneuronal activity, as measured by the amplitude of the gastrocnemius Hoffmann reflex. This suppression of motoneuronal activity was significant (P < 0.05) but transient, with a return to baseline values exhibited 30 seconds after intervention. CONCLUSIONS: Both spinal manipulation with thrust and mobilization without thrust procedures produce a profound but transient attenuation of alpha motoneuronal excitability. These findings substantiate the theory that manual spinal therapy procedures may lead to short-term inhibitory effects on the human motor system.     

Lumbar position sense acuity during an electrical shock stressor

Background  

Optimal motor control of the spine depends on proprioceptive input as a prerequisite for co-ordination and the stability of the spine. Muscle spindles are known to play an important role in proprioception. Animal experiments suggest that an increase in sympathetic outflow can depress muscle spindle sensitivity. As the muscle spindle may be influenced by sympathetic modulation, we hypothesized that a state of high sympathetic activity as during mental stress would affect the proprioceptive output from the muscle spindles in the back muscles leading to alterations in proprioception and position sense acuity. The aim was to investigate the effect of mental stress, in this study the response to an electrical shock stressor, on position sense acuity in the rotational axis of the lumbar spine.     

Osteopathic manipulative treatment techniques preferred by contemporary osteopathic physicians

Data presented in this study were gathered through a national mail survey of 3000 randomly selected osteopathic physicians. A total of 955 questionnaires were usable for analysis. Osteopathic physicians' likelihood of using eleven osteopathic manipulative treatment (OMT) techniques (articulatory, counterstrain, cranial, facilitated positional release, fascial ligamentous release, functional, high-velocity low-amplitude thrust, lymphatic, muscle energy, myofascial/integrated neuromuscular release, and soft tissue) was determined. The relative frequency of use from most (soft tissue) to least (cranial) used was also determined. Respondents were more likely to use direct techniques than indirect or direct-indirect techniques. Demographic variables of gender, age, and specialty training were found to be related to the techniques used most. Female osteopathic physicians and older osteopathic physicians were more likely to use indirect techniques, whereas male and younger physicians preferred direct techniques. Moreover, OMT specialists used a broader range of techniques than other osteopathic physicians, and family physicians were more apt to use high-velocity low-amplitude thrust than other primary care or non-primary care osteopathic physicians. These results not only have implications for curricular planning in all phases of osteopathic undergraduate medical education, graduate medical education, and continuing medical education programs, but also for research on the quality and effectiveness of various OMT techniques.     

基于腰椎间盘退变的脊柱稳定性改变的MRI研究进展

腰椎间盘是位于两个相邻椎体之间的圆盘状纤维软骨,是维持脊柱稳定性的重要解剖结构。目前,维持脊柱稳定性的解剖结构分为被动亚系、主动亚系和神经控制亚系,称为"三亚系模型",腰椎间盘退变(intervertebral disc degeneration,IVDD)会引起该模型其它组织的病理学改变,且彼此相互作用导致脊柱稳定性下降,是下腰痛最常见的原因。IVDD患者常伴有椎小关节及韧带的退变、邻近椎体Modic改变、椎体血流量减少、椎旁肌肉脂肪浸润增加、神经轴向牵拉损伤的代偿性减少等。磁共振成像(magnetic resonance imaging,MRI)是评估脊柱稳定性首选的影像学方法,常规MRI能完整显示IVDD患者三亚系模型相关组织形态学变化,MRI功能成像能定量分析其病理生理学变化的程度。本文综述IVDD患者腰椎间盘、椎小关节、韧带、椎体、肌肉、神经的MRI形态学及定量值变化,阐述IVDD引起脊柱稳定性改变的相关机制,旨在为下腰痛患者的精准诊疗提供更全面的信息。     

青少年特发性脊柱侧弯椎旁肌中肌梭的病理学研究

目的观察青少年特发性脊柱侧弯(AIS)患者椎旁肌中肌梭的变化,以明确其在AIS发生、发展中的作用,为预防及治疗AIS提供理论依据.方法对22例AIS患者及4例尸体对照中椎旁肌中肌梭的数目、密度、分布进行了观察.结果AIS患者中肌梭密度明显低于对照组.肌梭的病变在Cobb角>50°的患者中比较常见.肌梭数同侧弯度数及取材部位无关.结论AIS的病理变化是一个连续的渐进过程,应适早行手术治疗,中断病理力学的恶性循环.     

棘突截骨椎管成形术治疗单纯性腰椎管狭窄症

目的　采用棘突截骨椎管成形术治疗单纯性腰椎管狭窄症 ,并进行临床与影像学评估。方法　手术方法为单侧椎板显露棘突基底截骨 ,将棘突 -韧带 -骶棘肌整体推离对侧椎板。切除椎板上下缘和黄韧带 ,潜式扩大椎管和摘除椎间盘。 35例退行性腰椎管狭窄症患者接受该手术 ,术后进行疗效评分 (Oswestry问卷 )和腰椎管直径测量。结果　术后 1年腰腿痛平均改善78.4% ,术后 4年平均改善 76 .3 % ,术后中期疗效下降不显著 (P >0 .0 5 )。术后CT显示椎管矢径平均增加 19.7% ,横径平均增加 17.5 % ,棘突截骨后原位愈合率为 91%。结论　棘突截骨椎管成形术操作简单 ,神经减压充分 ,手术并发症少 ,腰椎稳定性破坏轻。该术式治疗单纯性腰椎管狭窄症术后近、中期疗效和影像学评估满意     

Spinal manipulation in physical therapist professional degree education: A model for teaching and integration into clinical practice

Spinal manipulation for low back complaints is an intervention supported by randomized clinical trials and its use recommended by clinical practice guidelines. Physical therapists in this country and internationally have used thrust spinal manipulation at much lower-than-expected rates, despite evidence supporting its efficacy for the treatment of acute low back pain (LBP). The purpose of this clinical commentary is to describe a physical therapist professional degree curriculum in thrust spinal manipulation and outline a method of monitoring ongoing student performance during the clinical education experience. Increased emphasis on evidence-based decision making and on the psychomotor skills of thrust spinal manipulation was introduced into a physical therapist professional degree curriculum. As part of ongoing student performance monitoring, physical therapy students on their first full-time (8-week) clinical education experience, collected practice pattern and outcome data on individuals with low back complaints. Eight of 18 first-year students were in outpatient musculoskeletal clinical settings and managed 61 individuals with low back complaints. Patients were seen for an average (+/-SD) of 6.2 +/- 4.0 visits. Upon initial visit the student therapists employed spinal manipulation at a rate of 36.2% and spinal mobilization at 58.6%. At the final visit, utilization of manipulation and mobilization decreased (13% and 37.8%, respectively), while the utilization of exercise interventions increased, with 75% of patients receiving some form of lumbar stabilization training. Physical therapist students used thrust spinal manipulation at rates that are more consistent with clinical practice guidelines and substantially higher then previously reported by practicing physical therapists. Education within an evidence-based framework is thought to contribute to practice behaviors and outcomes that are more consistent with best practice guidelines.     

Effect of isoflurane versus nicardipine on blood flow of lumbar paraspinal muscles during controlled hypotension for spinal surgery

STUDY DESIGN: This study compared the effects of isoflurane and nicardipine on regional blood flow of the lumbar paraspinal muscles. OBJECTIVES: The purpose of this study was to determine whether treatment with hypotensive agents result in ischemia of the lumbar paraspinal muscles, thereby facilitating surgical procedures. SUMMARY OF BACKGROUND DATA: Despite the general acceptance of controlled hypotension as effective in reducing blood loss during spinal surgery, the changes of blood flow that occur at the lumbar paraspinal muscles when this technique is applied remain unclear. The use of laser Doppler flowmetry allows changes of muscle blood flow to be easily detected in real time with minimal invasion, thereby allowing differences among distinct pharmacological approaches for induction and maintenance of controlled hypotension to be evaluated. METHODS: The prehypotensive and hypotensive (reduction of mean arterial pressure by 20 mm Hg) blood flow of the lumbar paraspinal muscles were assessed with a laser Doppler flowmeter in 40 patients undergoing lumbar spinal surgery. The first half of the patients (n = 20) received isoflurane, whereas the second half received nicardipine to achieve arterial hypotension. RESULTS: Compared with the prehypotensive state, during the hypotensive state, patients in the isoflurane group exhibited a 17% to 46% (mean, 33.7%) decrease in lumbar paraspinal muscle blood flow, whereas patients in the nicardipine group exhibited a 24% to 177% (mean, 82.5%) increase in lumbar paraspinal muscle blood flow. Statistical analysis showed a significant difference in the changes of flux after induced hypotension between the isoflurane and nicardipine group (P < 0.001). CONCLUSIONS: Depending on the pharmacological treatment used to achieve arterial hypotension in spine surgery, there will be either a reduction in paraspinal muscle blood flow (ischemia) or an enhancement of this blood flow (hyperemia).