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PubMed2005

The RNA binding protein TLS is translocated to dendritic spines by mGluR5 activation and regulates spine morphology.

Neuronal dendrites, together with dendritic spines, exhibit enormously diverse structure. Selective targeting and local translation of mRNAs in dendritic spines have been implicated in synapse remodeling or synaptic plasticity. The mechanism of mRNA transport to the postsynaptic site is a fundamental question in local dendritic translation. TLS (translocated in liposarcoma), previously identified as a component of hnRNP complexes, unexpectedly showed somatodendritic localization in mature hippocampal pyramidal neurons. In the present study, TLS was translocated to dendrites and was recruited to dendrites not only via microtubules but also via actin filaments. In mature hippocampal pyramidal neurons, TLS accumulated in the spines at excitatory postsynapses upon mGluR5 activation, which was accompanied by an increased RNA content in dendrites. Consistent with the in vitro studies, TLS-null hippocampal pyramidal neurons exhibited abnormal spine morphology and lower spine density. Our results indicate that TLS participates in mRNA sorting to the dendritic spines induced by mGluR5 activation and regulates spine morphology to stabilize the synaptic structure.

Actins↗
PubMed2005

Constraining spine stability levels in an optimization model leads to the prediction of trunk muscle cocontraction and improved spine compression force estimates.

A major limitation of optimization models of the spine has been the inability to accurately predict trunk muscle co-activity. Antagonist muscle activity is thought to be necessary to maintain adequate levels of spine stability but, in turn, creates increased loading on the spine. It is thus hypothesized that the CNS attempts to optimize the relationship between spine loading and spine stability in determining muscular activation patterns. This study presents an optimization model of the spine in which stability was constrained to target levels predicted from regression equations of independent loading variables. Objective functions were set to either minimize the sum of the cubed muscle forces or minimize the sum of the squared intervertebral forces at the L4-L5 disc level. Results demonstrate that the inclusion of stability constraints in optimization simulations produced realistic predictions of antagonist muscle activity and predictions of spine compression levels that agree more closely with EMG-based estimates, compared to simulations in which stability was unconstrained. It was concluded that spinal stability is a vital consideration for the CNS when dictating trunk muscle recruitment patterns.

Adult↗
PubMed1997

Mandibular fracture and associated cervical spine fracture, a rare and predictable injury. Protocol for cervical spine evaluation and review of 1382 cases.

OBJECTIVES: To assess the relationship and incidence of cervical spine injuries in patients with mandibular fractures and to recommend an organized approach to cervical spine evaluation in these patients. DESIGN: A retrospective review of medical records of all patients with mandibular fractures at a level I trauma hospital from 1984 through 1993. Patient demographics, injury, mechanism of injury, associated symptoms, physical presentation, and adjuvant radiographic evaluations were recorded. SETTING: Level I, 1000-bed, urban trauma center in Atlanta, Ga. RESULTS: A total of 1382 patients with mandibular fractures were examined during the 10-year period of review. Cervical spine radiographs were obtained on 501 (36.3%) of these patients. From these radiographs, only 8 cervical spine fractures were found. All of the patients with cervical spine injuries (n = 8) had other associated maxillofacial injuries (n = 4), were involved in a motor vehicle accident (n = 7), or sustained gunshot wounds (n = 1). CONCLUSIONS: Judicious use of cervical spine radiographs in the appropriate setting of mandibular trauma is beneficial. However, clinical criteria should dictate rational use of radiographs, since the association between cervical spine injuries and mandibular trauma is rare and predictable.

Adolescent↗
PubMed2001

Bone structure of the distal radius and the calcaneus vs BMD of the spine and proximal femur in the prediction of osteoporotic spine fractures.

The aim of this study was to compare structure measures obtained from high-resolution MR images of the calcaneus and the distal radius with bone mineral density (BMD) of the spine and hip in the prediction of osteoporotic spine fracture status. High-resolution MR images of the calcaneus and radius were obtained in 24 post-menopausal women with spine fractures and 22 age-matched controls. Imaging was performed at 1.5 T using a T1-weighted spin-echo sequence (slice thickness 1 mm, in-plane spatial resolution 195 x 195 microm(2)). Structure analysis was performed using parameters analogous to standard histomorphometry. Bone mineral density of the spine was obtained using quantitative CT and of the hip with dual-energy X-ray absorptiometry. Significant differences between both patient groups were obtained with BMD and all structure parameters ( p<0.05). Using receiver operating characteristic analysis to determine the diagnostic performance in differentiating both groups, the best results were found for BMD of the spine, one of the radial structure measures and a combination of the calcaneal structure measures. In this study BMD of the spine and structure measures of the distal radius were best suited to predict the osteoporotic fracture status of the spine. A combination of BMD and structure measures did not yield any additional information on fracture status.

Absorptiometry, Photon↗
PubMed2004

Temporal dynamics of NMDA receptor-induced changes in spine morphology and AMPA receptor recruitment to spines.

Recent studies have shown that the activation of NMDA receptors can induce rapid changes in dendritic morphology and synaptic recruitment of AMPA receptors in dendritic spines. Here, we analyze the time course of NMDA receptor-induced changes in dendrite morphology and recruitment of AMPA receptors to synapses in cultured neurons. Activation of NMDA receptors causes a rapid transient increase in the size of preexisting spines and then the gradual formation of new dendritic protrusions and spines. NMDA receptor activation also induced GFP-tagged AMPA receptors to cluster in dendrites and to be inserted into the surface of dendritic spines. These results indicate that NMDA receptor activation induces several phases of dendritic plasticity, initial expansion of dendritic spines, followed by the de novo formation of spines and AMPA receptor dendritic clustering and surface expression on spines. Each of these forms of plasticity may have significant effects on the efficacy of synaptic transmission.

Animals↗
PubMed2000

Minimally invasive spine surgery: an animal model for endoscopic approach to the anterior cervical and upper thoracic spine.

BACKGROUND: Minimally invasive video-assisted techniques are currently used for thoracic and lumbar spine surgery with the aim of reducing the morbidity. Recently, an endoscopic approach has been used for endocrine neck surgery, with reduced pain and improved cosmetic results. PURPOSE: To develop an animal model for an endoscopic neck approach to the anterior cervical and upper thoracic spine. METHODS: Five pigs were used. A combination of one 5- and two 3-mm laparoscopic instruments was used to dissect the spine, and dedicated instrumentation was then used to perform discectomies. Carbon dioxide was insufflated at 10 mm Hg. Dissection was carried out upward and downward on the anterior aspect of the spine; discectomy was performed at various levels and evaluated at autopsy. RESULTS: All pigs tolerated the procedure well. Visibility of the cervical spine was excellent, and exposure from C1 to T3 was obtained. For discectomy, an additional 10-mm trocar was inserted, and discectomy of C3-C4 and C4-C5 was performed. Proper location and adequacy were confirmed at autopsy. CONCLUSION: The endoscopic neck approach allows exposure of the entire cervical spine and the upper thoracic spine in the porcine model. This approach has the potential to reduce the morbidity associated with the open cervical approach and provides a wider view and exposure than conventional open surgery. The availability of the porcine model allows the acquisition of the necessary technical skills before introducing this advanced procedure in humans.

Animals↗
PubMed2000

Segmental cervical spine movement with the intubating laryngeal mask during manual in-line stabilization in patients with cervical pathology undergoing cervical spine surgery.

UNLABELLED: We quantified the extent and distribution of segmental cervical movement produced by the intubating laryngeal mask (ILM) during manual in-line stabilization in 20 anesthetized patients with cervical pathology undergoing cervical spine surgery. All patients had neurological symptoms preoperatively. The ILM was inserted with the head and neck in the neutral position. Intubation was facilitated by transillumination of the neck with a lightwand. Cervical movement was recorded with single-frame lateral radiographic images taken 1) immediately before induction (baseline); 2) during ILM insertion (insertion); 3) when transillumination was first seen at the cricothyroid membrane (intubation A); 4) when the tube was being advanced into the trachea (intubation B); and 5) during ILM removal (removal). Radiographic images were digitized and the degree of flexion/extension and posterior movement measured for the occiput (C0) through to C5. During ILM insertion, C0-5 were flexed by an average of 1-1.6 degrees (all P < 0.05). During intubation A/B, C0-4 were flexed by an average of 1.4-3.0 degrees (all P < 0.01), but C5 was unchanged. During ILM removal, C0-3 were flexed by an average of 1 degree (all: P < 0.05), but C3-5 were unchanged. During insertion and intubation A/B, C2-5 were displaced posteriorly by an average of 0.5-1.0 mm (all: P < 0.05). During removal, there was no change at C1-5. Neurological symptoms improved in all patients. We conclude that the ILM produces segmental movement of the cervical spine despite manual in-line stabilization in patients with cervical spine pathology undergoing cervical spine surgery. This motion is in the opposite direction to direct laryngoscopy, suggesting that different approaches to airway management may be more appropriate depending on the nature of the cervical instability. IMPLICATIONS: The intubating laryngeal mask produces segmental movement of the cervical spine, despite manual in-line stabilization in patients with cervical spine pathology undergoing cervical spine surgery. This motion is in the opposite direction to direct laryngoscopy, suggesting that different approaches to airway management may be more appropriate depending on the nature of the cervical instability.

Aged↗
PubMed2004

Spine-board transfer techniques and the unstable cervical spine.

STUDY DESIGN: A repeated-measures design using a cadaveric model was used in this preliminary investigation on the effectiveness of spine-board transfer techniques. OBJECTIVES: To compare the amount of angulation (flexion-extension) motion that results at the cervical spine during the execution of the log-roll maneuver and the lift-and-slide technique; and to examine how changes to the integrity of the cervical spine impacts the amount of motion generated during the transfer process. SUMMARY OF BACKGROUND DATA: Very little research has been performed to establish the efficacy of spine-board transfer techniques. Early studies have indicated that the log-roll maneuver may not be appropriate for transferring victims with thoracolumbar injuries. Also, there has not been a single study that has reported the impact of transfer techniques on the unstable cervical spine. This lack of data necessitated the present study. METHODS: Four groups (with six participants each) were asked to execute the log-roll maneuver and the lift-and-slide technique on five cadavers. An electromagnetic motion analysis device was used to assess the amount of angulation motion generated at the C5-C6 segment during the execution of these transfer techniques. To examine how changes to the integrity of the cervical spine impacts the amount of motion that is produced during the transfer process, flexion-extension motion was assessed under various conditions: across a stable C5-C6 segment, after the creation of a posterior ligamentous injury, and after a complete segmental injury. RESULTS: No significant differences in angulation motion were noted between transfer techniques. However, significant differences were noted between all three injury conditions. That is, as the severity of the injury increased, the average amount of angulation motion produced at the site of the lesion also increased, regardless of technique. CONCLUSION: The participants of this study were able to restrict flexion-extension motion equally well with thelog-roll maneuver as with the lift-and-slide technique. However, more research is needed to fully ascertain the effectiveness of spine-board transfer techniques.

Aged↗
PubMed2004

Hip-spine syndrome: total sagittal alignment of the spine and clinical symptoms in patients with bilateral congenital hip dislocation.

STUDY DESIGN: The influence of the pathologic state of the hip joint on the total sagittal alignment of the spine was investigated in patients with congenital hip dislocation retrospectively OBJECTIVE: The purpose of this study was to analyze the total sagittal alignment of the spine and the clinical symptoms in patients with bilateral congenital hip dislocation. SUMMARY OF BACKGROUND OF DATA: Abnormality in the hip joint causes abnormal curvature of the sagittal alignment of the spine and induces lumbago or lower leg pain. However, there have been no reports on the influence of bilateral congenital hip dislocation on the sagittal alignment of the spine. MATERIALS AND METHODS: A total of 9 patients (8 females and 1 male) were analyzed. Their average age was 57 years (range, 46-68 years). We measured the thoracic kyphosis (T1-T12), the lumbar lordosis (L1-S), the sacral inclination (SI), the femoral flexion angle (FFA), pelvic angulation (PA), and the distances from the pelvic hip axis (HA) to the C7 plumb line and from the promontorium to the C7 plumb line. To evaluate clinical symptoms, we used the Japanese Orthopedic Association (JOA) score of low back pain (full score is 29 points) and Visual Analog Scale (VAS) for lower back pain and lower leg pain, and the possible time of walking without rest. RESULTS: The average thoracic kyphosis, lumbar lordosis, SI, and PA were 42 degrees , -78 degrees , 68 degrees , and 27 degrees , respectively. The FFA averaged 10 degrees , leading to a duck-like posture. The distances from HA and, promontorium to the C7 plumb line averaged -2 cm and 4 cm, respectively. A posterior shift of the gravity line with respects to the hips was compensated for by lumbar hyperlordosis, which led to a posterior shift of the center of the spine. Regarding the clinical symptoms, the JOA score averaged 20 points and the VAS for lower back pain (lumbago) and lower leg pain averaged 6.4 and 3.1, respectively. The average possible walking time without rest was 20 minutes. CONCLUSION: The total sagittal alignment of the spine in patients with bilateral hip dislocation was compensated for by anterior angulation of the pelvis and by lumbar hyperlordosis. The main clinical symptoms were lower back pain, and not lower leg pain.

Aged↗
PubMed2002

[Cervical spine injuries in stable lower cervical spine with spinal stenosis].

The aim of the study was to investigate the neurological outcome of spinal cord injuries in the traumatized cervical spine with a stenosis of the spinal medullary canal. From 1992 to 1999 we treated 145 spinal cord injuries and/or injuries with an unstable cervical spine, 138 were treated operatively, in 7 patients we found an injury of the spinal cord with a stable cervical spine and a stenosis of the spinal medullary canal. The radiological diagnostics consisted of anterioposterior X-rays of the cervical spine, an X-ray view of the dens axis and a stress roentgenogramm in extension and flection. An MRI was performed within the first 12 hours after the accident. The stenosis of the spinal medullary canal was evaluated by the quotient of the mid-sagittal diameter of the spinal medullary canal as well as the vertebral body (Torg-quotient) and ranged from 0.5 to 0.8. Pathological changed values were found in 4 patients within 2 segments and in 3 patients within 3 segments. In the T2-turbospin echo sequence hyperintense lesions of the spinal cord, accordingly to an edema were found in 6 patients. The neurological evaluation was performed according to the "Standard Neurological Classification of Spinal Cord Injuries". Treatment of these 7 patients was performed conservatively, consisting of NSAR as well as Methyl-Prednisolon according to the pattern of NASCIS-II and III. The follow-up was performed after 12 to 18 months. We evaluated the X-rays in anterioposterior and lateral view, stress roentgenogramms and neurological status. Radiological findings showed stable conditions of the cervical spine with block vertebras and increased osteophytes. The neurological outcome was evaluated according to the "Motor-Score" and showed an improvement from 8 to 63 points within 13 months in one case. In 6 cases, the average "Motor-Score" of 78 increased to 100 points within 2 to 5 months after injury. Most defunctionalization symptoms were found in the upper extremities. Disturbances in fine motor movement were unable to be examined with the "Motor-Score". We can conclude that spinal cord injuries in stable cervical spines with stenosis of the spinal medullary canal can be treated conservatively with a good outcome. A regression of the neurological deficiency can be expected within 2 to 5 months, but even after one year, deficiency regression is possible.

Aged↗
PubMed1985

Granule cell dendritic spine density in the rat hippocampus varies with spine shape and location.

The number of granule cell dendritic spines per micrometer of dendritic length in the dorsal and ventral leaves of the dentate gyrus was quantified using light microscopic-Golgi preparations of normal adult rats. Spines were counted in terms of 3 categories of spine form for the 3 afferent termination zones of the molecular layer and corrected for shading errors. Total spine density averaged 1.6 spines/micron of dendritic length in the dorsal leaf and 1.3 spines/micron of dendritic length in the ventral leaf. Statistically significant differences in spine density existed among the 3 shape categories. Variations in spine density occurred by shape category among the afferent termination zones.

Animals↗
PubMed2000

The effect of polytrauma in persons with traumatic spine injury. A prospective database of spine fractures.

STUDY DESIGN: A mixed cross-sectional survey and cohort study using a prospectively gathered database of persons with traumatic spine injury. OBJECTIVES: To identify demographic and injury mechanism factors that predict greater injury severity, and to determine the effect of injury severity on outcomes in traumatic spine fracture. SUMMARY OF BACKGROUND DATA: Traumatic spine fracture outcome studies have focused on defining type and level of vertebral fracture without considering the severity of associated injuries. In the trauma population, greater injury severity has been shown to be related to worse outcome. No studies have been reported on the effect of injury severity on outcome in the traumatic spine fracture population. METHODS: Prospectively collected data on 830 persons with traumatic spine injury who were admitted to a trauma hospital were reviewed. Patient demographics; injury mechanism; hospital events; and disability, employment, and pain status at discharge, 1 year, and 2 years after injury were recorded. Associations between these factors and trauma severity (Injury Severity Score) were explored using Pearson's correlation and analysis of variance. RESULTS: Trauma was more severe in patients who had been married previously, who were involved in a motor vehicle accident, were ejected from the vehicle, had loss of consciousness, had higher-level and multiple complicated vertebral fractures, or had neurologic deficit. Those more severely injured had longer lengths of stay, more surgery, more complications, higher mortality, more disability, and less return to work. CONCLUSIONS: Persons with traumatic spine injury and polytrauma have poorer short- and long-term outcomes. This high-risk group may require aggressive interventions, more hospital resources, and close follow-up observation after discharge from hospital to optimize outcome.

Accidents, Traffic↗
PubMed2002

Lumbar spine bone measurements in infants: whole-body vs lumbar spine dual X-ray absorptiometry scans.

Availability of software delineation of the lumbar spine region from infant whole-body (IWB) dual energy X-ray absorptiometry scan offers an opportunity to gain additional information at the lumbar spine without a separate scan, although the validity of this technique has never been tested. Lumbar spine measurements derived from IWB scans using software-delineated first to fourth lumbar vertebrae, and from specific infant spine (IS) scans, were determined in 111 infants using two pencil-beam densitometers. Intraoperator repeatability determined by reanalysis of 10 pairs of IWB and IS scans from each densitometer. Lumbar spine area, bone mineral content, and bone mineral density from IWB and IS scans were significantly correlated r = 0.68-0.95, p < 0.001 for all comparisons) but show poor agreement (Bland-Altman method) with one SD of the differences equal to 26-55% of the mean. Intraoperator reanalysis shows good agreement with one SD of the differences from IWB scans at <7% of the mean, and <2.9% from IS scans. Findings were the same for both densitometers. We conclude that lumbar spine bone measurements from IWB or IS scans are highly reproducible and significantly correlated but data from IWB scans cannot substitute for data from IS scans.

Absorptiometry, Photon↗
PubMed2004

Biomechanical testing of anterior and posterior thoracolumbar instrumentation in the cadaveric spine. Invited submission from the Joint Section Meeting on Disorders of the Spine and Peripheral Nerves, March 2004.

OBJECT: Thoracolumbar burst fractures frequently require surgical intervention. Although the use of either anterior or posterior instrumentation has advantages and disadvantages, there have been few studies in which these two approaches have been compared biomechanically. METHODS: Ten human cadaveric spines were subjected to subtotal L-3 corpectomy. In five spines placement of L-3 wooden strut grafts with lateral L2-4 dual rod and screw instrumentation was performed. Five other spines underwent L1-5 pedicle screw fixation. The spines were fatigued between steps of the experiment. The spines were load tested with pure moments of 1.5, 3, 4.5, and 6 Nm in the intact state and after placement of instrumentation in six degrees of freedom (flexion, extension, right and left lateral bending, and right and left axial rotation). In axial rotation posterior instrumentation significantly increased spinal rigidity compared with that of the intact state, whereas anterior instrumentation did not. Combined anterior-posterior instrumentation did not significantly increase the rigidity of the spine when compared with anterior or posterior instrumentation alone. Posterior instrumentation alone provided a greater reduction in angular rotation compared with anterior instrumentation alone in all degrees of freedom; however, statistical significance was achieved only in extension at 6 Nm. CONCLUSIONS: The increased rigidity provided by pedicle screw instrumentation compared with the intact state or with anterior instrumentation is due to the longer construct spanning five levels and the three-column engagement of the pedicle screws. The decision to use anterior or posterior instrumentation should be based on the clinical necessity of canal decompression and correction of angulation.

Aged↗
PubMed1999

The porcine cervical spine as a model of the human lumbar spine: an anatomical, geometric, and functional comparison.

Animal models for analysis of spine injury and orthopaedic issues are common given concerns about bone integrity, disc degeneration, and controlled studies of identical specimens matched for age, weight, physical activity and genetic background. Given this asset, the question is asked: "Is the porcine cervical spine a reasonable model of the human lumbar spine?" Three porcine cervical spines (C2-C7) were assessed for geometric characteristics, with a larger cohort (N = 24) loaded to failure under compressive or shear loading. In addition, in vivo loading was estimated and compared between the human low back (biped) and the porcine neck (quadruped). Generally, the porcine vertebrae are smaller in all dimensions. The porcine vertebrae have anterior processes unlike humans; however, they possess similar ligamentous structure and facet joint orientation. Stiffness values (compression and shear) are similar, and comparable injuries resulted from applied compressive and shear loads. Given the scarcity of healthy, young human lumbar spines, porcine cervical spines may be a useful model for studying human lumbar injury because of the similarity of mechanical characteristics and the resulting injuries, particularly of the adolescent or young adult who has not experienced disc degeneration or calcified end-plates.

Adult↗
PubMed2006

Exploring the geometric and mechanical characteristics of the spine musculature to provide rotational stiffness to two spine joints in the neutral posture.

Joint stiffness is inherently linked to both performance and injury. Muscular activation is the predominant provider of stiffness to the lumbar spine, and is essential to ensure optimal spine performance. The purpose of the current paper was to examine the potential of the trunk muscles to provide rotational joint stiffness at two spine joints in the neutral posture, and to demonstrate the sensitivity of this stiffening potential to various muscle orientation and stiffness assumptions. Two separate anatomical models were utilized to analyze the muscular contributions to the 3-dimensional rotational stiffness about each of the L1-L2 and L4-L5 spine joints. Total muscular stiffening potentials, for both joints in each anatomical model, were found to be highest about the global lateral bend axis, and lowest about the global axial twist axis. The stiffening potential was found to depend highly on both the assumed muscle stiffness coefficient (q value) and the moment arm of the muscle about the joint in question. Analyses of spine stiffness were found to be greatly affected by both the anatomical representation of the surrounding musculature and the selection of the q value in the determination of muscular stiffness. Inappropriate choices of either of these factors could lead to errors in stiffness and subsequently stability estimates, and in the interpretation and possible clinical recommendations stemming from such estimates.

Biomechanical Phenomena↗