Thoracic Spinal Segments Research Articles

Treatment of subacute osteoporotic vertebral compression fractures with percutaneous vertebroplasty: A case report

Introduction. Percutaneous vertebroplasty (PVP), as a mini-invasive approach in the treatment of patients with osteoporotic vertebral compression fractures (OVCFs), provides stabilization of the spine and relives pain. The most commonly it is applied in the 3?6 weeks before bending of the spine. Complete cessation of pain is easier to achieve if you treat ?less mature? fractures. The aim of the report is to show that PVP is effective and safe for old fractures too. Case report. A 77-old patient suffered from a stable compression fracture of 3th lumbar (L3) vertebral body after minor trauma. This fracture was clinically and radiologically diagnosed. The conservative treatment that included lumbo-sacral orthosis (LSO), analgesic drugs and physical therapy, was primarily applied due to permanent pain and type of fracture. After a period of two months, pain persisted, but it was localized in a thoracic spinal segment with radiologically diagnosed fractured bodies of 8th (Th8) and 10th (Th10), thoracic vertebra without neurological deficit. Thoraco-lumbo-sacral orthosis (TLSO) was prescribed and after six months the indication for vertebroplasty of the Th8 and Th10 vertebral body was given. The pain relief had been achieved and the patient was discharged from the Clinic for Orthopedics on the postoperative day 2, and was symptom free during the follow-up period. Conclusion. In patients with stable OVCFs, PVP is an effective therapy for reducing pain and improving mobility of 6 months old fractures.

Chronic Unpredictable Mild Stress Causing Cardiac and Thoracic Spinal Cord Electrophysiological Abnormalities May Be Associated with Increased Cardiac Expression of Serotonin and Growth-Associated Protein-43 in Rats.

Background The aim of this study was to investigate the potential mechanisms by which chronic unpredictable mild stress (CMS) might induce cardiovascular disease. Methods Twenty male Sprague-Dawley rats (weighing 180–250 g) were divided into the CMS group (CMS for 3 weeks) and control group (n = 10/group). Sucrose solution consumption, sucrose solution preference rate, and the open field test (horizontal and vertical movements) were used to confirm the establishment of the CMS model. Heart rate was determined in Langendorff-perfused hearts, and field action potential duration (FAPD) was measured in cardiac atrial tissue, cardiac ventricular tissue, and thoracic spinal cord segments 1–5. The expressions of serotonin (5-HT) and growth-associated protein-43 (GAP-43) in cardiac ventricular tissue were analyzed using immunohistochemistry and immunofluorescence. Results Compared with the control group, sucrose solution consumption, sucrose solution preference rate, horizontal movement, and vertical movement were significantly lower in the CMS group (P < 0.01). The CMS group exhibited significant decreases in atrial and ventricular FAPDs (P < 0.05), as well as significant increases in heart rates (P < 0.05) and T1–5 spinal cord FAPD (P < 0.01), as compared with the control group. The expressions of 5-HT and GAP-43 in cardiac ventricular tissue were significantly higher in the CMS group than in controls (P < 0.01). Conclusions CMS causes cardiac and T1–5 spinal cord electrophysiological abnormalities as well as increased cardiac expression of 5-HT and GAP-43, indicating that CMS could potentially increase the risk of cardiovascular disease.

Effect of VEGF on Inflammatory Regulation, Neural Survival, and Functional Improvement in Rats following a Complete Spinal Cord Transection.

After complete transection of the thoracic spinal segment, neonatal rats exhibit spontaneous locomotor recovery of hindlimbs, but this recovery is not found in adult rats after similar injury. The potential mechanism related to the difference in recovery of neonatal and adult rats remains unknown. In this study, 342 animals were analyzed. The vascular endothelial growth factor (VEGF) level in spinal segments below injury sites was significantly higher in postnatal day 1 rats (P1) compared with 28-day-old adult rats (P28) following a complete T9 transection. VEGF administration in P28 rats with T9 transection significantly improved the functional recovery; by contrast, treatment with VEGF receptor inhibitors in P1 rats with T9 transection slowed down the spontaneous functional recovery. Results showed more neurons reduced in the lumbar spinal cord and worse local neural network reorganization below injury sites in P28 rats than those in P1 rats. Transynaptic tracing with pseudorabies virus and double immunofluorescence analysis indicated that VEGF treatment in P28 rats alleviated the reduced number of neurons and improved their network reorganization. VEGF inhibition in neonates resulted in high neuronal death rate and deteriorated network reorganization. In in vivo studies, T9 transection induced less increase in the number of microglia in the spinal cord in P1 animals than P28 animals. VEGF treatment reduced the increase in microglial cells in P28 animals. VEGF administration in cultured spinal motoneurons prevented lipopolysaccharide (LPS)-induced neuronal death and facilitated neurite growth. Western blots of the samples of lumbar spinal cord after spinal transection and cultured spinal motoneurons showed a lower level of Erk1/2 phosphorylation after the injury or LPS induction compared with that in the control. The phosphorylation level increased after VEGF treatment. In conclusion, VEGF is a critical mediator involved in functional recovery after spinal transection and can be considered a potential target for clinical therapy.

Severe focal myelopathy secondary to chronic compression by an arachnoid pseudocyst in a Rottweiler

A four-year old Rottweiler was presented with tetraplegia, established progressively over a 4-month period. Initiallythe dog developed paresis of the posterior limbs that subsequently evolved to tetraparesis and finally tetraplegia. Upon neurological examination the dog exhibited spastic tetraplegia with exaggerated spinal reflexes in all four limbs. The neuroanatomical lesion localization indicated a focal or diffuse cervical spinal cord disease. Cisternal myelography revealed obstruction of the contrast medium flow at the level of C5 vertebral body. Magnetic resonance imaging disclosed intradural-extramedullary compression of the spinal cord at the level of C5-C6 intervertebral disc by a spinal arachnoid pseudocyst, syrinx formation and myelopathy expressed as abnormally higher signal on T2-weighted images at the C5 segment level. Severe demyelination, involving exclusively the white matter of the grossly affected segments and extending rostrally into the brainstem and caudally into the thoracic spinal cord segments, was noticed on histopathology. The unusually severe secondary degenerative change in the cervical spinal cord white matter, inflicted by focal SAP compression, was the most interesting finding.

Relationship between tumor volume and quantitative values calculated using two-dimensional bone scan images

The bone scan index (BSI) is calculated from a whole-body bone scan image; it shows the tumor burden in bone as a percentage of total skeletal mass. It has been used to determine the prognosis and to assess treatment effects; however, little has been reported on whether the BSI calculated using a two-dimensional image can accurately evaluate the three-dimensional spread in tumor volume. We investigated the relationship between tumor volume and BSI using Monte Carlo simulation (MCS). We simulated a gamma camera and constructed a voxel phantom based on an anthropomorphic phantom computed tomography (CT) image and gamma rays emitted from each part according to technetium-99m-labeled methylene diphosphonate (99mTc-MDP) uptake (bone 1, soft tissue 0.2, tumor 2-32). We constructed bone scan images from the obtained counts and analyzed them using the BSI calculation software. The BSI increased with increased tumor uptake (two- to 32-fold). However, there was not always a significant difference between change in BSI and tumor uptake of eight times or greater than that of bone. When BSI was calculated with a tumor having an uptake of four-to-eight times higher than that of bone, the BSI was consistent with tumor volume, but decreased to about half the tumor volume when tumors were in the thoracic spine (Th-spine) segment. The BSI can be a good indicator of tumor volume in most segments, even though it is affected by the tumor's 99mTc-MDP uptake. Nevertheless, values calculated from the Th-spine should be interpreted carefully.

Three-dimensional geometric model of the middle segment of the thoracic spine based on graphical images for finite element analysis

Abstract Introduction: Biomedical studies involve complex anatomical structures, which require specific methodology to generate their geometric models. The middle segment of the thoracic spine (T5-T10) is the site of the highest incidence of vertebral deformity in adolescents. Traditionally, its geometries are derived from computed tomography or magnetic resonance imaging data. However, this approach may restrict certain studies. The study aimed to generate two 3D geometric model of the T5-T10 thoracic spine segment, obtained from graphical images, and to create mesh for finite element studies. Methods A 3D geometric model of T5-T10 was generated using two anatomical images of T6 vertebra (side and top). The geometric model was created in Autodesk® Maya® 3D 2013, and the mesh process in HiperMesh and MeshMixer (v11.0.544 Autodesk). Results The T5-T10 thoracic segment model is presented with its passive components, bones, intervertebral discs and flavum, intertransverse and supraspinous ligaments, in different views, as well as the volumetric mesh. Conclusion The 3D geometric model generated from graphical images is suitable for application in non-patient-specific finite element model studies or, with restrictions, in the use of computed tomography or magnetic resonance imaging. This model may be useful for biomechanical studies related to the middle thoracic spine, the most vulnerable site for vertebral deformations.

In vitro analysis of the segmental flexibility of the thoracic spine.

Basic knowledge about the thoracic spinal flexibility is limited and to the authors’ knowledge, no in vitro studies have examined the flexibility of every thoracic spinal segment under standardized experimental conditions using pure moments. In our in vitro study, 68 human thoracic functional spinal units including the costovertebral joints (at least n = 6 functional spinal units per segment from T1-T2 to T11-T12) were loaded with pure moments of ±7.5 Nm in flexion/extension, lateral bending, and axial rotation in a custom-built spine tester to analyze range of motion (ROM) and neutral zone (NZ). ROM and NZ showed symmetric motion behavior in all loading planes. In each loading direction, the segment T1-T2 exhibited the highest ROM. In flexion/extension, the whole thoracic region, with exception of T1-T2 (14°), had an average ROM between 6° and 8°. In lateral bending, the upper thoracic region (T1-T7) was, with an average ROM between 10° and 12°, more flexible than the lower thoracic region (T7-T12) with an average ROM between 8° and 9°. In axial rotation, the thoracic region offered the highest overall flexibility with an average ROM between 10° and 12° in the upper and middle thoracic spine (T1-T10) and between 7° and 8° in the lower thoracic spine (T10-T12), while a trend of continuous decrease of ROM could be observed in the lower thoracic region (T7-T12). Comparing these ROM values with those in literature, they agree that ROM is lowest in flexion/extension and highest in axial rotation, as well as decreasing in the lower segments in axial rotation. Differences were found in flexion/extension and lateral bending in the lower segments, where, in contrast to the literature, no increase of the ROM from superior to inferior segments was found. The data of this in vitro study could be used for the validation of numerical models and the design of further in vitro studies of the thoracic spine without the rib cage, the verification of animal models, as well as the interpretation of already published human in vitro data.

Autonomic dysreflexia after spinal cord injury: Systemic pathophysiology and methods of management.

Traumatic spinal cord injury (SCI) has widespread physiological effects beyond the disruption of sensory and motor function, notably the loss of normal autonomic and cardiovascular control. Injury at or above the sixth thoracic spinal cord segment segregates critical spinal sympathetic neurons from supraspinal modulation which can result in a syndrome known as autonomic dysreflexia (AD). AD is defined as episodic hypertension and concomitant baroreflex-mediated bradycardia initiated by unmodulated sympathetic reflexes in the decentralized cord. This condition is often triggered by noxious yet unperceived visceral or somatic stimuli below the injury level and if severe enough can require immediate medical attention. Herein, we review the pathophysiological mechanisms germane to the development of AD, including maladaptive plasticity of neural circuits mediating abnormal sympathetic reflexes and hypersensitization of peripheral vasculature that collectively contribute to abnormal hemodynamics after SCI. Further, we discuss the systemic effects of recurrent AD and pharmacological treatments used to manage such episodes. Contemporary research avenues are then presented to better understand the relative contributions of underlying mechanisms and to elucidate the effects of recurring AD on cardiovascular and immune functions for developing more targeted and effective treatments to attenuate the development of this insidious syndrome following high-level SCI.

A biomechanical investigation of different screw head designs for vertebral derotation in scoliosis surgery

Background ContextThe posterior pedicle screw-rod system, which is widely used to correct spinal deformities, achieves a good correction rate in the frontal and coronal planes but not in the axial plane. Direct vertebral derotation (DVD) was developed to correct axial plane deformities. However, the design of screw head and body connection, in terms of monoaxial, polyaxial, and uniplanar screw, may influence the efficiency of DVD. PurposeThis study compared the efficiency of a newly designed uniplanar screw with that of monoaxial and polyaxial screws in the DVD maneuver. Study DesignA porcine spine model and monoaxial, polyaxial, and uniplanar screws were used to examine the biomechanics of the DVD maneuver. MethodsSix T7–T13 porcine thoracic spine segments were used as test specimens in this study. Pedicle screws were inserted in the left pedicles of the T9–T11 spinal segments and then connected with a rod. Three types of pedicle screws with different screw head designs (monoaxial, polyaxial, and uniplanar) were employed in this study. The material testing system (MTS) machine generated a rotational moment through the derotational tube on the T10 (apical body) pedicle screw, which simulated the motion applied during the surgical vertebral derotational procedure. The pedicle strain and the kinematics of the vertebral body and derotational tube were recorded to evaluate the derotational efficiency of different pedicle screw head designs. ResultsThe variances of the derotation for the monoaxial, polyaxial, and uniplanar screws were 2.22°±1.43°, 32.23°±2.26°, and 4.75°±1.60°, respectively; the derotation efficiency was 0.65, 0.51, and 0.12, respectively, when the torques of the spinal constructs reached 3 Nm. The rotational variance of the polyaxial screw was statistically greater than that of the monoaxial and uniplanar screws (p<.05). The maximum micro-strains of the pedicles for the monoaxial, polyaxial, and uniplanar screws were 1,067.45±550.35, 747.68±393.56, and 663.55±271.04, respectively, with no statistically significant differences (p>.05). ConclusionsThe screw head design played an important role in the efficiency and variance of the derotation during the DVD maneuver. The derotational efficiency of the newly designed uniplanar screw was closer to that of the monoaxial screw group than to that of the polyaxial screw group. The polyaxial screw was inferior to DVD owing to a derotational variance between the derotational tube and the apical body that was correlated with the range of motion of the screw head. In the present study, the pedicle strain was similar in all groups. However, the pedicle strain of the uniplanar screw group was lower than that of the monoaxial screw group and was similar to that of the polyaxial screw group when the angle of rotation of the apical body increased.

Experimental study on pressure response to graded spinal canal compromise in an in vitro burst fracture mode.

Background:Spinal cord compression is a known cause of spinal cord injury. The purpose of this study is to measure pressure response during graded spinal cord compression. This information will be important in evaluating the amount of canal compromise that can be tolerated before risking neurological injury secondary to cord compression. To date, there is no published study that has evaluated pressure response to graded canal compromise in the thoracic and lumbar spine.Materials and Methods:A comparative biomechanical investigation using an in vitro burst fracture model of graded spinal canal compromise was performed. Four porcine spines, sectioned into four thoracics and four lumbar segments, were harvested from 30 kg pigs. Graded spinal canal compromise (0.75 mm/30 s) was achieved using a modified 12.7 mm dynamic hip screw. The real-time ventral epidural pressure was measured at each 0.75 mm of canal compromise.Results:A significant increase in spinal cord pressure was recorded during graded spinal cord compression (P < 0.0001), and there were no statistical differences between the increase in pressure measured in the thoracic and lumbar spinal segments (P = 0.83). The pressure to degree of canal compromise curve exhibited an initial rapid rise in pressure followed by incrementally smaller increases in pressure as canal compromise increased.Conclusions:Spinal cord pressure increased with any degree of canal compromise, the most important rise occurring with initial compression. Future studies will evaluate the usefulness of laminectomy in vivo to completely restore ventral epidural pressure in the thoracic and lumbar spine.

Posterior corrective surgery for moderate to severe focal kyphosis in the thoracolumbar spine: 57 cases with minimum 3years follow-up.

To evaluate the radiological and clinical outcomes of the corrective surgery for patients with moderate to severe focal kyphosis in thoracolumbar spine. Fifty-seven patients with moderate to severe focal kyphosis of the thoracolumbar spine underwent apical segmental resection osteotomy with dual axial rotation correction at our hospital. There were 30 male and 27 female patients. The mean age was 34.3years. The kyphosis level radiographs were obtained from each patient before surgery, immediately after surgery and at follow-up. Local kyphosis and scoliosis Cobb angles were measured. Full-spine standing radiographs were obtained before surgery and at follow-up, and the spine sagittal and coronal balance were evaluated. The height of patients, the Frankel grading system for neurological functions, the Oswestry disability index for life quality, the visual analogue score for back pain and the patient satisfactory index for satisfaction to surgery were applied before surgery and at follow-up. The radiological and clinical outcomes were further analyzed in different sub-groups of patients according to etiology, severity of kyphosis, age, level of kyphosis apex, Frankel grade before surgery, and complications. The average follow-up time of patients was 46.1months. The average kyphosis angle reduced from 94.6° before surgery to 31.0° immediately after surgery, and remained at 34.4° at follow-up. The sagittal balance of the spine, height of patients, Frankel grading, Oswestry disability index and visual analogue score were improved. The patient satisfactory index (PSI) showed a satisfied rate of 91.2%. The correction rate was significantly higher in patients with kyphosis angle less than 95° and age less than 35years. The clinical improvement rate was significantly higher in patient with kyphosis apex at lower thoracic spine or thoracolumbar segment, Frankel grade E before surgery and no complication group. The incidence of intra-operative and early stage complications was 38.6%, and the incidence of instrumentation failure was 10.5%. The most severe complication was transient spinal cord injury, and the incidence was 7.0%. All complications got good relief after appropriate intervention. Apical segmental resection osteotomy with dual axial rotation correction is an effective procedure to treat moderate to severe focal kyphosis, the prevention of serious neurological complications is fundamental to achieve the ideal clinical results.

Management of acute spontaneous thoracic spinal epidural hematoma causing paraplegia

Aim To emphasize the importance of early recognition, diagnostic processing and emergent surgical treatment of spontaneous spinal epidural hematoma (SSEH). Methods A 39-year-old female presented with sudden onset of severe pain between the shoulder blades followed by paraparesis and alerted sensibility in the lower extremities. An hour later she developed paraplegia with sensory deficits below ThIV level, absence of patellar reflex, ankle jerk reflex and sphincter dysfunction. Results Magnetic resonance imaging (MRI) demonstrated acute extensive epidural mass of thoracic spinal segments (ThI-ThIII). The patient underwent emergent decompressive laminectomy ThI-ThIII with epidural hematoma evacuation within 24 hours of symptoms onset. After the surgical treatment, because of suspicion on spinal arteriovenous malformation, complete diagnostic evaluation with spinal angiography was done and no form of vascular malformation was found. Idiopathic SSEH was diagnosed. Two months later the patient reached complete neurological improvement. Conclusion The SSEH is a rare condition that should be kept in mind in patients presenting with neurological deficit and a sudden onset of back pain like it was in our case. For early diagnosis, immediate MRI is essential. Prompt surgical decompression such as laminectomy is an absolute surgical indication widely accepted for patients with progressive neurological deficit. The SSEH should be considered as one of the important differential diagnoses in patients who have developed acute myelopathy.

The effect of direction specific thoracic spine manipulation on the cervical spine: a randomized controlled trial

Objectives: To determine the difference on neck outcomes with directional manipulation to the thoracic spine. There is evidence that thoracic spine manipulation is effective in treating patients with neck pain. However, there is no research that determines if the assessment of directional hypomobility and the selection of thrust direction offer improved outcomes. Methods: A total of 69 patients with cervical spine pain were randomly assigned to receive either a manipulation that was consistent with their thoracic spine motion loss (matched) or opposite their motion loss (unmatched). The patient was given care consistent with the orthopedic section guidelines for neck pain and the physical therapist’s clinical reasoning. Baseline outcome measures (NPRS, NDI, GROC) were taken and reassessed two days and two weeks after treatment. Results: Both groups had positive results when pain, neck disability index, and global rating of change were assessed. There was no difference between the matched and unmatched groups. Discussion: Directional manipulation of hypomobile thoracic spine segments may not be required to improved outcomes in patients with neck pain. Future studies should assess a variety of factors when determining the best available treatment, including manual therapy procedures, exercise, and patient selection. Level of Evidence: 1b.

Viral neurotropism, peripheral neuropathy and other morphological abnormalities in bovine ephemeral fever virus-infected downer cattle.

This study assessed the neurotropism of bovine ephemeral fever (BEF) virus (BEFV) and described histomorphological abnormalities of the brain, spinal cord and peripheral nerves that may causally contribute to paresis or paralysis in BEF. Four paralysed and six asymptomatic but virus-infected cattle were monitored, and blood and serum samples screened by qRT-PCR, virus isolation and neutralisation tests. Fresh brain, spinal cord, peripheral nerve and other tissues were qRT-PCR-tested for viral RNA, while formalin-fixed specimens were processed routinely and immunohistochemically evaluated for histomorphological abnormalities and viral antigen distribution, respectively. The neurotropism of BEFV was immunohistochemically confirmed in the brain and peripheral nerves and peripheral neuropathy was demonstrated in three paralysed but not the six aneurological but virus-infected animals. Wallerian degeneration (WD) was present in the ventral funicular white matter of the lumbar spinal cord of a paralysed steer and in cervical and thoracic spinal cord segments of three paralysed animals. Although no spinal cord lesions were seen in the steer euthanased within 7 days of illness, peripheral neuropathy was present and more severe in nerves of the brachial plexuses than in the gluteal or fibular nerves. The only steer with WD in the lumbar spinal cord also showed intrahistiocytic cell viral antigen that was spatially distributed within areas of moderate brain stem encephalitis. The data confirmed neurotropism of BEFV in cattle and documented histomorphological abnormalities in peripheral nerves and brain which, together with spinal cord lesions, may contribute to chronic paralysis in BEFV-infected downer cattle.

Comparison of Maitland Thoracic Spine Manipulation Versus Maitland Cervical Spine Mobilization in Chronic Unilateral C6 – C7 Cervical Radiculopathy

Background: Radicular pains are very common in cervical region due to C6 – C7 nerve root involvement which results discomfort and restriction of mobility of upper and lower segments of cervical and thoracic spine. A lot of evidences about non-operative treatments have been derived for managing cervical radiculopathies with a little documentation of manual therapy. So, in this study, Maitland concept of manipulation and mobilization at two different regions of spine (thoracic and cervical) respectively, was used to see the change in pain reduction and restoration of normal functional abilities.Methodology: A study design of Comparative single blinded, randomized control clinical trials was used. 100 patients having chronic unilateral C6 – C7 cervical radiculopathy’s symptoms due to disc prolapsed, divided into two groups with simple random sampling as guided per-consolidated standards of reporting trials (CONSORT) guidelines were used. First group was managed with Maitland thoracic spine manipulation (MTSM), mechanical intermittent cervical traction (MICT) for 10 minutes and regime of strengthening exercises (SE) and second group was managed with Maitland cervical spine mobilization (MCSM), MICT and SE. The duration of treatment was four weeks at the rate of three times in one week. Two outcome measures numeric pain rating scale (NPRS) and Neck disability index (NDI) questionnaire were used for evaluation and investigation. Data was collected at start, after two and after four Weeks’s treatment. Independent T test with extension of Levene’s test was used with 0.05% level of confidence.Results: The calculated p value for NPRS and NDI for group A (MTSM) was P = 0.000which was less than 0.05 having validation of significant changes. So, we reject our Null hypothesis that MTSM is more effective than MCSM.Conclusion: The result shows that MTSM and MC-SM were effective techniques for pain reduction and functional abilities restoration. However, the subjects of first group with MTSM, MICT and SE presented better progress in reduction of neck ache and refining functional status during comparison.

The Sympathetic Nervous System Mediates Functional and Robust Respiratory Recovery following Acute Cervical Spinal Cord Injury

Introduction The organization of the respiratory network has traditionally been described through descending medullary tracks. The diaphragm is innervated by the phrenic nucleus (C4-C6). However, the intercostal muscles are innervated by the intercostal motor nucleus (T1-T11) located at the thoracic spinal cord segments. Therefore, cervical spinal cord injury (SCI) can typically cause respiratory motor system dysfunction. From the literature, ventilation failure within the human lower cervical SCI population typically occurs 4.5 ± 1.2 days after injury, affecting 26.6% of patients. Also, the risk of apnea following low cervical SCI is increased during sleep. However, while intercostal muscles contribute to respiratory recovery post injury the pathways mediating this effect have never been fully elucidated. Methods Following complete C7 spinal cord transection in rats, we demonstrated the presence of intercostal-EMG activity synchronized to the inspiratory bursts of the diaphragm. We explored the anatomical, and latent, pathway that enables synchronized activation of the intercostal muscles after complete cord transection. Experimental work, in the form of bilateral dorsal/ventral rhizotomies, unilateral transection of the phrenic nerve and sympathetic chain ganglia and systemic application of salubutamol, suggested that intercostal activities is mediated through the sympathetic chain ganglion by means of connection to the ipsilateral phrenic nerve. Results In anesitised and unventilated rats, rhythmic inspiratory activity was present in the intercostal muscles following acute C7 transection and bilateral dorsal/ventral rhizotomies. This activity persisted up to five days following the initial trauma. Unilateral transection of the phrenic nerve and sympathetic chain ganglia eliminated ipsilateral intercostal motor activity. Systemic application of salubutamol (β2-agonist), not only increase intercostal activity but also restored it in transected rats which had not retained this activity following transection. Conclusions These data provide the first evidence of sympathetic nerve activity mediating synchronized and robust intercostal inspiratory muscle activity following severe, lower cervical transection. This activity occurs up to 5 days following trauma, an effect which correlates with the induction of ventilation failure and respiratory dysfunction in human patients with SCI. The clinical implications of this finding are provocative. 60% of patients undergo some degree of respiratory distress following acute C5–8 injuries. Using this pathway, it may be possible to modestly stimulate or activate sympathetic activity to further aid intercostal muscle activity and respiratory function following acute SCI. This thus represents a novel target for the treatment of respiratory dysfunction following spinal trauma. [Figure: see text]

AVALIAÇÃO DO DISCO INTERVERTEBRAL DE RATOS WISTAR APÓS USO DE EXPERIMENTAL SUIT THERAPY

Objetivos: visto que a sobrecarga ou pressão inadequada sobre as estruturas do disco intervertebral podem causar degeneração discal, este estudo teve como objetivo, avaliar um modelo experimental da suit therapy sobre os discos intervertebrais do segmento torácico da coluna, avaliando a altura na sua porção anterior, medial e posterior, como também da altura do núcleo pulposo. Métodos: 30 ratos Wistar, foram separados em 5 grupos (G1 – controle; G2 – simulação do uso da suit; G3 – 2 horas com a suit; G4 –2 horas com peso adaptado; G5 – 2 horas com a vestimenta e bandas de tração). Foi confeccionado um modelo experimental da vestimenta, tipo macacão terapêutico. O experimento teve duração de 4 semanas, com a colocação da vestimenta em 5 dias consecutivos, com pausa de 2 dias. Ao final o segmento torácico da coluna vertebral foi dissecado na região do cruzamento das bandas elásticas, entre T7 e T10. Os segmentos foram fixados em formol, clivados longitudinalmente, no plano mediano, tendo como base os processos espinhosos, seccionados em espessura de 7 μm, e corados em Hematoxilina Eosina (HE). As imagens foram obtidas por fotomicrografia e analisadas as alturas nas regiões anterior, média e posterior do disco, e ainda, a altura do núcleo pulposo. Resultados: não houve diferença significativa, na mensuração das alturas avaliadas. Conclusão: Conforme o protocolo, de compressão do disco, apresentado não houve alterações morfométricas do disco intervertebral torácico de ratos Wistar.

Accuracy of finite element analyses of CT scans in predictions of vertebral failure patterns under axial compression and anterior flexion

Finite element (FE) models built from quantitative computed tomography (QCT) scans can provide patient-specific estimates of bone strength and fracture risk in the spine. While prior studies demonstrate accurate QCT-based FE predictions of vertebral stiffness and strength, the accuracy of the predicted failure patterns, i.e., the locations where failure occurs within the vertebra and the way in which the vertebra deforms as failure progresses, is less clear. This study used digital volume correlation (DVC) analyses of time-lapse micro-computed tomography (μCT) images acquired during mechanical testing (compression and anterior flexion) of thoracic spine segments (T7–T9, n=28) to measure displacements occurring throughout the T8 vertebral body at the ultimate point. These displacements were compared to those simulated by QCT-based FE analyses of T8. We hypothesized that the FE predictions would be more accurate when the boundary conditions are based on measurements of pressure distributions within intervertebral discs of similar level of disc degeneration vs. boundary conditions representing rigid platens. The FE simulations captured some of the general, qualitative features of the failure patterns; however, displacement errors ranged 12–279%. Contrary to our hypothesis, no differences in displacement errors were found when using boundary conditions representing measurements of disc pressure vs. rigid platens. The smallest displacement errors were obtained using boundary conditions that were measured directly by DVC at the T8 endplates. These findings indicate that further work is needed to develop methods of identifying physiological loading conditions for the vertebral body, for the purpose of achieving robust, patient-specific FE analyses of failure mechanisms.

Cervical Sagittal Alignment in Scheuermann Disease.

Retrospective evaluation of radiographs. The aim of this study was to assess sagittal cervical balance in patients with the two types Scheuermann disease (SD). The structural hyperkyphosis characterizing SD may be localized in the thoracic (SDT) or thoraco-lumbar (SDTL) spine segments. This may affect sagittal cervical balance. Seventy-one patients (41 males and 30 females), aged 16.3 ± 3.8 years with SD, were enrolled into the study. On standing lateral long-cassette radiographs, the following measurements were made: C0-2 angle, C2-7 angle (CL), C1-C2 angle, relative rotation angle (RRA)-measured at levels from C2 to C7, cervical tilt (CT), thoracic inlet angle (TIA), T1 slope, neck tilt (NT), C0-angle, cranial offset (CO), and cranial tilt (CRT). Comparison with t test was performed with significance level P < 0.05. There were 38 SDT and 33 SDTL patients. In SDT, the T1 slope was significantly greater than that in SDTL (38.1° vs. 28.9°; P = 0.0002), and consequently CL (-19.8° vs. -8.9°; P = 0.0160), CT (29.8° vs. 24.3°; P = 0.0190), and TIA (81.9° vs. 71.1°; P = 0.0022) in SDT were significantly greater as well. The difference in CL was expressed mainly in C6-C5 (-4.8° vs. -1.4°; P = 0.0146) and C5-C4 (-4.4°; vs. -1.5° P = 0.0464) segments. There were no significant differences in proximal cervical lordosis: C0-2 angle (-21.6° vs. -20.8°; P = 0.7597), C1-C2 angle (-30.8°vs. -27.5°; P = 0.1746), C3-C2 (-5.4° vs. -5.1°; P = 0.7976), and C4-C3 (3.5° vs. -1.5°; P = 0.1464) segments. There was no significant difference in cranial parameters C0-angle, CRT, and CO. Scheuermann disease type has an influence on cervical sagittal balance. Localization of structural kyphosis affects the T1 slope as well as C2-C7 lordosis, cervical tilt, and thoracic inlet angle. Significant difference in C2-C7 lordosis in comparison to similar C0-2 lordosis demonstrates that compensation is present in subaxial cervical spine. Position of the head center of gravity is not dependent on the SD type. 4.

Range of Motion in Segmental Versus Nonsegmental Ultrahigh Molecular Weight Polyethylene Sublaminar Wire Growth Guidance Type Constructs for Early-Onset Scoliosis Correction.

An in vitro biomechanical study in porcine thoracic spine segments comparing range of motion (ROM) in segmental versus multiple nonsegmental ultrahigh molecular weight polyethylene (UHMWPE) sublaminar wire constructs. To determine the effect of varying instrumentation (wire) density in an UHMWPE sublaminar wire construct for patients with early-onset scoliosis (EOS) to find an optimal wire density, which allows maximum growth whereas still providing adequate correction and fixation. UHMWPE sublaminar wires in a segmental construct did not negatively affect longitudinal spinal growth during a 24-week period in an ovine model; application in growth guidance system for EOS may therefore be feasible. To avoid ectopic bone formation as much as possible, a reduction of instrumented levels, without affecting spinal stabilization, is desirable. ROM of 9 porcine thoracic spines (T6-T14) was determined in flexion/extension (FE), lateral bending (LB), and axial rotation up to ± 4 Nm. Tests were performed for the uninstrumented spine in a segmental construct with UHMWPE sublaminar wires and dual pedicle screws at the most caudal level, and in four nonsegmental constructs that were attained by stepwise removal of the most caudal wire. Segmental instrumentation led to a decrease in total ROM by approximately 70% for both FE and LB. A stepwise increase in ROM with decreasing number of consecutively instrumented levels was most clearly observed in LB. However, consistent significant but also relevant substantial differences in ROM for both FE and LB were noted only when comparing two and one consecutively instrumented end levels (P < 0.05). A construct with two consecutive end levels instrumented with UHMWPE sublaminar wires seems to provide the best balance between spinal stabilization and minimizing the number of instrumented levels and thereby surgical exposure, which is crucial for allowing longitudinal growth. N/A.