Objective
Cervical myelopathy due to ossification of the posterior longitudinal ligament (OPLL) is induced by static factors, dynamic factors, or a combination of both. We used a three-dimensional ...finite element method (3D-FEM) to analyze the stress distributions in the cervical spinal cord under static compression, dynamic compression, or a combination of both in the context of OPLL.
Methods
Experimental conditions were established for the 3D-FEM spinal cord, lamina, and hill-shaped OPLL. To simulate static compression of the spinal cord, anterior compression at 10, 20, and 30% of the anterior-posterior diameter of the spinal cord was applied by the OPLL. To simulate dynamic compression, the OPLL was rotated 5°, 10°, and 15° in the flexion direction. To simulate combined static and dynamic compression under 10 and 20% anterior static compression, the OPLL was rotated 5°, 10°, and 15° in the flexion direction.
Results
The stress distribution in the spinal cord increased following static and dynamic compression by cervical OPLL. However, the stress distribution did not increase throughout the entire spinal cord. For combined static and dynamic compression, the stress distribution increased as the static compression increased, even for a mild range of motion (ROM).
Conclusion
Symptoms may appear under static or dynamic compression only. However, under static compression, the stress distribution increases with the ROM of the responsible level and this makes it very likely that symptoms will worsen. We conclude that cervical OPLL myelopathy is induced by static factors, dynamic factors, and a combination of both.
Case studies of patients with cervical spondylotic amyotrophy used compound muscle action potentials (CMAPs) of deltoid and biceps brachii muscles and central motor conduction time (CMCT).
To discuss ...surgical outcome for proximal-type cervical spondylotic amyotrophy in the context of results obtained with CMAPs and CMCT.
There have been no reports that correlate surgical outcome with CMAPs of deltoid and biceps brachii muscles or with CMCT.
A retrospective study was performed for 24 patients with proximal-type cervical spondylotic amyotrophy who underwent surgical treatment of the cervical spine. Erb-point-stimulated CMAPs were recorded in the deltoid and biceps. The percent amplitude of CMAPs was calculated in comparison with the opposite side. Motor-evoked potentials were recorded from bilateral abductor digiti minimi. CMAPs and F waves were recorded after supramaximal electric stimulation of ulnar nerves. CMCT was calculated as follows: motor-evoked potentials latency - (CMAPs' latency + F latency - 1)/2 (ms). Muscle strength was evaluated using manual muscle testing. Improvements in strength were classified as excellent, good, or fair.
The improvement was graded as excellent in 12 cases, good in 2 cases, and fair in 10 cases. The average percentage for CMAPs' amplitude on the affected side compared with the normal side in deltoid and biceps brachii muscles was significantly different between the excellent and fair patient groups. The CMCT on the affected side was not significantly different between excellent and fair patient groups.
The average percentage range of deltoid and biceps brachii muscle CMAPs' amplitude determined at the onset of illness correlated significantly with postoperative recovery. Surgical intervention of the cervical spine should be performed in patients in whom the average percentage of CMAPs' amplitude in deltoid and biceps brachii muscles ranges from 30% to 50%.
Introduction: The pathophysiology of lumbar degenerative spondylolisthesis (LDS) is still unclear. LDS often occurs in middle-aged and older people, but few reports compare the features of LDS by ...age. This study compared age-specific differences in intervertebral components, such as facet joints and intervertebral discs.Methods: Patients with LDS who underwent surgery from the 50s to the 80s were randomly selected. Each group had 30 cases (15 males and 15 females), totaling 120 cases. The measurement was carried out using plain X-ray and computed tomography scan. This study investigated facet joint angle, the tropism of the facet joint, sex difference, and the degree of degeneration of the facet joints and intervertebral disc.Results: The facet joint angle grew gradually shallow with age. There was no significant correlation between the tropism of the facet joint and sex deference. Degeneration of the facet joints was severe throughout all ages. The degeneration of the intervertebral disc was higher in the elderly.Conclusions: Age-related changes in the spine are said to begin at the intervertebral disc. As a result of degeneration of the intervertebral disc, vertebral body slip may occur when the facet joint and posterior supporting tissue of the vertebra cannot support the vertebral body.
Objective: Although there are several classifications for cervical myelopathy, these do not take differences between spinal cord segments into account. Moreover, there has been no report of stress ...analyses for individual segments to date.
Methods: By using the finite element method, we constructed 3-dimensional spinal cord models comprised of gray matter, white matter, and pia mater of the second to eighth cervical vertebrae (C2-C8). We placed compression components (disc and yellow ligament) at the front and back of these models, and applied compression to the posterior section covering 10%, 20%, 30%, or 40% of the anteroposterior diameter of each cervical spinal cord segment.
Results: Our results revealed that, under compression applied to an area covering 10%, 20%, or 30% of the anteroposterior diameter of the cervical spinal cord segment, sites of increased stress varied depending on the morphology of each cervical spinal cord segment. Under 40% compression, stress was increased in the gray matter, lateral funiculus, and posterior funiculus of all spinal cord segments, and stress differences between the segments were smaller.
Conclusion: These results indicate that, under moderate compression, sites of increased stress vary depending on the morphology of each spinal cord segment or the shape of compression components, and also that the variability of symptoms may depend on the direction of compression. However, under severe compression, the differences among the cervical spinal segments are smaller, which may facilitate diagnosis.
Three-dimensional C3-C5 and C3-C4 finite element (FE) models were used to analyze biomechanical responses under compression and extension moments.
To validate our models against other published FE ...models and experimental studies and improve our understanding of the mechanism of spinal cord injury without radiologic abnormality (SCIWORA) in cervical spine.
The underlying mechanism for SCIWORA remains unclear. We hypothesized that the incidence of SCIWORA was associated with facet joint morphology and bony pincers mechanism.
FE models were constructed using data from computed tomography scans of the cervical spine of a healthy young man. The C3-C5 FE models consisted of bony vertebra, articulating facets, and intervertebral disc. Facet surfaces were oriented at 30 degrees , 45 degrees , and 60 degrees from the transverse plane. These models were constrained in all degrees of freedom at the C5 inferior vertebral body and a uniform axial displacement of 1 mm was applied to the superior nodes of C3. Three model versions changed to C3-C4 models with ligaments. The C4 inferior-most bony nodes were constrained, whereas the top of the C3 superior-most bony nodes were left unconstrained. These models were subjected to an axial compression load of 73.6 N with extension moments (1.8 Nm) applied to the upper bony section C3 vertebra. The predicted responses were compared with published results.
The response under axial compression was validated and corresponded closely with published results. Under sagittal moment, the C3-C4 FE model with 60 degrees facet was the most flexible in extension (4.22 degrees ). Total translation was highest for the model with 60 degrees facet.
The load displacement response of C3-C5 FE models was in agreement with published data. We confirmed that the C3-C4 FE model with 60 degrees facet was the most susceptible to SCIWORA and that the bony pincers mechanism was dependent on facet joint inclination.
Objective: Decompression procedures for cervical myelopathy of ossification of the posterior longitudinal ligament (OPLL) are anterior decompression with fusion, laminoplasty, and posterior ...decompression with fusion. Preoperative and postoperative stress analyses were performed for compression from hill-shaped cervical OPLL using 3-dimensional finite element method (FEM) spinal cord models.
Methods: Three FEM models of vertebral arch, OPLL, and spinal cord were used to develop preoperative compression models of the spinal cord to which 10%, 20%, and 30% compression was applied; a posterior compression with fusion model of the posteriorly shifted vertebral arch; an advanced kyphosis model following posterior decompression with the spinal cord stretched in the kyphotic direction; and a combined model of advanced kyphosis following posterior decompression and intervertebral mobility. The combined model had discontinuity in the middle of OPLL, assuming the presence of residual intervertebral mobility at the level of maximum cord compression, and the spinal cord was mobile according to flexion of vertebral bodies by 5°, 10°, and 15°.
Results: In the preoperative compression model, intraspinal stress increased as compression increased. In the posterior decompression with fusion model, intraspinal stress decreased, but partially persisted under 30% compression. In the advanced kyphosis model, intraspinal stress increased again. As anterior compression was higher, the stress increased more. In the advanced kyphosis + intervertebral mobility model, intraspinal stress increased more than in the only advanced kyphosis model following decompression. Intraspinal stress increased more as intervertebral mobility increased.
Conclusion: In high residual compression or instability after posterior decompression, anterior decompression with fusion or posterior decompression with instrumented fusion should be considered.
Objective
Patients with cervical spondylotic myelopathy (CSM) have the same clinical symptoms that vary according to the degree of spinal cord compression and the cross-sectional cord shape. We used ...a three-dimensional finite element method (3D-FEM) to analyze the stress distributions of the spinal cord with neck extension under three cross-sectional cord shapes.
Methods
Experimental condition for the 3D-FEM spinal cord, ligamentum flavum, and anterior compression shape (central, lateral, and diffuse types) was established. To simulate neck extension, the spinal cord was extended by 20° and the ligamentum flavum was shifted distally according to movement of the cephalad lamina.
Results
The stress distribution in the spinal cord increased due to invagination of the ligamentum flavum into the neck extension. The range of stress distribution observed for the diffuse type was wider than for the central and lateral types. In addition, the stress distribution in the spinal cord was increased by the pincer movement of the ligamentum flavum and by the anterior compression of the spinal cord. The range of stress distribution observed for the diffuse type under antero-posterior compression was also wider than for the central and lateral types.
Conclusion
This simulation model showed that the clinical symptoms of CSM due to compression of the diffuse type may be stronger than for the central and lateral types. Therefore, careful follow-up is recommended for anterior compression of the spinal cord of diffuse type.
Background
Ossification of the posterior longitudinal ligament (OPLL) in the thoracic spine produces myelopathy. This is often progressive and is not affected by conservative treatment. Therefore, ...decompressive surgery is usually chosen.
Objective
To conduct a stress analysis of the thoracic OPLL.
Methods
The three-dimensional finite element spinal cord model was established. We used local ossification angle (LOA) for the degree of compression of spinal cord. LOA was the medial angle at the intersection between a line from the superior posterior margin at the cranial vertebral body of maximum OPLL to the top of OPLL with beak type, and a line from the lower posterior margin at the caudal vertebral body of the maximum OPLL to the top of OPLL with beak type. LOA 20°, LOA 25°, and LOA 30° compression was applied to the spinal cord in a preoperative model, the posterior decompressive model, and a model for the development of kyphosis.
Results
In a preoperative model, at more than LOA 20° compression, high stress distributions in the spinal cord were observed. In a posterior decompressive model, the stresses were lower than in the preoperative model. In the model for development of kyphosis, high-stress distributions were observed in the spinal cord at more than LOA 20° compression.
Conclusions
Posterior decompression was an effective operative method. However, when the preoperative LOA is more than 20°, it is very likely that symptoms will worsen. If operation is performed at greater than LOA 20°, then correction of kyphosis by fixation of instruments or by forward decompression should be considered.
Cervical ossification of the posterior longitudinal ligament (OPLL) results in myelopathy. Conservative treatment is usually ineffective, thus, surgical treatment is required. One of the reasons for ...the poor surgical outcome following laminoplasty for cervical OPLL is kyphosis. In the present study, a 3-dimensional finite element method (3D-FEM) was used to analyze the stress distribution in preoperative, posterior decompression and kyphosis models of OPLL. The 3D-FEM spinal cord model established in this study consisted of gray and white matter, as well as pia mater. For the preoperative model, 30% anterior static compression was applied to OPLL. For the posterior decompression model, the lamina was shifted backwards and for the kyphosis model, the spinal cord was studied at 10, 20, 30, 40 and 50° kyphosis. In the preoperative model, high stress distributions were observed in the spinal cord. In the posterior decompression model, stresses were lower than those observed in the preoperative model. In the kyphosis model, an increase in the angle of kyphosis resulted in augmented stress on the spinal cord. Therefore, the results of the present study indicated that posterior decompression was effective, but stress distribution increased with the progression of kyphosis. In cases where kyphosis progresses following surgery, detailed follow-ups are required in case the symptoms worsen.
An unconscious 75-year-old female was admitted to our hospital. She went into cardiopulmonary arrest in the emergency room, but was resuscitated successfully. Abdominal computed tomography revealed a ...massive hematoma in the stomach. Gastrointestinal endoscopy was performed, but the source of the bleeding could not be identified. An emergency laparotomy was performed under a diagnosis of a hemorrhagic gastric ulcer. Laparotomy revealed ulcerative lesions in the posterior wall of the upper body of the stomach. A total gastrectomy was performed and the patient was rescued. On postoperative day 35, Roux-Y reconstruction was performed. We report herein on a case of cardiopulmonary arrest due to a hemorrhagic gastric ulcer successfully treated with a two staged operation and discuss the clinical implications based on a review of the literature.
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