经椎间孔入路切除椎管内外沟通型神经鞘瘤

目的 探讨经病理性扩大的椎间孔在袖套内切除偏一侧椎管内外沟通型神经鞘瘤手术方法的应用.方法 对11例疑为椎管内神经鞘瘤患者采用经椎间孔袖套内人路显微手术切除肿瘤.全部患者术前影像学检查均显示肿瘤为偏脊髓一侧骑跨椎间孔生长,形态为非明显哑铃彤,椎间孔扩大明显.肿瘤位于颈段者7例、胸段者2例、腰段者2例.结果 11例患者肿瘤均完全切除,术后第4天即可下床活动,随访4-24个月,平均11个月,症状和体征均明显改善,无手术并发症和脊柱畸形发牛.结论 经扩大的椎间孔袖套内入路显微手术切除肿瘤避免了术中的过度显露,不破坏脊柱的骨性结构,对椎旁肌及韧带的损伤与半椎板切除入路相同,有利于最大程度地保持脊柱的稳定性,适用于偏侧的骑跨椎间孔生长的非哑铃彤神经鞘瘤.     

Prevalence of osteoporosis in patients requiring spine surgery: incidence and significance of osteoporosis in spine disease

Summary The purpose of this study is to evaluate the incidence of osteoporosis in patients requiring spine surgery. Among patients older than 50 years, the rate of osteoporosis in males was 14.5% and the rate osteoporosis in females was 51.3%. We strongly recommend an evaluation and treatment for osteoporosis in the patients requiring spine surgery, especially in females over 50 years old. Introduction Because lifespan is increasing, there is an increase in the incidence of osteoporosis in elderly spine surgery patients. The osteoporosis may adversely influence the fusion rate and the surgical outcome. The purpose of this study is to evaluate the incidence of osteoporosis in patients requiring spine surgery. Methods A total of 1,321 patients underwent spine surgeries at our institute from January 1, 2005 to December 31, 2005. Among them, there were 562 patients (42.5%) younger than 50 years old, and 759 patients (57.6%) older than 50 years old. Prior to operation, we evaluated the patients for osteoporosis on both the femur head and lumbar spine by measuring the bone mineral density (BMD) by the dual-energy X-ray absorptiometry (DXA). Based on the World Health Organization (WHO) criteria for osteoporosis, we chose the T-score to determine normal (>−1), osteopenia (−1≥, >−2.5), and osteoporosis (≤−2.5). Among the 562 patients younger than 50 years, DXA was performed in 22 (3.9%) patients and there were 13 (2.3%) cases of osteopenia and 2 (0.3%) cases of osteoporosis. Results Among 759 patients older than 50 years, DXA was performed on 516 (68.0%) patients, 193 males and 323 females. Among the male patients, there were 89 (46.1%) patients with osteopenia and 28 (14.5%) with osteoporosis. Among the female patients, there were 134 (41.4%) with osteopenia and 166 (51.3%) with osteoporosis. The incidence of osteoporosis was higher in female patients and significantly increased with increasing age. Among 759 patients older than 50 years, 676 patients underwent a major spine operation with or without fusion. Among these patients, DXA was performed in 446 (66.0%) patients and there were 207 (46.4%) patients with osteopenia and 139 (31.1%) with osteoporosis. Conclusions The patients over 50 year-old who need spine operation have osteoporosis often. In conclusion, the number of spine operations in elderly patients is increasing and the incidence of osteoporosis in spine surgery patients is also increasing. We strongly recommend an evaluation for osteoporosis and post-operative treatment for osteoporosis in patients over 50 years old, especially for female patients.     

Positive and negative prognostic variables for patients undergoing spine surgery for metastatic breast disease

The histology of the primary tumor in metastatic spine disease plays an important role in its treatment and prognosis. However, there is paucity in the literature of histology-specific analysis of spinal metastases. In this study, prognostic variables were reviewed for patients who underwent surgery for breast metastases to the spinal column. Respective chart review was done to first identify all patients with breast cancer over an 8-year period at a major cancer center and then to select all those with symptomatic metastatic disease to the spine who underwent spinal surgery. Univariate and multivariate analyses were used to assess several prognostic variables. Presence of visceral metastases, multiplicity of bony lesions, presence of estrogen receptors (ER), and segment of spine (cervical, thoracic, lumbar, sacral) in which metastases arose were compared with patient survival. Eighty-seven patients underwent 125 spinal surgeries. Those with estrogen receptor (ER) positivity had a longer median survival after surgery compared to those with estrogen receptor negativity. Patients with cervical location of metastasis had a shorter median survival compared with those having metastases in other areas of the spine. The presence of visceral metastases or a multiplicity of bony lesions did not have prognostic value. In patients with spinal metastases from breast cancer, aggressive surgical management may be an option for providing significant pain relief and preservation/improvement of neurological function. Interestingly, in patients undergoing such surgery, cervical location of metastasis is a negative prognostic variable, and ER-positivity is associated with better survival, while presence of visceral or multiple bony lesions does not significantly alter survival.     

Hormones and growth factors in the pathogenesis of spinal ligament ossification

Ossification of the spinal ligaments (OSL) is a pathologic condition that causes ectopic bone formation and subsequently results in various degrees of neurological deficit, but the etiology of OSL remains almost unknown. Some systemic hormones, such as 1,25-dihydroxyvitamin D, parathyroid hormone (PTH), insulin and leptin, and local growth factors, such as transforming growth factor-β (TGF-β), and bone morphogenetic protein (BMP), have been studied and are thought to be involved in the initiation and development of OSL. This review article summarizes these studies, delineates the possible mechanisms, and puts forward doubts and new questions. The related findings from studies of genes and target cells in the ligament of OSL are also discussed. Although these findings may be helpful in understanding the pathogenesis of OSL, much more research needs to be conducted in order to investigate the nature of OSL.     

Neurovascular risks of sacral screws with bicortical purchase: an anatomical study

The aim of this cadaver study is to define the anatomic structures on anterior sacrum, which are under the risk of injury during bicortical screw application to the S1 and S2 pedicles. Thirty formaldehyde-preserved human male cadavers were studied. Posterior midline incision was performed, and soft tissues and muscles were dissected from the posterior part of the lumbosacral region. A 6 mm pedicle screw was inserted between the superior facet of S1 and the S1 foramen. The entry point of the S2 pedicle screw was located between S1 and S2 foramina. S1 and S2 screws were placed on both right and the left sides of all cadavers. Then, all cadavers were turned into supine position. All abdominal and pelvic organs were moved away and carefully observed for any injury. The tips of the sacral screws were marked and the relations with the anatomic structures were defined. The position of the sacral screws relative to the middle and lateral sacral arteries and veins, and the sacral sympathetic trunk were measured. There was no injury to the visceral organs. In four cases, S1 screw tip was in direct contact with middle sacral artery. In two cases, S1 screw tip was in direct contact with middle sacral vein. It was observed that the S1 screw tips were in close proximity to sacral sympathetic trunk on both right and the left sides. The tip of the S2 screw was in contact with middle sacral artery on the left side only in one case. It is found that the tip of the S2 screw was closely located with the middle sacral vein in two cases. The tip of the S2 pedicle screw was in contact with the sacral sympathetic trunk in eight cases on the right side and seven cases on the left side. Lateral sacral vein was also observed to be disturbed by the S1 and S2 screws. As a conclusion, anterior cortical penetration during sacral screw insertion carries a risk of neurovascular injury. The risk of sacral sympathetic trunk and minor vascular structures together with the major neurovascular structures and viscera should be kept in mind.     

Pain regulation and health-related quality of life after thoracolumbar fractures of the spine

Fractures of the thoracolumbar spine rank among the severest injuries of the human skeleton. Especially in younger patients they often result from high-energy accidents. Recently, a shift in paradigm towards more aggressive treatment strategies including anterior procedures could be observed. However, so far only few data exist reflecting the quality of life (QoL) after such injuries. The aim of this study was to evaluate medium-term QoL and further to identify factors that influence the clinical outcome in patients with fractures of the thoracolumbar spine. Data of 906 patients who were treated during a 10-year period in our institution were evaluated retrospectively. Only patients with single-level traumatic injuries aged between 18 and 65 years without neurological deficits, concomitant injuries of other locations and internal comorbidities were included into the investigation (n = 204). Three different treatment groups (i.e. non-operative, dorsal and dorsoventral stabilisation) were compared to healthy controls as well as different pain populations. The QoL was assessed using established questionnaires (SF-36, HFAQ, VAS-Spinescore, PRQ, and PTSD). Sixty-five percent of the included patients (n = 133) were studied at an average follow-up of 5.3 ± 1.7 years after injury. All treatment groups revealed an identical gender and age distribution. More severe and unstable injuries were found in the surgical groups associated with higher treatment costs and a longer inability to work. Compared to healthy controls, QoL was compromised to the same extent in all groups. Furthermore, all patients treated in this study did significantly better than low back pain individuals with regard to QoL and pain regulation parameters. In our study, patients with thoracolumbar spine fractures showed a reduced QoL compared to healthy controls. Thus, patients do not seem to regain their former QoL. However, the level of discomfort was comparably low in all groups, even in patients with more severe injuries requiring extensive surgery. Overall, outcome and QoL after traumatic fractures of the thoracolumbar spine rather seem to be determined by the severity of injury than by pain regulation or other psychosocial factors which is likely the case in low back pain disorders.     

Are the spines of calf,pig and sheep suitable models for pre-clinical implant tests?

Pre-clinical in vitro tests are needed to evaluate the biomechanical performance of new spinal implants. For such experiments large animal models are frequently used. Whether these models allow any conclusions concerning the implant’s performance in humans is difficult to answer. The aim of the present study was to investigate whether calf, pig or sheep spine specimens may be used to replace human specimens in in vitro flexibility and cyclic loading tests with two different implant types. First, a dynamic and a rigid fixator were tested using six human, six calf, six pig and six sheep thoracolumbar spine specimens. Standard flexibility tests were carried out in a spine tester in flexion/extension, lateral bending and axial rotation in the intact state, after nucleotomy and after implantation. Then, the Coflex interspinous implant was tested for flexibility and intradiscal pressure using another six human and six calf lumbar spine segments. Loading was carried out as described above in the intact condition, after creation of a defect and after implantation. The fixators were most easily implantable into the calf. Qualitatively, they had similar effects on ROM in all species, however, the degree of stability achieved differed. Especially in axial rotation, the ROM of sheep, pig and calf was partially less than half the human ROM. Similarly, implantation of the Coflex interspinous implant caused the ROM to either increase in both species or to decrease in both of them, however, quantitatively, differences were observed. This was also the case for the intradiscal pressure. In conclusion, animal species, especially the calf, may be used to get a first idea of how a new pedicle screw system or an interspinous implant behaves in in vitro flexibility tests. However, the effects on ROM and intradiscal pressure have to be expected to differ in magnitude between animal and human. Therefore, the last step in pre-clinical implant testing should always be an experiment with human specimens.     

Secondary Collapse of an Expandable Cage After Vertebral Corpectomy

Abstract Expandable vertebral body replacement systems have been increasingly used for anterior stabilization of spine. We report a secondary collapse of an expandable vertebral body replacement system. This specific complication has not been reported in the literature so far. The most obvious reason for failure was insufficient tightening of a locking screw. This paper emphasizes the importance of correct technical application.     

Asymmetrical loads and lateral bending of the human spine

The human spine is modelled as a cantilever-type beam column. Under the influence of static asymmetrical loads, muscle and low-back forces are predicted from a hypothetical but revealing model. Such forces produced by asymmetrical loads are much larger than for a corresponding symmetrical load. Asymmetrical loads can encourage, especially in young schoolchildren, lateral bending of the spine by alleviating muscle and low-back forces. This could possibly be a factor contributing to the surprisingly high percentage of schoolchildren with measurable scoliotic curves. The wearing of knapsack-type bags is advocated.     

Spinal subdural hematoma

 We report the case of a 68-year-old patient with a traumatic spinal subdural hematoma. MRI demonstrated an area of abnormal intensity and a black line in the inner part of the intradural space. We anti-cipate that MRI will help to make one more confident in the preoper-ative diagnosis of spinal subdural hematoma. The symptoms complet-ely disappeared immediately after the operation. Spinal subdural he-matoma requires immediate surgical evacuation. The prognosis for func-tional recovery is good if the condi-tion is appropriately diagnosed and treated before development of irre-versible paralysis. We recom-mend MRI to make an early diagnos-is and early evacuation of spinal subdural hematoma.