Intramedullary spinal cord metastasis: a clinical and imaging study of seven patients.

OBJECTIVES: Intramedullary spinal cord metastasis (ISCM) is a rare complication of cancer. This complication has been studied by magnetic resonance imaging (MRI) more frequently in the clinical context to improve the survival time of cancer patients. However, the number of the reports of its clinical management or radiographic findings is small. To investigate the clinical and imaging characteristics of ISCM, seven cases of ISCM of a nonneurogenic origin were examined retrospectively. METHOD: Data regarding the site of the primary neoplasm, location of other metastases, initial symptoms, interval from the original diagnosis of cancer to the onset of neurologic symptoms, time course from initial symptoms to urinary retention, MRI data, and outcome after radiologic or surgical intervention were investigated. RESULTS: Five patients had lung cancer metastases, and one each had breast or uterine cancer metastases. The progression of neurologic deficit was rapid, and the average period between the occurrence of initial symptoms and urinary retention was 25 days. The averaged survival period from the diagnosis of ISCM was 5 months in three patients. (One patient is alive, and the data could not be obtained in another three patients.) MRI characteristics were useful for diagnosis, including large high signal intensity areas on T2-weighted images and strong ring or inhomogeneous enhancement on gadopentetate dimeglumine-enhanced T1-weighted images. Surgery was performed on two patients, but total removal could not be achieved. Radiotherapy was effective in treating neurologic deficit in five patients. CONCLUSION: Surgical treatment is seldom indicated for ISCM, and radiotherapy is recommended as soon as possible after a diagnosis is made from MRI.

Surgical treatment for injuries of the middle and lower cervical spine.

We reviewed the surgical treatment of 31 patients with burst fractures or teardrop dislocation fractures in the middle and lower cervical spine. Patients were treated with anterior instrumentation, posterior instrumentation, or a combination of both. Patients were evaluated radiographically and with the Frankel neurological outcomes grading scale. Anterior decompression and fusion restored the spinal canal diameter by approximately 60% whereas the posterior or combined approaches restored the canal diameter by only 6%. In addition, nine of 24 patients treated anteriorly gained improved neurological function whereas none of the patients treated posteriorly had neurological improvement. Based on the anatomical and neurological findings, the study demonstrates that anterior fusion is preferable to posterior fusion for the treatment of burst fractures and tear-drop dislocation fractures of the middle and lower cervical spine.

The behavior of thoracic trabecular bone during flexion.

Thoracic compression fractures are often described as anterior wedge fractures. Although the radiographic signs of these fractures are easily identified, the mechanism of the trabecular failure is not well understood. The current study addressed this mechanism in the lower thoracic spine by measuring the trabecular strain. Trabecular strain was measured in six human thoracic cadaver spines during 1) compressive and 2) flexural loading. The strains were measured at incremental loads using a texture correlation. They were analyzed by global contour plots and regional analysis of the T11 vertebrae. Specimens loaded under only compression exhibited uniform strains in the vertebral body. During flexion, however, the strains were concentrated in the anterosuperior margin of the vertebral body and the compressive and shear strain magnitudes in this region were significantly increased. These results demonstrate that the flexural position places the lower thoracic spine at greater risk of anterior compression fracture as seen clinically.

Residual neck pain after traumatic spondylolisthesis of the axis.

OBJECTIVE: Most patients with traumatic spondylolisthesis of the axis are treated nonsurgically. Some patients do not develop symptoms, but others experience strong and persistent neck pain. To clarify the factor that plays a major role in residual neck pain after this fracture, we reviewed nine patients who underwent conservative treatment. METHODS: Patients were assessed via telephone interviews an average of 62 months after injury and were divided into two groups: those with and those without neck pain. Angulation and anterior translation between the second and third cervical vertebrae were measured on lateral radiograms at the time of injury, removal of brace, and final follow-up. Fracture lines were also investigated by computed tomography. RESULTS: At the time of final follow-up, the average angulation was 6.3 degrees and the average translation was 5.3 mm in the neck-pain group and 0.6 degrees and 0.2 mm, respectively, in the no-symptom group. In patients with fracture lines present on the articular surface of the inferior face joints, angulation persisted or increased, even though the fractures were hemilateral. This was compatible with severe neck pain. In contrast, angulation and translation were improved in patients with an intact inferior articular surface of the axis, and pain was not reported. CONCLUSIONS: Injury on the inferior articular surface of the axis may disturb spontaneous healing of C2-C3 subluxation and cause residual neck pain. It is necessary to assess the presence of injury to the inferior facet bilaterally with plain or computed tomograms.

Potential and origin of the hematopoietic population in human skeletal muscle.

While mononuclear cells isolated from murine skeletal muscle were shown to be capable of hematopoietic activity, similar hematopoietic cells (HC) recently were reported to exist in primate muscle. We investigated muscle-derived HC from young and adult human subjects. Although hematopoietic stem cells were rare in muscle, their frequency nonetheless was approximately four times greater than in peripheral blood. These cells in muscle appeared to originate from CD45(+) bone marrow cells. Our results suggested an additional function of human skeletal muscle as a reservoir of HC.

Immortalization of human nucleus pulposus cells by a recombinant SV40 adenovirus vector: establishment of a novel cell line for the study of human nucleus pulposus cells.

STUDY DESIGN: Establishment and characterization of a de novo cell line derived from human nucleus pulposus cells using a recombinant simian virus 40 (SV40) adenovirus vector. OBJECTIVES: To assess the feasibility of human nucleus pulposus cell line procurement and to evaluate the character of the resultant outcome to better understand the nature of human nucleus pulposus cells. SUMMARY OF BACKGROUND DATA: Despite recent advances in disc cell biologic research, the fundamental nature of nucleus pulposus cells, especially in the context of human cell lines, is still not well understood. Therefore, a broad-based analysis of these cells is of significant necessity. Because of the limited amount of existing human cells, establishment of an immortal cell line would greatly facilitate resource supply. METHODS: After release of informed consent, tissue samples of nucleus pulposus were obtained from the lumbar intervertebral disc of a 19-year-old man undergoing anterior fusion for burst fracture. Samples with no apparent damage were selected and digested enzymatically for primary culture and then were infected with recombinant SV40 adenovirus vector (Ad/SV40). The infected cells were maintained in culture for more than 40 population doublings, after which they were considered immortalized. Next, confirmation of expression of T antigen was performed and resultant immortalized cell lines were designated and classified as human nucleus pulposus cell line derived from Ad/SV40 infection-1 (HNPSV-1). HNPSV-1 cells were characterized and compared with their mother cells under two designated culture conditions: monolayer and three-dimensional. Morphologic and immunocytochemical analyses were performed at various intervals. Cell proliferation, DNA synthesis, proteoglycan synthesis, gene expression profiling, and karyotypic analyses were also performed. Moreover, HNPSV-1 cells were injected into rabbit discs to assess the presence of tumorigenesis. RESULTS: Recombinant SV40 adenovirus vector infected nucleus pulposus cells with relatively high efficiency (90%> at multiplicity of infection 100). HNPSV-1 demonstrated marked prolongation of cell life with continuous cell doublings for over 5 months (60-100 cell population doublings). Despite significant increase in cell proliferation and DNA synthesis when compared with its mother cells, resultant cell lines expressed strikingly similar cell morphology and functional characteristics. Atypical karyotypes were noted; however, no apparent tumorigenesis was seen in rabbit discs 24 weeks after injection of HNPSV-1. CONCLUSIONS: HNPSV-1 was successfully established using recombinant SV40 adenovirus vector. Results showed that human nucleus pulposus cells are capable of immortalization with maintenance of original cell characteristics. It is anticipated that these cells will be useful for in vitro studies of the biologic nature of human nucleus pulposus cells.

Spinal osteochondromas in middle-aged to elderly patients.

STUDY DESIGN: Three case reports of solitary spinal osteochondromas in middle-aged and elderly patients. OBJECTIVES: To describe the treatment of three rare cases of spinal osteochondromas in patients significantly older than the cases previously reported in the literature. SUMMARY OF BACKGROUND DATA: Osteochondromas arising in the vertebral column are considered rare. The mean age of clinical appearance is said to be in the second or third decade of life. METHODS: Clinical history, physical examinations, plain radiographs, magnetic resonance imaging, myelography, computed tomographic myelography, and histopathologic findings for each case were reviewed in conjunction with previous cases reported in the literature. RESULTS: Total removal of the tumor was effective in causing the symptoms to disappear. CONCLUSIONS: Spinal osteochondromas are rare and tend to appear in young adults. Three cases of spinal osteochondromas that were unusual in terms of age at clinical presentation and localization were reported, suggesting a continuous growth of the tumor beyond skeletal maturity.