Relationship between the histological findings of spondylolytic tissue, instability of the loose lamina, and low back pain.

STUDY DESIGN: We investigated the histomorphological features of the tissue occupying the spondylolytic defect (spondylolytic tissue), which was similar to ligament, and then graded the complete enthesis structure and the density of the fibrous portion. The relationships between the features, instability of the loose lamina against the affected vertebra, and the severity of low back pain were studied. OBJECTIVE: To elucidate the histomorphological features of spondylolytic tissue and the associations between the features, instability of the loose lamina, and low back pain. SUMMARY OF BACKGROUND DATA: Spondylolysis is thought to be caused primarily by a fatigue fracture and spondylolytic tissue has been recognized as being a fibrocartilaginous mass. Recently, innervation of the spondylolytic tissue was reported to be one of the sources of low back pain. METHODS: The spondylolytic tissue from 17 patients who underwent microscopic decompression of the pars defect was observed for histology including hematoxylin and eosin, elastica van Gieson, and immunohistochemical staining for S100 protein. Instability of the loose lamina against the affected vertebra was evaluated by flexion/extension radiographs. RESULTS: The spondylolytic tissue had a ligamentous structure without innervation. The histomorphological findings, instability of the loose lamina, and low back pain had no relationship to one another. CONCLUSION: Spondylolysis is a pseudarthorosis of the pars interarticularis and the spondylolytic tissue tends to develop noninnervated ligament-like tissue with an enthesis structure. The histomorphological features, instability of the loose lamina, and low back pain have no relationship to one another.

Clinical characterizations and radiologic findings of pure foraminal-type cervical disc herniation: CT discography as a useful adjuvant in its precise diagnosis.

STUDY DESIGN: A retrospective study of 15 cases of pure foraminal type cervical disc herniation (CDH) was performed. OBJECTIVES: The objectives were to describe the clinical characteristics and to assess the radiologic findings. SUMMARY OF BACKGROUND DATA: Although foraminal lumbar disc herniation has been reported, pure foraminal-type CDH has not been fully elucidated. It is not only a rare condition but also a difficult one to diagnose. METHODS: All patients underwent MRI, CT myelography (CTM), and CT discography (CTD). Herniated discs were removed by the posterior approach. Clinical symptoms were evaluated at preoperative and postoperative period. RESULTS: On MRI, 2 cases were positive, 6 cases were suspected, and 7 cases were negative. On CTM, 7 cases were positive and 8 cases were negative; and on CTD, all cases were positive. As to the association between the herniated disc and posterior longitudinal ligament, 12 cases were intraligamentous. The association between the herniated disc and nerve root revealed that 10 discs were at the axillary portion of the nerve root. CONCLUSIONS: Pure foraminal-type CDH may be overlooked with conventional MRI or CTM, so CTD should be performed. It provides valuable and additional information in difficult or ambiguous cases such as pure foraminal type.

Morphological changes of the ligamentum flavum as a cause of nerve root compression.

The ligamentum flavum is considered to be one of the important causes of radiculopathy in lumbar degenerative disease. Although there have been several reports anatomically examining the positional relationship between the ligamentum flavum and nerve root, there are few reports on ventral observation. The purpose of this study is to clarify the shape of the ligamentum flavum seen ventrally, and to obtain anatomic findings related to nerve root compression. The subjects were 18 adult embalmed cadavers, with an average age of 78 years at the time of death. The ventral shapes of the ligamentum flavum were observed. The relationships between the morphological change of the ligamentum flavum and nerve root compression or radiographic findings were statistically evaluated. Among the shapes of the ligamentum flavum, bulging of the ligament was most frequently observed. Proximal bulging indicates the type with the cranial portion bulging from the subarticular zone to the foraminal zone of the ligamentum flavum. In this type associated with a decrease in disc height, nerve root compression was frequently observed. Thus, we could more realistically grasp the relationship between bulging morphology of the ligamentum flavum and nerve root compression.

The pathology of ligamentum flavum in degenerative lumbar disease.

STUDY DESIGN: A pathologic study of the ligamentum flavum in degenerative lumbar disease. OBJECTIVES: To elucidate the clinical significance of each pathologic finding of the ligamentum flavum. SUMMARY OF BACKGROUND DATA: In many reports, researchers observed the ligamentum flavum removed partially during surgery and did not evaluate the whole image of the ligamentum flavum. In addition, there are only a few reports that examined the possible association between various histologic findings and clinical findings. And, thus, there are many unclear points in the clinical significance indicated by each pathologic finding. METHODS: The study participants were 50 patients with degenerative lumbar diseases who underwent surgical decompression with removal of the ligamentum flavum of the affected spinal level. Tissue specimens of the removed ligamentum flavum in cross section were prepared, and changes in the elastic fibers and collagen fibers were evaluated in three grades to evaluate the whole image. In addition, we observed the presence or absence of any focal lesions and statistically analyzed the possible association between these histologic findings and clinical symptoms or image findings. RESULTS: In regard to the association between histologic findings and clinical symptoms or image findings, calcification was observed in significantly older patients, who tended to have low scores in preoperative JOA score, and was frequently observed in patients with cauda equina symptoms. Patients with ossification had a significantly greater % slip, and chondroid cells were frequently observed in patients with spondylolisthesis. CONCLUSION: Various pathologic findings provided important foundations for discussing the pathogenesis of lesions in ligamentum flavum. Calcification was frequently observed in elderly patients and those with cauda equina symptoms, and these patients tended to have severer preoperative symptoms. Chondroid cells were frequently observed in patients with spondylolisthesis, and patients with ossification had a greater % slip, suggesting involvement of mechanical load in ossification of ligaments. The pathologic findings were significantly related to the clinical features, and these findings will be profitable for understanding the pathogenesis of degenerative lumbar disease.

Pathophysiology and treatment for cervical flexion myelopathy.

Previous studies have suggested that spinal cord compression by the vertebral bodies and intervertebral discs during neck flexion cause cervical flexion myelopathy (CFM). However, the exact pathophysiology of CFM is still unknown, and surgical treatment for CFM remains controversial. We examined retrospectively patients with CFM based on studies of the clinical features, neuroradiological findings, and neurophysiological assessments. The objectives of this paper are to investigate the pathophysiology of CFM, and to examine an optimal surgical treatment. Twenty-three patients (20 male, three female) with age of onset ranging from 11 to 23 years (mean 15.7 years) were examined for the study. All patients were inspected by magnetic resonance imaging (MRI), myelogram, or computed tomographic myelogram (CTM) of the cervical spine. In eight patients, dynamic motor evoked potentials (MEP) studies were performed. Five patients underwent surgical treatment; two patients had cervical duraplasty with laminoplasty, two patients had musculotendinous transfer, one patient had both of these procedures, and the remaining 18 patients were treated conservatively. Amyotrophy of the hand intrinsic and flexor muscle group of the forearm except the brachioradial muscle was observed hemilaterally in 20 patients and bilaterally in three patients. In three patients, T1-weighted MRI with neck flexion showed linear high intensity regions in the epidural space. In all patients, axial MRI/CTM demonstrated flattening of the spinal cord with the posterior surface of the dura mater shifting anteriorly. The amplitude of MEPs decreased after cervical flexion in two patients with progressive muscular atrophy. In three patients, dysesthesia of the upper extremities disappeared following cervical duraplasty. Musculotendinous transfer for three patients significantly improved the performance of their upper extremity. The findings of this study suggest that degenerative changes of the dura mater may be a characteristic pathology of CFM. Cervical duraplasty with laminoplasty is effective for cases at an early stage, and musculotendinous transfer should be selected in patients at a late stage.

Microsurgical transdural discectomy with laminoplasty: New treatment for paracentral and paracentroforaminal cervical disc herniation associated with spinal canal stenosis.

STUDY DESIGN: A clinical study of the surgical procedure for cervical disc herniation was conducted. OBJECTIVES: To describe microsurgical transdural discectomy with laminoplasty, and to assess the clinical outcome of this surgical technique. SUMMARY OF BACKGROUND DATA: A posterior approach for cervical disc herniation has been considered risky, and few reports on a transdural approach to this disorder have appeared in the past decade. However, a transdural approach with recent innovations (a microsurgical technique, intraoperative spinal cord monitoring, and laminoplasty) has not been reported. METHODS: For this study, 30 patients with myelopathy or radiculomyelopathy accompanied by cervical disc herniation, aged 30 to 77 years (mean, 55 years), underwent microsurgical transdural discectomy with laminoplasty. Preoperative images showed multisegmental disc degeneration, developmental canal stenosis, or both for all the patients. The intraoperative evoked spinal cord potentials were recorded for neurophysiologic assessment. The follow-up period averaged 52 months (range, 24-118 months). RESULTS: The operative time averaged 239 minutes (range, 160-340 minutes), and the mean blood loss was 169 mL (range, 30-701 mL). The Japanese Orthopedic Association score improved from 3.5 to 15 (mean, 11.4) before surgery to 9 to 17 (mean, 15.2) after surgery. The intraoperative evoked spinal cord potentials indicated the affected spinal cord level and reflected the severity of myelopathy. Postoperative cerebrospinal fluid leakage, pseudomeningocele, and progression to cervical deformity were not observed. Transient palsy of the C5 nerve root was observed in two patients with C4-C5 central cervical disc herniation. CONCLUSIONS: Microsurgical transdural discectomy with laminoplasty can be performed safely as a selected surgical option for paracentral and paracentroforaminal cervical disc herniation with multisegmental canal stenosis.