Takui Ito

Histologic evidence of absorption of sequestration-type herniated disc.

Study Design The reactions to sequestrated disc fragments, which were removed surgically from 35 patients, were examined histologically. Objectives To elucidate whether or not there is histologic evidence of absorption of sequestrated discs. Summary of Background Data Spontaneous disappearance of diminution of lumbar herniated discs in the spinal canal has been recognized, and this could be a possible explanation for relief of symptoms without surgery. The mechanism of this phenomenon is unclear. Methods Sequestrated discs removed surgically from 35 patients were examined histologically. Results In 30 cases, neovascularization was observed at the periphery of the sequestrated discs. Many foamy cells (macrophages) were present in the vascularized areas. In addition, immunohistochemistry revealed that many spindle-shaped, fibroblast-like cells were positive for CD68, a marker of macrophages. No fibrous scar formation was observed in any region. Conclusion These findings suggest that organization is not a main course for this type of herniated disc and that a kind of “absorption” process occurs predominantly in the healing stage.

Cervical Spondylotic Myelopathy: Clinicopathologic Study on the Progression Pattern and Thin Myelinated Fibers of the Lesions of Seven Patients Examined During Complete Autopsy

Study Design This study was designed to reveal the progression pattern and essential histological findings of the lesions in the spinal cord affected by cervical spondylotic myelopathy. Objectives The purpose of this study was to gain new information about symptom progression and recovery in cervical spondylotic myelopathy. Summary of Background Data The characteristics of the distribution and the progression pattern of the lesions and whether demyelination and remyelination processes actually occur in cervical spondylotic myelopathy remain unclear. Methods Tissues from seven patients with cervical spondylotic myelopathy were taken during autopsy and examined macroscopically and microscopically. An ultrastructural examination of spinal cord from two patients was also performed. Results The anterior horn and intermediate zone of the gray matter in the compressed segments showed atrophy in all the cases and in one, atrophy was limited to these areas. Atrophy and myelin pallor in the lateral and posterior funiculi were observed in six patients, and the lateral funiculi of two were severely affected. Many thin myelinated fibers and denuded axons were demonstrated ultrastructurally in the damaged white matter of two patients. Conclusion There appears to be a common pattern of lesion progression in cervical spondylotic myelopathy: atrophy and neuronal loss in the anterior horn and intermediate zone develop first, followed by degeneration of the lateral and posterior funiculi. Eventually, marked atrophy develops throughout the entire gray matter and severe degeneration occurs in the lateral funiculus. Furthermore, the existence of thin myelinated fibers in the white matter suggests focal demyelinating and remyelinating processes occur in cervical spondylotic myelopathy.

Polymethylmethacrylate augmentation of pedicle screws increases the initial fixation in osteoporotic spine patients.

Study Design: A retrospective comparative study. Objectives: To investigate the clinical efficacy of polymethylmethacrylate (PMMA) augmentation in vertebral pseudarthrosis after osteoporotic vertebral fractures. Summary of Background Data: Despite being the most rigid form of posterior instrumentation, pedicle screws sometimes achieve poor initial fixation primarily in patients with osteoporosis. One method for improving pedicle screw fixation in osteoporotic spines is pedicle augmentation using bone cement such as PMMA. Although various biomechanical studies of osteoporotic spines have shown improved pullout strength of pedicle screws augmented with bone cement, there have been few studies that have examined the clinical significance of PMMA augmentation. Methods: Thirty-eight patients with posterior fusion using pedicle screws for vertebral pseudarthrosis after osteoporotic vertebral fracture were included in the study. The level of fracture ranged from T7 to L5. The mean follow-up period was 31 months. Patients were divided into 2 groups: those with posterior instrumentation using pedicle screws augmented with PMMA (group C, N=17) and those without PMMA augmentation (group NC, N=21). Clinical and radiographic results for the 2 groups were compared. Results: With the exception of osteoporotic status, there were no significant differences in the baseline data of the 2 groups. The incidence of clear zones around the pedicle screws was significantly suppressed in group C compared with group NC (29.4% vs. 71.4%). Correction loss was significantly decreased (3 degrees vs. 7.2 degrees) and fusion rate was significantly higher in group C (94.1% vs. 76.1%). Back pain improved in 64.7% of the group C patients. There were no perioperative complications related to the PMMA cement in group C. Conclusions: Reinforcement of pedicle screws using PMMA augmentation may be a feasible surgical technique for osteoporotic spines.

Types of lumbar herniated disc and clinical course.

Study Design. A retrospective study of different types of herniated discs and duration of symptoms in patients with lumbar disc herniation, and a trial of longer conservative treatment to reduce the number of operations. Objective. To determine whether noncontained and contained herniated discs have different clinical courses and to evaluate the results of the clinical trial of longer and vigorous conservative treatment. Summary of Background Data. The possibility of a difference in clinical features between contained and noncontained disc herniation has been suggested previously. Methods. In the first study, the medical history and intraoperative findings of 156 patients who had undergone herniotomy were reviewed. In the second study, conservative treatment of at least 2 months’ duration was recommended for all patients with lumbar disc herniation. Results. In the first study, patients with noncontained disc herniation had a shorter preoperative clinical course than those with contained disc herniation. It was rare for noncontained herniation to require surgery 4 months or more after the onset of symptoms. In the second study, the authors’ protocol reduced the number of herniotomies required, especially the number of operations for the patients with noncontained disc herniation. Conclusions. The authors believe that patients with noncontained lumbar disc herniation can be treated without surgery, if these patients can tolerate the symptoms for the first 2 months.

Neovascularization induced by anulus and its inhibition by cartilage endplate : Its role in disc absorption

Study Design. A study of neovascularization with respect to the anulus and the endplate. Objectives. To determine the ability of the anulus and endplate to induce neovascularization and to study the effect of the endplate on the neovascularizing activity of the anulus. Summary of Background Data. Previous studies showed that herniations contain varying amounts of nucleus pulposus, anulus fibrosus, and endplate. Results of recent studies have shown preferential neovascularization around the herniated anulus rather than the endplate. Methods. Human L4-L5 discs were harvested from three specimens. In the left cornea of New Zealand White rabbits, an anulus (AF group) or an endplate (EP group) was implanted 4 mm from the superior corneoscleral limbus. In a third group (AF and EP group), an endplate was implanted between the anulus and the limbus. Twelve assays were done for each group. Sham surgeries were done on a fourth group as a control. Neovascularization was monitored by stereomicroscopy and scored from 0 (no neovascularization) to +5 (capillaries growing around the implant). Histologic studies were done at weekly intervals. Results. In the AF group, the anulus induced neovascularization in 11 of 12 corneas. By the third week, the anulus appeared thinner, and the newly formed vessels regressed. In the EP group, only two corneas showed neovascularization; 10 corneas showed no vascularization. In the AF and EP group, three corneas showed no neovascularization, seven had unsustained neovascularization, and two had vascularization. In the corneas containing the endplates, the implants remained unchanged. Control corneas did show vascularization. Histologic sections showed that neovascularization and cell infiltration were most abundant in the AF group, followed by the AF&EP and the EP groups. Conclusion. The reactions to anulus fibrosus and to cartilage endplate differ. Anulus fibrosus may contain soluble substances that induce neovascularization, leading to its degradation and absorption. Cartilage endplate fails to induce neovascularization or diminishes the neovascular response, preventing its degradation. Disc herniations that contain a significant amount of endplate may not be degraded nor absorbed, leading to failure in spontaneous remission of symptoms.

Neurological complications of cervical laminoplasty for patients with ossification of the posterior longitudinal ligament - A multi-institutional retrospective study

Study Design. Retrospective multi-institutional study. Objective. To investigate the incidence of neurological deficits after cervical laminoplasty for ossification of the posterior longitudinal ligament (OPLL). Summary of Background Data. According to analysis of long-term results, laminoplasty for cervical OPLL has been reported as a safe and effective alternative procedure with few complications. However, perioperative neurological complication rates of laminoplasty for cervical OPLL have not been well described. Methods. Subjects comprised 581 patients (458 men and 123 women; mean age: 62 ± 10 years; range: 30–86 years) who had undergone laminoplasty for cervical OPLL at 27 institutions between 2005 and 2008. Continuous-type OPLL was seen in 114, segmental-type in 146, mixed-type in 265, local-type in 24, and not judged in 32 patients. Postoperative neurological complications within 2 weeks after laminoplasty were analyzed in detail. Cobb angle between C2 and C7 (C2/C7 angle), maximal thickness, and occupying rate of OPLL were investigated. Pre- and postoperative magnetic resonance imaging was performed on patients with postoperative neurological complications. Results. Open-door laminoplasty was conducted in 237, double-door laminoplasty in 311, and other types of laminoplasty in 33 patients. Deterioration of lower-extremity function occurred after laminoplasty in 18 patients (3.1%). Causes of deterioration were epidural hematoma in 3, spinal cord herniation through injured dura mater in 1, incomplete laminoplasty due to vertebral artery injury while making a trough in 1, and unidentified in 13 patients. Prevalence of unsatisfactory recovery not reaching preoperative level by 6-month follow-up was 7/581 (1.2%). Mean occupying rate of OPLL for patients with deteriorated lower-extremity function was 51.2 ± 13.6% (range, 21.0%–73.3%), significantly higher than the 42.3 ± 13.0% for patients without deterioration. OPLL thickness was also higher in patients with deterioration (mean, 6.6 ± 2.2 mm) than in those without deterioration (mean, 5.7 ± 2.0 mm). No significant difference in C2/C7 lordotic angle was seen between groups. Conclusion. Although most neurological deterioration can be expected to recover to some extent, the frequency of short-term neurological complications was higher than the authors expected.

Descending aortic injury by a thoracic pedicle screw during posterior reconstructive surgery: a case report.

Study Design. Case report. Objective. To describe an iatrogenic aortic injury by pedicle screw instrumentation during posterior reconstructive surgery of spinal deformity. Summary of Background Data. Iatrogenic major vascular injuries during anterior instrumentation procedures have been reported by several authors, but there have been few reports regarding iatrogenic major vascular injuries during posterior instrumentation procedures. Methods. A 57-year-old woman with thoracolumbar kyphosis due to osteoporotic T12 vertebral fracture underwent posterior correction and fusion (T10–L2), using segmental pedicle screw construct concomitant with T12 pedicle subtraction osteotomy. Postoperative routine plain radiographs and computed tomography myelography demonstrated a misplaced left T10 pedicle screw, which was in contact with the posteromedial aspect of the thoracic aorta, and suspected penetration of the aortic wall. The patient underwent removal of the pedicle screw, and repair of the penetrated aortic wall through a simultaneous anterior-posterior approach. Result. The patient tolerated the procedure well without neurologic sequelae, and was discharged several days after removal of a left tube thoracostomy. Plain radiographs demonstrated solid fusion at the osteotomy site and no loosening of hardware. Preoperative neurologic symptoms improved completely at 18-months follow-up. Conclusion. Use of pedicle screw instrumentation has the potential to cause major vascular injury during posterior spinal surgery, and measures to prevent this complication must be taken. Timely diagnosis and treatment are essential to prevent both early and delayed complications and death.

Traumatic spinal cord injury: a neuropathological study on the longitudinal spreading of the lesions

Abstract Eight patients died after traumatic spinal cord injuries. At autopsy, neuropathological examination revealed longitudinal spreading of cord lesions in two of these patients. One developed progressive paralysis 43 h after fracture of the fifth cervical (C5) vertebra and died 38 days after injury. Necrotic lesions extended upward to the medulla oblongata and downward to the C7 cord segment. Pencil-shaped necrosis (C7–T4) and marginal spongiosis (C7–T2) were also found. A second patient died 5 months after C5 subluxation with tetraplegia. His spinal cord was severely compressed at C4/5 and pencil-shaped necrosis, which had become partially cystic, extended upward to C3 and downward to T1; marginal spongiosis was also found in C4–C5. In both cases, complete necrosis without cell reaction was found in several cord segments, including the initially impacted segment. These findings suggest that intra- and extramedullary circulatory impairment occurred not only at the initial impact level, but also in the adjacent levels. Increased intramedullary pressure, resulting from this circulatory disturbance, in combination with a narrowed spinal canal, may induce the upward and downward spreading of the lesion.

Sciatica caused by cervical and thoracic spinal cord compression.

STUDY DESIGN Two case reports of sciatica that was considered to be caused by cervical and thoracic spinal cord compression. OBJECTIVES To point out that sciatica can be an initial major symptom in patients with cervical or thoracic spinal cord lesions. SUMMARY OF BACKGROUND DATA Usually, tract pain caused by cord compression is considered to be diffuse and does not resemble sciatica. METHODS Medical history, physical findings, and the results of imaging studies were reviewed in one case of cervical cord tumor and one case of thoracic kyphosis. RESULTS In both cases, sciatica was the initial and major symptom. Imaging studies showed no lesion in the lumbar spine. In one patient, a cervical dumbbell tumor was found to compress the cervical cord, and in the other the spinal cord was severely compressed at the thoracic kyphosis. The sciatica disappeared immediately after decompression surgery in both cases. CONCLUSIONS Leg pain resembling sciatica can be caused by cord compression at the cervical and thoracic level. Thoracic kyphosis may be a causative factor in sciatica, in addition to spinal cord tumor and disc herniation, which have been reported previously.

Is angiomatosis an intrinsic pathohistological feature of massive osteolysis? Report of an autopsy case and a review of the literature.

We report here an autopsied patient who had died during the clinical course of massive osteolysis (MO), which is a rare chronic disease that begins insidiously and is characterized by progressive regional loss of bone. Since the original description by Gorham and Stout in 1955, vascular proliferation, e.g., hemangiomatosis, has been considered to be the characteristic feature related to the pathogenesis. However, no such vascular changes were observed in the present patient. It was also important to note that a significant number of cases of MO that showed no vascular proliferation have been described previously. Therefore, we consider that vascular proliferation is not always associated with the osteolysis in MO and that the increased vascularity, if any, may be one of the results of the disease rather than the cause.