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.

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.

A technique of covering the proximal nerve stump (PNS) has been reported as a preventative method or treatment for neuroma. However, its detailed pain relief mechanism remains unknown. We created a silicone tube model in which the PNS of the rat sciatic nerve was introduced into the tube, whereas the controls had no tube. The score of autotomy observed in the tube group was lower than that in the control group at 3 days to 2 weeks after surgery, which suggested that the silicone tube had pain-like behavior inhibitory action. To elucidate the mechanism of autotomy inhibition, immunohistochemistry and Toluidine blue staining were performed in the PNS. The increase in S-100-immunoreactivity (IR) including Schwann cells was inhibited at 1 week after surgery in the tube group, and the increase in the number of macrophages shown by ED-1-IR at 1, 2, and 4 weeks after surgery was similarly inhibited. Toluidine blue staining showed that the increase in the number of mast cells was inhibited at 1, 2, and 4 weeks after surgery and in the number of lymphocytes at 1 and 2 weeks after surgery in the tube group. Therefore, blocking of the infiltration of inflammatory cells into the PNS by the silicone tube was thought to be the mechanism of autotomy inhibition. To further explore details of this mechanism, the expression of nerve growth factor (NGF), production of which is induced by inflammatory cells and of the NGF receptor TrkA was examined in the PNS and the dorsal root ganglion using immunohistochemistry and a ribonuclease protection assay. In the PNS, the increase in NGF-IR was inhibited at 1, 2, and 4 weeks after surgery in the tube group, suggesting that this could be one of the pain-like behavior inhibitory effects. ß

angerhans cell histiocytosis sometimes involves the cervical spine and can be associated with collapse of the vertebral body 1 , but involvement of the atlas is rare. To the best of our knowledge, the cases of only eight patients with Langerhans cell histiocytosis of the atlas have been reported 2-8 .We report the cases of three patients with Langerhans cell histiocytosis of the atlas, two of whom appeared to have been successfully treated with low-dose chemotherapy. The patients and/or their parents were informed that information concerning the case would be submitted for publication.Case Reports ASE 1. An eleven-year-old boy had neck pain for two weeks followed by the development of persistent torticollis. The neck pain gradually increased, and the symptoms did not improve after the administration of antipyretic drugs. Two weeks after he began treatment, magnetic resonance imaging showed a destructive process within the lateral mass of C1, and the patient was referred to our hospital. The medical history was otherwise unremarkable.Four weeks after the onset of symptoms, the boy required walking aids because of severe neck pain and persistent torticollis; the neck was bent to the left side and slightly rotated to the right side. Physical examination revealed stiffness, pain upon motion of the cervical spine, and tenderness of the left upper cervical spine. There were no neurological deficits. Blood tests showed a slightly increased C-reactive protein level of 0.5 mg/dL (5 mg/L) (normal, 0.0 to 0.4 mg/dL [0 to 4 mg/ L]) and alkaline phosphatase of 414 U/L (normal range for an adult, 90 to 340 U/L), while the white blood-cell counts were within the normal range.Cervical radiographs showed torticollis of the cervical spine, and computed tomography demonstrated an osteolytic lesion in the left lateral mass of the atlas (Fig. 1). Magnetic resonance imaging confirmed a mass that was isointensive on the T1-weighted image and high-intensity on the T2-weighted image (Fig. 2). The mass was shown to be expanding to the outside of the atlas on the left side.With the patient under local anesthesia and in a prone position, a percutaneous needle biopsy was performed with computed tomography guidance (Fig. 3, A and B). The biopsy needle was inserted posterolaterally to the lesion. There were no complications, and the histologic findings were diagnostic of Langerhans cell histiocytosis (Fig. 3, C).After immobilization of the cervical spine with a collar, the pain and torticollis gradually improved. Low-dose chemotherapy with oral alternate-day prednisone (40 mg per square meter of skin per day) and weekly methotrexate (20 mg per square meter of skin once weekly) was administered for six months, and a cervical collar was worn for four months. No complications accompanied the chemotherapy. The symptoms resolved at twelve weeks, and computed tomography demonstrated partial bone-remodeling. No new symptoms occurred during the follow-up period of twenty-four months, and computed tomography scans made at the latest follow-up examinati...

Clinical and radiologic parameters were not significantly different between the 2 groups. This technique of MLF using either approach did not increase the dynamic % slip and showed favorable medium-term clinical results in cases of lumbar degenerative spondylolisthesis.