Pathologic features of spinal disorders in patients treated with long-term hemodialysis.

STUDY DESIGN

Pathologic features of hemodialysis-associated spinal disorders were evaluated using preoperative radiographic images and histologic findings of the spinal lesions resected during surgery.

OBJECTIVES

To investigate the pathology of hemodialysis-related spinal disorders and to determine the role of amyloidosis in the establishment of severe destruction of the spine.

SUMMARY OF BACKGROUND DATA

The pathologic events leading to hemodialysis-associated spinal disorders are poorly understood. The distribution of amyloid deposits in the spine also has not been clarified.

METHODS

Twenty patients with hemodialysis-associated spinal disorders were investigated regarding pathologic features of neural compression and spinal destruction. Preoperative radiographic images such as plain radiography, tomography, computed tomography, magnetic resonance imaging, and scintigraphy were assessed for the existence of an intracanal mass, hypertrophy of the ligamentum flavum, and destructive changes of the spinal components. Histologic examination also was conducted by light microscopy and scanning electron microscopy to determine the distribution pattern of amyloid deposits in the spinal components.

RESULTS

Six patients with no destructive changes in the spine showed spinal canal stenosis. In the cervical spine, a main factor associated with spinal canal stenosis was the presence of intracanal amyloid deposits in three patients. In the lumbar spine, a main factor associated with spinal canal stenosis was hypertrophied ligamentum flavum in three patients. Destructive changes of the facet joints, intervertebral disc, and vertebral body were seen in the other 14 patients. Amyloid deposits were densely distributed at the enthesis of capsular fibers to the bone and in anular tears in the intervertebral discs. Vertebral end plates were destroyed by penetration of amyloid granulation into the vertebral body. Osteoclast activity in the destroyed vertebral bodies was enhanced, with no evidence of new bone formation.

CONCLUSIONS

Amyloid deposits played an important role in the progression of spinal destruction and severe instability.