Clinical and radiographic features of adult calcified thoracic disc herniation: a retrospective analysis of 31 cases.

Purpose: To analyze the clinical and radiographic characteristics of calcified thoracic disc herniation (CTDH) and explore the possible pathogeneses.

Methods: This is a retrospective clinical review of prospectively collected imaging data based at a single institute from 2004 to 2021. Clinical and radiographic parameters of CTDH patients were retrospectively collected and analyzed.

Results: All 31 patients included presented thoracic myelopathy with a 17.05-month preoperative disease duration. Three (9.7%) patients had a history of trauma, and the rest had insidious onset. The average spinal canal ventral-occupying ratio was 74.90 ± 15.16%. The most prominent radiographic feature was the calcification of the nucleus pulposus in the intervertebral disc and the calcified lesion contiguous with the disc space protruding into the spinal canal. Three main imaging forms of CTDH were found: calcium-ringed lesion (5), heterogeneous calcification lesion (19), and homogeneous calcification lesion (7). The radiographic manifestations, intraoperative findings, and postoperative pathologies of the three subtypes were different. The calcium-ringed lesion type was younger and had a shorter preoperative duration and significantly lower mJOA score. A special case was observed conservatively for five years, which suggested that a heterogeneous lesion could progress to a homogeneous lesion.

Conclusions: Adult CTDH is a special thoracic disc disease with insidious onset, a long course, and a high spinal canal-occupying ratio. Calcium deposits in the spinal canal originate from the nucleus pulposus. The intraoperative findings and postoperative pathology of subtypes are different, which might indicate different pathological mechanisms.