Study Design.Prospective longitudinal study.Objective.The aim of this study was to evaluate long-term degenerative changes in intervertebral discs in the thoracic spine in healthy asymptomatic subjects.Summary of Background Data.Longitudinal magnetic resonance imaging (MRI) studies of intervertebral disc degeneration have been reported for the cervical and lumbar but not the thoracic spine.Methods.In this longitudinal study (average follow-up 10.0 ± 0.6 years), we assessed degenerative changes in the thoracic spine of 103 volunteers (58 men) of 223 healthy volunteers in the initial MRI study of the thoracic spine (follow-up rate 46.2%). The mean age at the initial study was 45.0 ± 11.5 years (24-77 years). Initial and follow-up thoracic-spine MRIs were graded for the following 4 factors of degenerative changes: decrease in signal intensity of intervertebral disc (DSI), posterior disc protrusion (PDP), anterior compression of dura and spinal cord (AC), and disc-space narrowing (DSN) from T1-2 to T12-L1. We assessed associations between changes in MRI grade and demographical factors such as age, sex, body mass index, smoking habits, sports activities, and disc degeneration in the cervical spine.Results.MRIs revealed that 63.1% of the subjects had degenerative changes in the thoracic intervertebral discs that had progressed at least one grade during the follow-up period. DSI progressed in 44.7% of subjects, PDP in 21.4%, and AC in 18.4% during the 10-year period. No DSN progression was seen. DSI was frequently observed in the upper thoracic spine (T1-2 to T4-5). Disc degeneration was relatively scarce in the lower thoracic spine (T9-10 to T12-L1). PDP was frequently observed in the middle thoracic spine (T5-6 toT8-9). We found significant associations between DSI and cervical-spine degeneration (P = .004) and between AC and smoking (P = .04).Conclusion.Progressive thoracic disc degeneration, observed in 63.1% of subjects; was significantly associated with smoking and with cervical-spine degeneration.Level of Evidence: 2.
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