A systematic review of the spectrum of magnetic resonance imaging features of degenerative thoracic myelopathy

Purpose. Degenerative thoracic myelopathy (DTM) encompasses a range of degenerative pathologies associated with symptomatic spinal cord compression. Diagnosis is achieved through clinical history, examination, and magnetic resonance imaging (MRI). A comprehensive review of the MRI features of DTM and their clinical significance is currently lacking. The objective was therefore to synthesise current evidence. Methods. A systematic review was performed adhering to PRISMA guidelines. MEDLINE and Embase were searched. Screening, data extraction and risk of bias assessments were performed in duplicate. A qualitative synthesis was conducted following the Synthesis Without Meta-Analysis (SWiM) guidelines. Results. Of 7937 records, 59 papers studying 2940 patients satisfied inclusion criteria, including one cross-sectional and 58 cohort studies. DTM was most common in the lower thoracic spine (62.5%, 880/1409), with a roughly equal prevalence in the upper (18.2%, 256/1409) and middle regions (19.4%, 273/1409). Ossification of the ligamentum flavum (OLF) was the most common pathology (71.4%, 2065/2893), followed by intervertebral disc herniation (20.1%, 582/2893) and ossification of the posterior longitudinal ligament (OPLL) (19.7%, 569/2893). Measurements of spinal canal compromise were described in 55.5% of patients (1631/2940) and spinal cord signal change in 30.0% (881/2940). Spinal canal compromise, spinal cord signal change, OLF, OPLL and multilevel disease were associated with greater DTM severity and poorer functional recovery. Conclusion. Ligamentous pathologies are significantly more prevalent than disc related pathologies in the DTM literature. Spinal cord signal change and extent of spinal canal compromise correlate with clinical outcomes. Standardisation of terminology for imaging features and study design are required to improve future research.