Abstract Purpose Thoracic disc herniation (TDH) is a spinal condition with significant clinical implications due to its proximity to the spinal cord and unique anatomical challenges. Despite advancements in imaging and surgical techniques, the relationship between herniation characteristics and clinical outcomes remains poorly understood. This study aims to analyze the clinical and radiological features of TDH in a large cohort of surgically treated patients, focusing on volumetric assessments and a novel classification system based on anatomical landmarks. Methods A retrospective review was conducted on 994 patients who underwent surgical treatment for TDH at a single institution over 20 years. Patient demographics, clinical presentations, and radiological characteristics were analyzed. Two systems were used to classify TDH based on radiologic axial area (A, B, and C) and radiologic laterality (central, unilateral, and bilateral, subscripted as X 0 , X 1, and X 2 , respectively). The ratio of hernia to canal volumes was calculated, and associations between hernia characteristics and symptoms were examined. Results The mean age was 49.2 years, with a slight female predominance (58.7%). Most herniations (71.5%) occurred in the lower thoracic spine, with T7-T8 being the most common level. Hernias were primarily central (67.4%) and filled an average of 45% of the spinal canal. Type B hernias (intermediate size) were the most frequent (48%), followed by the more prominent type C (32.6%) and the smaller type A (19.4%). Pain was reported by 99.1% of patients, with 65% describing it as severe. Motor deficits were present in 20.1% of patients, sensory deficits in 26.1%, and gait abnormalities in 18.2%. Larger hernias (types B and C) were associated with fewer motor and reflex impairments compared to smaller hernias (type A), potentially reflecting adaptive spinal cord remodeling. Unilateral lesions were linked to a higher likelihood of neurological deficits, while bilateral lesions were associated with increased pain and reduced gait impairment. Conclusions TDH presents with diverse clinical and radiological features. Despite their size, larger hernias have shown lower odds of neurological impairments, suggesting compensatory mechanisms. This study underscores the importance of volumetric assessments and systematic classification to better understand and manage TDH. Further research is needed to explore the natural history and long-term outcomes of TDH.
Vico et al. (Mon,) studied this question.