Clinical Features of Thoracic Spinal Stenosis-associated Myelopathy A Retrospective Analysis of 427 Cases

Study Design: This was a retrospective review. Objective: The aim of this study was to examine the epidemiological characteristics and causes of spinal cord compression in thoracic spinal stenosis (TSS). Summary of Background Data: As the thoracic spinal canal is relatively narrow and the thoracic cord has a poor blood supply, severe neurological symptoms may develop if TSS is not treated promptly. However, as it is rare, TSS is less often studied and its clinical features are often not recognized. Methods: Between 2005 and 2012, 427 patients diagnosed with TSS underwent surgery in our department. The male to female ratio was 1.4:1. The mean age was 53 years. The most reported symptom was motor deficit in the lower extremities (347 cases, 81%), followed by sensory deficit in the lower limbs (271 cases, 64%). Falls were the most common trigger of acute symptoms (29 cases, 7%). Preoperative imaging results of each case were reviewed to summarize the causes and site of cord compression and coexisting spinal diseases. Results: The most reported compressive factor was ossification of the ligamentum flavum (OLF), which implicated in 309 cases, followed by thoracic disk herniation (TDH) and ossification of the posterior longitudinal ligament (OPLL). The most common site of OLF and TDH was T9-L1 (56% and 89%, respectively), whereas OPLL was mainly found at T1-8 (90%). Forty-seven patients (11%) had coexisting lumbar spinal disease and 64 (15%) had cervical disease. Conclusions: Onset of TSS was generally insidious but may be triggered acutely by apparently trivial events. Myelopathy mainly affected the lower limbs. The most common cause was OLF in the lower thoracic spine. Cervical or lumbar spinal disease was often also evident; therefore, comprehensive clinical assessment is required to avoid delays in diagnosis and treatment.