BackgroundNo prior reports have focused on spinal cord injury (SCI) characteristics or inflammation after destruction of the blood-spinal cord barrier by syringomyelia. This study aimed to determine the differences in syringomyelia-related central SCI between craniocervical junction (CCJ) syringomyelia and post-traumatic syringomyelia (PTS) before and after decompression. MethodsIn all, 106 CCJ, 26 CCJ revision and 15 PTS patients (mean history of symptoms, 71.5 +/- 94.3, 88.9 +/- 85.5, and 32.3 +/- 48.9 months) between 2015 and 2019 were included. The symptom course was analyzed with the American Spinal Injury Association ASIA and Klekamp-Samii scoring systems, and neurological changes were analyzed by the Kaplan-Meier statistics. The mean follow-up was 20.7 +/- 6.2, 21.7 +/- 8.8, and 34.8 +/- 19.4 months. ResultsThe interval after injury was longer in the PTS group, but the natural history of syringomyelia was shorter (p = 0.0004 and 0.0173, respectively). The initial symptom was usually paraesthesia (p = 0.258), and the other main symptoms were hypoesthesia (p = 0.006) and abnormal muscle strength (p = 0.004), gait (p < 0.0001), and urination (p < 0.0001). SCI associated with PTS was more severe than that associated with the CCJ (p = 0.003). The cavities in the PTS group were primarily located at the thoracolumbar level, while those in the CCJ group were located at the cervical-thoracic segment at the CCJ. The syrinx/cord ratio of the PTS group was more than 75% (p = 0.009), and the intradural adhesions tended to be more severe (p < 0.0001). However, there were no significant differences in long-term clinical efficacy or peripheral blood inflammation markers (PBIMs) except for the red blood cell (RBC) count (p = 0.042). ConclusionPTS tends to progress faster than CCJ-related syringomyelia. Except for the RBC count, PBIMs showed no value in distinguishing the two forms of syringomyelia. The predictive value of the neutrophil-to-lymphocyte ratio for syringomyelia-related inflammation was negative except in the acute phase.