The improvement of preclinical emergency medicine, better surgical and conservative therapies, and the development of intensive care units and specialized centers have improved the survival rate for patients with serious spinal cord injuries. Therefore, more sequelae of chronic spinal cord injuries such as post-traumatic spinal cord cavitations also occur. The first such case was described by Bastian in 1867. Generally, these cavitations were diagnosed from 2 months up to 32 years after the trauma. The overall prevalence of post-traumatic syringomyelia (PTS) is not known; however, with the increasing use of magnetic resonance imaging (MRI), its diagnosis has increased, ranging from 2.3% of paraplegic and tetraplegic patients in 1976 and 3.2% in 1985, to nearly 50% in a selected group of patients in 1991 and 1993. In 1995, a 4.45% incidence was reported. In our clinic we are currently treating 440 cases of syringomyelia, 140 of which are PTS. Several observations suggest more than one potential mechanism for the evolution of a post-traumatic cyst or PTS. Various factors, such as hemorrhage or, in particular, ischemia within the spinal cord, blockage of the cerebrospinal fluid (CSF) pathways around the cord or localized meningeal fibrosis either alone or in combination with other factors, may be involved. Clinically, sensory disturbances, loss of motor function, pain, and modification of the deep tendon reflexes are observed in most patients. On MRI, PTS is seen as a longitudinal, cystic cavity within the spinal cord, giving a hypointense signal on T1-weighted images and a hyperintense signal on T2-weighted images. For treatment planning it is mandatory to identify the lower and upper end of the PTS on the MRI.