Post-traumatic and post-arachnoiditic syringomyelia is described in 31 patients from the Midland Centre for Neurosurgery and Neurology (MCNN). It is suggested that the mechanisms may be similar in the two groups and that treatment is best directed to disabling the likely filling mechanisms by opening up the cerebrospinal fluid (CSF) pathways and deliberately leaving the dura open to create an artificial meningocele. It is suggested that drainage on its own is inappropriate but that when drainage of the syrinx is chosen as an ancillary technique then syringopleural drainage may be the procedure of choice.