Author’s response to reviews Title: Is a Persistent Central Canal a Risk Factor for Neurological Injury in Patients Undergoing Surgical Correction of Scoliosis? Authors:

Response: A central canal is defined in the opening of the discussion section (lines 196 – 199) as ‘The central canal is an ependymal lined structure in the spinal cord that extends inferiorly from the fourth ventricle to the conus medullaris. Anatomical studies suggest the central canal is only seen in fetal and new born spinal cords and undergoes age related stenosis such that it is obliterated in the vast majority of adults. It may persist however as shown in autopsy studies, and although reported to be seen in only 1.5% of MRI studies of the spinal cord it can normally be regarded as an incidental finding.’