For all visits SBP patients completed the short–form of the McGill pain questionnaire (MPQ). The main component of the MPQ consists of 12 sensory and 4 affective descriptors, which are used to compute the sensory and affective scores respectively. Radiculopathy scores were quantified from pain locations that patients had shaded in with pencil on the MPQ form15 . Patients also completed the Positive Affect Negative Affect Score (PANAS), which includes 60 items and measures the two order scales for positive and negative affect. Depression scores were assessed using BDI. All questionnaires were given 1 hour prior to brain scanning. Pain and mood parameters for SBPp and SBPr and the differences between the two groups at visits 1 and 4 are presented in Supplementary Tables 2A and 2B.