Imaging findings in patients with failed back surgery syndrome

The incidence of low back pain and leg pain related to the spine is very high in the Western population. As a result of conservative treatment failure there are roughly 200,000 lumbar disk operations performed annually. Unsuccessful surgical outcome is known as the failed back surgery syndrome (FBSS). FBSS is a complex and poorly understood syndrome, with as many different imaging findings as different possible etiologic mechanisms. Still we believe some imaging aspects deserve special attention. Firstly it is of particular importance to correctly differentiate residual disk herniation from epidural scar tissue since disk herniation can be an indication for repeat intervention. Secondly when residual disk herniation is present, one should keep in mind that it is not necessarily responsible for the patients complaints. Thirdly, late nerve root enhancement should be considered as pathological. Finally one should be aware of the mechanical back stress that may develop as a result of discectomy. One of the consequences can be secondary foraminal stenosis which is probably one of the most common causes of FBSS.