The failed back syndrome: the diagnostic contribution of computed tomography.

Up to 30% of patients who undergo surgery for lumbar disc disease experience recurrent symptoms postoperatively.1 2 This so-called 'failed back syndrome' is a complex phenomenon influenced by organic, psychological, economic and social factors.3,4 Radiological examination is frequently requested in order to exclude-an anatomical basis for the patient's complaints3 (Table 1). Re -exploration in the presence of significant epidural scarring (fibrosis) from previous surgery may lead to further more severe scarring,5 although some surgeons may consider microsurgical lysis of scar tissue (DP Byrnes, personal communication). Neural compression due to recurrent disc protrusion or canal or lateral recess stenosis may be relieved surgically.',6 Accurate radiological diagnosis of these and other possible abnormalities is therefore of paramount importance,'17especially in view of the difficulties in performing re-exploration of the lumbar spine.