THE ROLE OF MRI IN DIAGNOSIS OF FAILED BACK SURGERY SYNDROME F.B.S.S.

Abstract

Post - operative back pain and leg radiculopathy are non specific presentations of recurrent symptoms after lumbar disc operation in what is called failed back surgery syndrome (FBSS). The proper diagnosis of the causes of symptoms recurrence is very important and different methods are used for it.

The most common causes of FBSS include epidural fibrosis, recurrent disc herniation, lateral stenosis, arachnoiditis and pseudomeningocoele. MR imaging plays a vital role in the evaluation of these patients. The anatomic information provided by imaging study together with the patients clinical presentation allows the choice of the proper surgical procedure if indicated. This should in turn diminish the number of cases of FBSS as diagnostic failure leads to surgical failure.

Although clinical assessment of the patients presenting with FBSS is non specific, the clinical presentation and time of appearance of recurrent symptoms may be helpful in some cases to reach accurate diagnosis as in the following:

Early and persistent postoperative radicular pain within the first two weeks, postoperative haematoma at the site of surgery can be suspected. MRI can diagnose the condition at this stage accurately due• to its tissue characterization.

In cases of postoperative infection especially discitis the clinical findings include severe recurrent back pain after relief of the initial symptoms. Recurrent pain is frequently accompanied by decreased back motion, muscle spasm and positive straight leg raising test. Only one third of these patients will have a substantial fever and mild leukocytosis which are unreliable indicators. Although elevation of ESR is uniformly present in discitis this test is non specific.