MR Neurography of Lumbosacral Plexus in Failed Back Surgery Syndrome

Retrospective clinical case series. To study the role of MRN of lumbosacral plexus in management of patients with FBSS. Failed back surgery syndrome (FBSS) is one of the major problems in health care, affecting up to 40% of patients following spine surgery. To date, no imaging modality has been used to effectively classify nerve compression, since nerve injuries are challenging to detect on conventional lumbar spine MRI. To our knowledge, no previous studies have addressed the use of MR Neurography (MRN) in FBSS or compared it to lumbar spine MRI. From 203 consecutive 3T MRN studies of lumbosacral plexus in one year, 12% (25/203) presented as FBSS. Demographic data, number of previous lumbar MRIs and their findings, MRN findings, interval between MRI and MRN, pre-and post-MRN diagnosis, pain levels, and treatments were recorded. Changes in diagnosis, treatment and outcomes following MRN were determined. The final sample of 25 patients had a mean age 62 ± 15 and male to female ratio 1:1.08. 88% (22/25) had previous lumbar MRI, of which 27% had 3 or more. Most common imaging findings were neuroforaminal stenosis 22.6% (7/31) on MRI and neuropathy 22.9% (19/83) on MRN. Mean interval between MRI and MRN was 13.9 ± 28.3 months. Lumbar MRIs were inconclusive in 36% (8/22). MRN detected 63% (52/83) more findings and changed the diagnosis and treatment in 12% and 48% of FBSS cases, respectively. Favorable outcomes were recorded in 40-67% of patients following MRN guided treatments. FBSS is a complex problem and MRN of lumbosacral plexus impacts its management by better directing source of symptoms. 4.