Does a history of lumbar spine surgery predict radiological cauda equina compression in patients undergoing MRI for suspected cauda equina syndrome?

Background: The clinical symptoms and signs of Cauda equina syndrome (CES) are non specific and poorly predictive of cauda equina compression on MRI. We aimed to establish whether a history of lumbar spine surgery predicts cauda equina compression on MRI in those presenting with suspected CES. Methods: A retrospective electronic record review was undertaken of 276 patients referred with clinically suspected CES who underwent a lumbosacral spine MRI. Those with a history of prior lumbar surgery were compared to those without. The likelihood of cauda equina compression was compared between the two groups. Results: About 78/276 (28%) patients with suspected CES had radiological compression of the cauda equina and went on to surgical decompression. A total of 54 (20%) patients had undergone prior lumbar surgery. Patients with a history of lumbar surgery were less likely to have cauda equina compression on MRI (chi(2) - p = .035). Twenty six (9%) patients presented more than once with suspected CES. Patients with a history of lumbar surgery were more likely to re-present with suspected CES (chi(2) - p = .002). Conclusions: Prior lumbar surgery was associated with a higher frequency of re-presentation with clinically suspected CES but a lower frequency of radiological cauda equina compression.