Cauda equina syndrome with normal MR imaging.

The aim of this study was to compare the clinical characteristics of patients with and without abnormal MR imaging admitted to a neurosurgical unit with suspected cauda equina syndrome using a retrospective study of consecutive admissions to a regional neurosurgical unit over a 10-month period. Clinical details were obtained from the case notes. A lumbar spine MR scan to investigate possible cauda equina syndrome was performed in 66 patients. There were no significant differences between those with abnormal imaging (n = 34, 52%) and those with a normal scan (n = 32, 48%) in respect of sex, clinical history or features recorded on examination. Those with normal imaging had a high frequency of weakness (n = 18, 59%), saddle numbness (n = 17, 57%), leg numbness (n = 24, 80%), urinary incontinence (n = 13, 54%) and urinary retention (n = 9, 53%). A large number of patients present to neurosurgical units with symptoms suggestive of cauda equina syndrome without any radiological evidence of structural pathology. While some may have had an alternative organic cause, we propose that these symptoms may have a "functional" origin in many patients.