title: Cauda equina syndrome presentation of sacral insufficiency fractures.
abstract: BACKGROUND
  Sacral insufficiency fractures are a well recognised cause for low back, buttock and groin pain in the elderly. However, over a 4 year period, four patients have presented with symptoms of cauda equina syndrome, who were found on investigation to have acute sacral insufficiency fracture without any other aetiological spinal abnormality.
  
  
  METHODS
  Four patients who presented to the spinal surgeons of our institution with symptoms of cauda equina syndrome were referred for spinal MR. Sagittal and axial T1 and T2 weighted turbo spin echo sequences of the lower thoracic and lumbar spine were performed on all patients. Subsequent studies included MR of the sacrum supplemented where appropriate by CT and technetium MDP bone scintigraphy.
  
  
  RESULTS
  No evidence of a compressive lesion of the lower thoracic or lumbar spine was present in any of the four patients. Dedicated MR examination of the sacrum in these patients revealed unilateral acute insufficiency fractures involving zone 1 from S1 to S3 extending from the sacro-iliac joint to the lateral margin of the sacral foramen. There was no evidence of compression of the sacral nerve roots. The possible mechanism for the symptomatic presentation is discussed.
  
  
  CONCLUSIONS
  Sacral insufficiency fractures should be excluded in elderly or osteoporotic patients presenting with cauda equina syndrome who have no evidence of compression in the thoraco-lumbar MR studies.
authors.affiliation: Department of Radiology, The Robert Jones and Agnes Hunt Orthopaedic Hospital, Oswestry, Shropshire SY10 7AG, UK.
authors.forename: T
authors.initials: T
authors.lastname: Muthukumar
authors.forename: S H
authors.initials: SH
authors.lastname: Butt
authors.forename: V N
authors.initials: VN
authors.lastname: Cassar-Pullicino
authors.forename: I W
authors.initials: IW
authors.lastname: McCall
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001416:Back Pain / Q000209:etiology; D005260:Female; D015775:Fractures, Stress / Q000150:complications / Q000175:diagnosis*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008875:Middle Aged; D010024:Osteoporosis / Q000150:complications; D011128:Polyradiculopathy / Q000175:diagnosis* / Q000209:etiology; D011446:Prospective Studies; D012447:Sacrum / Q000000981:diagnostic imaging / Q000293:injuries* / Q000473:pathology; D016103:Spinal Fractures / Q000150:complications / Q000175:diagnosis*; D014057:Tomography, X-Ray Computed / Q000379:methods