title: Sacral malformations: use of imaging to optimise sacral nerve stimulation.
abstract: BACKGROUND
  The success of sacral nerve stimulation, a common treatment for pelvic floor disorders, depends on correct placement of the electrodes through the sacral foramina. When the bony anatomy and topography of the sacrum and sacral spinal nerves are intact, this is easily achieved; where sacral anomalies exist, it can be challenging. A better understanding of common sacral malformations can improve the success of sacral nerve stimulation (SNS) electrode placement.
  
  
  METHODS
  We reviewed 998 consecutive MRI scans performed to investigate low back pain in patients who had undergone CT and/or X-ray.
  
  
  RESULTS
  Congenital sacral malformations were found in 24.1%, the most common being sacral meningeal cysts (16%) and spina bifida occulta (9.9%). Others were lumbosacral transitional vertebrae (2.5%), anterior occult meningocele (0.5%), partial sacral agenesis (0.2%) and vertebral dysplasia of S1 (0.2%).
  
  
  CONCLUSIONS
  This radiologic review uncovered a high incidence of sacral malformations, and most were asymptomatic. All surgeons who perform SNS should have a basic understanding of sacral malformations, their incidence and effect on foraminal anatomy. Imaging will aid procedural planning.
authors.affiliation: Department of Anatomy, Faculty of Medicine, University of Porto, Porto, Portugal. anapovo@sapo.pt.|Centro Integrado de Cirurgia Ambulatório Centro Hospitalar do Porto, Porto, Portugal. anapovo@sapo.pt.|Department of Anatomy (Faculdade de Medicina Universidade do Porto), Alameda Professor Hernâni Monteiro, 4200-319, Porto, Portugal. anapovo@sapo.pt.
authors.forename: A
authors.initials: A
authors.lastname: Povo
authors.affiliation: Department of Anatomy, Faculty of Medicine, University of Porto, Porto, Portugal.|Instituto Português de Oncologia, Porto, Portugal.
authors.forename: M
authors.initials: M
authors.lastname: Arantes
authors.affiliation: Department of Surgery, University of Erlangen, Erlangen, Germany.
authors.forename: K E
authors.initials: KE
authors.lastname: Matzel
authors.affiliation: Center for Medical Education, Faculty of Medicine, University of Porto, Porto, Portugal.
authors.forename: J
authors.initials: J
authors.lastname: Barbosa
authors.affiliation: Department of Anatomy, Faculty of Medicine, University of Porto, Porto, Portugal.
authors.forename: M A
authors.initials: MA
authors.lastname: Ferreira
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D058070:Asymptomatic Diseases; D004599:Electric Stimulation Therapy / Q000379:methods*; D004566:Electrodes; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012447:Sacrum / Q000002:abnormalities* / Q000000981:diagnostic imaging / Q000294:innervation*; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: Imaging anatomy; Sacral malformations; Sacral nerve stimulation; Sacral plexus; Sacrum