title: Recurrent adjacent segment disease and cauda equina syndrome.
abstract: OBJECTIVE
  A case of cauda equina lesion as a result of recurrent adjacent segment degeneration (ASD) after multiple lumbar fusions is reported. ASD might be a consequence of biomechanical overload or simply a normal degenerative process. The reported clinical relevance of ASD is rather low. We describe an unusual case of cauda equina compression at L1-L2 in a patient who had undergone L2-L4 fusion 8 years previously and 2 decompression-fusion surgeries 16 years before.
  
  
  METHODS
  A 72-year-old man, who had two previous lumbar fusion-decompression procedures, underwent a third lumbar surgery in December 2000 to treat symptomatic spinal canal stenosis associated with L3-L4 pseudoarthrosis. After a symptom-free period of 8 years, the patient experienced low back pain radiating to both legs while standing, associated with saddle sensory disturbances and incontinence. Physical examination ruled out significant motor deficits. Plain radiographs showed solid fusion from L2 to L4, good spinal alignment, and low-grade L1-L2 retrolisthesis. Stainless steel pedicular instrumentation distorted magnetic resonance imaging, preventing adequate spinal canal evaluation. Electromyography demonstrated signs of cauda equina compression (bilateral L3-S2). CT myelography showed a stop at L1-L2, due to a severe spinal canal stenosis. L1-L2 decompression and fusion were performed.
  
  
  RESULTS
  After an uneventful surgery with no complications, the symptoms abated and incontinence recovered.
  
  
  CONCLUSIONS
  Even if the reported clinical relevance of ASD is very low, fused patients with a constitutional narrow spinal canal are at risk of developing severe neural compression at the level adjacent to the fusion.
authors.affiliation: Unitat d'estudi de la Patologia del Raquis, Hospital Universitari Vall d'Hebron, Pg/Vall d'Hebron 119-129, 08035 Barcelona, Spain. xaviconesa@hotmail.com
authors.forename: Xavier
authors.initials: X
authors.lastname: Conesa
authors.forename: Ferran
authors.initials: F
authors.lastname: Pellisé
authors.forename: Susana
authors.initials: S
authors.lastname: Núñez
authors.forename: Carlos
authors.initials: C
authors.lastname: Villanueva
authors.forename: Enric
authors.initials: E
authors.lastname: Cáceres
mesh_terms: D000368:Aged; D002420:Cauda Equina / Q000000981:diagnostic imaging / Q000601:surgery; D019299:Decompression, Surgical; D006801:Humans; D017116:Low Back Pain / Q000000981:diagnostic imaging / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D011128:Polyradiculopathy / Q000000981:diagnostic imaging / Q000601:surgery*; D011859:Radiography; D012008:Recurrence; D013123:Spinal Fusion; D013130:Spinal Stenosis / Q000000981:diagnostic imaging / Q000601:surgery*; D016896:Treatment Outcome