title: Cervical spondylotic myelopathy: the relevance of the spinal cord back shift after posterior multilevel decompression. A systematic review.
abstract: OBJECTIVE
  Spinal cord back shift has been considered the desired end point of posterior decompression procedures for cervical spondylotic myelopathy (CSM). However, the association with postoperative outcomes has not been definitively demonstrated. The aim of this review is to obtain an overview of the current knowledge on the spinal back shift after posterior decompression to clarify the main controversial aspects and provide recommendations for further studies on the subject.
  
  
  METHODS
  A comprehensive quantitative review of the literature was performed. Bibliographic databases were searched using the following keywords: spinal cord drift, spinal cord shift, CSM, ossification of posterior longitudinal ligament, posterior decompression, laminoplasty, laminectomy and fusion.
  
  
  RESULTS
  Twelve eligible studies were included. The authors measured the spinal cord back shift in different ways, using the posterior edge, the center or the anterior margin of the spinal cord as reference points. Six studies analyzed the correlation between the spinal cord back shift and the recovery rate, but their results were discordant. The correlation between the posterior cord migration and cervical alignment was not confirmed in all studies.
  
  
  CONCLUSIONS
  There is a need for a consensus on the best way to measure the spinal cord back shift. The action of multiple factors on spinal cord back shift can explain the difference in the results collected from the studies. We recommend further studies to clarify the behavior of the spinal cord after posterior decompression and its clinical meaning.
authors.affiliation: Department of Orthopaedic and Trauma Surgery, Campus Bio-Medico University, Via Alvaro del Portillo, 200, 00128, Trigoria, Rome, Italy. denaro@unicampus.it.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Denaro
authors.affiliation: Department of Orthopaedic and Trauma Surgery, Campus Bio-Medico University, Via Alvaro del Portillo, 200, 00128, Trigoria, Rome, Italy.
authors.forename: Umile Giuseppe
authors.initials: UG
authors.lastname: Longo
authors.affiliation: Department of Orthopaedic and Trauma Surgery, Campus Bio-Medico University, Via Alvaro del Portillo, 200, 00128, Trigoria, Rome, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Berton
authors.affiliation: Department of Orthopaedic and Trauma Surgery, Campus Bio-Medico University, Via Alvaro del Portillo, 200, 00128, Trigoria, Rome, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Salvatore
authors.affiliation: Department of Neurosurgery, University-Hospital of Padua, Via Giustiniani, 5, Padua, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Denaro
mesh_terms: D002574:Cervical Vertebrae / Q000601:surgery*; D019299:Decompression, Surgical / Q000379:methods*; D006801:Humans; D019637:Orthopedic Procedures / Q000379:methods*; D013118:Spinal Cord Diseases / Q000209:etiology / Q000503:physiopathology / Q000601:surgery*; D055009:Spondylosis / Q000150:complications / Q000503:physiopathology / Q000601:surgery*; D016896:Treatment Outcome
keywords: Cervical spondylotic myelopathy; Laminectomy and fusion; Posterior decompression; Spinal cord shift