title: Predictive factors for neurological deterioration after surgical decompression for thoracic ossified yellow ligament.
abstract: To investigate the rate and predictive factors of post-operative neurological deterioration in ossified yellow ligament (OYL) surgery.
  
  
  
  A retrospective review was conducted for all patients with thoracic OYL causing myelopathy requiring surgical decompression from January 1998 to December 2012. Clinical parameters under study included clinical presentation, distribution of OYL, pre-operative walking score, pre- and post-operative neurological status, status of intra-operative neurophysiological monitoring, and modified Japanese Orthopaedic Association (mJOA) score. Any complications were also recorded. All outcomes were measured at post-operative 1 week and at 2 years.
  
  
  
  A total of 26 patients were included in this study. Most patients (92.3%) had Frankel grade D pre-operatively. The rate of neurological deterioration was 15.4% and was correlated with the presence of dural tear, extra-dural hematoma and spinal cord injury. Pre-operative walking score was prognostic of patients' walking ability in the post-operative period. Intra-operative monitoring of Somatosensory Evoked Potentials (SSEP) was found to be useful for monitoring spinal cord injury in OYL surgery, with a positive predictive value of 100% and a negative predictive value of 92.3%. The false negative rate of a SSEP signal drop was only 7.7% CONCLUSIONS: This is the first study exploring risk factors for post-operative neurological deterioration after surgery for thoracic OYL. The rate of neurological deficit is not small and prognostic factors for poor outcome include poor pre-operative walking score, presence of intra-operative dural tear, extra-dural hematoma and spinal cord injury, and intra-operative drop of SSEP signal.
authors.affiliation: Department of Orthopaedics and Traumatology, The University of Hong Kong, Queen Mary Hospital, Professorial Block, 5th Floor, 102 Pokfulam Road, Hong Kong, SAR, China.
authors.forename: Chris Yuk Kwan
authors.initials: CYK
authors.lastname: Tang
authors.affiliation: Department of Orthopaedics and Traumatology, The University of Hong Kong, Queen Mary Hospital, Professorial Block, 5th Floor, 102 Pokfulam Road, Hong Kong, SAR, China. cheungjp@hku.hk.
authors.forename: Jason Pui Yin
authors.initials: JPY
authors.lastname: Cheung
authors.affiliation: Department of Orthopaedics and Traumatology, The University of Hong Kong, Queen Mary Hospital, Professorial Block, 5th Floor, 102 Pokfulam Road, Hong Kong, SAR, China.
authors.forename: Dino
authors.initials: D
authors.lastname: Samartzis
authors.affiliation: Department of Orthopaedics and Traumatology, The University of Hong Kong, Queen Mary Hospital, Professorial Block, 5th Floor, 102 Pokfulam Road, Hong Kong, SAR, China.
authors.forename: Ka Hei
authors.initials: KH
authors.lastname: Leung
authors.affiliation: Department of Orthopaedics and Traumatology, The University of Hong Kong, Queen Mary Hospital, Professorial Block, 5th Floor, 102 Pokfulam Road, Hong Kong, SAR, China.
authors.forename: Yat Wa
authors.initials: YW
authors.lastname: Wong
authors.affiliation: Department of Orthopaedics and Traumatology, The University of Hong Kong, Queen Mary Hospital, Professorial Block, 5th Floor, 102 Pokfulam Road, Hong Kong, SAR, China.
authors.forename: Keith Dip Kei
authors.initials: KDK
authors.lastname: Luk
authors.affiliation: Department of Orthopaedics and Traumatology, The University of Hong Kong, Queen Mary Hospital, Professorial Block, 5th Floor, 102 Pokfulam Road, Hong Kong, SAR, China. cheungmc@hku.hk.
authors.forename: Kenneth Man Chee
authors.initials: KMC
authors.lastname: Cheung
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019299:Decompression, Surgical; D004185:Disability Evaluation; D004388:Dura Mater / Q000293:injuries; D005260:Female; D006406:Hematoma; D006801:Humans; D017843:Ligamentum Flavum / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D051346:Mobility Limitation; D009460:Neurologic Examination; D009999:Ossification, Heterotopic / Q000150:complications*; D011183:Postoperative Complications; D012189:Retrospective Studies; D012678:Sensation Disorders / Q000209:etiology; D013117:Spinal Cord Compression / Q000601:surgery*; D013119:Spinal Cord Injuries; D013904:Thoracic Vertebrae / Q000601:surgery*
keywords: Neurological deterioration; Ossified yellow ligament; Surgery