title: Traumatic atlantooccipital dislocation: comprehensive assessment of mortality, neurologic improvement, and patient-reported outcomes at a Level 1 trauma center over 15 years.
abstract: BACKGROUND
  Only Level 3 evidence exists for the diagnosis and treatment of atlantooccipital dislocation (AOD) with few studies examining mortality, neurologic improvement, and patient-reported outcomes (PROs).
  
  
  OBJECTIVE
  First, the aim was to determine: the incidence of AOD, 90-day surgical morbidity and mortality after AOD, patient factors that may be associated with delayed or missed diagnosis, and factors that were associated with mortality and neurologic improvement after AOD. Secondly, the aim was to quantify the pain, disability, and quality of life experienced by patients surviving AOD.
  
  
  METHODS
  This was a retrospective cohort study.
  
  
  METHODS
  A total of 5,337 consecutive spine computed tomography traumagrams from 1997 to 2012 were included.
  
  
  METHODS
  Mortality, neurologic improvement, complications, EuroQol five dimensions (EQ-5D), Neck Disability Index (NDI), Numeric Rating Scale (NRS)-neck, NRS-arm, and return-to-work were the outcome measures.
  
  
  METHODS
  Patients were considered to have AOD if they met one of the following radiographic criteria: basion-dens interval greater than 10 mm; basion-axial interval: anterior displacement greater than 12 mm or posterior displacement greater than 4 mm between the basion and posterior C2 line; and condyle to C1 interval greater than 1.4 mm. Linear regression analysis was performed to identify factors associated with 90-day mortality, neurologic improvement, and missed diagnosis. Patient-reported outcomes were assessed via phone interview.
  
  
  RESULTS
  Thirty-one patients met radiographic criteria for AOD; an incidence of 0.6% over 15 years. Twenty-one (68%) patients were treated with occipital cervical fusion. At 90 days postoperatively, there were no new neurologic deficits or reoperations. Eight (26%) patients died within 90 days. All patients who died had no documented AOD diagnosis and were not treated surgically. Missed AOD diagnosis was the strongest predictor of mortality. Younger age, lower Glasgow Coma Score, lower Injury Severity Score (ISS) score, and worse initial American Spinal Injury Association (ASIA) score were significantly associated with greater neurologic improvement. Higher ISS score and better ASIA score were significantly associated with missed AOD diagnosis. The average PROs metrics at time of telephone follow-up were as follows: EQ-5D=0.73±0.19, NDI=30.89±18.57, NRS-neck=2.33±2.21, NRS-arm=2.00±2.54. Of the patients with follow-up data, four were employed full-time, and five were receiving disability.
  
  
  CONCLUSIONS
  Our work suggests that failure to diagnose AOD is a powerful predictor of mortality. Higher ISS scores and better neurologic presentation were significantly associated with missed diagnosis. Craniocervical arthrodesis preserved neurologic function with low complication rate and unexpectedly high PROs and return-to-work. These results must be carefully interpreted because it is unclear whether missed AOD diagnosis accompanies another death-causing injury (eg, traumatic brain injury) or if failure to treat AOD contributes to mortality in a multifactorial manner.
authors.affiliation: Department of Neurological Surgery, Vanderbilt University Medical Center, T-4224 Medical Center N., 1611 21st Ave. S., Nashville, TN 37232, USA.
authors.forename: Stephen K
authors.initials: SK
authors.lastname: Mendenhall
authors.affiliation: Department of Neurological Surgery, Vanderbilt University Medical Center, T-4224 Medical Center N., 1611 21st Ave. S., Nashville, TN 37232, USA.
authors.forename: Ahilan
authors.initials: A
authors.lastname: Sivaganesan
authors.affiliation: Department of Neurological Surgery, Vanderbilt University Medical Center, T-4224 Medical Center N., 1611 21st Ave. S., Nashville, TN 37232, USA.
authors.forename: Akshitkumar
authors.initials: A
authors.lastname: Mistry
authors.affiliation: Department of Orthopedic Surgery, Vanderbilt University Medical Center, 1215 21st Ave. S. #4200, Nashville, TN 37232, USA.
authors.forename: Priya
authors.initials: P
authors.lastname: Sivasubramaniam
authors.affiliation: Department of Neurological Surgery, Vanderbilt University Medical Center, T-4224 Medical Center N., 1611 21st Ave. S., Nashville, TN 37232, USA; Carolina Neurosurgery and Spine Associates, 225 Baldwin Ave., Charlotte, NC 28204, USA.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: McGirt
authors.affiliation: Department of Orthopedic Surgery, Vanderbilt University Medical Center, 1215 21st Ave. S. #4200, Nashville, TN 37232, USA. Electronic address: clintondevin@gmail.com.
authors.forename: Clinton J
authors.initials: CJ
authors.lastname: Devin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001269:Atlanto-Occipital Joint / Q000293:injuries* / Q000601:surgery; D005260:Female; D006801:Humans; D004204:Joint Dislocations / Q000453:epidemiology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D013123:Spinal Fusion / Q000009:adverse effects / Q000706:statistics & numerical data*; D013124:Spinal Injuries / Q000453:epidemiology / Q000601:surgery*; D014193:Trauma Centers / Q000706:statistics & numerical data*
keywords: Cervical spine; Craniocervical junction; Diagnosis; Outcomes; Trauma; Treatment