Occipitocervical dissociative injuries: common in blunt trauma fatalities and better detected with objective computed tomography-based measurements.

Background Context: Occipitocervical injuries (OCIs) are generally not common in blunt trauma victims, but autopsy studies of blunt trauma fatalities consistently report a high prevalence of these injuries. New computed tomography (CT)-based quantitative criteria have recently been developed for use in assessing the occipitocervical spine. The efficacy of these new criteria for detecting OCI would be supported if the high prevalence of OCI in blunt trauma fatalities can also be detected using these objective CT-based criteria.

Purpose: To test the hypothesis that the prevalence of OCI in blunt trauma fatalities, determined using objective CT-based measurements and reliable reference data, will be similar to the prevalence reported in prior autopsy studies.

Study Design/setting: Retrospective assessment of the CT examinations of blunt trauma fatalities at a Level 1 trauma center.

Patient Sample: Seventy-four consecutive patients who died within 21 days of blunt trauma and had a CT examination of the cervical spine.

Outcome Measures: Quantitative measurements from CT examinations of the occiput-C1 and C1-C2 levels.

Methods: Measurements were made on a Picture Archiving and Communication System (PACS) from the CT images that were originally used for diagnosis and also using imaging software that allowed for precisely reoriented slices that correct for variations in the alignment of the upper cervical spine. The prevalence of abnormal measurements found by each method and the interobserver reliability of the measurements were assessed.

Results: At least one abnormal measurement was found in 50% of cases based on measurements made on the PACS, and in 34% of cases using measurements from carefully reoriented images. At least three abnormal measurements were found in 22% and 14% of patients, respectively. Only one of the patients had been diagnosed as having an OCI before death. Interobserver reliability measurements of more than 80% were found for most measurements.

Conclusions: Using precise CT-based measurements and reliable reference data for diagnosis of occipitocervical dissociative injuries, the prevalence of injuries in severely injured blunt trauma patients was close to the levels reported in prior autopsy studies (approximately 30%). This supports that with careful measurements, both soft- and hard-tissue OCI can be detected by CT. This study is limited by the fact that a gold standard was not available to confirm the injuries.