Traumatic Brain Injury in Spinal Cord Injury: Frequency and Risk Factors

Abstract

Background: The frequency of traumatic brain injury (TBI) co-occurring with traumatic spinal cord injury (tSCI) is unclear despite a number of past studies; as well, limited research has examined predictors of co-morbid TBI in tSCI patients.

Objectives: (1a) To summarize past literature on comorbid diagnosis of TBI in tSCI in order to reexamine the frequency of dual diagnosis in a study designed to obviate past methodological limitations; (1b) to compare dual-diagnosis frequency with vs without the inclusion of diagnostically ambiguous cases; and (2) to measure risk factors for tSCI and comorbid TBI.

Methods: Ninety-one of 135 eligible adults with tSCI, 3 to 6 months postinjury, were prospectively recruited from a tertiary inpatient tSCI rehabilitation program. TBI diagnosis was based on comprehensive, validated clinical neurological and neuroimaging measures.

Results: Objective 1: 39.6% of the tSCI patients sustained a concomitant TBI, but when ambiguous cases were removed from analysis, frequency rose to 58.1%. Objective 2: Motor vehicle collisions were most likely to yield a comorbid TBI diagnosis, but 31.6% of falls also resulted in TBI. Patients with cervical and thoracic injuries showed a very similar frequency of comorbid TBI.

Conclusions: Varied methodological approaches, particularly the decision to include/exclude ambiguous cases, likely explain disparate past estimates of TBI in tSCI. However, even this study's lower frequency estimate, at nearly 40%, is clinically important. The prevailing assumption that dual diagnosis is less common in thoracic than cervical spine injuries was not supported. Finally, while comorbid TBI most frequently occurred in motor vehicle collisions, nearly a third of tSCIs sustained in falls resulted in comorbid TBI in our sample.