Factor analysis of persistent postconcussive symptoms within a military sample with blast exposure

OBJECTIVE:: To determine the factor structure of persistent postconcussive syndrome symptoms in a blast-exposed military sample and validate factors against objective and symptom measures. SETTING:: Veterans Affairs medical center and military bases. PARTICIPANTS:: One hundred eighty-one service members and veterans with at least 1 significant exposure to blast during deployment within the 2 years prior to study enrollment. DESIGN:: Confirmatory and exploratory factor analyses of the Rivermead Postconcussion Questionnaire. MAIN MEASURES:: Rivermead Postconcussion Questionnaire, PTSD (posttraumatic stress disorder) Symptom Checklist-Civilian, Center for Epidemiological Studies Depression scale, Sensory Organization Test, Paced Auditory Serial Addition Test, California Verbal Learning Test, and Delis-Kaplan Executive Function System subtests. RESULTS:: The 3-factor structure of persistent postconcussive syndrome was not confirmed. A 4-factor structure was extracted, and factors were interpreted as reflecting emotional, cognitive, visual, and vestibular functions. All factors were associated with scores on psychological symptom inventories; visual and vestibular factors were also associated with balance performance. There was no significant association between the cognitive factor and neuropsychological performance or between a history of mild traumatic brain injury and factor scores. CONCLUSION:: Persistent postconcussive symptoms observed months after blast exposure seem to be related to 4 distinct forms of distress, but not to mild traumatic brain injury per se, with vestibular and visual factors possibly related to injury of sensory organs by blast.