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Outcome Following Concussion: Prospective Investigation into the Cumulative Effects of a Prior History of Brain Injury and a History of Repeated Sub-Concussive Injuries on Recovery


 
 
 To investigate the impact of patient history of repeated head injury (RHI) and mild traumatic brain injury (mTBI) on recovery from an acute concussion.
 
 
 
 There were 64 participants from 3 military installations treated for an acute concussion ( < 72 hours) and monitored at < 72 hours, 1 week, 1 month, 3 months, and 6 months. Participants had no concussion in the last year and no history of moderate/severe TBI. TBI history was based on the Ohio State University TBI Identification Method and limited to mTBI with loss of consciousness. Primary outcome was symptoms evaluated using the Neurobehavioral Symptom Inventory. A total of 33 participants completed the study.
 
 
 
 Participants were as follows: n = 12 TBI(-)/RHI(-); n = 6 TBI(+)/RHI(-); n = 9 TBI(-)/RHI(+); n = 6 TBI(+)/RHI(+). A multivariate ANOVA examining TBI/RHI group effect on symptoms was significant (F = 2.31, p = 0.010), whereby the TBI(+)/RHI(+) had higher symptom scores than other groups at < 72 hours, 1 week, and 6 months. At 1 month, TBI(+)/RHI(+) had more symptoms than the TBI(-)/RHI(+). At 3 months, the TBI(+)/RHI(+) had higher symptom scores than the TBI(-)/RHI(-) and the TBI(-)/RHI(+). The TBI(-)/RHI(+) did not differ from TBI(-)/RHI(-) except at 1 week where they had lower overall symptoms.
 
 
 
 Participants with an acute mTBI had more severe symptoms if they had RHI and a prior remote mTBI. The combination of these two factors had a negative impact on recovery for up to 6 months. RHI in the absence of TBI did not impact recovery.
