Systematic review of hearing loss after traumatic brain injury without associated temporal bone fracture

Objective: While hearing loss following temporal bone fracture is a well-described phenomenon, few data exist on auditory dysfunction in patients with traumatic brain injury (TBI) without temporal bone fracture. Herein, we aim to systematically review hearing loss after TBI without bony fracture and describe its etiologies. Data sources: Pubmed, Embase, Cochrane databases. Review methods: A systematic review of the literature from 1966 to January 2017 was performed using Preferred Reporting Items for Systematic Reviews and Meta-analyses recommendations. Data were obtained from studies that investigated hearing loss in TBI without skull fracture according to an a priori protocol with inclusion and exclusion criteria. Variables included type and severity of hearing loss, as well as pathophysiology of hearing loss. Results: There were 13 studies with 773 patients that met study criteria. Overall, there was one prospective cohort study, four retrospective cohort studies, two case-control studies, and six case reports. The studies with the highest level of evidence report a change in hearing of at least 10-15 dB across a range of frequencies in as many as 58% percent of TBI patients without bony fracture, which was transient or chronic. The mechanism/severity of injury may impact the rate of hearing loss. Conclusions: Hearing loss after TBI in the absence of bony injury appears to be a clinically significant but poorly characterized phenomenon.