Tympanic membrane perforation and hearing loss from blast overpressure in Operation Enduring Freedom and Operation Iraqi Freedom wounded.

BACKGROUND: Tympanic membrane perforation is the most common primary blast injury in the current conflicts and occurs in approximately one tenth of service members wounded by combat explosions. We wanted to determine the severity of perforation and its effect on hearing and combat readiness.

METHODS: This analysis is a retrospective study of US service members injured in combat explosions in Afghanistan or Iraq and treated at our institution between March 2003 and July 2006. Data captured included location and grade of perforation, symptoms, healing rates, audiogram results, need for hearing aids, and loss of eligibility for military service.

RESULTS: Of 436 explosion-wounded patients admitted to our facility, 65 (15%) patients had tympanic membrane perforation diagnosed by the otolaryngology service. A total of 97 tympanic membrane perforations occurred among 65 patients. The average surface area involved was 41% +/- 32% (right) and 35% +/- 34% (left). More than one third of perforations were grade 4. The most common locations were central and anterior-inferior. Most (83%) patients reported symptoms, most commonly diminished hearing (77%) and tinnitus (50%). Outcome data were available for 77% of perforations. Spontaneous healing occurred in 48%. The remainder (52%) had surgical intervention. The most common audiogram abnormality was mild high frequency hearing loss. Ultimately, three patients (5%) required hearing aids and one discharge from military service.

CONCLUSIONS: Tympanic membrane perforation occurs in 16% of explosion-injured patients. Most patients are symptomatic and many have large perforations requiring operative intervention. Long-term hearing loss is uncommon but does impact ability to continue military service.