Traumatic posterior tympanic membrane perforation.

We evaluated a young man 2 weeks after he had sustained an accidental head trauma. The patient exhibited a posterior tympanic membrane perforation across from the round window membrane (figure). Some residual blood was present in the middle ear. The remainder of the tympanic membrane was thin and monomeric, indicating a history of chronic eustachian tube dysfunction prior to the accident.

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Small traumatic perforations usually heal spontaneously, while larger perforations may necessitate a tympanoplasty. Posterior perforations across from the round window may cause significant hearing loss secondary to the "cancellation effect" that occurs when sound reaches the oval and round windows simultaneously. The patient was instructed to keep the ear dry.

From the House Ear Clinic and the Keck School of Medicine, University of Southern California, Los Angeles.