Progressive hearing loss after closed head injury: a predictable outcome?

OBJECTIVES: To evaluate the prevalence of progression of closed head injury (CHI)-induced hearing impairment, defined as > or = 15 dB HL deterioration at 1 or more frequencies, and to identify risk factors in patient history and initial status that could predict progression.
MATERIAL AND METHODS: A total of 600 patients with major CHI were admitted to 2 Swedish medical centres during a 14-year period. The type of injury was established by means of CT and the severity of head injury was measured using the Swedish Reaction Level Scale (RLS). In 62 of these patients, pure-tone audiometry was performed soon after the injury. Forty-three patients agreed to participate in the present investigation, which was carried out 2-13 years after the injury. Each participant was evaluated using pure-tone audiometry and an itemized anamnesis was obtained.
RESULTS: There was a higher prevalence of hearing impairments in the study group compared to a control group. Thirty-two subjects (74%,) showed a progression of > or = 15 dB, which was significantly greater than the spontaneous progression in the control group. Age and temporal bone fracture were risk factors for progression but not brain contusion only or RLS. There was an association between early pure-tone average (PTA) and progression as well as regression, i.e. the poorer the initial PTA the greater the progression as well as regression, indicating increased instability in the auditory system. Examination of patient histories did not reveal any single risk factors for progression. A serendipitous finding was a higher prevalence of reported memory shortcomings among those with post-traumatic tinnitus.
CONCLUSION: Especially for those with fracture of the temporal bone the present results stress the importance of audiometric evaluation and follow-up, from both rehabilitation and medicolegal perspectives,