Long-term follow-up of sensorineural hearing loss in patients exposed to explosions

OBJECTIVE: This prospective follow-up study assesses and quantifies the improvement of sensorineural hearing loss in patients with an abnormal audiogram obtained shortly after exposure to an explosion. PATIENTS AND METHODS: Fifty-two patients (31 men, 21 women [104 ears]; mean age, 43 +/- 18 years) experienced a sensorineural hearing loss confirmed within 4 hours after exposure to an explosion. Fifty-four ears were followed up with repeat audiograms over 4 to 6 years, and 50 ears were monitored for 1 year. RESULTS: In the 104 ears studied, the mean hearing thresholds shortly after the explosion were 22 dB (pure tone average of speech frequencies) and 41 dB (mean of high frequencies). Of those patients monitored for 4 to 6 years, 56% showed an improvement of more than 10 dB. The average improvement for that period of time was 12 dB for speech frequencies (P < .0001) and 10 dB for high frequencies (P < .03). No significant difference in the percentage or extent of improvement was found according to the subjects' sex or age. Sixty-three percent of the overall improvement in speech frequencies occurred during the first 2 months, and the remaining improvement was noted during subsequent years. CONCLUSION: A relatively small but significant improvement in sensorineural hearing loss occurs in patients exposed to an explosion. This study is distinctive because the initial audiograms were obtained within hours after the explosion and because of the long-term follow-up. The results may help to determine the prognosis for hearing in patients exposed to a blast.