Otologic consequences of blast exposure: a Finnish case study of a shopping mall bomb explosion.

OBJECTIVE: On 11 October, 2002, in the Myyrmanni shopping mall, Vantaa city, Finland, an explosion by a suicide bomber killed 7 people and injured at least 160,44 of whom had ear trauma. We investigated the acute and subacute otologic consequences of the explosion.
MATERIAL AND METHODS: Otologic examination of the 29 patients treated for ear trauma at the ENT clinic of the University Hospital of Helsinki was performed during the first month after the explosion, and a questionnaire was completed regarding subjective aural symptoms. Symptoms occurring directly after the explosion and for up to 1 month afterwards were assessed.
RESULTS: Of the 29 patients, 66% had tinnitus as the initial symptom, 55% hearing loss, 41% pain in the ears and 28% sound distortion. Tinnitus and hearing loss in combination were experienced by 12 patients (41%). Eight patients who had been situated<10 m from the center of the explosion had a rupture of the tympanic membrane. This supported the initial evaluation by the authorities that the bomb had consisted of approximately 3 kg ammonium nitrate, equivalent to approximately 0.5 kg of trinitrotoluene. It was estimated that some kind of ear injury was likely for individuals situated<70 m from the center of the explosion.
CONCLUSIONS: People often think that tinnitus and hearing impairment are naturally occurring phenomena after blast exposure, and if their symptoms resolve they do not seek medical advice. However, some of them may have substantial hearing impairment, particularly at high frequencies. Otologic consultation, or at least an audiometric screening test to exclude hearing impairment, should be performed regardless of symptoms, on the basis of exposure data only. Some symptoms, such as tinnitus and hearing loss, may be permanent consequences of a blast injury and their effect on quality of life may be substantial.