Airbags and permanent auditory deficits. A real correlation?

OBJECTIVES

To evaluate the relationship between airbag-induced noise and individual metabolic risk factors in determining persistent hypoacusia in drivers after road accidents.

METHODOLOGY: We selected 22 patients previously involved in a car accident with deployment of airbags. Patients underwent general and audiological clinical history, tonal audiometric examination, vocal audiometric examination, impedance meter examination and blood tests.

RESULTS

We divided patients, according to audiometric data, into 2 groups: group A with no residual otological disturbances (6 subjects) and group B with persistent hypoacusia (16 subjects). Blood parameters were into physiological levels in all group A patients; on the contrary 12 (subgroup B1) out of 16 group B patients had altered blood levels of glucose, urea and cholesterol, with mean values of 155.8 +/- 38.6 mg/dl, 48.2 +/- 8.3 mg/dl and 250.8 +/- 28.1 mg/dl, respectively, revealing statistically significant differences in these parameters when compared with the other 4 hypoacusic cases (Sub-group B2) and with the normal subjects (Group A) (p < 0.01 for glucose, p < 0.05 for urea and p < 0.001 for cholesterol).

CONCLUSIONS

Our findings confirm the transitory otological damage due to airbag deployment: the intensity of the acoustic wave hitting the ear after airbag deployment is responsible for a temporary rise in the acoustic threshold but the persistence of an auditory deficit can be due to co-factors able to interfere with the acute acoustic trauma recovery processes through a metabolic, angiopathic, neuropathic or unknown mechanism. Moreover, also the age of the patients could affect in a significant way the recovery from the acoustic trauma.