Audiological deficits after closed head injury.

BACKGROUND

Damage to the peripheral auditory structures has long been recognized as a common component of head injury. It is estimated that a majority of patients with skull trauma have resultant hearing impairment. Damage to the peripheral and/or central auditory pathways can occur as a primary or secondary injury. Considering the high incidence of hearing loss, it was considered worthwhile to conduct an in-depth investigation by administering a comprehensive audiological test battery on head-injured patients.

METHOD

The sample population consisted of 290 subjects with closed head injury (study group) and 50 subjects with otologically normal subjects (control group). The subjects in the study group were further divided into mild (n = 150), moderate (n = 100), and severe (n = 40) category on the basis of Glasgow Coma Scale score. The audiological assessment consisted of pure tone audiometry, speech audiometry, tympanometry, acoustic reflex testing, auditory brain stem response audiometry, and middle latency response audiometry.

RESULTS AND CONCLUSIONS

It is concluded that there is higher prevalence of hearing impairment in the study group compared with control group. Majority of the patients who incur hearing loss after closed head injury have mild degree of hearing impairment. A significant difference between the study and control group observed on majority of the auditory brain stem response and middle latency response parameters studied.