Selective inner hair cell loss in premature infants and cochlea pathological patterns from neonatal intensive care unit autopsies

Background: Deafness and handicapping sensorineural hearing impairment occu r frequently in neonatal intensive care unit survivors for unknown reasons. Patients and Methods: Hearing was tested early and repeatedly in neonatal i ntensive care unit patients with an auditory brainstem response (ABR) scree ner. The temporal bones of 15 nonsurvivors (30 ears) were fixed promptly (a verage, 5 hours) after death for histological evaluation. Results: Among these patients, 12 failed the ABR screen bilaterally, 1 pass ed unilaterally, and 2 passed bilaterally. Cochlear histopathologic conditi ons that could contribute to hearing loss included bilateral selective oute r hair cell loss in 2 patients, bilateral selective inner hair cell loss in 3 tall premature), and a combination of both outer and inner hair cell los s in 2. Other hair cell abnormalities were noted; the 2 infants who had pas sed the ABR screen demonstrated normal histological features. Neuronal coun ts were normal. Conclusions: Auditory brainstem response failure among these neonatal inten sive care unit infants who died was extremely common in part owing to an un expected histological alteration, selective inner hair cell loss among prem ature newborns, that should be detectable uniquely by the ABR testing metho d. Additional histological patterns suggest more than one cause for neonata l intensive care unit hearing loss. Hair cell loss patterns seem frequently compatible with in utero damage.