Bases Histopatológicas da Perda Auditiva em Recém-nascidos de Alto Risco Histopathological Patterns of the Hearing Loss in High Risk Neonates

SUMMARY Introduction: Handicapping sensorineural hearing loss occurs in 2% to 4% of Neonatal Intensive Care Unit survivors. Several etiological factors have been suggested, but little is known about the pathological changes in the cochlea of these patients. Objective: Describe the histopathological changes of the cochlea of neonates with hearing loss and correlate the findings with the clinical data. Methods: We studied the histopathological aspects of 26 cochleas of 13 newborns, who died in the NICU of the Hospital Nacional de Ninos in Costa Rica after failing the auditory screening. The ALGO 1 automated evoked response infant hearing screener was used for all tests. The histological study was done at the Massachusetts Eye and Ear Infirmary in Boston. The technique of two-dimensional reconstruction was used for displaying hair cells, neurons, Reissner's membrane, stria vascularis, spiral ligament and the presence of blood. Results: There were histological alterations that could be responsible for the hearing loss in the cochlea of seven patients: outer hair cell loss in two patients, inner hair cell loss in three patients and a combination of both outer and inner hair cell loss in two patients. All patients with inner hair cell loss were premature. Six patients had variable amounts of blood in the perilymphatic space of the cochlea. Conclusions: The heterogeneity of the histological findings indicates the likely participation of more than one etiology for hearing impairment in critically ill newborns.