Rapidly declining unilateral hearing within 1 month in a newborn with internal auditory canal stenosis and facial palsy.

Most newborns with congenital unilateral facial palsy are expected to recover; however, when a patient has hearing loss, underlying developmental ear structure abnormalities should be investigated, particularly when the patient has internal auditory canal stenosis, which is rarely reported in newborns. All cases of internal auditory canal stenosis are accompanied by concomitant unilateral or bilateral hearing loss, but none with progressive hearing loss has been reported. We present the case of a newborn with rapidly declining hearing in the left ear within 1 month after birth. The hearing decline was associated with unilateral facial palsy. Using high-resolution computed tomography (CT) of the temporal bone, we diagnosed the patient with congenital internal auditory canal stenosis. This is the first case detected with progressive hearing loss after birth, which implies that prompt diagnosis and early habilitation are warranted, even when the hearing loss is initially mild.