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TORCH, toxoplasmosis, other (infections), rubella, cytomegalovirus (infection), and herpes (simplex); CNS, central nervous system Congenital infection caused by cytomegalovirus (CMV) is the most common intrauterine infection that produces sensorineural hearing loss Congenital infection from rubella, syphilis, toxoplasmosis, and perinatally acquired herpes simplex infections are also associated with acquired sensorineural hearing loss The hearing loss associated with these infections may occur in infants without other manifestations of congenital infection, and may not develop until early childhood Thus, many experts advocate for universal newborn hearing screening and regular monitoring of children with known congenital infections or high-risk infants such as neonatal intensive care unit patients Viral infections of the labyrinth caused by measles, mumps, parainfluenza, adenovirus, herpes simplex, CMV, rubella, and rubeola have been described and confirmed by serologic studies Labyrinthitis usually has symptoms related to inflammation of the inner ear and involvement of the vestibular apparatus Patients may complain of vomiting, tinnitus, and vertigo, and may have examination findings such as nystagmus Vascular Insufficiency Sudden hearing loss caused by vascular insufficiency has been described in the pediatric patient Vascular insufficiency may compromise blood flow to the cochlea, producing a hypoxic insult to the sensitive nerve cells in the organ of Corti Once injured, these nerve cells may not regenerate and profound sensorineural hearing loss can develop In children, sickle cell disease, longstanding diabetes mellitus, and hyperviscosity states associated with polycythemia can compromise cochlear blood flow and produce sudden hearing loss Perilymphatic Fistula Anatomic defects in the bony or membranous enclosure of the perilymphatic space may produce a perilymphatic fistula and result in an anomalous communication between the middle and inner ear compartments, leading to acute sensorineural hearing loss A perilymphatic fistula can occur at any age and symptoms/signs may include tinnitus, vertigo, dizziness, and nystagmus Antecedent trauma usually underlies the development of a fistula, and may include vigorous exercise or changes in barometric pressure associated with airplane travel or scuba diving Although unilateral hearing loss is most common, bilateral hearing deficits have been described Occasionally, a perilymphatic
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