title: Hearing and neurologic impairment: insult timing indicated by primary tooth enamel defects.
abstract: The association between hearing loss, neurologic impairment, and primary tooth enamel defects was examined in a group of 88 children presenting for hearing evaluation at a tertiary care children's hospital. Forty-one had classifiable enamel defects, reflecting the time and duration of prenatal or perinatal insult. Hearing loss was more prevalent and severe in 19 children with enamel defects of the incisal tooth edge (mean = 61 dB) reflecting a systemic insult at 14 to 16 weeks gestation, than in 7 children with cervical third tooth defects (mean = 23 dB) reflecting insult near term (X2 = 4.08; p less than 0.05). Audiometric findings among the 15 children with incisor defects of the middle third varied; 7 had significant hearing loss and 8 were normal. A correlation was observed between severity of hearing loss (in dB) and estimated time of systemic insult (in weeks gestational age) determined by tooth defect site (r = -0.48; p less than 0.01). The neurologic data revealed similar trends. The group with early systemic insults more frequently had moderate or severe neurologic deficits known to originate early in fetal development. The two groups with third trimester or term insults tended to have mild or no neurologic impairment. A differential susceptibility for developing auditory and neurologic structures based on insult timing is supported.
mesh_terms: D001299:Audiometry; D002648:Child; D002675:Child, Preschool; D003743:Dental Enamel; D006311:Hearing Disorders / Q000150:complications* / Q000175:diagnosis; D006801:Humans; D007223:Infant; D009422:Nervous System Diseases / Q000150:complications*; D013997:Time Factors; D014076:Tooth Diseases / Q000150:complications