Cortical auditory dysfunction in children with oral clefts:: relation with cleft type

Objective: Up to 46% of individuals with oral clefts suffer from language-learning disabilities. The degree of these disabilities varies according to cleft type. The pathogenesis of cognitive malfunctioning or its relationship with cleft type is not known. We investigated persistence of auditory short-term memory (STM) that is implicitly involved in language-specific perception in children with clefts, grouped using fine-graded cleft classification. Methods: Cortical evoked potentials were recorded in 78 children with non-syndromic oral clefts and in 32 healthy peers. A mismatch negativity (MMN) potential that indexes preattentive detection of change in auditory input was obtained in response to tone sounds. In order to test durability of short-term memory traces, sounds were presented with three stimulation rates. Results: With slowest stimulation, MMN amplitudes were reduced in cleft children as compared to the healthy peers (P < 0.00065). Only cleft-lip children did not significantly differ from controls. Among isolated palatal clefts, the more posteriorly delimited the cleft was, the smaller was the amplitude of MMN. MMNs of smallest amplitudes were obtained in the subgroup of complete unilateral cleft of lip and palate. Conclusions: Reduced MMN amplitudes, found in cleft children, imply deficiency in auditory STM trace maintenance. This dysfunction is likely to contribute to their language and learning disabilities. The MMN diminution with shorter/more posterior clefts suggests that differences in auditory cortex function are one of the underlying mechanisms of the cleft type-malcogniton association. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.