Comparison of Neural Response to Language in Infants with Nonsyndromic Craniosynostosis
Alexander H. Sun, BS, Max J. Rolison, BS, Taylor A. Halligan, BS, Carolyn Chuang, BS, Jenny F. Yang, MD, MHS, Peter W. Hashim, MD, MHS, Derek M. Steinbacher, DMD, MD, John A. Persing, MD, James C. McPartland, PhD.
Yale School of Medicine, New Haven, CT, USA.
PURPOSE: There is growing evidence that nonsyndromic craniosynostosis (NSC) is associated with functional disabilities in learning and language. To further characterize the neurocognitive changes associated with this condition, we have used auditory event-related potentials (ERPs) to study language acquisition in NSC infants. Mismatch negativity (MMN) is an ERP component that has been used to predict language acquisition in childhood. It indexes perceptual narrowing, the behavioral and neural process of experience-driven discrimination and specialization for phonemes encountered by an infant (native) versus those that are unfamiliar (non-native); atypical perceptual narrowing has been associated with language delays. Infants with sagittal NSC (SSO) have previously demonstrated significantly attenuated MMN, a potential biomarker for abnormal phonetic processing and impaired language acquisition in NSC. This research aims to extend our study to patients with metopic craniosynostosis (MSO) and to compare the MMN component between different forms of NSC.
METHODS: Thirty-one NSC infants (16 SSO, 15 MSO) and 35 age-matched controls were enrolled. Severity of MSO trigonocephaly was determined by the endocranial bifrontal angle measured from three-dimensional reconstruction, and six subjects were classified as severe. Patients were presented with an auditory non-native phoneme discrimination task played at 80 dB, and EEG was recorded at 250 Hz using a 128-channel HydroCel Geodesic Sensor Net. Analysis focused on selected electrode clusters from four regions of interest: the left and right frontal clusters and the left and right central clusters. The MMN component was calculated as the largest negative amplitude in the difference wave between 80-300ms after the stimulus.
RESULTS: Preoperatively, SSO demonstrated significantly attenuated MMN in the left frontal cluster compared to controls (p=0.003); this effect was no longer significant postoperatively (p=0.849). Overall, the MSO group did not demonstrate significant attenuation of MMN in the left frontal cluster preoperatively or postoperatively (p=0.119 and p=0.321, respectively); however, among the severe MSO subgroup, this attenuation was significant preoperatively in the left frontal cluster (p=0.002). As with SSO, this difference was no longer significant postoperatively (p=0.700). All other comparisons at the other electrode regions did not show significant differences.
CONCLUSION: This auditory ERP study sought to characterize the neural response to language by studying an ERP component reflective of normative language acquisition. This study demonstrated that infants with severe MSO have significantly attenuated MMN components, a finding that was also previously identified in SSO infants. In both groups, these differences were no longer significant postoperatively. This altered MMN was not seen in the general MSO group that also included infants with moderate trigonocephaly. While neurocognitive impairments in metopic synostosis have not yet been well-characterized by neuropsychological testing, this study provides electrophysiologic evidence of aberrations in perceptual narrowing that may exist in MSO infants prior to surgical correction.
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