Effect of congenital toxoplasmosis on the encoding of speech in infants.

OBJECTIVE:To investigate the effect of congenital toxoplasmosis (CTP) on the Frequency-Following Response (FFR) in infants. STUDY DESIGN:11 infants diagnosed with CTP and 12 healthy infants with no risk indicators for hearing impairment, aged 29-90 days old. All infants underwent an FFR neurophysiological assessment. The test stimulus was the syllable [da], 40 ms in duration, which was monaurally presented to the right ear at an intensity of 80 dBnHL. Absolute latencies and amplitudes of the V, A, C, D, E, F, and O waves, the slope (μV/ms) and measure between onset (A) and offset (O), were compared between the two groups. RESULTS:Infants with CTP had increased latency of FFR waves V, A, E, F, and O, and decreased amplitude for waves A and F. They also showed a reduction in A-O slope and a higher latency difference between onset (A) and offset (O). CONCLUSION:The neurophysiological responses of Frequency-Following Response can be influenced by congenital toxoplasmosis. Since, the CTP showed prolongation of the V, A, E, F and O waves and decrease of the amplitude for waves A and F.