Authors: Larissa Fernandes Gomes¹, Sheila Andreoli Balen¹, Joseli Soares Brazorotto¹, Edgard Morya²
¹Laboratory for Technological Innovation in Health, Graduate Program in Speech and Hearing Therapy, Federal University of Rio Grande do Norte
²Edmond and Lily Safra International Institute of Neurosciences
Background: Functional Near Infrared Spectroscopy (fNIRS) allows assessment of cortical development in children with hearing devices. In children with bimodal hearing, the transition to bilateral implantation and auditory training should be carefully monitored to optimize gains.
Methods: The study, approved by the Ethics Committee (opinion no. 5,989,435), investigated the cortical responses in a child (case report) with profound bilateral sensorineural hearing loss, using the fNIRS NIRXSport1, speech stimuli /ba/ and /da/ in a free field, electronic devices turned on, to identify auditory detection and discrimination. Eight emission and detection optodes, 20 channels, were positioned in the temporal region of both cerebral hemispheres. fNIRS was applied in three conditions: child using Cochlear Implant (CI) in the Left Ear and Hearing Aids (HA) in the Right Ear (1); child using bilateral CI, pre-intervention (2) and post-intervention (3). Auditory training occurred over two weeks, in 5 sessions of 50 minutes each. Data were analyzed with the MNE and MNE-NIRS tools in Spyder.
Results: superior performance in the /ba/ stimulus after CI activation, in the condition (2) was observed, with significant differences in relation to condition (1) (p = 0.042) and (3) (p = 0.002). In the comparison of the /ba/, /da/ and /bl/ (silent time) stimuli, the Kruskal-Wallis test indicated significant difference only in the bilateral CI condition pre-intervention (2) (p = 0.026). There were no differences in the anterior, middle and posterior regions of the temporal lobe in the three conditions (p1 = 0.546; p2 = 0.910; p3 = 0.223).
Conclusions: The child showed physiological responses in the bilateral temporal cortex to speech stimuli. The higher oxyhemoglobin level to the /ba/ stimulus after the CI activation suggested adaptation to the second CI. The nonsignificant post-intervention findings likely reflect training dosage and timing. Monitoring with bilateral CI and fNIRS is ongoing.
