Discussion
hemisphere or injury location, brain injuries, Stroke, stroke, functional neurological disorders, brain injury, slowness, stroke-related neurological sequelae, impaired auditory, brain disorders, auditory perception skills, auditory and cognitive function disorders, strokes
STROKE, STROKE, ISCHEMIC STROKE, BRAIN DISORDERS, SEPARATION, DISEASES, CORTEX, STROKES
Stroke has a significant functional impact on an individual's quality of life.The present study described the function of the auditory pathway in children and adolescents with stroke and proposed new therapeutic perspectives that can help recover communicative functions in this population.The present data demonstrated a close connection between the structural damage caused by stroke and impaired auditory pathway functionality (auditory perception skills), both through behavioral and electrophysiological tests.The SG comprised 24 individuals: 13 girls (54 %) and 11 boys (46 %). Some studies have reported a higher prevalence in malesRegarding the type of stroke, most of the sample consisted of ischemic stroke (92 %). This prevalence has been corroborated by several studies on stroke in both adult and pediatric populations.The injury locations in the study population showed a wide diversity in neuroimaging findings. However, most patients had an injury to the temporal left hemisphere (63 %). This is due to the location of the Middle Cerebral Artery (MCA), the most commonly affected vascular region, which is more prone to injury due to its anatomy and thinner walls.The results of the behavioral tests, DDT, and PPS, showed that the SG performed worse than the CG in all the tasks.In the DDT, the SG performed worse in the tasks of integration and binaural separation in both ears than the CG. These findings corroborate those of other studies that examined the same population.In the dichotic listening task, different verbal stimuli were presented concurrently to each ear. To evaluate the binaural integration, the authors measured the neural capacity to integrate each stimulus presented simultaneously to both ears. With respect to binaural separation, the authors evaluated the neural capacity to direct attention to each ear. That is, information from one ear must be ignored and attention must be directed to the other. Neural injuries/dysfunctions resulting from strokes in the SG compromise these auditory skills, and consequently, healthy auditory processing of acoustic information in the brain.Another important issue in the dichotic listening task is that when an individual is asked to respond to different verbal stimuli presented simultaneously to each ear, the stimuli are processed predominantly by the contralateral auditory pathway owing to the suppression of its ipsilateral counterpart.As the hemispheric specialization of language occurs in the left hemisphere, in most cases, the right ear usually performs better, a phenomenon known as right ear advantage.SG performed worse in the PPS test in both the labeling and humming modes. This result showed that the SG was inefficient at perceiving, associating, and interpreting the non-verbal patterns of the message received, such as rhythm and intonation, which are most often processed by the right hemisphere, affecting comprehension with regard to phoneme voicing and syllable order.The present results corroborate those of previous studies, demonstrating that individuals with brain injury perform worse on the PPS than normal individuals, regardless of the affected hemisphere or injury location.The activation of these different regions of the brain is associated with several neural processes required to perform this test. Recognizing an acoustic pattern and intonation, presumably, has been predominantly associated with the right hemisphere (humming mode). When the task requires labeling, in addition to the right hemisphere, the corpus callosum and language-related regions in the left hemisphere are activated.Electrophysiological tests contribute to behavioral assessments of auditory processing because they objectively check the functional and structural integrity of the auditory pathway in the brain.In this study, the P300 was used because this potential is associated with cognitive skills related to the auditory system and reflects activity in the auditory cortex in terms of attention, discrimination, integration, and memory.The results obtained in the SG showed an increased latency compared to those in the CG. Thus, the authors can infer that the central auditory nervous system takes longer to process auditory information in children and adolescents with brain injuries. The damage caused by the injury itself likely impairs the normal functioning of neural pathways, causing auditory and cognitive function disorders. Some studies on brain disorders have demonstrated that this neural slowness is a result of injury.The P300 amplitude has been widely questioned in the literature owing to its high variabilityVaughan and Kurtzberg studied children and adolescents with functional neurological disorders and found increased amplitudes in this population compared to their healthy peers. The authors hypothesized that these participants would exhibit cortical excitation. The baseline state of high excitation could be a pre-condition for generating functional neurological symptoms in these individuals, justifying their higher potential amplitude when compared to controls, which is a plausible hypothesis because stroke may cause interhemispheric imbalance.In this study, the small sample size represented one of the limitations and reinforced the series of diseases presented in the literature, since the authors identified only 35 children or adolescents diagnosed with stroke over a period of 15 years (2003 to 2018), of which 24 were eligible for the analyses. Another limiting factor for this investigation was the scarcity of audiometric studies involving children with stroke-related neurological sequelae caused by stroke. Therefore, the authors emphasize the importance of future studies that address these issues in greater detail.