Functional near-infrared spectroscopy (fNIRS) in infants with congenital syphilis.
Spectroscopy, Near-Infrared; Newborn infants; Speech Perception; Auditory Perception; Syphilis, Congenital
Introduction: Neurosyphilis is an infection of the central nervous system caused by Treponema pallidum and can be symptomatic or asymptomatic in children with congenital syphilis. Syphilis infection can cause different alterations, including hearing loss as a possible late manifestation of congenital syphilis, and is a globally recognized risk indicator for hearing loss. However, there is little information on the consequences for cerebral hemodynamics. Research combining near-infrared spectroscopy (fNIRS) and auditory stimuli in infants plays a significant and multifaceted role in science and society. One of the main contributions of this research is to provide information on how babies' brains develop in response to auditory stimuli.
Objective: To identify the acquisition parameters of functional near-infrared spectroscopy (fNIRS) with speech stimulation in infants up to two years of age, through a systematic review. To describe the cortical activation pattern of a four-month-old infant with neurosyphilis using fNIRS with speech stimulation.
Method: Two studies were carried out. Study 1 was a systematic review of fNIRS parameters (Prospero n. CRD42022311267). The search was carried out in PubMed, Embase, Scopus, Web of Science, LILACS, PsycINFO, Livivo, Google Scholar and ProQuest. We included cross-sectional studies of normal-hearing infants aged 0-24 months using fNIRS with monosyllabic speech stimuli. Study 2 is a clinical case study (CEP/HUOL n. 5.323.957). The clinical case is of a four-month-old infant referred by an infectious disease specialist for audiological assessment. The audiological assessment included the following procedures: Tympanometry, Evoked Otoacoustic Emissions, Brainstem Evoked Response Audiometry with click stimulus and fNIRS with speech stimulus.
Results: A total of 932 articles were identified in the database (DB) and 770 in the gray literature (LC). After removing duplicates, 409 remained in the DB and 499 in the LC. The titles and abstracts were then read in phase 1, when 64 articles in the DB and 25 articles in the LC were selected for full reading, of which four remained for final analysis and data extraction. From the articles included, the conformity of only three parameters involved in the experimental designs was evidenced: the presentation of stimuli bilaterally as well as the bilateral capture of response in the temporal lobes and the use of natural sleep. In study 2, a similar tetha was observed between the conditions and channels evaluated in both cerebral hemispheres, with greater oxyhemoglobin (HbO) amplitude being observed in the frontal position when compared to the posterior region.
Final Considerations: In study 1, there was a lack of uniformity in the parameters adopted by the various studies, which shows the absence of a standardized procedure. Study 2 showed development within the expected range for hearing, with cortical responses to speech stimuli.