Congenital toxoplasmosis: Auditory and language outcomes in early diagnosed and treated children

Abstract

Aims: To describe the auditory and language outcomes of children with early diagnosis and treatment for congenital toxoplasmosis. Methods: A cross-sectional study included all children diagnosed with congenital toxoplasmosis, through the Minas Gerais State Neonatal Screening Program, from September 2006 to March 2007. All children received early treatment, initiated before the age of 2.5 months, and were periodically assisted by a team of specialists including pediatricians, ophthalmologists and speech-language therapists and audiologists. Hearing function was evaluated with the following procedures: tympanometry, transient evoked otoacoustic emissions, distortion product otoacoustic emissions, behavioral observation audiometry, and brainstem auditory evoked potentials. Hearing function and sensitivity was estimated and audiological results were classified as normal, conductive hearing loss, sensoryneural hearing loss and central dysfunction. Language performance was assessed and classified as normal or abnormal, according to test results. The following variables were studied: audiological results, neurological and ophthalmological conditions, language performance and presence of risk indicator for hearing loss other than congenital toxoplasmosis. Univariate analysis was conducted using the chi-square or Fisher's Exact test. Results: From September 2006 to March 2007, 106 children were diagnosed with congenital toxoplasmosis through the neonatal screening program, and were included in the study. Data analysis showed normal hearing in 60 children (56.6%), while 13 children (12.3%) had conductive hearing loss, four children (3.8%) had sensory-neural hearing loss and 29 children (27.4%) presented central hearing dysfunction. There was association between hearing problems and language deficits. The comparison between children with additional risks for hearing loss other than toxoplasmosis and children who only presented toxoplasmosis as a risk factor showed no differences. This finding suggests that audiological problems were due to congenital toxoplasmosis alone. Conclusions: Even with early diagnosis and treatment, a high prevalence of hearing problems and language delays was observed in children with congenital toxoplasmosis.

Alterações auditivas em crianças expostas à toxoplasmose durante a gestação

“…The occurrence of retrocochlear auditory disorders in 20.8% of the SG children in the present study is similar to that found in the literature, between 21.1 and 35.5% 4,11,25 . However, it differed from other studies in which the prevalence found was significantly lower or even zero 14,23,26,27 .…”

“…The greater occurrence of cochlear loss in the CG of the present study was not expected and may be justified by the reduced number of the sample or by the fact that 50% of the cochlear hearing losses are of genetic origin 22 . The occurrence of cochlear loss in the SG (2.1%) is similar to the result of a study with treated children with congenital toxoplasmosis, which obtained 3.8% of cochlear losses 11 . These results are in contrast to studies conducted in Europe and the United States which, with the same drug therapy used in the present study, observed a reduction of auditory sequelae with early detection and treatment of congenital toxoplasmosis 14,23 .…”

“…This was expected, since evasion is a trend observed in longitudinal studies 11 . There were conductive losses in all evaluations, with no statistically significant difference between the groups.…”

“…In fact, 29.6% of language alterations were found in children with congenital toxoplasmosis treated early and followed up to three years of age 11 . Thus, the child with congenital toxoplasmosis, even when treated early, needs to be accompanied by a multidisciplinary team throughout its development, in order to detect early changes in auditory processing and language, which may negatively affect school learning.…”

“…Auditory deficit has been reported in about 20% of cases of congenital toxoplasmosis, especially in children not treated or treated for a very short period 10 . A study with 174 Brazilian children with toxoplasmosis diagnosed and treated early found a 3.4% cochlear loss, a 4.6% conductive loss, and a 3.4% central alteration 11 . The occurrence of profound deafness has been almost totally limited to cases with high clinical manifestations 12 , but another study reports the occurrence of unilateral or bilateral hearing loss in 26% of the 19 children with subclinical infection 13 .…”