Absence of Sensorineural Hearing Loss in Treated Infants and Children with Congenital Toxoplasmosis

Abstract

Educationally significant hearing loss has been reported in 10% to 15% of children with congenital toxoplasmosis. As part of a pilot study to assess feasibility and safety of prolonged therapy for congenital toxoplasmosis, 30 congenitally infected infants and children were evaluated for auditory function. Serial testing, beginning within 2 months of birth, was performed. Availability of auditory brainstem response (ABR) testing made evaluation at an earlier age than previously possible. Six (20%) of the 30 infants had mild to moderate conductive type hearing loss associated with otitis media. No infant or child had sensorineural hearing loss. The better outcome we observed compared to previous reports of a 15% to 26% incidence of sensorineural hearing loss and 10% to 15% incidence of educationally significant, bilateral hearing impairment may be related to early initiation and/or prolonged institution of antimicrobial therapy. Continued followup to exclude progressive hearing impairment and study of larger numbers of children are needed to verify these preliminary findings.

Deficiência auditiva na toxoplasmose congênita detectada pela triagem neonatal

“…In the present study, proper treatment of two of these children with hearing loss did not help avoid the loss, and this is different from the results attained by McGee et al 15 and McLeod et al 20 who reported hearing normality in treated children, even when they had neurologic and ocular involvement. The follow up of these children may provide new data to clarify these issues.…”

“…Table 5 shows comparisons of three studies which encompassed hearing evaluation in children with congenital toxoplasmosis. The Chicago Study 15,20 evaluated children treated with the classical antiparasitic drugs for 12 The results observed in this study are similar to those found by Wilson et al 19 Studies with larger samples, submitted to long stand treatment (12 months), did not identify the presence of hypoacusis, concluding for a better prognosis of the treated children 20 . In the present investigation, among the 16 children properly treated, for long time and regularly, two presented hearing deficit, but only one had an important functional loss.…”

“…Long standing treatments (one year) for congenital toxoplasmosis have been associated to better children prognosis by some authors 15,20 . Among the four children in the present study, one received antiparasitic drugs for three months only (this mother, a teenager, was not interested in her child's problem) and the other was irregularly treated for 10 months (did not regularly come for visits at the ward); the most affected child and the other one with unilateral hearing loss were treated during 12 months.…”

“…17 ; however, Wilson et al 18,19 reported unilateral or bilateral hearing loss in 5 (26%) of the 19 children with subclinical infection. Other authors have found no association between the parasites and hypoacusis, when children are treated 15,20 , and there still are doubts as to the rate at which toxoplasmosis can cause hearing deficit 13,17,21 .…”

“…Hearing loss has been reported in about 20% of the congenital toxoplasmosis cases, especially in untreated children or those treated for a very short period 4,15,16 . Eichenwald (1947), studied children who had not been treated in the first year of life and found hearing loss in 17% (12/70) of those children who had the neurologic form of the disease and in 10% (3/31) of those with the generalized form.…”