For assessment of risk factors for congenital hearing loss, detailed history of the period of pregnancy and early childhood are taken preferably from the mother of the subject.
Risk factors for deafness can be identified in 60% of the subjects with congenital hearing loss. Fetal distress signifying fetal anoxia, infection during pregnancy and early childhood, jaundice, use of high risk drugs in first trimester, family history of deafness and prematurity are taken as risk factors. In many cases, there are more than 1 factor identified conjointly.
The second most important risk factor is prematurity at 16%, the births occurred at 29 to 34 weeks. Another important cause is jaundice of the child in 9%. In most cases this is the normal physiological jaundice at about 3 days after birth but which was severe and according to history had to be medically treated. Family history of deafness suggesting an inherited disorder is seen in 9% of the cases.
Another cause identified sometimes a bout of very high fever occurring in most cases in the first year of the child and which might have been due to meningitis, septicemia and such other known deafness inducing pathologies. Infection signified by very high fever during pregnancy is also identified as a cause and they are often stated to have been treated by 'strong drugs'. Incidence of malaria and the use of antimalarial drugs may be identified in the histories. In many cases, more than 1 condition may be identified. Studies have found that elevated auditory threshold is found more frequently in neonates with multiple clinical adverse factors than in those having single risk factor.
Presence of risk factors is an important indication for diagnostic testing for hearing deficiency. Most neonatal screening programs should be focused on infants who satisfy one or more of a number of criteria for inclusion in a "high-risk registry." The most common possible risk factors for the delayed maturation pattern observed on BERA were found to be parental consanguinity, prematurity, perinatal anoxia and jaundice, and postnatal seizure and infection. In a study by Savic et al, some conditions were found in 40% of the cases, with the most common being family history of deafness, followed by prematurity, fetal distress, jaundice and ototoxic drugs.
The higher incidence of complications during birth in the Indian population is believed to account for the higher incidence of risk factors, and also fetal asphyxia being the commonest cause By maintaining a high degree of suspicion wherever these risk factors are present, we can be more attuned to detecting hearing loss at an early age thus enabling effective remedial measures
Dr. P. J. Mazumdar is an ENT doctor from Guwahati specialized in ENT diseases. You can visit his website at ENT doctor Guwahati and also at Guwahati ENT doctor.
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