|Year : 2011 | Volume
| Issue : 4 | Page : 162-164
Etiological factors for pediatric sensorineural hearing loss
Sanjay Kumar, Prachi Gautam, Ravinder Sharma, Vivek Taneja
Department of ENT and Pediatrics, Subharti Medical College, Subharti Puram, Meerut, India
|Date of Web Publication||29-Mar-2012|
Department of ENT, Subharti Medical College, Meerut
Source of Support: None, Conflict of Interest: None
Introduction: The prevalence of sensorineural hearing loss (SNHL) is 2-3 per 1000 live births in India. The present study was carried out to identify and diagnose children with SNHL and study their etiological profile. Materials and Methods: The study was conducted at tertiary care hospital. A total of 150 cases were evaluated. Data on epidemiological factors were collected. Detailed clinical and audiological assessment of patients was performed by conducting audiological tests like free field audiometry, pure tone audiometry (PTA), oto-acoustic emissions (OAE) and brainstem-evoked response audiometry (BERA). Results: Majority of cases were diagnosed between 0 and 5 years of age; male:female ratio was almost equal. Out of 150 cases, the maximum number of cases [24 (16%)] were having genetic etiology, 15 (10%) were having history of prenatal complications, 18 (12%) cases were having perinatal complications and 39 (26%) presented with acquired factors responsible for SNHL, while in 54 (36%) cases, the etiological factors remained undetermined. Conclusions: In most cases of SNHL, the cause is undetermined. The maximum number of cases in which the cause is determined are of genetic etiology. 12% cases have perinatal insult as cause.
Keywords: Congenital, Genetic, Perinatal, Sensorineural hearing loss
|How to cite this article:|
Kumar S, Gautam P, Sharma R, Taneja V. Etiological factors for pediatric sensorineural hearing loss. Indian J Otol 2011;17:162-4
| Introduction|| |
The prevalence of sensorineural hearing loss (SNHL) is 2-3 per 1000 live births in India, and out of 1000 babies, 1 is profoundly deaf at birth or in the pre-lingual age group. 
SNHL in children may be congenital (like in genetic disorders) or due to non-genetic causes like intrauterine infections, use of ototoxic drugs during pregnancy; it can be due to perinatal factors like neonatal hypoxia and hyperbilirubinemia, or due to acquired factors like trauma, meningitis, ototoxic drugs, and infections like mumps and herpes. Several studies have independently indicated that approximately 50% of all childhood deafness is genetic in etiology. The clinical spectrum of inherited deafness is broad and ranges from simple deafness to genetically determined syndromes affecting several different body systems.
The present study was done to identify and diagnose children with SNHL and study the etiological profile, so that all necessary timely precautions may be taken as SNHL in pediatric age group affects not only development of speech and language, but also emotional, social and behavioral development.
| Materials and Methods|| |
The study was carried out in the Department of ENT of a tertiary care center of Uttar Pradesh. The study included 150 children having SNHL and below the age of 14 years. Patients with middle pathologies like acute suppurative otitis media (ASOM), chronic suppurative otitis media (CSOM), otitis media effusion (OME) were excluded from the study.th
Detailed clinical and audiological assessment of patients was done by conducting audiological tests like free field audiometry, pure tone audiometry (PTA), oto-acoustic emissions (OAE) and brainstem-evoked response audiometry (BERA).
Data on epidemiological factors were collected which included detailed medical history of child and mother, socioeconomic status, age, sex, birth order, sib mortality, details of milestone and family history of SNHL in siblings. Details regarding parental age at conception, maternal health, reproductive history, history of teratogens used during conception, exposure to X-ray, maternal infections (TORCH titers), birth history details like birth trauma, birth asphyxia, prematurity, neonatal jaundice, history of acquired factors (postnatal) like meningitis, head injury, ototoxic drugs, infections like measles and mumps were recorded using a standard questionnaire.
Besides this, the patients were also examined for the presence of other associated impairments like mental retardation, cerebral palsy, attention deficit hyperactive disorder and for syndromes associated with SNHL in children.
| Results|| |
On evaluation of 150 cases the maximum number of cases 114 were in age group of 0-5 years . male:female ratio was 81:69.
The mean age at the time of diagnosis was 5.60 years and 64% of the patients were from rural area.
Probable genetic etiology was present in 24 (16%) cases; among these, 4 cases were of Waardenburg syndrome, 3 cases of Alport's, 3 cases of osteogenesis imperfecta and 1 case was of Treacher Collins syndrome More Details. Family history of deafness was present in six cases and there was a family in which three consecutive offsprings were deaf.
Fifteen (10%) cases were found to have prenatal (non-genetic) factors like intrauterine infections and use of ototoxic drugs during pregnancy.
Perinatal factors [Table 1] like neonatal hypoxia, neonatal jaundice, prematurity and prolonged neonatal intensive care unit (NICU) stay were present in 18 (12%) cases.
Acquired factors [Table 2] like meningitis, measles, mumps, head injury and ototoxic drugs were present in 39 (26%) cases.
[Table 3] shows the probable etiological factors for SNHL in the 150 cases studied: 24 (6%) were having genetic factors, 15 (16%) cases were having prenatal (non-genetic) factors, 18 (12%) cases presented with perinatal complications, 39 (26%) were having acquired factors, while in 54 (36%) cases, no etiological factor could be found.
|Table 3: Probable etiological factors in 150 cases of pediatric sensorineural hearing loss|
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| Discussion|| |
In the present study, the maximum number of cases [114 (76%)] were in the age group of 0-5 years, with the mean age of cases being 5.60 years. The male:female ratio was 81 (54%): 69 (46%). The findings correlate with those of Kathleen et al. who reported male and female distribution to be approximately equal and the mean age at diagnosis to be 3.52 years, while Walch et al. reported in a study of 106 children (52 males and 54 females) with bilateral SNHL, the mean age of children to be 42 months.
Family history of deafness was present in six cases in our study, while seven cases had history of delayed milestones, and three cases had other associated neurological impairments like mental retardation. Cerebral palsy was found in one case and attention deficit hyperactive disorder in one case.
Kathleen et al. stated that the most common associated medical problem encountered was recurrent otitis media, which was excluded in our study, while the neurological abnormalities that they found were developmental and motor delays, cerebral palsy and seizure disorders. Parving  stated that up to 33% of children with SNHL were having family history of deafness, while Pappas and Schaibly found 10% of deaf children to be having family history of deafness. 
History of perinatal complication was present in 18 (12%) cases; most of the cases had more than one factor, e.g. the cases having history of prematurity were also having history of neonatal hypoxia and required prolonged NICU stay. Billings et al. found in their study that 8% of their cases were having history of perinatal complications like premature birth and NICU stay. Reddy,  in a study of perinatal risk factors for congenital SNHL, found birth asphyxia to be the most common cause in 16% of cases. According to Robertson et al.,  of the 81 cases who were survivors of greater than or equal to 34 weeks of gestation at birth with severe neonatal respiratory failure, 43 cases had SNHL. Marlow et al. concluded that in preterm babies with median birth weight of 960 g, the children who had longer period of intubations, ventilation and oxygen treatment, acidosis and more frequent treatment with dopamine had SNHL. However, SNHL was more likely if peak bilirubin levels coexisted with netilmicin use or if acidosis occurred when bilirubin level was high. Coenraada et al. studied the risk factors for SNHL in NICU infants and found neonatal hypoxia, hyperbilirubinemia requiring phototherapy, low APGAR scores, use of ototoxic drugs and meningitis as the important causative factors.
Acquired factors of SNHL were present in 39 (26%) of our cases, of which 12 were having history of meningitis, 6 of measles, 9 of head injury, 3 of mumps, 6 of ototoxic drugs and 3 cases were having history of tubercular meningitis and ototoxic ATT.
Walch et al. found that 38% of children suffered from acquired SNHL, while Billings et al. in their study reported that acquired factors like meningitis were present in 4% cases, chemotherapy in 2.3% cases, aminoglycosides in 0.7% cases, while history of head trauma was present in 6.7% cases.
In our study, the acquired factors like use of ATT are probably due to higher prevalence of tuberculosis in our country, and cases due to measles and mumps are also in high proportion due to poor immunization as compared to western countries.
In the present study, the probable etiological factors for SNHL in the pediatric age group could be determined in 64% of cases, of which 24 (6%) were having genetic etiology, 15 (10%) were having prenatal factors like intrauterine infection and use of ototoxic drugs during pregnancy, 18 (12%) were having history of perinatal complication, 39 (26%) were having history of acquired factors, while in 54 cases (36%), no etiological factor could be determined.
Parring  could identify the known causes for SNHL in 72.6% children, while in 27.4% cases, no etiological factor could be determined. The maximum number of cases (33.3%) presented with genetic causes. In the study of Billings et al.,  the probable causes for SNHL were identified in 68% of cases and 32% had no obvious cause. In their study, 28.6% cases were having perinatal complications, while syndromes like multiple congenital anomalies, meningitis and prenatal maternal factors were present in 38.5% cases. Walch et al. studied 106 children, of whom in 47 children (44%), no cause of SNHL could be determined, 19 (18%) had a history of familial hearing loss, while 40 (38%) suffered from acquired hearing loss in which 7 children had perinatal cause. Cristine et al., in a study conducted at University Hospital, France, found that out of 1461 infants, 46 children were having SNHL, of whom 34 were having bilateral hearing loss. Risk factors diagnosed were birth asphyxia, TORCH infections, low birth weight and family history of deafness.
| Conclusion|| |
A total of 150 cases below the age of 14 years were included in study. The maximum number of cases [114 (76%)] were diagnosed in the age group of 0-5 years and the male:female ratio was 81 (54%): 69 (46%). The mean age at the time of diagnosis was 5.60 years.
The probable etiological factors for SNHL were diagnosed in 96 cases, while in 54 cases, the cause remained undetermined. The maximum number of cases in which the cause was determined were of genetic etiology [24 (16%)]; 15 cases (10%) were probably due to prenatal factors, 18 (12%) were of perinatal complications, while 39 (26%) cases were due to acquired factors.
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[Table 1], [Table 2], [Table 3]