Etiologies of Childhood Hearing Impairment in Schools for the Deaf in Mali

Abstract

Objectives: To identify the etiologies of hearing impairment (HI) in schools for students who are deaf and to use a systematic review to summarize reports on the etiologies and clinical and genetic features of HI in Mali.Methods: We included individuals with HI that started before the age of 15 years old. Patients were carefully evaluated under standard practices, and pure-tone audiometry was performed where possible. We then searched for articles published on HI in the Malian population from the databases' inception to March 30, 2020.Results: A total of 117 individuals from two schools for the deaf were included, and a male predominance (sex ratio 1.3; 65/52) was noted. HI was pre-lingual in 82.2% (n = 117), and the median age at diagnosis was 12 years old. The etiologies were environmental in 59.4% (70/117), with meningitis being the leading cause (40%, 20/70), followed by cases with genetic suspicion (29.3%, 21/117). In 11.3% (8/117) of patients, no etiology was identified. Among cases with genetic suspicion, three were syndromic, including two cases of Waardenburg syndrome, while 15 individuals had non-syndromic HI. An autosomal recessive inheritance pattern was observed in 83.3% of families (15/18), and consanguinity was reported in 55.5% (10/18) of putative genetic cases.Conclusion: This study concludes that environmental factors are the leading causes of HI in Mali. However, genetic causes should be investigated, particularly in the context of a population with a high consanguinity rate.

Childhood Hearing Impairment in Senegal

“…In the context of limited resources, particularly in SSA, educating hearing-impaired girls are relegated to the back burner. Prelingual HI was the most common type of HI with a late diagnosis of congenital HI, which is consistent with the previous reports from SSA countries [ 13 , 14 , 32 , 34 ]. However, in the developed regions, HI is detected earlier.…”

“…Similar to other reports from SSA countries, in Mali [ 14 ], Ghana [ 32 ], and Cameroon [ 13 ], the sex ratio (1.33) is biased towards the male sex. The Joint Committee on Infants Hearing has not reported gender as a CHI-associated risk factor, however, it has been postulated that the anatomical and physiological differences between male and female auditory systems might potentially explain the bias in favor of the male sex [ 33 ].…”

“…Postlingual HI in SSA is mainly caused by environmental factors. As previously reported in Ghana [ 32 ], Mali [ 14 ], and Cameroon [ 13 ], cerebrospinal meningitis, is the most common cause of postlingual HI. In this study, HI as sequelae of cerebral meningitis accounted for 6.2% ( n = 25 cases).…”

“…For suspected syndromic HI, based on the clinical assessment or family history, additional tests were performed when applicable, including thyroid hormones (FT4, T3, and TSH), glycemia, serum creatinine level, kidney and thyroid gland ultrasounds, electrocardiography, and/or fundus examination, to refine the diagnosis as described previously in Mali [ 14 ]. For familial or sporadic cases with a putative genetic origin, peripheral blood samples were taken when possible and three-generation pedigrees were drawn using Progeny software (Progeny Genetics LLC, Delray Beach, FL, USA).…”

“…This disparity could be attributed to the distribution of the risk factors that vary significantly between high- and lower-income countries. In the high-income countries, more than 50% of congenital HI are due to genetic etiologies, while in the lower-income countries, specifically in SSA, environmental factors remain a major cause of CHI, with cerebral spinal meningitis being the most prevalent in the African Meningitis Belt [ 13 , 14 , 15 ]. Despite the notable progress made to address the rising prevalence of CHI by implementing vaccine programs with widespread coverage and prenatal follow-up care visits, the overall picture of CHI continues to worsen in SSA [ 8 ].…”