Hearing Impairment Overview in Africa: the Case of Cameroon.

The incidence of hearing impairment (HI) is higher in low- and middle-income countries when compared to high-income countries. There is therefore a necessity to estimate the burden of this condition in developing world. The aim of our study was to use a systematic approach to provide summarized data on the prevalence, etiologies, clinical patterns and genetics of HI in Cameroon. We searched PubMed, Scopus, African Journals Online, AFROLIB and African Index Medicus to identify relevant studies on HI in Cameroon, published from inception to 31 October, 2019, with no language restrictions. Reference lists of included studies were also scrutinized, and data were summarized narratively. This study is registered with PROSPERO, number CRD42019142788. We screened 333 records, of which 17 studies were finally included in the review. The prevalence of HI in Cameroon ranges from 0.9% to 3.6% in population-based studies and increases with age. Environmental factors contribute to 52.6% to 62.2% of HI cases, with meningitis, impacted wax and age-related disorder being the most common ones. Hereditary HI comprises 0.8% to 14.8% of all cases. In 32.6% to 37% of HI cases, the origin remains unknown. Non-syndromic hearing impairment (NSHI) is the most frequent clinical entity and accounts for 86.1% to 92.5% of cases of HI of genetic origin. Waardenburg and Usher syndromes account for 50% to 57.14% and 8.9% to 42.9% of genetic syndromic cases, respectively. No pathogenic mutation was described in GJB6 gene, and the prevalence of pathogenic mutations in GJB2 gene ranged from 0% to 0.5%. The prevalence of pathogenic mutations in other known NSHI genes was <10% in Cameroonian probands. Environmental factors are the leading etiology of HI in Cameroon, and mutations in most important HI genes are infrequent in Cameroon. Whole genome sequencing therefore appears as the most effective way to identify variants associated with HI in Cameroon and sub-Saharan Africa in general.

GJB2 and GJB6 Mutations in Hereditary Recessive Non-Syndromic Hearing Impairment in Cameroon.

This study aimed to investigate GJB2 (connexin 26) and GJB6 (connexin 30) mutations associated with familial non-syndromic childhood hearing impairment (HI) in Cameroon. We selected only families segregating HI, with at least two affected individuals and with strong evidence of non-environmental causes. DNA was extracted from peripheral blood, and the entire coding region of GJB2 was interrogated using Sanger sequencing. Multiplex PCR and Sanger sequencing were used to analyze the prevalence of the GJB6-D3S1830 deletion. A total of 93 patients, belonging to 41 families, were included in the analysis. Hearing impairment was sensorineural in 51 out of 54 (94.4%) patients. Pedigree analysis suggested autosomal recessive inheritance in 85.4% (35/41) of families. Hearing impairment was inherited in an autosomal dominant and mitochondrial mode in 12.2% (5/41) and 2.4% (1/41) of families, respectively. Most HI participants were non-syndromic (92.5%; 86/93). Four patients from two families presented with type 2 Waardenburg syndrome, and three cases of type 2 Usher syndrome were identified in one family. No GJB2 mutations were found in any of the 29 families with non-syndromic HI. Additionally, the GJB6-D3S1830 deletion was not identified in any of the HI patients. This study confirms that mutations in the GJB2 gene and the del(GJB6-D13S1830) mutation do not contribute to familial HI in Cameroon.

Cochlear implantation in patients with enlarged vestibular aqueduct. A case series with literature review.

OBJECTIVES: To report our institutional experience of the management of patients with enlarged vestibular aqueduct (EVA) and compare it to the literature. METHODS: We carried out a retrospective review of patients' records from 1993 to 2015. The age, sex, associated malformations, relevant past medical history, genetic screening results, possible surgical incident, implant model and duration of follow- up, outcome in terms of Categories of Auditory Performance (CAP scores), and integration or resuming mainstream school or work were recorded. RESULTS: We had 11 patients (six boys and five girls) with EVA who underwent cochlear implant surgery in our center during the 22-year study period, out of a total of 827 implanted (1.3%). The mean age at surgery was 8.9 years ranging from 0.6 to 35 years. EVA was bilateral in 10 cases, isolated anatomical finding in seven cases, and associated with other malformations in four. Cochlear implantation was bilateral in five cases and unilateral in six. The mean follow- up duration was 48.3 months (range: 3-120). No postoperative complication was observed and all the patients could regain a serviceable hearing, attending normal school and working normally. CONCLUSION: EVA is frequently observed in the deaf population without an identifiable cause. The hearing loss is usually progressive and may result in cochlear implantation which has proved its efficiency in rehabilitating EVA patients.

Epidemiological and histopathological patterns of salivary gland tumors in Cameroon.

INTRODUCTION: Tumors of salivary glands are rare. According to Johns and Goldsmith in 1989, their annual incidence is less than 1/100000 without noteworthy geographical gap. But other authors suggest that their distribution may vary according to the race and geographical location. In Cameroon, existing studies give incomplete data. Hence, we underwent this study in order to draw the general profile of salivary gland tumors in Cameroon. METHODS: A retrospective study was carried out on the period spanning from January 2000 to December 2010 (11 years). It was done in nine Pathology services of different hospitals in Yaoundé, Douala and Bamenda. We consulted the archive registers of those services, retaining any patient with salivary gland tumor, whatever the histological type or location. Information gathered was the year of diagnosis, the service, the age and sex, the site of the tumor (gland) the histological type and the benign/ malignant character. RESULTS: We recruited a total of 275 files. Women were 56% (154/275) and men 44% (121/275) of the sample. Fifty eight tumors were malignant (21.9%) while 217 were benign (78.1%). The overall mean age was 37.44 years, with extremes between 1 and 84 years. Pleomorphic adenoma (60.36%) was the most common benign tumor. Adenoid cystic carcinoma (31%), mucoepidermoid carcinoma (22.4%) and adenocarcinoma (19%) were the most common malignant tumors. Palate (66.7%), cheek (30%) and lips (3.3%) were the sites were the minor salivary glands were mostly involved. CONCLUSION: The differences with western world authors suggest a geographical variability of salivary gland tumors.

Management of subglottic hemangiomas with carbon dioxide laser: Our 25-year experience and comparison with the literature.

INTRODUCTION: Subglottic hemangiomas (SGH) are rare tumors of infancy arising between the perichondrium and the mucosa of the subglottic space. It is a potential life-threatening condition. Many therapeutic options exist for this disease, including lasers. OBJECTIVE: To report our 25-year experience of laser treatment of SGH. MATERIAL AND METHODS: Retrospective review of charts. SETTING: Clarós' Otolaryngology and Head and Neck Surgery Clinic in Barcelona, Spain. RESULTS: We recruited a total of 97 patients of whom 89 were treated with CO2 laser. Mean age at first contact was 2.1 months (range: 1.5-6.5). Sex ratio was 10 girls for 1 boy. Eighty percent of patients presented with stridor and 30.3% with recurrent acute laryngitis. Forty percent had associated cutaneous hemangiomas. They received an average of 1.85 laser session (range: 1-4) and 78.5% were healed after a maximum of 2. We had a 100% success rate and 1.1% complication rate (subglottic stenosis). CONCLUSION: CO2 laser is a very effective and recommendable tool against subglottic hemangiomas. To achieve good results traditional laser safety measures should be respected besides some useful surgical tips.

Effect of HIV Infection and Highly Active Antiretroviral Therapy on Hearing Function: A Prospective Case-Control Study From Cameroon.

IMPORTANCE: Human immunodeficiency virus (HIV) infection remains a major cause of morbidity and mortality worldwide. Many studies have found a higher prevalence of hearing impairment among HIV-positive individuals. OBJECTIVE: To investigate the effect of HIV and highly active antiretroviral treatment (HAART) on the hearing function in a Cameroonian population. DESIGN, SETTING, AND PARTICIPANTS: We conducted a prospective case-control study from March 1, 2012, through January 31, 2013. The study took place at the National Social Insurance Fund Hospital in Yaoundé, Cameroon, a public health facility. We included 90 HIV-positive case patients and 90 HIV-negative control patients aged 15 to 49 years without any history of hearing loss or treatment with a known ototoxic drug. The case group was further divided into 3 subgroups: 30 HAART-naive patients, 30 patients receiving first-line HAART, and 30 patients receiving second-line HAART. INTERVENTIONS: Hearing function was assessed by pure-tone audiometry and classified according to the criteria of the Bureau International d'Audio-Phonologie. MAIN OUTCOMES AND MEASURES: Hearing loss due to HIV and HAART. RESULTS: The HIV-positive patients had more otologic symptoms (hearing loss, dizziness, tinnitus, and otalgia) than HIV-negative patients (41 vs 13, P = .04). There were 49 cases (27.2%) of hearing loss in the HIV-positive group vs 10 (5.6%) in the HIV-negative group (P = .04). Compared with HIV-negative individuals, the odds of hearing loss were higher among HIV-infected HAART-naive patients (right ear: odds ratio [OR], 6.7; 95% CI, 4.3-9.7; P = .004; left ear: OR, 6.2; 95% CI, 3.5-8.3; P = .006), patients receiving first-line HAART (right ear: OR, 5.6; 95% CI, 1.9-10.5; P = .01; left ear: OR, 12.5; 95% CI, 8.5-15.4; P < .001), and patients receiving second-line HAART (right ear: OR, 6.7; 95% CI, 3.3-9.6; P = .004; left ear: OR, 3.7; 95% CI, 3.0-5.0; P = .08). CONCLUSIONS AND RELEVANCE: Hearing loss is more frequent in HIV-infected patients compared with uninfected patients. Therefore, HIV-infected patients need special audiologic care. Further studies are needed because controversy remains regarding the factors that lead to ear damage.

Metabolic syndrome and fatal outcomes in the post-stroke event: a 5-year cohort study in Cameroon.

BACKGROUND AND PURPOSE: Determinants of post-acute stroke outcomes in Africa have been less investigated. We assessed the association of metabolic syndrome (MetS) and insulin resistance with post-stroke mortality in patients with first-ever-in-lifetime stroke in the capital city of Cameroon (sub-Saharan Africa). METHODS: Patients with an acute first-stroke event (n = 57) were recruited between May and October 2006, and followed for 5 years for mortality outcome. MetS definition was based on the Joint Interim Statement 2009, insulin sensitivity/resistance assessed via glucose-to-insulin ratio, quantitative insulin sensitivity check index and homeostatic model assessment. RESULTS: Overall, 24 (42%) patients deceased during follow-up. The prevalence of MetS was higher in patients who died after 28 days, 1 year and 5 years from any cause or cardiovascular-related causes (all p≤0.040). MetS was associated with an increased overall mortality both after 1 year (39% vs. 9%) and 5 years of follow-up (55% vs. 26%, p = 0.022). Similarly, fatal events due to cardiovascular-related conditions were more frequent in the presence of MetS both 1 year (37% vs. 9%) and 5 years after the first-ever-in-lifetime stroke (43% vs. 13%, p = 0.017). Unlike biochemical measures of insulin sensitivity and resistance (non-significant), in age- and sex-adjusted Cox models, MetS was associated with hazard ratio (95% CI) of 2.63 (1.03-6.73) and 3.54 (1.00-12.56) respectively for all-cause and cardiovascular mortality 5 years after stroke onset. CONCLUSION: The Joint Interim Statement 2009 definition of MetS may aid the identification of a subgroup of black African stroke patients who may benefit from intensification of risk factor management.