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 Table of Contents  
ORIGINAL ARTICLE
Year : 2020  |  Volume : 26  |  Issue : 1  |  Page : 38-42

Meningitis and hearing loss during an outbreak of meningococcal meningitis


1 Department of ENT, Usmanu Danfodiyo University Teaching Hospital Sokoto, Sokoto, Nigeria
2 Department of ENT, Sokoto State Specialist Hospital, Sokoto, Nigeria
3 Department of Veterinary Public Health and Preventive Medicine, University of Abuja, Abuja, Nigeria

Date of Submission13-Aug-2019
Date of Acceptance01-Jan-2020
Date of Web Publication19-Feb-2020

Correspondence Address:
Dr. Stephen Semen Yikawe
Department of ENT, Usmanu Danfodiyo University Teaching Hospital Sokoto, Sokoto
Nigeria
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/indianjotol.INDIANJOTOL_89_19

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  Abstract 


Background: A large-scale outbreak of meningococcal meningitis, serotype C, occurred from December 2016 to June 2017 in some states in Nigeria. Meningitis is associated with significant morbidity and mortality. The most common sequel of this disease is hearing loss. The mechanism could be through spread of infection to the ear via the cochlear duct. Objective: The study objective was to assess the hearing threshold of patients diagnosed with meningitis during an outbreak of meningococcal meningitis in Sokoto. Materials and Methods: This was a cross-sectional descriptive study carried out on patients diagnosed with meningitis managed at the meningitis emergency response center in Sokoto. A standardized semi-structured questionnaire was used to obtain relevant information after which the patients were examined and their hearing thresholds were measured. Results: A total of 72 patients were recruited in the study. Twenty-eight (38.9%) patients had varying degrees of hearing loss. The mean duration of illness was 3.28 ± 2.75 days. The mean duration of illness among patients with hearing loss was 5.32 ± 3.28 days and that among those without hearing loss was 1.98 ± 1.13 years (t = 6.230,P< 0.001). Steroids were administered to forty (55.6%) patients by the managing physician. Out of these, only seven (17.5%) were observed to have hearing loss. Conclusion: Meningitis is a common cause of acquired hearing loss. We observed a prevalence of early hearing loss of 38.9% among our patients. Patients who stayed longer before presenting to the hospital had worse hearing compared with those that presented earlier. We observed that steroid use was beneficial and was associated with reduced prevalence of hearing loss.

Keywords: Hearing loss, meningitis, outbreak


How to cite this article:
Yikawe SS, Manya C, Solomon JH, Yaroko AA, Aliyu N, Inoh MI, Adamu AM. Meningitis and hearing loss during an outbreak of meningococcal meningitis. Indian J Otol 2020;26:38-42

How to cite this URL:
Yikawe SS, Manya C, Solomon JH, Yaroko AA, Aliyu N, Inoh MI, Adamu AM. Meningitis and hearing loss during an outbreak of meningococcal meningitis. Indian J Otol [serial online] 2020 [cited 2020 Jul 14];26:38-42. Available from: http://www.indianjotol.org/text.asp?2020/26/1/38/278741




  Introduction Top


Meningitis is a life-threatening disease, with significant morbidity and mortality.[1] It is caused by bacteria, viruses, fungi, parasites, and drugs.[2] Bacterial meningitis is commonly caused by Streptococcus pneumoniae,  Neisseria More Details meningitidis, and Haemophilus influenzae.[2],[3] Meningococcal meningitis caused by  N.meningitidis Scientific Name Search , a Gram-negative diplococcus, found in the nasopharynx of humans, is the most common type observed during outbreaks.[4],[5] Serotypes A and C of N. meningitidis are commonly associated with outbreaks.[6],[7] Serotype A has been responsible for most outbreaks in Africa, but with widespread vaccination against this serotype, outbreaks have significantly reduced.[8],[9] Serotype C is a common cause of meningococcal disease in Europe, and large-scale outbreaks of this serotype were not a problem in Africa until 2015.[10],[11] Over a period of 19 weeks, a total of 5855 cases and 406 deaths were reported by Niger Republic's Ministry of Public Health, with laboratory tests confirming a predominance of serotype C in affected areas.[11] An outbreak of meningitis was first reported by the Nigerian government on February 20, 2017. Between December 2016 and June 2017, a total of 14,513 cases with 1166 deaths were reported from 24 states of Nigeria (WHO). Zamfara, Sokoto, and Katsina states accounted for 86% of cases. Out of these, 1002 cases were laboratory tested. Of those that tested positive, 75.4% were serotype C N. meningitidis (WHO). The Sokoto state government with the support of local and foreign partners set up a Meningitis Emergency Response Center to treat patients that were affected by the outbreak. Patients from all affected local governments within the state and nearby towns in Zamfara state were treated at this center.

Complications such as hearing loss, visual loss, disseminated intravascular coagulopathy, encephalitis, seizures, cerebral palsy, and learning disabilities can arise as a result of meningitis.[10],[12],[13],[14],[15] Bacterial meningitis is one of the most common causes of acquired hearing loss.[13],[15],[16] This is much so in developing countries where weak health systems and poor health indices make the burden of preventable deafness high.[17]S. pneumoniae which is the most common organism causing meningitis has been observed to be associated with a high prevalence of post meningitic hearing loss, followed by N. meningitidis.[18],[19],[20] The exact mechanism by which meningitis causes hearing loss is not fully understood, but suppuration of the labyrinth, cochlear neuroepithelial damage, and vascular insult have been postulated as possible mechanisms.[16],[21] Infection may spread from the subarachnoid space to the cochlear via the cochlear duct. In an outbreak scenario, however, the case fatality and resultant complications are usually high. Are there similarities between the rate of hearing loss associated with serotype C N. meningitidis outbreaks and that seen in other species? In this study, we assess the hearing threshold of patients diagnosed with meningitis during an outbreak of meningococcal meningitis in Sokoto.


  Materials and Methods Top


This was a cross-sectional, descriptive study carried out on patients diagnosed with meningitis managed at the Meningitis Emergency Response Center in Sokoto (Murtala Mohammed Hospital, Sokoto). The inclusion criteria included patients clinically diagnosed by a physician to have meningitis admitted at the Meningitis Emergency Treatment Center (bacterial meningitis as defined according to the WHO Workbook recommendations based on laboratory findings, symptoms, and signs).[22] The exclusion criteria were critically ill patients, patients receiving treatment for other ailments apart from meningitis at the center, patients above 50 years of age, those aged below 5 years, and those with preexisting hearing loss. The study was approved by the Ethical Committee of the Sokoto State Ministry of Health with approval number SKHREC/028/017.

Sampling technique

Patients on admission were randomly selected to participate in the study.

Data collection

The instrument of data collection included a set of standardized, semi-structured questionnaire. Consent was obtained from the study participants using the consent form after a good explanation of the objectives of the study. Patients then had their ears examined (any obstructing wax in the external auditory canal was removed).

Pure tone audiometry

Hearing thresholds were measured using the Modified Hughson–Westlake method at 500, 1000, 2000, 4000, and 8000 Hz for air and bone conduction (excluding 8000 Hz for bone conduction) using a diagnostic audiometer (Vaansari Marketing Services, Chennai, Tamil Nadu, India) in a sound-controlled room, which satisfied the criteria of ISO 8253-1. The average of audiometric hearing threshold at 500, 1000, 2000, and 4000 Hz for both air and bone conduction was determined; this was taken to be the pure tone average. This was categorized in accordance to the WHO grades of hearing impairment as follows: normal hearing (<25 dB), mild hearing loss (26–40 dB), moderate hearing loss (41–60 dB), severe hearing loss (61–80 dB), and profound hearing loss (81 dB or greater).

Data management

The data collected were entered and processed using Statistical Package for the Social Sciences (SPSS) software version 21 (IBM, Chicago, Illinois, USA). Chi-square test was used for the comparison of proportions/discrete data, and differences between means were compared using Student's t-test. Statistical significance was considered at 95% confidence level and α = 0.05.

Limitation

The limitations included lack of ideal audiological environment in the Meningitis Emergency Treatment Center and inability to follow-up the patients over a long period of time after the outbreak was over and the center was closed.


  Results Top


A total of 72 patients were recruited in the study. Out of these, 49 (68.1%) were males, whereas 23 (31.9%) were females. The mean age was 23.24 ± 10.00 years, with ages ranging from 8 to 45 years [Table 1]. Twenty-eight (38.9%) patients had varying degrees of hearing loss, whereas 44 (61.1%) had normal hearing [Table 2].
Table 1: Age of participants

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Table 2: Degree of hearing loss among participants

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Among the 44 patients that had normal hearing, the mean age was 24.09 ± 8.12 years, whereas the mean age among the 28 patients with hearing loss was 21.89 ± 12.54 years. There was no statistically significant difference in age among the two groups (t = 0.904, P= 0.369). The mean duration of illness was 3.28 ± 2.75 days [Table 3]. Patients with shorter duration of illness had better hearing outcomes (P < 0.001). The mean duration of illness among patients with hearing loss was 5.32 ± 3.28 days and that among those without hearing loss was 1.98 ± 1.13 years (t = 6.230, P< 0.001).
Table 3: Duration of illness before presenting to the hospital

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All patients that presented to the hospital were treated with ceftriaxone-based, broad-spectrum antibiotics. Steroids were administered to forty (55.6%) patients by the managing physician. Out of these, only seven (17.5%) were observed to have hearing loss [Table 4].
Table 4: Steroid administration among patients with hearing loss

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The mean hearing thresholds in the frequencies tested were observed to be elevated [Table 5]. The patients who did not have steroids administered and those that presented late to the hospital were observed to have higher mean hearing thresholds [Figure 1] and [Figure 2].
Table 5: Mean hearing thresholds among participants in frequencies tested

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Figure 1: Mean hearing threshold and use of steroids among participants

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Figure 2: Mean pure tone average and duration of illness among participants

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  Discussion Top


This study is different from other works on hearing loss among meningitis patients. This study was conducted during the active phase of an outbreak of meningitis. From our literature search, we have not been able to identify any study on hearing loss among patients with meningitis during an outbreak. This is the first large-scale outbreak of serotype C-predominant meningococcal meningitis in Nigeria and the second in Africa.[11],[23] It has been well established that pneumococcal meningitis presents with the highest prevalence of hearing loss.[15] However, could this be different if it happens during an outbreak, in a population with no immunity against a certain serotype? Another unique feature of this study is the assessment of immediate hearing loss in these patients. Most studies assess permanent or delayed hearing loss. The typical patients assessed are those with a history of meningitis who come down with hearing loss. This study, however, assessed all newly diagnosed patients with meningitis. Most times, patients have some form of hearing loss in the immediate postinfective period, which resolves with treatment. Studies that assess patients after discharge or when they are much better will fail to quantify this very important aspect of the pathogenesis. The limitation we had in this study was the inability to follow up these patients after discharge. We were unable to assess the permanent hearing loss among these patients, as some of them were expected to have improvements in their hearing thresholds following treatment.

We observed a male preponderance of 68.1% in this study. Authors differ in the sex distribution of hearing impaired patients following meningitis. Some report a male preponderance,[16],[24] another had more females in their study,[18] while others did not observe any difference in sex distribution among their patients.[25],[26] The mean age in this study was 23.24 years, with ages ranging from 8 to 45 years. Most studies on this topic were conducted among children, as they are the ones most commonly affected by meningitis. Jusot et al. in Nigeria observed a mean age of 12.8 years (5–55 years), whereas Heckenberg et al. observed a mean age of 59 (45–68) years.[18],[26] The prevalence of hearing loss in this study was 38.9%. We observed that 19.4% had mild hearing loss, 9.7% had moderate hearing loss, whereas 9.7% had profound hearing loss. All patients had sensory neural hearing loss. The prevalence of hearing loss following meningitis varies depending on the causative organism, the time at which hearing was assessed, and the methodology of the study. In a survey of sequelae following meningitis in Nigeria, the authors reported a prevalence of hearing loss of 31.3%.[26] This was permanent hearing loss, and the predominant organism identified in the cerebrospinal fluid of patients was N. meningitidis. In a review of disabling sequelae of meningococcal meningitis, the prevalence of hearing loss was observed to be 33.9%.[15] A prevalence of 35% was reported in a retrospective study of hearing loss following pneumococcal meningitis in adults.[18] They also observed that mild hearing loss accounted for 37%, moderate hearing loss 30%, whereas severe hearing loss accounted for 22% of cases.[18] Douglas et al., while attempting to demonstrate if a causative agent of meningitis was more likely to cause profound hearing loss, observed an 11.4% of profound hearing loss among patients infected with N. meningitidis and an 85.7% of profound hearing loss among those who had S. pneumoniae.[19] In a 5-year retrospective review of 343 patients who had pneumococcal meningitis, 54% of the 240 who had audiometry had hearing loss.[3] Although most authors report sensory neural hearing loss, others have observed conductive hearing loss among their patients.[27] Compared with other studies, and considering the fact that we reported early hearing loss, which may improve with time, N. meningitidis serotype C does not appear to be associated with higher prevalence of hearing loss during an outbreak.

The mean duration of illness in this study was 3.28 days. The mean duration was higher among patients that had hearing loss (P < 0.000). The findings in this study are not too different from that reported by other authors.[25],[28] We observed a relationship between late hospital presentation and hearing loss. Patients that stayed longer at home before coming to the hospital for treatment were more likely to have hearing loss than those who came to the hospital earlier. Health education and advocacy is important in an environment like ours where patients and caregivers are not well enlightened about the dangers of staying away from hospitals. Patients often prefer to seek cheaper alternatives, and even when services are made free by the government as was the case in our study, traditional beliefs often guide their choices.

Corticosteroids have an established benefit in the treatment of meningitis.[29],[30],[31] It has been found to reduce post meningitis sequelae, especially hearing loss in children and mortality in adults.[30],[32] Steroids were not used in all patients in this study; the use of steroids depended on the managing physician. Forty (55.6%) patients had steroids. Out of these, only seven (17.5%) had hearing loss. In two Dutch prospective cohort studies of community-acquired meningococcal meningitis, adjunctive use of dexamethasone was studied. The first group had dexamethasone use in 17% of patients, whereas the second group had dexamethasone use in 90% of patients. It was observed that hearing loss was less among the second group.[30] Other authors also observed steroids to be beneficial in reducing the prevalence of hearing loss following meningitis.[29],[32] Heckenberg et al., however, observed that the proportion of patients with hearing loss treated with or without dexamethasone was similar.[18] We advocate the use of steroids in the management of all patients with meningitis.


  Conclusion Top


Meningitis is a common cause of acquired hearing loss. We observed a prevalence of early hearing loss of 38.9% among our patients. Patients who stayed longer before presenting to the hospital had worse hearing compared with those that presented earlier. We observed that steroid use was beneficial and was associated with reduced prevalence of hearing loss. Advocacy, health education, and affordable health financing options are necessary. The use of steroids on all patients with meningitis is advocated.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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    Figures

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  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]



 

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