Hearing Profile of Multiple Sclerosis Patients in Jordan: A Case-Control Study

Research Article

Ann Hematol Oncol. 2019; 6(4): 1244.

Hearing Profile of Multiple Sclerosis Patients in Jordan: A Case-Control Study

Baeth Mohd Al-Rawashdeh1*, Khader J Abdul- Baqi1*, Margaret Zuriekat1, Oday Halhouli2, Mohammad Alkhoujah2, Murad Alkharabsheh2 and Omar Qudah2

1Department of Ear, Nose, Throat (ENT), The University of Jordan, Jordan

2King Hussein Medical Center, Royal Jordanian Medical Services, Jordan

*Corresponding author: Baeth Mohd Al-Rawashdeh, Department Ear, Nose, Throat (ENT), Consultant of Otolaryngology, The University of Jordan, School of Medicine, Amman, Jordan

Khader J Abdul-Baqi, Department Ear, Nose, Throat (ENT), Consultant of Otolaryngology, The University of Jordan, School of Medicine, Amman, Jordan

Received: February 02, 2019; Accepted: March 09, 2019;Published: March 16, 2019

Abstract

Objective: To determine and evaluate the difference in audiometric hearing status between individuals with and without Multiple Sclerosis (MS).

Background: MS is a chronic degenerative disease characterized by multifocal demyelination of the Central Nervous System (CNS), and thus resulting in many neurologic findings that are disseminated in place and time. Although MS affects the CNS as a whole, MS patients rarely report any complaints about their hearing status. The estimates regarding the prevalence of pure tone hearing abnormality in this patient population vary greatly. Several studies reported conflicting results about the chronic effect of MS on hearing thresholds and while some studies concluded no significant association, other studies reported a significant association. The frequencies at which MS patients had hearing deficits were various in these studies.

Methods: Using Pure Tone Audiometry (PTA), pure tone air-conduction thresholds were recorded at 0.25, 0.5, 1, 2, 4, and 8 kHz in 60 MS patients and 89 healthy controls. According to the means of the thresholds across these frequencies, the ears of each MS patient were classified to Better Hearing Ear (BE) or Worse Hearing Ear (WE). Mean thresholds of BEs and WEs were then compared to the mean thresholds of both ears of healthy controls.

Results: Hearing thresholds of WEs of MS patients were significantly higher than controls at all tested frequencies (all Ps ‹0.01). Moreover, hearing thresholds of BEs of MS patients were significantly higher than controls at 0.5, 4, and 8 kHz (all Ps < 0.05). No correlation was found between auditory thresholds and duration of the disease.

Conclusions: The study supports that MS does influence auditory thresholds unilaterally at low-mid frequencies and asymmetrically and bilateral at mid-high frequencies.

Keywords: Multiple sclerosis; Hearing; Hearing loss; Pure tone thresholds; Audiometry

Introduction

Multiple Sclerosis (MS) is a chronic degenerative disease characterized by multifocal demyelination of the Central Nervous System (CNS), and thus resulting in many neurologic findings that are disseminated in place and time. Interestingly, despite the fact that MS affects the CNS as a whole, it can present with many visual, sensory, motor, autonomic and cognitive symptoms with some symptoms being more common and consistent with MS than others, depending on the site of the lesion [1]. For instance, auditory system is one of the sensory neurologic systems that can be affected by MS. However, there is no solid consensus in the literature about the prevalence, pattern or types of auditory deficits that are caused by MS. This may be attributed to the nature of the disease itself or the variety of tests used to assess hearing. Despite that, it is generally agreed that when such deficits do occur, they are mild and usually go unnoticed [2].

Acute effect of MS on hearing can be attributed to lesions that involve the eighth cranial nerve, the cochlear nucleus and the pontine trapezoid body of the brainstem. However, the mechanism for its chronic effect on hearing is still unclear [3].

In order to evaluate the chronic effect of MS on hearing, several studies have used Pure Tone Audiometry (PTA) to compare hearing thresholds between MS patients and controls. While some studies reported no significant influence of MS on pure-tone hearing thresholds [3-5], others reported that hearing loss is present more in MS patients compared to controls at variable frequencies [6- 10]; suggesting that there is no unique pure-tone audiometric configuration specifically associated with the disease.

Despite of the discrepancies between the studies, all aforementioned studies compared the means of hearing thresholds for right ears, left ears, or both ears between MS and control groups without considering better and worse hearing ears in MS patients. Therefore, in order to evaluate the effect of MS on the auditory system, we compared hearing thresholds of better and worse hearing ears of MS patients and controls using PTA.

Methods

Study population

Study protocol was approved by the Research Ethics Committee at Jordan University Hospital. MS patients with definite MS according to the revised McDonald Criteria [11] at the Health Insurance Directorate of the Ministry of Health, Jordan University Hospital, and Multiple Sclerosis Society of Jordan, who agreed to provide their contact information for future research projects [12], were invited to participate in this study.

Patients were then interviewed and assessed for eligibility. MS patients older than 18 years old, with no other disorders affecting hearing, no family history of hearing loss and with normal otoscopic examination and tympanometric measurements were included.

Controls were recruited from the local community. Controls were included if they were older than 18 years old, had no comorbidity or health problem, had no hearing complaints or difficulty, had no noise exposure, and had normal otoscopic examination and tympanometric measurements.

Participants from both groups were asked to fill an informed consent and provide demographic information. After that they underwent PTA testing at the otolaryngology department at Jordan University Hospital.

Hearing measurement

Hearing thresholds in Decibels (dB) were measured at 0.25, 0.5, 1, 2, 4, and 8 kHz for both ears of MS patients and controls using PTA. The measurement was conducted using standard procedures recommended by the American Speech-Language-Hearing Association [13].

According to the means of the thresholds across all measured frequencies, each ear of every MS patient was classified into Better Ear (BE) or Worse Ear (WE). Mean thresholds of BEs and WEs were then compared to the mean thresholds of both ears of healthy controls.

Degree of Hearing Loss (HL) according to the mean hearing thresholds (dB) at (0.5, 1, 2, and 4 kHz) for each ear was classified into: Normal hearing (-10–15); Slight HL (16–25); Mild HL (26–40); Moderate HL (41–55); Moderately severe HL(56–70); Severe HL(71– 90); or Profound (HL) (>91) [14].

Statistical analysis

Data was entered into and analyzed using the Statistical Package for Social Sciences (SPSS), version 20. Categorical variables were described as frequencies and percentages and compared using Pearson’s X2 -test. For analysis of continuous variables, all data were analyzed initially using the Kolmogorov-Smirnov test, histograms and Q-Q plots to assess for normality. Continuous variables were described as mean ± Standard Deviation (SD) and compared using t test and Mann-Whitney U test. Correlations between variables were assessed using Spearman’s rank correlation test. P ‹0.05 was assigned as the alpha.

Results

Participant characteristics

A total of 60 MS patients and 89 healthy controls participated in the study. The study participants’ demographic characteristics are presented in Table 1. Both groups had similar gender composition (P=0.726), but MS patients were older than controls (P=0.000).