Role of acute cochlear neuritis in sudden hearing loss in multiple sclerosis

Management of Sudden Sensorineural Hearing Loss in Multiple Sclerosis: A Comprehensive Case Report of a Patient with Bilateral Loss and Literature Review

In multiple sclerosis (MS), the occurrence of sudden sensorineural hearing loss (SSNHL) is considered rare, with reported cases predominantly being unilateral. Bilateral cases are even rarer. Here, we report a case of bilateral SSNHL in a 20-year-old male diagnosed with MS. The patient, undergoing corticosteroid therapy for the management of MS, additionally received an intratympanic dexamethasone injection; however, it could not achieve significant improvement. Subsequently, the systemic dosage was increased for one week, resulting in substantial hearing improvement in both ears after three months. A review of MS-related SSNHL cases from 1987 to 2022 revealed 39 ears in the literature, with only five ears showing no hearing recovery. A remarkable 87.2% exhibited restored hearing, presenting a more favorable prognosis compared with idiopathic SSNHL. Although there were slight variations in administration methods and duration, all documented treatment approaches involve systemic corticosteroids. In some instances, SSNHL manifested as the initial symptom of MS. When SSNHL occurs in MS, auditory brainstem response (ABR) tests may reveal prolonged abnormalities, making ABR testing effective in cases where MS is suspected following SSNHL. In conclusion, the treatment of MS-related SSNHL appears appropriate with systemic corticosteroids, showing a significantly superior prognosis compared with idiopathic SSNHL.

Hearing abnormalities in multiple sclerosis: clinical semiology and pathophysiologic mechanisms

Auditory manifestations from multiple sclerosis (MS) are not as common as the well-recognized sentinel exacerbations of optic neuritis, partial myelitis, motor weakness, vertiginous episodes, heat intolerance, and eye movement abnormalities. This paper discusses four cases of auditory changes, secondary to MS, and describes the first case, to our knowledge, of palinacousis, the perseveration of hearing, despite cessation of the sound stimulus. For each we characterize the initial complaint, the diagnostic work up, and ultimately, underscore the individualized treatment interventions, that allowed us to achieve a remission in all four cases. Individually codifying the treatment regimens served to mitigate, if not to abolish, the clinical derangements in hearing. Special attention is focused upon examination of the clinical manifestations and the pathophysiologic mechanisms which are responsible for them. We further emphasize the differential diagnostic considerations, and physical exam findings, along with the results of laboratory testing, neuro-imaging sequences, and lesion localization. Taken together, such information is germane to organizing cogently coherent strategic treatment plan(s). We believe that this small case series represents a clinically pragmatic example of 'precision medicine'; a principal theme and goal throughout this paper, the achievement of such in MS, but also as an illustration for the assessment and management schema for neuroimmunologic disorders in general.

Acute vestibular syndrome and hearing loss mimicking labyrinthitis as initial presentation of multiple sclerosis

Acute vestibular syndrome is most often caused by vestibular neuritis or stroke, although demyelinating diseases may be responsible for 4% of all AVS episodes. The authors present the case of a previously healthy 17-year-old female patient complaining of spontaneous vertigo and right-sided hearing loss. Otoneurological examination suggested a peripheral vestibular cause and video head impulse test revealed a reduced vestibulo-ocular reflex gain. The presence of sensorineural hearing loss raised the suspicion of a central cause and prompted imaging evaluation. A brain MRI evidenced demyelinating lesions in the right middle cerebellar peduncle and the patient was ultimately diagnosed with Multiple Sclerosis.

Association of multiple sclerosis and sudden sensorineural hearing loss

Background

Multiple sclerosis (MS) may affect other cranial nerves besides the optic nerve. Sudden sensorineural hearing loss (SSHL), possibly caused by a deficit in the auditory tract, including the vestibulocochlear nerve, is sometimes associated with MS.

Objectives

We aimed to assess the incidence of SSHL among MS patients, its frequency as an initial symptom of MS, and magnetic resonance imaging (MRI) findings associated with SSHL in MS.

Methods

We collected retrospectively all patients diagnosed with MS and SSHL at the Helsinki University Hospital between 2004 and 2014. Patients with both diagnoses were re-evaluated using hospital medical records, audiograms and head MRI scans.

Results

A total of 2736 patients were diagnosed with MS, 1581 patients with SSHL, and 18 patients (0.7% of all MS patients) with both; two patients presented with SSHL as an initial symptom of MS. The annual incidence of SSHL was 59.8/100 000 (95% confidence interval (CI) 37.7–94.9) in MS patients, and 12.4/100 000 (95% CI 11.8–13.0) in the normal population.

Conclusion

SSHL is a rare symptom of MS and is even less frequent as an initial symptom. Its incidence in MS patients, however, markedly exceeds that in the normal population.

Sudden sensorineural hearing loss and polymorphisms in iron homeostasis genes: new insights from a case-control study

Background. Even if various pathophysiological events have been proposed as explanations, the putative cause of sudden hearing loss remains unclear. Objectives. To investigate and to reveal associations (if any) between the main iron-related gene variants and idiopathic sudden sensorineural hearing loss. Study Design. Case-control study. Materials and Methods. A total of 200 sudden sensorineural hearing loss patients (median age 63.65 years; range 10-92) were compared with 400 healthy control subjects. The following genetic variants were investigated: the polymorphism c.-8CG in the promoter of the ferroportin gene (FPN1; SLC40A1), the two isoforms C1 and C2 (p.P570S) of the transferrin protein (TF), the amino acidic substitutions p.H63D and p.C282Y in the hereditary hemochromatosis protein (HFE), and the polymorphism c.-582AG in the promoter of the HEPC gene, which encodes the protein hepcidin (HAMP). Results. The homozygous genotype c.-8GG of the SLC40A1 gene revealed an OR for ISSNHL risk of 4.27 (CI 95%, 2.65-6.89; P = 0.001), being overrepresented among cases. Conclusions. Our study indicates that the homozygous genotype FPN1 -8GG was significantly associated with increased risk of developing sudden hearing loss. These findings suggest new research should be conducted in the field of iron homeostasis in the inner ear.

Auditory Efferent Function Is Affected in Multiple Sclerosis

OBJECTIVE

This study evaluated efferent medial olivocochlear (MOC) function in patients with multiple sclerosis (MS). Various afferent auditory abnormalities have been described in MS, but there is a paucity of data on efferent function. The brain stem is a site of predilection for MS plaques and the efferent MOC pathway may be affected at this level.

METHODS

The study included 30 patients who had normal hearing. According to MRI findings, they were divided into two groups: those with an identifiable brain stem lesion (n = 10) and those with MS lesions in other parts of the central nervous system but without demonstrable MS plaques in the brain stem (n = 20). MOC function was evaluated by the olivocochlear suppression test, using transient evoked otoacoustic emissions. All subjects underwent standard auditory tests, including pure-tone audiometry and recording of auditory brain stem evoked responses. Twenty-two healthy subjects with normal hearing, matched for age and gender, served as a reference group for the auditory data.

RESULTS

The results showed that 66.6% of all patients had reduced MOC function, particularly those (90%) with identified lesions of the brain stem on MRI. Furthermore, abnormal MOC function was found in 55% patients without evidence of a brain stem lesion on MRI.

CONCLUSIONS

This study provides the evidence for a deficit of efferent auditory function in the majority of patients with MS. Taking into consideration the possible roles of the MOC system in processing of auditory information, abnormal MOC suppression in patients with MS may explain a variety of auditory presentations that are currently largely overlooked. This study also highlights the diagnostic value of the MOC suppression test as a site-of-lesion diagnostic test in MS and in identifying subtle brain stem lesions undetected by MRI, suggesting that subtle brain stem lesions may exist and that the MOC suppression test is sufficiently sensitive to detect them. Accordingly, the MOC suppression test may provide a tool for an early diagnosis of MS.

Surdités brusques idiopathiques

Idiopathic Sudden Sensorineural Hearing Loss (ISSHL) remains one of the major unsolved otologic emergencies. It is characterized by the onset of an unilateral sensorineural hearing loss developing within 24 hours, and averaging on pure tone audiogram at least 30 dB HL for three subsequent octave steps, with no marked vestibular symptoms and no identifiable cause. ISSHL is a syndrome covering several heterogeneous entities resulting from different pathogenetic mechanisms. At this time, the audiogram is the unique tool which may help clinicians to identify these entities and provide a classification based on 5 types of hearing loss. Numerous experimental and clinical studies have investigated the mechanisms by which infectious, ischemic, mechanic or immunologic insults may induce cochlear dysfunction. However, extrapolation to humans and rationale therapeutic approaches to ISSHL remain uncertain. SSHL being a diagnosis of exclusion, retrocochlear and neurologic etiologies should be eliminated. No argument allows to consider ISSHL a therapeutic emergency. More precisely, the experimental data presently available on cochlear physiology suggests that a treatment could have some chance to be effective if undertaken within minutes following the onset of ISSHL, a condition never encountered in daily practice. Conversely, it is not justifiable to impute the absence of hearing recovery to a delay in therapy. The various therapeutic strategies currently recommended are highly empirical and should be questionned in terms of cost-effectiveness, the most common being high-dose corticosteroids. New investigation tests are required for improving our approach to ISSHL.