Introduction
Sudden sensorineural hearing loss (SNHL) is a rare condition, affecting 5–20 per 100 000 population. It is defined as a loss of at least 30 dB over 3 contiguous frequencies or more, over a period of 3 days or less.Reference Stachler, Chandrasekhar, Archer, Rosenfeld, Schwartz and Barrs 1 Although multiple aetiologies have been described, including autoimmune, vascular, viral and neurological diseases, direct causal links for these aetiologies have not been well established.Reference Chau, Lin, Atashband, Irvine and Westerberg 2 Sudden SNHL can be classified according to audiometric severity, audiometric configuration, onset timing and laterality.
Bilateral sudden SNHL represents a rare subset (affecting less than 5 per cent of reported sudden SNHL cases), which carries with it a higher association with systemic disease, increased morbidity and a mortality rate reported to be as high as 15.5 per cent.Reference Oh, Park, Lee, Shin and Choung 3 , Reference Sara, Teh and Friedland 4 Bilateral sudden SNHL can be further classified by timing of bilateral symptoms as either simultaneous (second ear affected within 3 days), sequential (within 3–30 days) or progressive (more than 30 days).Reference Sara, Teh and Friedland 4 In contrast, acute otitis media is a very common otological condition with well understood pathology. Whilst conductive hearing loss in patients with acute otitis media is well recognised, an association with sudden SNHL is still considered controversial.Reference Akdag, Uysal, Bakir, Ozkurt, Muderris and Yorgancilar 5
Case report
A previously healthy 26-year-old female presented with complete bilateral hearing loss in the context of concurrent bilateral acute otitis media. The patient initially suffered from a non-productive cough, rhinorrhoea and malaise for one week, which was treated by her general practitioner with roxithromycin. She went on to develop left-sided otalgia and re-presented to her general practitioner, who prescribed amoxicillin and clavulanate for an assumed acute otitis media. Over the next day, the patient gradually developed simultaneous complete bilateral hearing loss, with associated tinnitus, neck stiffness, subjective fevers and left-sided facial pain. After 3 days with these symptoms, the patient presented to the emergency department of the local hospital and was urgently referred to the otolaryngology department.
Examination revealed bilaterally erythematous tympanic membranes and bilateral cervical lymphadenopathy. The patient had normal neurological examination (excluding VIIIth cranial nerve) findings, with no signs of meningism beyond mild neck stiffness. She had no personal or family history of autoimmune conditions. Pure tone audiometry (Figure 1) revealed bilaterally equal moderate-to-severe SNHL, with an additional conductive component culminating in severe-to-profound hearing loss.
Fig. 1 (a) Pre- and (b) post-treatment pure tone audiometry, and (c) tympanometry findings. < = bone conduction right ear; ] = bone conduction left ear; ○ = air conduction right ear; × = air conduction left ear
A clinical diagnosis of bilateral acute otitis media was made, and antibiotic treatment with amoxicillin and clavulanate was continued. Therapeutic myringotomy was refused by the patient, preventing drainage of the middle-ear cleft and potential identification of the causative pathogen. In view of the patient's SNHL, treatment was extended to include systemic corticosteroids and hyperbaric oxygen therapy (Appendix I).
Subsequent investigations revealed an elevated white cell count (14.0 × 109/l) and C-reactive protein level (186 mg/l). Serology for toxoplasmosis, rubella, herpes simplex virus, human immunodeficiency virus, cytomegalovirus and Epstein–Barr virus were negative.
Urgent magnetic resonance imaging of the internal auditory meati (Figure 2) and brain was performed. This showed bilateral suppurative otitis media, with no evidence of retrocochlear or intracranial pathology. There was also no evidence of labyrinthine ossification, although this scan was performed early in the clinical course.
Fig. 2 (a) & (b) Axial magnetic resonance imaging scans of the internal auditory meati. A = anterior; R = right; L = left; P = posterior
Whilst subjective neck stiffness and bilateral cervical lymphadenopathy were concerning presenting features, further history, examination and investigation revealed no frank meningism or systemic pathology. The cervical lymphadenopathy was deemed likely from the preceding upper respiratory tract infection. Given the lack of further findings and the patient's therapeutic response, acute otitis media was considered the likely aetiology of her bilateral sudden SNHL.
Since treatment, the patient's acute otitis media and conductive hearing loss has resolved, and her sensorineural deficit has improved by an average of 22.5 dB in the right ear and 15 dB in the left. Although this is not back to pre-morbid baseline levels, the improvement has allowed her to have functional hearing with the assistance of hearing aids.
Discussion
Bilateral sudden SNHL may be considered a medical emergency, requiring urgent investigation and treatment because of its heightened morbidity and mortality. Despite rarely being identified as idiopathic in comparison to unilateral disease, bilateral sudden SNHL remains a diagnostic and therapeutic dilemma given its rare incidence, varied aetiology and ambiguous presentation.
Sensorineural hearing loss has become an increasingly recognised possible sequelae of chronic serous otitis media.Reference da Costa, Rosito and Dornelles 6 , Reference MacAndie and O'Reilly 7 The pathogenesis of this loss has been well studied, with the leading theory proposing inflammation-induced permeability of the round window membrane, allowing passage of endotoxins and ionic disequilibrium within the cochlea.Reference Engel, Blatz, Kellner, Palmer, Weller and Bhadki 8 Numerous inflammatory mediators and bacterial by-products associated with otitis media, including by-products of Streptococcus pneumoniae, have been demonstrated to cause increased round window membrane permeability and cochlear damage.Reference Engel, Blatz, Kellner, Palmer, Weller and Bhadki 8 – Reference Joglekar, Morita, Cureoglu, Schachern, Deroee and Tsuprun 10 The above is supported further by the fact that the typical resulting hearing loss predominantly affects high frequencies, which are detected by hair cells in the cochlear basal turn adjacent to the round window membrane.Reference Huang, Dulon and Schacht 11 Although it has been hypothesised that acute otitis media has inherently greater potential to cause increased round window membrane permeability, a link with sudden SNHL is still considered controversial.Reference Ludman and Kerr 12
A review of the available English-language literature within PubMed and Medline databases was performed, using the Medical Subject Heading terms ‘acute disease’, ‘otitis media’ and ‘hearing loss, sensorineural’, with the additional key words ‘bilateral’ or ‘sudden’. Additional manual searching was performed through open access journals.
There is limited evidence of acute otitis media associated sudden SNHL within the literature,Reference Akdag, Uysal, Bakir, Ozkurt, Muderris and Yorgancilar 5 , Reference Nishioka, Masuda, Okada, Takata, Tasaka and Ogura 13 – Reference Furuhashi, Matsuda, Asahi and Nakashima 19 with only three case series reporting patients suffering bilateral sudden SNHL (Table I).Reference Nishioka, Masuda, Okada, Takata, Tasaka and Ogura 13 – Reference Hyden, Akerlind and Peebo 15 Two of the case series feature considerable confounding factors, whilst the third focuses on the microbiological features of the cases. Five case series and one case study report unilateral SNHL associated with acute otitis media, with a total of 46 patients described (Table II).Reference Akdag, Uysal, Bakir, Ozkurt, Muderris and Yorgancilar 5 , Reference Kanazawa, Hagiwara and Kitamura 14 – Reference Jang, Park and Wang 18 Common findings of note within the literature include a high prevalence of bacterial pathology and tinnitus, and favourable treatment outcomes with early myringotomy (with or without ventilation tubes) and antibiotics.
Table I Literature review summary: bilateral sudden SNHL cases associated with AOM
*Treatment outcome assessed through Furuhashi classification or, if not available, author description.Reference Furuhashi, Matsuda, Asahi and Nakashima 19 †With or without ventilation tubes. ‡Successful treatment outcome was not qualified or quantified. SNHL = sensorineural hearing loss; AOM = acute otitis media; ATP = adenosine triphosphate; PR = partial response; NR = no response; CR = complete response
Table II Literature review summary: unilateral SNHL cases associated with AOM
*Treatment outcome assessed through Furuhashi classification or, if not available, author description.Reference Furuhashi, Matsuda, Asahi and Nakashima 19 †With or without ventilation tubes. ‡Successful treatment outcome was not qualified or quantified. SNHL = sensorineural hearing loss; AOM = acute otitis media; CR = complete response; PR = partial response; NR = no response
Pathogenic organisms
Nishioka et al. reports three cases of bilateral sudden SNHL in patients suffering bilateral acute otitis media and confirmed Mycoplasma pneumoniae.Reference Nishioka, Masuda, Okada, Takata, Tasaka and Ogura 13 M pneumonia is a known risk factor for sudden SNHL, thus the presence of pneumonia is a significant confounder.Reference Okada, Kato, Miho, Minami, Kinoshita and Akao 20 Kanazawa et al. describe a case of bilateral sudden SNHL secondary to acute otitis media caused by group A streptococci, and complicated by multiple tympanic perforations and necrosis of the middle-ear cavity.Reference Kanazawa, Hagiwara and Kitamura 14 Other factors likely contributed to this patient's hearing loss, beyond acute otitis media.
In a retrospective case series investigating the complications of acute otitis media, with a focus on bacteriology and virology, Hyden et al. reports two patients with bilateral sudden SNHL.Reference Hyden, Akerlind and Peebo 15 These two patients were confirmed to have a bacterial acute otitis media and had complete resolution of symptoms once treated, with myringotomy and antibiotics being the only common treatment modalities.
Presenting symptoms
Park et al. report tinnitus, a symptom not typically suffered in uncomplicated acute otitis media, as the most common complaint of the patients included in their series.Reference Park, Park, Kim and Park 16 Akdag et al. report the incidence of tinnitus in their series to be as high as 42.8 per cent.Reference Akdag, Uysal, Bakir, Ozkurt, Muderris and Yorgancilar 5 This association is significant as tinnitus has been previously identified as a negative prognostic indicator in SNHL, and it may act as a red flag symptom for patients with acute otitis media, signifying a higher risk of sudden SNHL.Reference Kuhn, Heman-Ackah, Shaikh and Roehm 21
Treatment options
Song et al. differentiate patients with acute otitis media associated sudden SNHL, labelling the clinical entity as ‘pseudo-sudden deafness’.Reference Song, Sapthavee, Cager and Saadia-Redleaf 17 The authors proposed that this differentiation is necessary, given the specific underlying aetiology, and the belief that treatment with early myringotomy (with or without ventilation tubes) and antibiotics significantly improves prognosis. Amongst the 46 reported patients with unilateral disease, 76.1 per cent were found to have audiometric improvement, with the most common treatment offered being myringotomy and antibiotics. Amongst the patients with non-binary treatment outcomes, 52.2 per cent had a complete recovery.
Although these studies were limited by a small sample size, and heterogeneous treatment regimens and outcomes, they do suggest that patients with acute otitis media related sudden SNHL will have improved treatment outcomes with early myringotomy and antibiotics.
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• Sudden sensorineural hearing loss (SNHL) is rare, with potential dire outcomes including permanent hearing loss
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• Bilateral sudden SNHL represents a rare subset, and has a higher association with systemic disease and poorer outcomes
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• Acute otitis media is a controversial possible aetiology for sudden SNHL, with evidence limited to case series
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• This paper describes a very rare case of bilateral sudden SNHL associated with acute otitis media
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• The limited evidence suggests that acute otitis media with tinnitus and/or bacterial pathology may have increased the sudden SNHL risk
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• Early myringotomy and antibiotics may improve treatment outcomes for patients with acute otitis media associated sudden SNHL
Current American Academy of Otolaryngology guidelines for sudden SNHL recommend treatment options of systemic corticosteroids and/or hyperbaric oxygen therapy if within three months of diagnosis, with intratympanic steroids suggested as a possible salvage therapy. The caveat to this treatment guideline is that any underlying aetiology should be addressed if identified. The patient discussed in this case report received early antibiotics, but declined myringotomy and ventilation tube insertion. This and the patient's middle-ear infection precluded the use of intratympanic steroids. Whilst the patient's conductive hearing loss completely resolved, and her sensorineural loss improved to a level which provided functional hearing with the assistance of hearing aids, the literature suggests that the patient would have had a greater chance of complete recovery if early myringotomy and ventilation tubes were utilised.
Conclusion
Sudden SNHL is a rare but profound possible complication of acute otitis media. In adults with acute otitis media, evaluation for hearing loss should be performed and the risk of sudden SNHL considered. This may be especially pertinent if the patient presents with tinnitus or if bacterial infection is suspected. Conversely, patients with sudden SNHL should be screened rigorously for acute otitis media through history, examination and audiology. If acute otitis media is present, early and aggressive treatment with myringotomy (with or without ventilation tubes) and antibiotics should be offered, in addition to the recommended modalities of systemic corticosteroids and hyperbaric oxygen therapy.
Acknowledgements
The authors acknowledge the support of the Royal Brisbane and Women's Hospital, and the neurosensory team, for the provision of pure tone audiometry.
Appendix I. TREATMENT REGIMEN
