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Year : 2022  |  Volume : 28  |  Issue : 4  |  Page : 325-327

Case report on rare otologic sequelae of coronavirus disease-2019: Labyrinthine ossificans

1 Department of ENT and Head Neck Surgery, 5 Air Force Hospital, Jorhat, Assam, India
2 Department of Radiodiagnosis, 5 Air Force Hospital, Jorhat, Assam, India
3 Department of ENT and Head Neck Surgery, Centre – Army Hospital (Research and Referral), New Delhi, India

Date of Submission05-Sep-2022
Date of Acceptance30-Oct-2022
Date of Web Publication29-Dec-2022

Correspondence Address:
Dr. Shikha Gianchand
Department of ENT and Head Neck Surgery, 5 Air Force Hospital, Jorhat, Assam
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/indianjotol.indianjotol_151_22

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Among multiple etiologies of hearing loss, viral infections often goes unnoticed due to flu like symptoms.Otologic dysfunctions have been reported with COVID – 19 infection as well. however, this case report is unique in terms of otologic dysfunction following the COVID illness. This case report is indicative of the intracochlear damage following COVID - 19 illness. So far, there is no reported case of LO following COVID -19 in the literature. This article brings out the first reported case of SNHL due to labyrithnine ossificans following covid-19 infection.

Keywords: Auditory rehabilitation, coronavirus disease-2019 infection, labyrinthine ossificans

How to cite this article:
Gianchand S, Ali M, Swami H. Case report on rare otologic sequelae of coronavirus disease-2019: Labyrinthine ossificans. Indian J Otol 2022;28:325-7

How to cite this URL:
Gianchand S, Ali M, Swami H. Case report on rare otologic sequelae of coronavirus disease-2019: Labyrinthine ossificans. Indian J Otol [serial online] 2022 [cited 2023 Mar 29];28:325-7. Available from: https://www.indianjotol.org/text.asp?2022/28/4/325/365955

  Introduction Top

Coronavirus is the largest RNA virus containing nonsegmented, enveloped, positive-sense, single-stranded RNA.[1] With the ongoing global pandemic of novel coronavirus disease-2019 (COVID-19), literature has reported a number of cases with associated otologic dysfunctions.

Hearing loss linked with viral infections may be congenital or acquired, unilateral or bilateral, and sensorineural, conductive, or mixed type.[2] Typically, viruses are known to be related to sensorineural hearing loss. However, conductive hearing loss due to otitis media effusion and otosclerosis are also implicated.

Labyrinthitis is most commonly associated with viral or bacterial infections of the inner ear. The source may be hematogenous, tympanic, or meningeal. The ossification following labyrinthitis typically occurs 3–4 months following infection, which is usually unilateral.

Commonly reported viral infections causing labyrinthine ossificans (LO) are herpes, measles, mumps, and rubella.[3] The best treatment option for the hearing loss acquired after the LO includes cochlear implantation. However, the surgery may be challenging due to significant ossification of membranous labyrinth that makes the electrode insertion difficult. The other treatment options such as bone-anchored hearing aid may then be resorted to.[3]

  Case Report Top

Medical history

A 36-year-old male, following recovery from mild COVID infection, presented with complaints of left-sided progressive hearing loss, developed gradually over a period of 6 months. The patient was diagnosed positive for COVID-19 infection 8 months ago. He noticed difficulty in hearing in the left ear after 20 days of onset of flu-like symptoms. The hearing loss progressed over 6 months to difficulty in hearing conversational voices from the affected ear.

Audiological investigations

The pure tone audiometry suggested a left-sided profound sensorineural hearing loss. Brain stem electric response audiometry confirmed hearing thresholds above 90 dB on the affected side.

Radiological investigations

Noncontrast computed tomography temporal bone revealed that bony cochlea, semicircular canals, and vestibule on the left side were not seen. A new bone formation was confirmed in labyrinthine ossification with osseous density matrix (HU = 1940). The right side showed the preserved bony labyrinth. Bilateral facial nerve canals were normal [Figure 1]. No abnormality was seen in the bilateral external or middle ear cavities. Magnetic resonance imaging brain confirmed loss of fluid signal of membranous labyrinth of the left side on highly fluid sensitive three-dimensional T2-weighted drive sequence as seen in labyrinthine ossification. The radiological architecture of right sided membranous labyrinth and bilateral vestibulo-cochlear nerve complexes were preserved. On the basis of radiological findings, the diagnosis of LO (severe disease) was given.
Figure 1: (a) Labyrinthine ossification on left side. Noncontrast computed tomography temporal bone shows new bone formation involving the left side bony labyrinth (black arrow). The facial canal (white arrow) and the internal auditory meatus (arrow head) are preserved. (b) Magnetic resonance imaging brain three-dimensional T2-weighted drive sequence shows loss of fluid signal of membranous labyrinth (white arrow) with nonvisualization of the membranous cochlea, vestibule, and semicircular canals on the left side

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Final diagnosis

Based on the clinical and radiological investigations, the final diagnosis of severe labyrinthine ossification of the left side likely secondary to COVID-19 infection was given.


The patient was managed with Bone Bridge® [Figure 2] on the left side for hearing rehabilitation.
Figure 2: Intraoperative images of the same patient undergoing left-sided Bone Bridge® placement

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The device switch on was done 3 weeks postoperatively with the necessary acoustic adjustments. The operated site was healthy [Figure 3] and aided audiometry showed improvement in thresholds with AC mean of 30 dB.
Figure 3: Postoperative images (without and with external device)

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  Discussion Top

Among multiple etiologies of hearing loss, viral infections often go unnoticed due to flu-like symptoms. Otologic dysfunctions have been reported with COVID-19 infection. The resultant hearing loss following COVID-19 is postulated to be a consequence of virus-triggered immune-mediated inflammation.

This case report is unique in terms of otologic dysfunction following the COVID illness. The findings reported in the review by Maharaj et al.[4] are indicative of the intracochlear damage and there is a mention of radiological assessment among 13 subjects. Despite this, there is no reported case of LO following COVID-19 in the literature [Table 1].
Table 1: Review of cases of otologic disorders following coronavirus disease illness (5)

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LO occurring secondary to inner ear inflammation may occur months or years following the insult to membranous labyrinth. Following the insult, an initial inflammatory process begins with the leukocytes in the perilymphatic space. Subsequently, the fibrous stage takes over with a serofibrinous exudate resulting in fibroblasts proliferation. Finally, the ossification stage comprises the fibroblasts differentiating into osteoblasts, resulting in the formation of osteoid matrix within the labyrinthine spaces.[3]

A grading system[5] introduced during the study of LO for decision on the auditory rehabilitation was devised according to site and extent of ossification of the cochlea [Figure 4].
Figure 4: Kaya et al.[5] pathologic grading system of labyrinthine ossificans (*) associated with round window membrane

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Kaya et al.[5] grading system of LO:

Grade I: Ossification of a part of RWM with/without calcification of scala tympani. (A) arrowhead indicates RWM ossification

Grade II: Whole of RWM with/without less than half of scala tympani. (B)

Grade III: Involves whole RWM, and half of scala tympani or more than half of scala tympani. (C)

Grade IV: Whole RWM, more than half of scala tympani, and at least other scala (vestibuli and/or media). (D)

Patients who develop profound hearing loss following viral/bacterial labyrinthitis may have a good preservation of the cochlear structures that favor the outcome of cochlear implantation. However, there is a detrimental effect of duration of deafness and the degree of LO on the number of healthy spiral ganglion cells. The cochlear damage is more pronounced in the basal turn and reduces toward the apical turn. Grade III and IV are the most commonly reported, suggesting severe ossification around RWM.[5] In cases that report late, ossification of cochlea hinders the electrode placement. Therefore, once LO-associated sensorineural hearing loss is diagnosed, the patient must undergo cochlear implantation immediately.

In the present case, the patient reported after 8 months of onset of symptoms. Imaging confirmed cochlear apparatus replacement with new bone formation. Therefore, the role of cochlear implantation was not assuring. Thus, BAHA was the only viable option for rehabilitation.

  Conclusion Top

COVID-19 has deleterious effects on hearing by initiating an immune-mediated inflammation that leads to membranous cochlea damage. The diagnosis, if made in time, affects the rehabilitation modalities.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that his name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Glass WG, Subbarao K, Murphy B, Murphy PM. Mechanisms of host defense following severe acute respiratory syndrome-coronavirus (SARS-CoV) pulmonary infection of mice. J Immunol 2004;173:4030-9.  Back to cited text no. 1
Cohen BE, Durstenfeld A, Roehm PC. Viral Causes of Hearing Loss: A Review for Hearing Health Professionals. Trends in Hearing. 2014; 18:1-17. doi:10.1177/2331216514541361.  Back to cited text no. 2
Taxak P, Ram C. Labyrinthitis and labyrinthitis ossificans – A case report and review of the literature. J Radiol Case Rep 2020;14:1-6.  Back to cited text no. 3
Maharaj S, Bello Alvarez M, Mungul S, Hari K. Otologic dysfunction in patients with COVID-19: A systematic review. Laryngoscope Investig Otolaryngol. 2020;5:1192-6. doi: 10.1002/lio2.498. PMID: 33365394; PMCID: PMC7752038.  Back to cited text no. 4
Kaya S, Paparella MM, Cureoglu S. Pathologic Findings of the Cochlea in Labyrinthitis Ossificans Associated with the Round Window Membrane. Otolaryngol Head Neck Surg. 2016;155:635-40.  Back to cited text no. 5


  [Figure 1], [Figure 2], [Figure 3], [Figure 4]

  [Table 1]


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