Labyrinthitis ossificans with fluctuating symptoms lasting for more than 10 years: a case report and literature review

Introduction

Labyrinthitis ossificans (LO) is the end stage of labyrinthitis, typically caused by infections that lead to inflammation of the membranous labyrinth, resulting in fibroblastic proliferation and ossification of the labyrinth, which ends in irreversible profound sensorineural hearing loss (SNHL) (1). Besides hearing loss, patients with LO may also suffer from residual balance dysfunction, which can significantly affect their quality of life.

Typical LO may leave a sense of instability after several days of severe dizziness; however, in this case, the patient continued to experience episodic dizziness accompanied by fluctuating hearing more than 10 years after the onset, which might have been easily misdiagnosed as Ménière’s disease or delayed endolymphatic hydrops.

LO is rare in clinical practice and mostly secondary to other diseases. Currently, there is no extensive epidemiological investigation. However, this disease can lead to severe complications, such as profound hearing loss and instability, which seriously affect the daily life of patients. Through extensive literature research, we found that early case reports largely focused on the pathological and radiological changes in the inner ear of labyrinthitis patients found during autopsy (2,3), and the current treatment of this disease mainly focuses on improving hearing. In the early stage, steroids application is generally attempted, and in the late stage, cochlear implantation is recommended (4,5). Nevertheless, there is no satisfactory solution to the common problem of poor balance in patients. We have supplemented the treatment in this aspect and achieved good results. We present this article in accordance with the CARE reporting checklist (available at https://tp.amegroups.com/article/view/10.21037/tp-2025-128/rc).

Case presentation

All procedures performed in this study were in accordance with the Helsinki Declaration (as revised in 2013), and approved by the ethics committee of Shandong Provincial ENT Hospital (No. 2023-040-01). Written informed consent was obtained from the patient’s mother for the publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

At the age of 8 months, the female patient presented with a high fever, and was subsequently diagnosed with meningitis. Following the resolution of the fever, the patient showed a diminished response to auditory stimuli, and demonstrated developmental delays, specifically in the acquisition of ambulatory skills. Between the ages of 4 to 5 years, the patient’s mother incidentally discovered that the patient had profound SNHL in her left ear. At approximately 13 years of age, the patient began to experience a decline in auditory acuity in her right ear without any identifiable precipitating factors. This was concomitant with a sensation of aural fullness, dizziness, and disequilibrium. There were no reports of fluctuating tinnitus or vertigo. The symptoms of aural fullness would abate after 3 to 4 hours, culminating in the return of her hearing to its premorbid level. At the age of 16, the patient attended Shandong Provincial ENT Hospital complaining of hearing loss that was difficult to recover from, and frequent dizziness in the past 2 weeks.

Additionally, the patient reported a long-standing complaint of instability during nocturnal ambulation. The patient and her mother stated that she had no history of otitis media, and there was no history of congenital deafness in the patient’s family. The physical examination revealed that the patient’s bilateral external acoustic meatus were patent, with intact tympanic membranes and no signs of congestion, otorrhea, or otalgia. The Romberg test was negative; the Mann test was positive; and the patient was unable to cooperate to complete the Fukuda test. The progression of the patient’s illness and treatment are shown in Figure 1.

Figure 1 Timeline of the patient’s illness onset.

Computed tomography (CT) showed no obvious abnormal changes in the bilateral cochleae. The local areas of the bilateral horizontal semicircular canals showed bony high density, of which the left side was more prominent (Figure 2). Gadolinium-enhanced magnetic resonance imaging (Gd-MRI) was performed. The bilateral internal acoustic meatus were of equal width, with natural neural courses, and no obvious abnormal signals. Local non-visualization was observed in the bilateral horizontal semicircular canals. Contrast agent signals were present in the perilymphatic spaces of the bilateral cochleae, vestibules, and anterior and posterior semicircular canals. The visualization range of the bilateral cochleae and vestibules was slightly decreased, with small, round, low-signal areas visible inside, which had clear boundaries. The right side was more prominent, with the low-signal area in the vestibule accounting for more than 1/3 but less than 1/2 of the total vestibule area on the same side. The low-signal area in the left vestibule was less than 1/3 of the total vestibule area on the same side (Figure 3).

Figure 2 CT scans of the patient’s ear. (A) The right ear; (B) the left ear. The local areas of the bilateral horizontal semicircular canals showed bony high density, of which the left side was prominent. The surrounding mastoid process is well pneumatized. The red arrow points to the ossified part of the bilateral horizontal semicircular canals. CT, computed tomography.

Figure 3 Gd-MRI of the patient. The red arrow shows significant endolymphatic hydrops in the right ear. There is no obvious hydrops found in the vestibule and cochlea on the left side. Gd-MRI, gadolinium-enhanced magnetic resonance imaging.

Further, the patient’s caloric tests did not induce significant nystagmus, suggesting a decreased low-frequency response in the bilateral horizontal semicircular canals. The video head impulse test (vHIT) showed gains in the anterior semicircular canal, horizontal semicircular canal, and posterior semicircular canal of 0.81, 0.05, and 0.16 for the right ear, and of 1.01, 0.05, and 0.28 for the left ear, respectively. All of these findings indicated a decline in the patient’s vestibular function. The sinusoidal rotation tests showed abnormal gains and phase shifts in the frequency range of 0.01–0.64 Hz, indicating a decline in the mid-frequency function of both the horizontal semicircular canals. Cervical vestibular-evoked myogenic potentials (VEMPs) indicated abnormal function of the bilateral saccule pathways, while ocular VEMPs had a normal response. In summary, the patient showed a decline in low, mid, and high-frequency functions of both horizontal semicircular canals, as well as abnormal function of the saccule. The sensory organization test (SOT) indicated that while the patient had decreased vestibular function, her balance function was still acceptable. The detailed test results are shown in Table 1.

The patient was diagnosed with LO. Treatment was carried out with ginaton, sodium aescinate, and mecobalamin, and methylprednisolone sodium succinate was administered intravenously. The steroids treatment lasted for 6 days, and began with an initial dose of 80 mg that was gradually reduced. To prevent the side effect caused by steroids, the patient took calcium supplements and stomach-protecting drugs for a short period during the treatment, and made no complaints of discomfort during the medication period.

During the treatment period, the pure tone audiometry (PTA) examination indicated that the patient’s hearing in the right ear had returned to a previously level, and the patient reported that the dizziness had not recurred (Figure 4). However, based on the patient’s gadolinium contrast results, we informed the patient that there was an 87% probability of further hearing loss in the right ear. We recommended early cochlear implantation to reduce the surgical difficulty and achieve optimal hearing. However, the patient’s mother declined this recommendation.

Figure 4 Changes in the pure tone audiometry threshold during treatments.

In the follow-up, we found that the patient’s right-ear hearing gradually deteriorated. In February 2023, the patient underwent cochlear implantation on the left side,and showed good hearing recovery after the surgery.

Review of literature

According to the referenced literature, it is clear that labyrinthitis can be induced by multiple infection routes, such as otitis media, meningitis, and trauma (6). Among these, meningitis represents the most prevalent route leading to bilateral labyrinthitis. In most case reports, the focus has predominantly been on the hearing loss in patients, while relatively little attention has been paid to the symptoms of dizziness. Even when dizziness was investigated, it was often merely based on patients’ subjective experiences, lacking a systematic assessment. However, as noted in certain articles, patients with LO demonstrate notable balance impairments during Caloric testing and the vHIT. Specifically, 86.9% of them exhibit unilateral weakness in caloric testing. Moreover, 72.5% of patients diagnosed with idiopathic labyrinthitis report balance problems or a sense of instability. Thus, addressing the balance problems in patients with LO is an urgent concern that demands immediate attention. For the detailed literature information, please refer to Table 2.

Discussion

Labyrinthitis, an inflammation of the inner ear, is most commonly caused by infections that can access the inner ear through various routes. LO represents the final stage of labyrinthitis.

Irrespective of the cause, the pathogenesis of LO commences with an acute inflammation stage, and is succeeded by a phase marked by fibroblast proliferation and fibrosis that leads to labyrinth ossification (7). Labyrinthitis caused by meningitis may be related to the two connections between the inner ear and the central nervous system; that is, the internal auditory canal and the cochlear aqueduct. Infection diffuses from the subarachnoid space to the labyrinth through the cochlear aqueduct (13). Typically, LO emerges first and is most severe at the location where the cochlear aqueduct enters the labyrinth. Unlike LO of a tympanogenic origin, the etiological factors of LO related to the central nervous system usually present bilaterally (8,9).

Paparella et al. reported a substantial reduction in the overall quantity of spiral ganglion cells, which might be due to the spread of infection via the perivascular and perineural spaces of the modiolus and/or the infarction of the cochlea’s vascular supply (14). Fortunately, a large meta-analysis by Cheng and Svirsky found that the number of spiral ganglion cells has no significant relationship with the auditory and speech outcomes of cochlear implant patients (15). Retro-cochlear structures have also been implicated as another potential cause of meningitis-linked hearing damage. However, this is highly uncommon and is presumably caused by brainstem ischemia or elevated intracranial pressure (16). Further, studies have shown that LO may cause endolymphatic hydrops, possibly due to bacterial toxins entering the endolymph through perforations in the basilar membrane and/or the Reissner’s membrane, causing cellular changes in the Reissner’s membrane, osmotic pressure imbalance, and other chemical changes in the labyrinthine fluid (3,17). Ossification of the labyrinth may commence as soon as three weeks after the onset, and the processes of ossification, calcification, and remodeling can persist for a period of 12 months (18).

Females tend to be slightly more susceptible to developing labyrinthitis than males, with a prevalence ratio of approximately 1.5:1 (1). Suppurative bacterial labyrinthitis, which is a complication of bacterial meningitis, is the leading cause of deafness among children under two years old. One study reported that 7% of children who have had meningitis experience hearing loss, with most of these children suffering from severe or profound hearing loss (19), and the hearing loss is often irreversible. The acute phase of labyrinthitis generally lasts for a few days, but the subsequent residual dizziness symptoms may persist for several weeks. Another study indicated that after a median follow-up period of 61 months, 72.5% of patients continued to experience balance issues (10).

Occasionally, the symptoms of LO might not be characteristic, particularly when the root cause remains elusive. Both MRI and CT imaging can prove valuable in the process of diagnosis and differential diagnosis. CT can reveal high-density bone deposition in the membranous labyrinth. LO might exhibit sclerosis, irregularities, or obliteration of the cochlea, semicircular canals, or vestibule with varying degrees of involvement. CT is specific but has a relatively lower sensitivity than MRI. In this case, although the patient has already suffered from severe hearing loss, no obvious cochlear ossification was found in the CT scan.

In the acute/subacute phase of labyrinthitis without ossification, MRI shows enhancement of the membranous labyrinth; after ossification occurs in the labyrinth, MRI shows a loss of normal fluid signal in the inner ear. Previous studies showed that gadolinium-enhanced MRI is capable of detecting meningitic labyrinthitis in the early phase and precisely forecasting which patients will experience hearing loss in the future (11,12). Meanwhile, imaging findings are of great significance for the selection of the timing of cochlear implantation and the prediction of patient prognosis. Different from the literature, in this case, although the patient’s left ear has profound SNHL, the Gd-MRI does not show hydrops.

Labyrinthitis frequently follows another infection, such as otitis media or meningitis. Thus, the early diagnosis and efficient management of such infections are crucial for the prevention of labyrinthitis. Corticosteroids are currently recognized as effective drugs for the treatment of labyrinthitis, but their efficacy remains inadequate. A retrospective study has suggested that steroids play a certain role in preventing the occurrence of LO in children with pneumococcal meningitis (20). Recently, another study on the use of biologics in the treatment of labyrinthitis has suggested that infliximab significantly improves vestibulocochlear function in patients with bilateral labyrinthitis and reduces dependence on corticosteroids (21).

For patients with severe SNHL, cochlear implantation may be considered. In this case, hormone therapy was effective for a period; however, as the disease progressed, the patient ultimately chose cochlear implantation. Notably, cochlear implantation is not the end of treatment for patients with labyrinthitis who continue to experience dizziness. For patients who experience frequent dizziness attacks that severely affect their lives, continuous intervention is required.

In previous research on LO, little attention has been paid to the vestibular function of patients. In this case, the patient experienced early balance dysfunction, which mainly manifested as delayed walking and unstable gait, but she gradually adapted over several months. The patient experienced a significant decline in her bilateral vestibular function; however, her subjective symptoms were not prominent. This may be attributed to the vestibular rehabilitation effect of activities such as learning to walk since childhood. The SOT indicated that the patient’s proprioception and vision effectively compensated for the balance impairment caused by the vestibular deficit. However, when her proprioception or vision was blocked, the patient became significantly unstable and even fell. Therefore, during the consultation process, patients need to be informed that their balance function will be significantly impaired in dark environments or on uneven surfaces, and they should be cautious and preferably accompanied by someone to ensure their safety. Some studies have shown that for patients with vestibular diseases, regular vestibular rehabilitation training can improve their balance function (22,23). Vestibular rehabilitation training can promote the coordination of the vestibular system, vision, and proprioception, thereby improving the patient’s symptoms of instability and facilitating the restoration of balance (24,25).

In conclusion, based on the high sensitivity of current Gd-MRI, we recommend that inner ear Gd-MRI should be performed as early as possible after the diagnosis of LO. If the result is positive, audiological examinations should be completed in a timely manner. Once hearing loss is detected, corticosteroids therapy or other hearing-protecting intervention measures should be taken promptly. In addition, considering that the lesions in most patients will involve the vestibular system, regardless of whether the patients have dizziness symptoms or not, we recommend early initiation of vestibular rehabilitation training. For patients with already decreased vestibular function, regular rehabilitation training should be adhered to, and the vestibular function should be re-examined regularly to dynamically monitor the disease progression, so as to effectively improve the long-term quality of life of patients.

However, the retrospective nature of the study and potential recall bias in reporting symptoms over a decade may affect the accuracy of the clinical timeline.

Conclusions

We reported a rare case of LO that was unstable for over a decade. We comprehensively evaluated the patient’s audiovestibular function and provided regular vestibular rehabilitation therapy, which controlled the patient’s dizziness symptoms and restored the balance function. Therefore, we recommend that a comprehensive vestibular function examination is necessary for LO patients with recurrent dizziness., with the aim of achieving a better therapeutic effect.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the CARE reporting checklist. Available at https://tp.amegroups.com/article/view/10.21037/tp-2025-128/rc

Peer Review File: Available at https://tp.amegroups.com/article/view/10.21037/tp-2025-128/prf

Funding: This study was funded by National Natural Science Foundation of China (Nos. 82101225 and 82471175), Traditional Chinese Medicine Science and Technology Project of Shandong Province (No. M20243002), China Postdoctoral Science Foundation (No. 2024M761821), and the Natural Science Foundation of Shandong Province (No. ZR2024MH027).

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://tp.amegroups.com/article/view/10.21037/tp-2025-128/coif). All authors report that this study was funded by National Natural Science Foundation of China (Nos. 82101225 and 82471175), Traditional Chinese Medicine Science and Technology Project of Shandong Province (No. M20243002), China Postdoctoral Science Foundation (No. 2024M761821), and the Natural Science Foundation of Shandong Province (No. ZR2024MH027). The authors have no other conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the Helsinki Declaration (as revised in 2013), and approved by the ethics committee of Shandong Provincial ENT Hospital (No. 2023-040-01). Written informed consent was obtained from the patient’s mother for the publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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