Bilateral osteomas arising from the internal auditory canal: case report

[On the question of choosing a surgical approach when removing an osteoma of the external auditory canal]

The article presents the results of the surgery treatment of osteomas in external auditory canals of 24 patients. The quantity and the location of osteomas with respect to the tympanic membrane determine a surgical approach. Retroauricular approach (n=19) was applied in cases of multiple osteomas or their close location with the tympanic membrane. Single osteomas located laterally of the isthmus of the external auditory canal were removed with the endaural approach (n=5). The overall follow-up period was 5 years. Postsurgical supervision did not register illness recurrence or any complications such as the trauma of the tympanic membrane or the stenosis of the external auditory canal.

Unilateral cochleovestibular nerve compression syndrome in a patient with bilateral IAC osteoma

INTRODUCTION

Osteomas of the internal auditory canal are rarely reported in the literature. Patients may complain of disabling symptoms of dizziness, hearing loss, and vestibular dysfunction. We report the case of a patient with bilateral osteomas of the internal auditory canal (IAC) associated with bilateral neurovascular compression mainly affecting the right cochleovestibular nerve (VIII) and right anterior inferior cerebellar artery (AICA).

OBSERVATION

This 75-year-old woman patient complained of disabling paroxysmal vertigo, typewriter tinnitus and hearing loss of the right ear. Temporal bone computed tomography showed bilateral osteoma arising from the posterior superior wall of the IAC. MRI sequences of the right VIII demonstrated compression by the right AICA against the inferior wall of the narrowed IAC. Treatment with oxcarbazepine allowed marked and lasting improvement of the patient's symptoms.

CONCLUSION

To our knowledge, this is the first description of an ipsilateral neurovascular compression syndrome of the VIII secondary to the presence of an osteoma narrowing the IAC.

Internal Acoustic Canal Stenosis Due to Hyperostosis

Background  Exostoses and osteomas are benign, insidious lesions of the bone involving the internal acoustic canal (IAC). We present two cases of IAC exostoses managed with surgical decompression and review the clinical outcomes of previously reported cases in the literature. Methods  A comprehensive search was conducted using PubMed Central, Web of Science Core Collection, and Google Scholar databases to identify previous reports of IAC exostoses and osteomas. A total of 26 reported cases were identified, and patient presenting symptoms, management strategies, and response to surgery was obtained when available. Results  Of the 13 patients who underwent surgical decompression, 8 patients had resolution of vertigo symptoms, 10 patients had improvement of tinnitus symptoms, and all patients maintained some level of serviceable hearing. Conclusion  IAC exostoses and osteomas are rare lesions that lead to insidious onset of debilitating symptoms from vestibulocochlear nerve dysfunction. Although the role of surgical decompression remains unclear, it appears that patients presenting with vertigo have more favorable response to surgical decompression as compared with those presenting with tinnitus and sensorineural hearing loss.

Bilateral Cerebellopontine Angle Osteomas: Case Report and Review of the Literature

Osteomas and exostoses of cerebellopontine angle (CPA) are very rare, benign, and usually slow-growing lesions; few case reports have been published about these lesions in literature. The most common localizations of these temporal bone lesions are the mastoid cortex and the external acoustic canal. To our knowledge, only two cases of bilateral osteoma arising from both internal acoustic canals (IACs) have been reported. However, these tumors are usually asymptomatic and diagnose incidentally, and they can cause symptoms related to the 7^th and 8^th cranial nerve involvement. We report on a 75-year-old woman affected with bilateral osteoma of CPA and review the literature that 27 cases of IAC osteoma and exostoses have been reported.

Bilateral osteomas and exostoses of the internal auditory canal

Osteomas and exostoses are benign tumors of the bone that occur in the head and neck region but are rarely found within the internal auditory canal (IAC). In this report, we review the literature on bony lesions of the IAC and present two cases: one case of bilateral compressive osteomas and one case of bilateral compressive exostoses of the IAC.

[Hyperostosis of the internal auditory canal : An incidental finding?]

In contrast to the fairly common exostoses in the external auditory canal, hyperostoses and osteomas of the internal auditory canal are extremely rare. In this case report we present a patient with sudden right-sided sensorineural hearing loss, in whom imaging revealed hyperostosis with bilateral stenosis of the internal auditory canal. Whether the connection of such radiological findings with dysfunction of cranial nerves VII and VIII be causal or coincidental is controversially discussed in the literature. Therefore, the indication for surgical intervention should be considered with extreme caution. Despite examination of our radiology database comprising almost 1000 MRI/CT temporal bone investigations, we could find no other cases of hyperostosis of the petrous bone. This case thus represents a rare disease, which should be considered a differential diagnosis.

External auditory osteoma

External auditory canal (EAC) osteomas are rare, benign bony neoplasms that occur in wide range of patients. While chronic irritation and inflammation have been suggested as causal factors in several cases, significant data is lacking to support these suspicions. Symptoms are rare and can include hearing loss, vertigo, pain and tinnitus. Diagnosis is made based on a combination of clinical history and examination, radiographic imaging, and histopathology. Osteomas of the EAC are usually found incidentally and are unilateral and solitary. Computed tomography reveals a hyperdense, pedunculated mass arising from the tympanosquamous suture and lateral of the isthmus. Histopathologically, EAC osteomas are covered with periosteum and squamous epithelium, and consist of lamalleted bone surrounding fibrovascular channels with minimal osteocysts. Osteomas have historically been compared and contrasted with exostoses of the EAC. While they share similarities, more often than not it is possible to distinguish the two bony neoplasms based on clinical history and radiographic studies. Debate remains in the medical literature as to whether basic histopathology can distinguish osteomas of the EAC from exostoses. Surgical excision is the standard treatment for EAC osteomas, however close observation is considered acceptable in asymptomatic patients.

Comparative case series of exostoses and osteomas of the internal auditory canal

Exostoses and osteomas are benign bony lesions of the auditory canal. Although common in the external auditory canal, they are rare and difficult to distinguish in the internal auditory canal (IAC). In this literature review and case presentation, we define radiologic and histologic criteria to differentiate exostoses from osteomas of the IAC. Two patients with exostoses and 1 patient with an osteoma of the IAC are described here. Patient 1 presented with disabling vertigo and was found to have bilateral exostoses with nerve impingement on the right. After removal of the right-sided exostoses via retrosigmoid craniotomy, the patient had complete resolution of her symptoms over 1 year. Patient 2 presented with bilateral pulsatile tinnitus and vertigo and was found to have bilateral IAC exostoses. Patient 3 presented with hearing loss and tinnitus, and a unilateral IAC osteoma was ultimately discovered. Because of the mild nature of their symptoms, patients 2 and 3 were managed without surgery. We show that IAC osteomas can be differentiated from exostoses by radiographic evidence of bone marrow in high-resolution computed tomography scans, or by the presence of fibrovascular channels on histologic analysis. Management of these rare entities is customized on the basis of patient symptoms.

Osteoma of the internal auditory canal

OBJECTIVE

Osteoma occurs almost exclusively in the head and neck region, only rarely developing into the internal auditory canal. We report an incidental finding of a case in the radiological evaluation of a patient with left hemifacial spasm.

PATIENTS AND METHODS

A 79-year-old woman consulted for left hemifacial spasm associated with left anacusis. Symptoms occurred up to 30 years prior to the first radiological investigations. Computed tomographic (CT) and magnetic resonance (MRI) images were taken.

RESULTS

MRI demonstrated a left internal auditory canal lesion with spontaneous hypointense signal on T1- and T2-weighted images. CT showed the lesion as a typically dense and opaque osteoma. It measured 0.6 cm in maximum size. No surgery was performed because of the slow-growing features of the lesion. Clinical monitoring was recommended.

CONCLUSION

Osteomas are diagnosed incidentally in asymptomatic patients. Our case was symptomatic and raised the question of surgical management. This article discusses the presentation and management associated with this exceptional osteoma location.