Surgical treatment of auditory canal exostoses

BACKGROUND: Although complications of surgical removal of external auditory canal exostoses are rare, reported surgical complications include tympanic membrane perforation, postoperative hearing loss, canal stenosis, and facial nerve injuries. PATIENTS AND METHODS: We report on our experience in exostosis surgery, consisting of 59 procedures in 48 patients. Preoperative and postoperative complaints and findings, intraoperative complications, and audiologic results are described and discussed. There has been a minimum of one year of follow-up in every case. RESULTS: Postoperative canal stenosis was seen in 2 cases of preoperative severe persistent external otitis. Temporary threshold shift was recorded in 6 patients. Persistent sensorineural hearing loss occurred in 4 patients. Six of the 10 patients with temporary or persistent hearing loss had already shown preoperative sensorineural hearing loss. Intraoperatively tympanic membrane perforation occurred in 3 cases, accidental opening of the mastoid in 1 case. CONCLUSIONS: Exostosis surgery should be reserved for uninfected ear canals. Meatal skin preservation without circular meatal flap incision is recommended to avoid postoperative canal stenosis. Especially in cases of preexisting sensorineural hearing loss, attention should be focused on the intraoperative noise reduction by tympanic membrane protection and pauses of noise exposition.     

Prevalence of external auditory canal exostoses in surfers.

OBJECTIVE: To determine (1) the prevalence of external auditory exostoses in a population of surfers and (2) the relationship between the length of time spent surfing and the prevalence, severity, and location of the exostoses. DESIGN: Cross-sectional epidemiological study. SETTING: General community. PATIENTS: Three hundred seven avid surfers (93.5% males and 6.5% females; age distributions: 11.2% were < or =20, 67.9% were 21 to 40, 17.5% were 41 to 50, and 3.3% were >50 years). MAIN OUTCOME MEASURES: Questionnaires focusing on surfing habits (number of years, geographic region, and number of days per year of surfing) were correlated with otoscopic findings. A simple grading system was devised, based on the degree of external auditory canal stenosis. Grades of normal, mild, moderate, and severe corresponded to 100%, 99% to 66%, 65% to 33%, and less than 33% effective patent surface area, respectively. RESULTS: There was a 73.5% overall prevalence of external auditory exostoses and a 19.2% overall prevalence of osteomas in the group studied. Of 441 ears with exostoses, 54.2% were mild, 23.6% were moderate, and 22.2% were severe. Of individuals who had surfed for 10 years or less, 44.7% had normal ear canals and only 6% had severely obstructed auditory canals. In comparison, in the group that had surfed for longer than 20 years, only 9.1% had normal auditory canals and 16.2% were severely affected. Of surfers with no exostoses, 61.1% had surfed for 10 years or less. In contrast, of surfers with severe exostoses, 82.4% had surfed for more than 10 years. Finally, the lesions seemed to affect all external auditory canal quadrants equally. CONCLUSION: A positive association exists between the amount of time individuals spend surfing and the presence and severity of exostoses of the external auditory canal.     

Ganglioneuroma of the internal auditory canal: a case report

Ganglioneuroma is a rare, benign, slow-growing tumor thought to develop from cells of neural crest origin, even though hypotheses on the pathogenesis of that lesion differ. Ganglioneuromas, which do not release excessive catecholamine or steroid hormones, develop primarily in the posterior mediastinum and retroperitoneum. Because of their slow growth, many ganglioneuromas are large when they are diagnosed. In this case report, a 50-year-old woman with hearing loss is described. Magnetic resonance imaging revealed a mass (3 x 4 mm) in the internal auditory canal (IAC). The encapsulated tumor was entirely excised via the middle fossa approach. The results of histopathological examination indicated that the excised lesion was a ganglioneuroma. To our knowledge, this is the first report of a ganglioneuroma of the IAC. We suggest that ganglioneuroma be considered in the differential diagnosis of all tumors of the IAC.     

Patulous internal auditory canal

OBJECTIVE: To investigate a rare anomaly of the internal auditory canal known as a patulous canal and its relationship to hearing impairment. METHODS: High-resolution computed tomographic scans of the temporal bones of patients who presented between August 2001 and August 2002 were reviewed. The patients' medical charts were evaluated for age, sex, and hearing impairment, and the computed tomographic scans were examined for the presence of a patulous canal. RESULTS: The study group included 645 patients who underwent high-resolution computed tomography of the temporal bones for various reasons, including sensorineural hearing loss (50% of patients). A patulous canal without any associated anomaly of the labyrinth was the only finding in 2 patients. Both patients had chronic middle ear disease along with conductive hearing loss. CONCLUSION: Patulous canal is a rare anatomical variant of the internal auditory canal (0.3%), and its association with inflammatory ear disease accompanied by conductive hearing impairment appears to have been incidental in both cases in the present study.     

Meningioma of the internal auditory canal

A comprehensive literature search identified only 14 well-documented cases of intracanalicular meningioma. A case is presented of meningioma confined to the internal auditory canal which was excised using a sub-occipital retrosigmoid approach. Preoperative MRI and CT scans were suggestive of intracanalicular vestibular schwannoma. Only the intraoperative findings, which were confirmed by the histological data, revealed that the tumor was a meningioma. We review the literature and discuss the diagnostic and therapeuticissues relating to these tumors.     

Meningioma of the internal auditory canal

The great majority of tumors that arise in the internal auditory canal are schwannomas of the eighth cranial nerve (acoustic neuromas). Meningiomas constitute the second largest group of posterior fossa tumors. Meningiomas arise from arachnoid villae, the apparatus responsible for cerebrospinal fluid absorption, in proximity to a major vein or dural sinus in most cases. Arachnoid villae are also present along neural foramena at the base of the skull. They have been observed histologically in the internal auditory canal (IAC), and are the probable site of origin of meningiomas in this location. Larger cerebellopontine angle meningiomas occasionally possess a significant intracanalicular component; however, these lesions usually originate from the meningeal lining of the posterior petrous face adjacent to the sigmoid, superior petrosal, or inferior petrosal sinuses and prolapse into the IAC. Two meningiomas have recently been observed that extensively involved the IAC, one of which arose from the lining of the IAC. The clinical manifestations of these meningiomas mimicked those of acoustic neuromas. Preoperative radiographic studies, including magnetic resonance imaging, were unable to differentiate these from acoustic neuromas. Meningiomas have a higher rate of recurrence than acoustic neuromas and should be excised with surrounding dura and several millimeters of subjacent bone. Meningiomas that extensively involve the IAC have a tendency to invade the inner ear and the deeper portions of the temporal bone. In meningiomas that involve the lateral portion of the IAC, consideration should be given to exenteration of the cochlea and semicircular canals.     

Exostosis of the internal auditory canal

Although exostoses of the external auditory canal are not uncommon, those of the internal canal are extremely rare. One of these is described occurring in a 53-year-old man whose rapidly progressive hearing loss was without any associated abnormality.     

Meningioma of the internal auditory canal

A comprehensive literature search identified only 14 well-documented cases of intracanalicular meningioma. A case is presented of meningioma confined to the internal auditory canal which was excised using a sub-occipital retrosigmoid approach. Preoperative MRI and CT scans were suggestive of intracanalicular vestibular schwannoma. Only the intraoperative findings, which were confirmed by the histological data, revealed that the tumor was a meningioma. We review the literature and discuss the diagnostic and therapeutic issues relating to these tumors.