Jensen also described 3 boys who had an enlarged vestibule, an irregularly dilated cochlear lumen, a dilated lateral end of the IAC, and an associated mixed hearing loss of about 60 dB. Jensen 1 reported that among 62 deaf children, the CT scans of 2 brothers, 1 with retinitis pigmentosa, revealed extreme dilatation in the lateral portion of the IAC. Davis and Rumbaugh 2 reported that patulous canals may appear in patients with a sensorineural hearing loss of undefined etiology. The reason for this striking development variation was not known. The nerves appeared somewhat small on an air cisternographic study. Swartz and Harnsberger 6 found a strikingly wide IAC in both ears of an elderly patient with profound sensorineural hearing loss that had begun very early in life. The significance of a dilated IAC in the pathogenesis of hearing impairment is questionable. 4 The patulous canal differs from dilatation that results from acoustic neuromas because of the presence of cortical margins of the canal and the absence of any destruction of the crista falciformis. This anomaly is characterized by a bilateral, usually symmetrical, increase in height at the midportion of the IAC. To my knowledge, there is not a lot of information about the patulous canal. In 1964, Valvassori 5 concluded that a normal IAC ranges from 2.0 to 9.0 mm in diameter, with less than 2 mm of difference between 2 sides. High-resolution CT of the temporal bone is an important modality for the evaluation of bony abnormalities of the ear. Both patients had chronic middle ear disease along with conductive hearing loss.Ĭonclusion 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.
A patulous canal without any associated anomaly of the labyrinth was the only finding in 2 patients. 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). 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. Methods High-resolution computed tomographic scans of the temporal bones of patients who presented between August 2001 and August 2002 were reviewed. Objective To investigate a rare anomaly of the internal auditory canal known as a patulous canal and its relationship to hearing impairment. Shared Decision Making and Communication.Scientific Discovery and the Future of Medicine.Health Care Economics, Insurance, Payment.Clinical Implications of Basic Neuroscience.Challenges in Clinical Electrocardiography.
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