Discussion
The main finding of this study was that Valsalva CT was effective in demonstrating the whole length of Eustachian tube in patients with suggestive symptoms of patulous Eustachian tube (PET). We could visualize ET in its entirety in all six ears.
Patulous Eustachian tube is generally diagnosed based on suggestive symptoms, physical examination, and audiologic findings. However, no diagnostic gold standard is currently available. With an attempt to reduce the subjectivity in the diagnosis of PET, several specialized tests, including tubomanometry, sonotubometry, and tubotympanoaerodynamography, have been devised (13, 14). However, these methods provide indirect information and cannot provide the anatomic nature of the ET. Computed tomography and magnetic resonance imaging have been used to visualize ET in patients with ET dysfunction. Yoshida et al. reported that standard CT visualized only 13 ETs entirely as open out of 31 PET ears. A systematic review evaluating the value of the imaging modalities in PET revealed that CT and MRI provided detailed anatomic information about the ET; nevertheless no single test emerged as a stand-alone diagnostic method in PET (15).
One inherent nature of the ET that is closure of the cartilaginous part of the tube in the recumbent position makes these methods unreliable in the evaluation of PET.
To be able to show the patency status of the ET with cross-sectional imaging modalities, several groups attempted various methods. Yoshida et al. (16) compared the air space lumen between the sitting and recumbent positions in CT in two PET patients. The size of the airspace lumen was larger during the sitting CT. Kikuchi and colleagues reported the beneficial use of sitting position Valsalva CT in the diagnosis of PET (17). Kawamura and coworkers showed the value of sitting position CT relative to other diagnostic tests in Patients with PET (4). However, sitting position CT is not feasible with standard CT machines. Thus, methods to prevent the collapse of the ET in recumbent positions were sought.
One such method that enables ET to open is the performance of Valsalva maneuver during the CT when the patient is in the supine position. Tarabichi et al. (11) performed Valsalva CT in 38 patients who had nose pathologies but no ear disease. The authors concluded that Valsalva CT could visualize the whole length of the ET tube in 35% of the ears, whereas in 94% of the ears, distal one-third of ET could be visualized. Poor Valsalva technique was associated with paradoxical closure of the ET in this study. Another case-control study conducted by the same authors and recruited patients who would undergo surgery for chronic ear diseases found that Valsalva CT could visualize distal one-third of the ears in 96% of the ears (12). However, to the best of our knowledge, the value of the Valsalva CT in visualization of the entire ET has not been evaluated in patients who had clinically diagnosed PET or patients who had suggestive symptoms for PET yet.
Our results showed that in all 6 ears studied; ET could be visualized entirely by Valsalva CT. We also demonstrated 3D and air-reconstructed images of patent ET. Our findings lend support to previous studies in which Valsalva CT had merit in visualization of the ET in patients who had ear or nose diseases other than PET. Our findings extend the prior findings to patients with clinically-proven PET. In all ears, the Valsalva maneuver could preclude the collapse of the distal part of the ET.
Some limitations of the present study deserve mention. First, ours was a preliminary study with only 6 ears. The number of the patients in this study is relatively small however, all of the patients were selected to represent clinical characteristics of PET. None of them had chronic ear and/or nose disease other than aforementioned symptoms. Moreover, patients with relatively severe PET visit our Hospital department to seek treatment.