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.