Masked patulous Eustachian tube: an important diagnostic precaution before middle ear surgery.

The Eustachian tube is normally closed, but it opens upon swallowing for only less than one second to equalize the middle ear pressure with the atmospheric pressure, and immediately closes again. Patients with patulous Eustachian tube (PET) suffer from annoying symptoms, such as aural fullness (sensation of fullness in the ear), autophonia (abnormally loud audition of own voice), audition of breathing sound, and fluctuating sensation of the tympanic membrane upon respiration. The diagnosis of PET is not difficult when patients complain of such typical symptoms. However, there is an unexpected pitfall, in which the symptoms of PET are masked by the presence of conductive hearing loss and obvious middle ear pathology. Here, we propose that this condition be termed 'masked patulous Eustachian tube' to promote correct diagnosis prior to planning the middle ear surgery. Four representative patients with 'masked patulous Eustachian tube' are presented: two exhibited symptoms after repair of chronic perforation of the tympanic membrane, one after stapes surgery for otosclerosis, and one after cholesteatoma surgery. In these patients, the symptoms of PET became evident only after surgery due to the improvement of hearing. The degree of hearing improvement varied among the patients from 15 to 40 dB in average hearing level. It is therefore important to examine the presence of 'masked patulous Eustachian tube', in addition to a middle ear disease for which surgery is planned. The surgeon should inform the patient of the possibility of 'masked patulous Eustachian tube' to avoid the postoperative disappointment.