Qualification of Pilots with Aero-Otitis Media After Balloon Eustachian Tuboplasty

CASE REPORT

A 40-yr-old transport pilot with 3200 total flying hours of flight time was transferred to our hospital in October 2014. In September 2013, he suffered right aural fullness, deafness, bilateral tinnitus, and otalgia as a result of flying after catching a cold, with the right side being worse. The local hospital’s acoustic immittance test revealed an “A” type of tympanogram for the left ear and a “B” type of tympanogram for the right ear. Based on “secretory otitis media”, the pilot received tympanic membrane puncture and drainage, vasoconstrictors, and other medications accordingly to treat the symptoms, after which he returned to flying status. During the flight, a number of unsettling symptoms recurred, such as right aural fullness, otalgia, and deafness. In October 2014, after numerous treatments, including tympanic membrane puncture and drainage, proved unworkable, he was transferred to our hospital for therapy. The pilot did not have any pre-existing conditions, such as ear infections as a child, earlier ear surgery, etc. Before this illness, the results of the otorhinolaryngology examination during the pilot health check were normal. Pure tone audiometry showed high-frequency sensorineural hearing loss in the left ear and mixed hearing loss in the right ear (as shown in Test 1 of Fig. 1 ). A tinnitus test showed bilateral tinnitus, heavier on the right side, which was causing a cicada-like sound in the pilot’s ear. Acoustic immittance test showed an “A” type of tympanogram for the left ear and a “B” type of tympanogram for the right ear ( Fig. 2A ). Endoscopic examination of the bilateral tympanic membrane showed mild invagination, no perforation, no thickening, normal tympanic cavity, and no red granulation tissue, polyp tissue, or gray-white tissue. A CT scan of the middle ear showed that the right tympanum and mastoid were almost full of soft tissue density, the ossicular chain of the right ear was intact, and the tympanic wall was intact. No abnormality was found in the left tympanum or mastoid. No abnormality was found in the inner ear on either side. The diagnosis of AOM was made in the end. After several performances of Valsalva and extended Valsalva, two tympanic membrane punctures, and drainage, the prognosis remained poor. Based on these results and the fact that the pharyngeal opening of the Eustachian tube was unaffected, the pilot was diagnosed with primary AOM, and a right BET was performed. Postoperatively the stuffy feeling in the right ear substantially improved and the right Eustachian tube could be opened by pinching the nose to puff. Pure tone audiometry indicated that both ears’ low- and intermediate-frequency hearing was normal 16 d after surgery (as shown in Test 2 of Fig. 1), and the acoustic immittance test revealed all being an “A” type of tympanogram for both ears (as shown in Fig. 2B ). The pilot was deemed unfit to fly temporarily and returned to hospital for reexamination after 2 mo.

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At reexamination 2 mo after the operation, the hypobaric chamber test simulated flight: pressure rose rapidly to 4 km at 10∼15 m · s⁻¹, stopping 5 min, and then fell rapidly to ground level at a speed of 8∼10 m · s⁻¹. Before and after the hypobaric chamber test, pure tone audiometry revealed normal low- and intermediate-frequency hearing in both ears (as shown in Test 3 of Fig. 1), and acoustic immittance tests revealed all being an “A” type of tympanogram for both ears, which indicated good ear pressure function. It showed that the curative effect was significant after the right BET, and the pilot was found fit to fly. After returning to the team, he participated in a flight for 60 h in 3 mo and occasionally suffered bilateral tinnitus and hearing loss, with the right side being worse but no longer affecting flight.

The pilot returned again for reexamination 5 mo after the operation. The hypobaric chamber examination method remained the same as at 2 mo; during the drop from 4000 m to 2000 m at 10 m · s⁻¹, the pressure in the left ear appeared, and the tympanic membrane was not congested. After pinching the nose to puff, the symptoms of ear compression disappeared. The acoustic immittance test showed a “C” type curve in the right ear and an “A” type curve in the left ear; the negative pressure vanished after pinching the nose to puff, and both ears showed an “A” type curve. A CT-nasopharyngeal skull base scan revealed the right mastoiditis was significantly reduced compared with the previous one, and he was considered fit to fly. Within 6 mo of being released from hospital, he had a flight for 280 h with good air adaptation and no complaints of discomfort.

After 12 mo post-operation, he returned to our hospital for reexamination again and the hypobaric chamber examination was performed with the same method. Pure tone audiometry demonstrated normal low- and intermediate-frequency hearing in both ears (as shown in Test 4 of Fig. 1), and the acoustic immittance displayed an “A” type curve in both ears. This indicated that after BET, the Eustachian tube was normal during simulation of the changes of flight pressure. The pilot was considered fit to fly. During 3 yr of continuous follow-up, he participated in flight for 800 h and his air adaptation was good.

DISCUSSION

The Eustachian tube is a tube connecting the tympanic cavity of the middle ear and the nasopharynx, and its main function is to adjust the pressure inside and outside the tympanic chamber. Eustachian tube dysfunction (ETD) is considered to play a key role in the etiology of AOM. The current international consensus of medical experts and scientists in the field of Eustachian tube dysfunction categorizes ETD into three types: ⁹ dilatory ETD, baro-challenge-induced ETD, and Patulous ETD. Professor Xu Xianrong divides AOM into primary AOM and secondary AOM according to long-term clinical aeromedical practice. The traditional therapies ⁷ include drugs, Eustachian tube dilation, tympanic membrane incision, and catheterization, which only removes the effusion in the middle ear and temporarily improves the ventilation condition of the middle ear. The curative effect is limited and recurrence is likely. In recent years, BET in the treatment of ETD has been the focus of research. It expands the cartilage of the Eustachian tube mechanically by placing a balloon directly in the Eustachian tube cartilage, and it also improves Eustachian tube function by 60–100%. ² In 2010, Ockerman et al. ⁵ first reported BET under an endoscope. Both patients’ symptoms and pharyngeal function scores continued to improve within 3 wk of follow-up. Oehlandt et al. ⁶ followed 39 patients with baro-challenge-induced ETD treated with BET. The average postoperative follow-up time was 8 mo to 4 yr, and 81% of patients had good surgical results. Since BET was introduced in China in 2013, relevant studies have been carried out in numerous hospitals. In 2014, Dai Song and Liang Maojin et al. ⁴ revealed successively that patients with hearing loss and aural fullness improved considerably after BET. Additionally, many successful results have also been observed in children. A study reported that BET dramatically enhanced audiological outcomes in children with exudative otitis media in comparison to tympanostomy tube insertion alone. ¹ However, no reports of BET related to AOM in pilots were found. In this study, BET was successfully applied for the first time to treat AOM in pilots.

In our study, the pilot developed symptoms of right ear stuffiness and hearing loss while flying after having a cold. Then he was diagnosed with “secretory otitis media” in a local hospital. After several therapies, the result was still unsatisfactory. The pilot was referred to our hospital. After careful inquiry of medical history and a series of examinations, primary AOM was considered and we treated him with BET on the right side. After the operation, pure tone audiometry showed that low- and intermediate-frequency hearing in the right ear returned to normal. In terms of the left ear’s high-frequency hearing loss, it was considered that the environmental noise of the aircraft was the main factor and that air-pressure-related cumulative damage was the other. Based on the curve and degree of hearing loss, the likelihood of hearing loss due to noise was higher. During the 12 mo after the operation, the Eustachian tube function and ear air compressor function were both normal. He flew 800 h within 3 yr of the follow-up, and his air adaption was good. At present, the pilot is still qualified, with a total flight time of more than 6000 h. It is of the utmost therapeutic importance to carry out this surgery in primary AOM in pilots because BET is unquestionably effective in treating this illness and has dependable long-term efficacy.

Poe et al. ⁸ studied the cadaveric head’s anatomical structure and found that the mechanism of BET was in the cartilage of ET. By applying pressure with a balloon, the cartilage was microfractured, and cartilage fibrosis caused it to harden and thin; the middle ear pressure balanced the outside ambient pressure, the ventilatory function was restored, and the secretion could be evacuated smoothly. Kim et al. ³ established a rat model of full-thickness cartilage fracture and went on to describe a series of histological alterations of Eustachian tube cartilage after receiving BET for the first time. It was found that the cartilage structure frequently returned to its original shape, demonstrating the safety of BET. In this case, frequent ear pressure appeared while flying. A CT scan of the middle ear revealed that the right tympanic chamber and mastoid process were almost completely filled with soft tissue density shadow, which was considered to be produced by inflammatory epithelial proliferation and mucosal edema. By applying pressure to the balloon, the cartilage was microfractured, the Eustachian lumen was widened, the middle ear ventilation and drainage were restored, and the inflammatory response was diminished. A CT-Nasopharyngeal skull base scan revealed the right mastoiditis was noticeably less severe than it had been after the operation.

Although the positive effect after BET is considerable, clinicians must still pay attention to the adverse effects and risks caused by BET. First, the carotid is placed just next to the tuba auditiva. Second, it is a risk of further constricting tissue in the tuba. In a specially selected population as pilots, the need for BET should be restricted to a minimum until risk assessment studies have been performed. An ear pressure injury is an occupational aviation disease of pilots. Compared with common diseases, their diagnosis, prevention, and identification have their particularity. We should start with how to reduce the suspension rate of pilots, prolong their professional life, establish strict diagnostic and treatment standards, and establish clear identification standards.

Since the debut of BET, it has drawn considerable attention from medical specialists everywhere and has sparked the investigation and therapy of disorders associated with ET. Over the last ten years, a remarkable amount of research findings has accumulated that supports the therapeutic practice’s efficacy and safety. Additional randomized controlled trials and multicenter studies with sizable sample sizes will be needed in the future as there is still controversy over the benefits and risks of BET. If the conservative primary AOM treatment is ineffective, pilots may elect to have BET. After the operation, the symptoms go away, and the pure tone audiometry, acoustic conductance test, and ear pressure function test all meet the standards for the physical examination of flight personnel, allowing the determination of flight qualification.