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Background
Few studies or reports exist on the effect of sudden atmospheric pressure changes on professional train operators. Our follow-up showed the existence of ear and vestibular symptoms among some operators when exposed to rapid changes in cabin pressure, although mostly under-reported (for fear of losing their job). Pressure-equalising devices were initially installed but never used (because of side effects: with the slightly increased pressure inside the cabin, operators felt enclosed and claustrophobic). Hence the importance of including occupational health physicians when introducing new technical features such as pressure control systems, as in this case. Occupational medical check-up should include awareness of the possible impact of these symptoms on operators and, indirectly, on passengers' safety.
Case presentation
An otherwise healthy 31-year-old train operator, during his medical check-up, reported of regular symptoms of pressure on his ears, ear aches, headache and tinnitus. This occurred after he had started to operate from a new type of train cabin. He experienced sudden pressure changes in the cabin but could not equalise his ears (swallowing, slight Valsalva manoeuvre), resulting in pressure discomfort and pain in his ears, and even temporary tinnitus. There was neither hearing loss nor vertigo. He was an experienced operator with 5 years' experience. He was subsequently examined by an ear, nose and throat (ENT) consultant specialised in otology with full ENT examination including micro-otoscopy, rhinoscopy, rotational and caloric testing and nine-step tympanometry. These tympanometry findings showed a normal trace but with the existing symptoms and history a diagnosis of 'baro-challenged Eustachian tube dysfunction' was made. Treatment with an antihistamine and nasal spray resulted in a subjective improvement after 3 months.
Investigations
Pressure waves that penetrate into the inner ear may inappropriately activate the oto-vestibular system, causing transient pressure-induced ear problems, such as alternobaric vertigo. Alternobaric vertigo is caused by unequal middle ear pressure due to a difference in Eustachian tube patency, stimulating the inner ear and thus provoking vertigo and/or unsteadiness. This has been well-documented in pilots and divers, and is considered a potential major factor in diving accidents. 1-3
In the type of train cabin where symptoms were most frequently reported, pressure variations were measured with a pressure transducer inside the cabin and one external transducer connected to a Pilot tube. Internal pressure fluctuations...