Appendix 1. Detailed descriptions of diver histories.
All audiograms for the cases are summarised in Appendix 2. The original copies of the audiograms have been withheld for privacy and anonymity.
Case 1
A 51 YO male scientific diver (Body Mass Index (BMI) = 26 kg/m2) with a normal audiogram at last medical. He was competing in an underwater hockey tournament and presented with hearing loss and tinnitus in the right ear (maximum depth 2.4 m). There were no vestibular symptoms. The subject had no previous issues or injuries to his ears from underwater hockey or diving, and all audiograms for his previous 20 years’ scientific diving medicals were normal. No compressed air diving had been undertaken in the week before or during the tournament. He was completely well before the tournament and denied any respiratory symptoms. Following the first day’s competition, he noted painless reduced hearing and tinnitus in his right ear. There were no ear clearing problems or other impact/injury. He played a further 6 games over 6 days with no change in his symptoms. After consulting a diving medicine specialist, an AC/BC audiogram was performed day 7 by an independent audiologist, before assessment day 8. Both tympanic membranes were normal appearance and the subject could demonstrate normal ear clearing. There were so symptoms or signs of vestibular disturbance, and full neurological examination was normal. The left ear was unaffected. The right ear audiogram was consistent with a mild to severe down-sloping sensorineural hearing loss affecting 1-8 kHz. No imaging was undertaken.
The diver’s case information was discussed with an Ear Nose and Throat (ENT) specialist, but was not reviewed in person by that specialist. In view of the likely causation from breath hold diving to 2.4m, a diagnosis of inner ear barotrauma was made. He agreed to a trial of HBOT following detailed instruction to undertake very gentle ear clearing. The subject was provided 9 treatments of HBOT, at 2.43 kPa (14:90:20 table, 3 x 5-minute air breaks). Prednisolone 50 mg daily was commenced day 2 after the second HBOT. No other specific treatment was advised apart from avoiding strong Valsalva manoeuvres and heavy lifting. Following two HBO treatments within 24 hours, and a single oral prednisolone dose, the subject’s hearing returned to normal range for 1kHz to 2kHz and had significantly improved in 3 and 4 kHz. He received ENT assessment with no changes to management. HBOT was continued daily to a total of 9 treatments. At no stage did he develop any vestibular symptoms. By end of 9 treatments, hearing in the right ear was normal for all frequencies except 6 kHz and 8 kHz. The subject received follow-up at 3, 6 and 12 months and his hearing has remained stable. After assessment by ENT and Diving Medicine Specialists, he was cleared for returning to occupational diving. He successfully resumed all diving activities including underwater hockey and has had no further issues with hearing.
Case 2
A 22 year-old male commercial diver (BMI = 24 kg/m2) had an uneventful 4-year diving career with more than 300 hours spent underwater. He received a comprehensive AS/NZS 2299.1 occupational diving medical one day prior to his incident, and did not dive that day. At that assessment, he demonstrated normal ear clearing, tympanometry and his audiogram was normal. He had no respiratory symptoms at the time of the medical and none on the day following. He undertook two brief dives the day after his medical, to 18 metres for 5 minutes each. The dives were separated by a surface interval under 15 minutes (a common practice for the industry). The diver noted no ear clearing difficulties, ascents were fully controlled and no symptoms were noted during or after the dive. He did not experience vertigo or disequilibrium at any stage, before, during or after the dives, and no lifting, straining, forced Valsalva, coughing or sneezing occurred. He was well when retiring to bed the same night. The next morning, he woke with hearing loss and tinnitus in his left ear. Of his own volition he returned to the same audiologist who had performed his AS/NZS 2299.1 audiogram, and asked for a repeat test. This demonstrated 60-85dB sensorineural hearing loss across all frequencies from 500 to 8 KHz. An urgent ENT/diving medicine assessment revealed normal tympanic membranes normal middle ear function and a negative fistula test, completely normal neurological examination, no nystagmus and sharpened Romberg test stable for 60 seconds. He agreed to a trial of HBOT following detailed instruction to undertake very gentle ear clearing. No imaging was undertaken before treatment. He was provided with a 14/90/10 hyperbaric oxygen treatment table the night of his presentation. Improvements in hearing were noted of 15-30dB across frequencies 500Hz-3KHz, immediately after the first treatment. It was decided to continue HBOT on a daily basis and Prednisolone 50mg was prescribed after the second HBO treatment. By day 10 (10th HBOT), hearing had improved in the left ear, with mild impairment only in 6-8kHz. High resolution CT scan of his petrous temporal bones was normal. He was reviewed by an ENT specialist, and no further treatment was advised. His hearing recovery persisted to 8 months at follow-up. After detailed discussion regarding his diving career, it was decided to advise against further diving. He is reconfiguring his career to train as a Ship’s Master.
Case 3
A 52-year-old recreational snorkeler (BMI not calculated, but not clinically obese) had a previous history of high frequency hearing loss from 3 – 8 kHz due to industrial noise. He was breath-hold diving for abalone and crayfish to a maximum of 4-5 metres depth. He undertook multiple descents and ascents over a 30-minute period. He experienced difficulty in clearing both ears and experienced pain and diminution of hearing in his right ear. He had no vertiginous symptoms. He denied respiratory symptoms prior to his breath-hold dives. He presented to his GP who referred him to an ENT specialist. After a normal MRI scan, he was prescribed 50mg prednisolone daily for 10 days. After no benefit from steroids, he was then referred for HBOT. His audiogram at the commencement of HBOT was identical to post injury 10 days before, demonstrating 55-70 dB sensorineural hearing loss across all frequencies right ear. Neurological examination was normal, with no signs of vestibular dysfunction. Middle ear clearing was normal at the time of diving specialist assessment. Given failure to improve with steroids, HBOT was commenced as a possible salvage. He was provided 10 daily HBOT using 14/90/20 or 14/90/10 schedules. There was normalisation of his hearing in 500-1.5 kHz and significant improvement of 2 kHz, following three hyperbaric oxygen treatments. He completed the 10 treatments and at discharge, was counselled against further breath-hold diving. His hearing remained stable at follow-up 6 months after treatment.
Case 4
A 31-year-old male commercial diver (BMI = 27 kg/m2) with 10 years’ experience, had a previous history of mild musculoskeletal decompression sickness, seven years prior to presentation. His previous annual dive medical health risk assessment showed normal hearing nine months before his injury. He had no symptoms or ear issues in the ensuing months. Just before his presentation, he been diving daily within dive table limits over a four-day period. There was no strenuous activity, no trauma, no ear clearing problems during his diving, and no respiratory symptoms. On the fourth day, starting with repetitive factor 1.0, he completed a single dive (with five-minute safety stop) to 15m for 53 minutes – he had no ear clearing issues and was symptom free immediately post dive. The evening after his dive, he noted reduced hearing in his right ear, “like water in the ear”, but did not report his symptoms until three days later (this period spanned a weekend). After reporting, his supervisors referred him for medical assessment. He had no symptoms or signs of vestibular dysfunction, no nystagmus, normal balance, normal tympanic membranes which cleared easily with gentle Valsalva, negative fistula test. His audiometry at day four showed sensorineural hearing loss in his right ear at four days post-diving across 500 Hz – 8 kHz. Impedance audiometry showed normal middle ear pressure with increased tympanic compliance. Findings were consistent with sensorineural hearing loss right ear, probably due to IEBT, however isolated cochlear decompression illness (although unlikely) could not be absolutely ruled out. Following discussion with ENT specialists, he was treated with a series of 14/90/20 tables for 10 consecutive days. Steroids were not prescribed. Audiometry was independently undertaken at the hospital’s audiology service, returned to normal after HBO treatment four. His hearing has remained stable and normal to 3 months follow up.
He received an MRI scan of his brain which demonstrated no abnormalities in his cranial nerves 7 and 8, and membranous labyrinth, and an incidental tiny cyst in the right sella turcica. High resolution CT scan was normal except for a slightly narrow right cochlear aqueduct (of uncertain significance). Following review and discussions with his employer, he chose not to dive again.
Case 5
A 62-year-old male hyperbaric professional (BMI = 27), with 3,500 hours recreational diving experience and no previous ear issues or barotrauma. Previous audiograms for occupational medicals had been normal with all frequencies demonstrating 20 dB or less hearing loss. Two uneventful dives were completed day one, well inside no-decompression limits, to maximum 21 m depth. The diver noted mild upper respiratory symptoms at the start of day 2. Following a 21-hour surface interval (at 0926), an uneventful multilevel dive was undertaken day two to 16 metres for 64 minutes, average 11.3 metres including five minutes at 3-5 metres safety stop. The diver had no problems clearing his ears on the first dive, day two. After a one-hour surface interval a second dive was commenced to 16 metres. The diver made camera adjustments whilst descending and omitted ear clearing. He noted pain in his right ear, which settled after some sub-surface ascents and further descent. The dive was completed with no further issues and no reverse ear squeeze, 57 minutes dive including a five-minute safety stop at 3-5 m. During the afternoon, the diver snorkelled with a number of free dive descents, and noted right ear stickiness when clearing. He noted a minor hearing impairment and crackling that evening. The diver woke the next day with significant hearing impairment and tinnitus in the right ear, and 2/10 pain. He was unable to hear conversation with the right ear when his left ear was occluded. He did not dive or snorkel again and flew home to Australia day 10 without ear clearing difficulties, although with some perception of moist crackling in the middle ear. Following air and bone conduction audiograms, he was assessed by an ENT specialist who diagnosed inner ear barotrauma with moderate sensorineural hearing loss. At the diver’s request, he was referred for HBO treatment, and received 5 daily treatments using 14:90:10 tables, and had no difficulties in clearing his ears. The diver chose to stop HBOT at treatment number 5, because hearing in the right ear had returned during treatment 2. Steroids were not prescribed. No imaging or further investigations were performed. He returned to diving one month later and has completed 65 more dives in 2023-24 without incident.