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Unlocking the Key After experiencing balance problems in her 40s, an Emerging Research Grants scientist discovers the cause of her childhood hearing loss. By Lina A.J. Reiss, Ph.D. I became interested in the fields of hearing research, biomedical engineering, and neuroscience in part from my own hearing loss. I have had a severe to profound hearing loss since early childhood. Diagnosed at age 2 ½ and fitted with powerful hearing aids, I learned to speak and listen only with intensive speech therapy. I am the only person with a hearing loss in my family, so we always thought the cause was due to illness or possibly ototoxic medications. In my early 40s, I started having vestibular (balance) problems. It started in November 2018, when we took a big family fishing trip on the Amazon River in Brazil. It involved four flights each way, with the last leg a few hours in a small, unpressurized aircraft. On landing I felt a sensation of fullness and muffled hearing in my left ear that took several minutes to resolve, and a few days later, I noticed some mild imbalance walking around. It was on the return trip when I again experienced problems with my left ear on landing. I was unable to walk straight in the airport, and head movements, especially nodding, caused disorientation. Based on these symptoms, my otolaryngologist and colleague Yael Raz, M.D., and I thought I had benign paroxysmal positional vertigo (BPPV). A common vertigo triggered by movement, BPPV occurs more often with age and is attributed to calcium crystals that get dislodged and move more slowly than fluid through the inner ear’s semicircular canals. I did the recommended treatment for BPPV, the Epley maneuver, and symptoms gradually disappeared after a month.
More Flights, and Imbalance
In the months afterward, I had two other (unavoidable) cross-country flights that put the BPPV diagnosis in question. Now my vertigo was triggered by head nods as well as head turns—and then also head tilts. Walking around stairwells or turning my head to see someone’s face while walking was challenging. I started touching the wall at intervals to keep my balance. Then a new vestibular symptom appeared. In response to loud sounds—especially low-frequency sounds like my husband’s voice—I felt the room start to spin slowly. While disconcerting, this indicated to me that my vestibular cells could now respond to sounds, which would normally only be detected by auditory hair cells. We thought I had superior canal dehiscence (SCD), 16
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discovered by Lloyd Minor, M.D., at Johns Hopkins University in the 1990s, coincidentally while I was a graduate student there. SCD is essentially a hole in the superior semicircular canal, leading to a “third window” (alternate pathway) for sound transmission through the vestibular system that would explain balance responses to sound. This was worrying because SCD often gets worse over time, and outcomes with cranial surgery are not good. But, unlike me, individuals with SCD usually have typical hearing.
Uncovering the Source
When a CT scan, confusingly, came back negative for SCD, Dr. Raz said, “Lina, I think we may have learned the cause of your deafness. You don’t have SCD, but you do have an enlarged vestibular aqueduct, or EVA.” Dr. Raz was also at Johns Hopkins, a resident working with Dr. Minor. She said they had talked about looking at the third window effect in patients with EVA and that it was likely, though there was no published data, that EVA also acts like a third window syndrome, similar to SCD. The EVA itself is not necessarily the cause of the hearing loss but is associated with a mutation of the gene SLC26A4. A 2017 eLife paper discussed how this may
