By Lina A.J. Reiss, Ph.D.
I am an associate professor at Oregon Health & Science University and became interested in the fields of hearing research, biomedical engineering, and neuroscience in part from my own hearing loss. I have had severe to profound hearing loss since early childhood, diagnosed at 2 ½ years old. 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 drugs.
In my early 40s, I started having vestibular (balance) problems. It started in November 2018. My husband Mike, my then 12-year-old son Jake, and I were flying back from Brazil—an extended-family fishing trip for peacock bass on the Amazon River. The trip involved four flights each way: Portland to Dallas, Dallas to Miami, Miami to Manaus, and then Manaus to the small river town to board the fishing yacht. The last flight was a few hours flight in a small, unpressurized aircraft, and on landing I felt a sensation of fullness and muffled hearing in my left ear that did not resolve for several minutes, even when yawning or blowing to “pop” the ears.
A few days later, I started noticing some mild imbalance walking around, but attributed it to the prophylactic antimalarial and antibiotic medications we were taking. But on the return trip, after landing in Miami, I again noticed a sudden fullness and temporary threshold shift in the left ear on landing, and was unable to walk straight in the airport. Any type of head movement, particularly in the vertical plane (up-down or nodding movements), would cause disorientation.
Lina Reiss (left) holds a catch during a family fishing trip next to her husband, Mike. Four flights to the Amazon River in Brazil triggered Reiss’s difficulties with balance.
Based on these symptoms, I initially was diagnosed with benign paroxysmal positional vertigo (BPPV), a common type of vertigo triggered by movement. Occurring more often with age, BPPV is attributed to calcium crystals that get dislodged and move more slowly than fluid through the inner ear’s semicircular canals. Although I did not have eye movements consistent with BPPV (not always present), I did the recommended treatment for BPPV, the Epley maneuver, and symptoms gradually disappeared after a month.
More Flights, and Imbalance
I had two other cross-country flights that put the BPPV diagnosis in question. A few months after the Brazil trip, I was flying back to the West Coast from the annual Association for Otolaryngology meeting in Baltimore, and again found myself having trouble walking straight in the airport. Now, the imbalance was triggered by head movement in two planes—both vertical and horizontal, head nods as well as head turns.
For months afterward, walking around stairwells or turning my head to see someone’s face while walking was challenging. I started touching the wall at intervals while walking to keep my balance. Another flight for a long-planned visit to family a month later added head tilts (a third dimension) to my symptoms.
I also started to notice a new vestibular symptom: vertigo in response to loud noise. In response to loud sounds, I felt the room start to spin slowly, especially when hearing low-frequency sounds—like my husband’s voice. I experienced vertigo with very low-frequency sounds below the threshold of hearing, such as from lawn equipment or industrial power generators. 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.
The first explanation that came to mind was superior canal dehiscence (SCD), 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” for sound transmission through the vestibular system that would explain vestibular responses to sound. This third window acts as an alternate pathway, versus the typical pathway for sound transmission from the oval window to the round window in the cochlea.
Imbalance caused by head movement in flights troubled Reiss as she searched for answers to her mysterious disorientation.
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.
To assess vestibular nerve function, my otolaryngologist, OHSU colleague Yael Raz, M.D., tested VEMP (vestibular evoked myogenic potentials) responses. These revealed abnormally large responses for the left side, but with typical thresholds. This could be consistent with SCD, so Dr. Raz then ordered a CT scan to check for SCD.
Uncovering the Source
When, confusingly, the scan was negative for SCD, Dr. Raz sat me down and said, “Lina, I think we may have found out the cause of your deafness. Are you ready?” I nodded. “It turns out that the radiologist missed something. You don’t have SCD, but you do have another abnormality, something called an enlarged vestibular aqueduct, or EVA.”
Then she told me how several years ago when she was a resident at Johns Hopkins, working with Dr. Minor, they had talked about looking at the third window effect in patients with EVA. She said it was likely, though there was no published data, that EVA also acts like a third window syndrome, similar to SCD.
Remarkably, the EVA diagnosis is consistent with my hearing loss pattern—a likely delayed/progressive hearing loss from birth to age 2 ½, as I spoke for a little while before I lost my hearing.
The EVA itself is not necessarily the cause of the hearing loss but is associated with a gene mutation that encodes a chloride transporter—SLC26A4, the gene associated with Pendred syndrome (a disorder that affects hearing and the thyroid). Interestingly, there was a 2017 eLife paper by a multi-institutional team of researchers on this gene and how it may cause EVA by changing how the electrolyte sodium chloride, and thus fluid, is reabsorbed by mitochondrial-rich cells in the endolymphatic sac during development.
Their paper also noted that fluid reabsorption appears to be critical for proper development of the inner ear and auditory and vestibular function, and may have a role in regulating endolymphatic pressure, which can affect hearing and balance.
This diagnosis also fit better with the movement-related vestibular symptoms. In retrospect, the imbalance was more precisely described as a “tugging” or “lagging” sensation of balance behind perception of movement, in the left ear. This lag was rapid and brief after each movement, on the order of milliseconds. In contrast, the vertigo in BPPV is described more as a slower, room-spinning sensation on the order of 30 to 60 seconds.
Also, people with EVA sometimes experience sudden hearing loss after flying. So it is plausible that they can also experience sudden vestibular loss after flying.
Genetic testing confirmed that I had two different mutations in the SLC26A4 gene, consistent with the severity of the hearing loss as well as with my South Korean ancestry. Compound heterozygous mutations in SLC26A4 are more common in East Asian populations.
After Diagnosis, Treatment
My imbalance issues, while luckily not causing nausea, had a profound, disabling effect on my ability to concentrate, focus, and be productive, even while avoiding obvious triggers such as flying.
Months later, my imbalance had become tolerable, but I still had movement errors. I could ride my bike as long as my head wasn’t moving relative to my body, but if I stopped, turned my head to look for cars, and tried to turn left, I would end up going right instead. I would bend to pick up apples in our yard, twist and turn to throw them in the compost bin, and fall down.
I decided to pursue vestibular rehabilitation therapy, starting with classic exercises, such as focusing on a single letter while moving my head, proceeding to walking with head turns. After six months, I gradually made small improvements in my ability to walk and turn my head without balance.
As my improvement plateaued, we started using a dynamic posturography machine, which involved standing in a phone booth-like box and actively working to maintain my center of gravity while the walls and floor moved, sometimes in different directions. We also started using virtual reality goggles: I watched Mike steer a plane, and kept falling backward every time upward movement was simulated.
But after just a few weeks, my vestibular testing showed dramatic improvement. I felt like my function was back to what it was. Compared with the incremental changes using classic vestibular rehabilitation, the simulations and virtual reality were dramatically effective. I also recently received a cochlear implant to help with my hearing loss.
As part of this journey, I had joined several Facebook groups to learn more about other people’s experiences with vestibular dysfunction. Many go undiagnosed, and untreated, and even with EVA—one of the most common genetic causes of childhood hearing loss in the world—very little is known, including its triggers and susceptibility. My hope is that more research will help us understand the various types of balance problems.
Lina A.J. Reiss, Ph.D., is a 2012-13 Emerging Research Grants scientist and an associate professor of otolaryngology–head and neck surgery, and of biomedical engineering, in the Oregon Hearing Research Center at the Oregon Health & Science University's School of Medicine. A version of this article originally appeared in the Summer 2020 issue of Hearing Health magazine. Reiss also wrote about hybrid cochlear implants in our Winter 2014 issue.
