Why can I hear my eyes move sometimes?

Author

Wayne T Shaia, MD Director, The Balance and Ear Center

Disclosure: Nothing to disclose.

Coauthor(s)

Jack M Kartush, MD Clinical Professor, Department of Otolaryngology, Wayne State University School of Medicine; Professor Emeritus, Michigan Ear Institute at Providence Hospital; Clinical Professor, Oakland University William Beaumont School of Medicine

Jack M Kartush, MD is a member of the following medical societies: American Academy of Otolaryngology-Head and Neck Surgery, American Otological Society, American Neurotology Society

Disclosure: Nothing to disclose.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Gerard J Gianoli, MD Clinical Associate Professor, Departments of Otolaryngology-Head and Neck Surgery and Pediatrics, Tulane University School of Medicine; President, The Ear and Balance Institute; Board of Directors, Ponchartrain Surgery Center

Gerard J Gianoli, MD is a member of the following medical societies: American Academy of Otolaryngology-Head and Neck Surgery, American College of Surgeons, American Neurotology Society, American Otological Society, Society of University Otolaryngologists-Head and Neck Surgeons, Triological Society

Disclosure: Nothing to disclose.

Chief Editor

Arlen D Meyers, MD, MBA Professor of Otolaryngology, Dentistry, and Engineering, University of Colorado School of Medicine

Arlen D Meyers, MD, MBA is a member of the following medical societies: American Academy of Facial Plastic and Reconstructive Surgery, American Academy of Otolaryngology-Head and Neck Surgery, American Head and Neck Society

Disclosure: Serve(d) as a director, officer, partner, employee, advisor, consultant or trustee for: Cerescan, Ryte, Neosoma, MI10<br/>Received income in an amount equal to or greater than $250 from: , Cliexa;;Neosoma<br/> Received ownership interest from Cerescan for consulting; for: Neosoma, eMedevents, MI10.

Additional Contributors

Robert A Battista, MD, FACS Assistant Professor of Otolaryngology, Northwestern University, The Feinberg School of Medicine; Physician, Ear Institute of Chicago, LLC

Robert A Battista, MD, FACS is a member of the following medical societies: American Academy of Otolaryngology-Head and Neck Surgery, Illinois State Medical Society, American Neurotology Society, American College of Surgeons

Disclosure: Nothing to disclose.

Acknowledgements

Angela Shu-Yuen Peng, MD Resident Physician, Department of Otolaryngology/Head and Neck Surgery, Virginia Commonwealth University Medical Center

Angela Shu-Yuen Peng, MD is a member of the following medical societies: American Academy of Otolaryngology-Head and Neck Surgery, American Medical Association, and Virginia Society of Otolaryngology-Head and Neck Surgery

Disclosure: Nothing to disclose.

Simply moving the eyes triggers the eardrums to move too, says a new study by Duke University neuroscientists.

The researchers found that keeping the head still but shifting the eyes to one side or the other sparks vibrations in the eardrums, even in the absence of any sounds.

Surprisingly, these eardrum vibrations start slightly before the eyes move, indicating that motion in the ears and the eyes are controlled by the same motor commands deep within the brain.

"It's like the brain is saying, 'I'm going to move the eyes, I better tell the eardrums, too,'" said Jennifer Groh, a professor of psychology and neuroscience at Duke.

The findings, which were replicated in both humans and rhesus monkeys, provide new insight into how the brain coordinates what we see and what we hear. It may also lead to new understanding of hearing disorders, such as difficulty following a conversation in a crowded room.

The paper appeared Jan. 23 in Proceedings of the National Academy of Sciences.

It's no secret that the eyes and ears work together to make sense of the sights and sounds around us. Most people find it easier to understand somebody if they are looking at them and watching their lips move. And in a famous illusion called the McGurk Effect, videos of lip cues dubbed with mismatched audio cause people to hear the wrong sound.

But researchers are still puzzling over where and how the brain combines these two very different types of sensory information.

"Our brains would like to match up what we see and what we hear according to where these stimuli are coming from, but the visual system and the auditory system figure out where stimuli are located in two completely different ways," said Groh, who holds a joint appointment in the department of neurobiology at Duke. "The eyes are giving you a camera-like snapshot of the visual scene, whereas for sounds, you have to calculate where they are coming from based on differences in timing and loudness across the two ears."

Because the eyes are usually darting about within the head, the visual and auditory worlds are constantly in flux with respect to one another, Groh added.

In an experiment designed by Kurtis Gruters, a formal doctoral student in Groh's lab and co-first author on the paper, 16 participants were asked to sit in a dark room and follow shifting LED lights with their eyes. Each participant also wore small microphones in their ear canals that were sensitive enough to pick up the slight vibrations created when the eardrum sways back and forth.

Though eardrums vibrate primarily in response to outside sounds, the brain can also control their movements using small bones in the middle ear and hair cells in the cochlea. These mechanisms help modulate the volume of sounds that ultimately reach the inner ear and brain, and produce small sounds known as otoacoustic emissions.

Gruters found that when the eyes moved, both eardrums moved in sync with one another, one side bulging inward at the same time the other side bulged outward. They continued to vibrate back and forth together until shortly after the eyes stopped moving. Eye movements in opposite directions produced opposite patterns of vibrations.

Larger eye movements also triggered bigger vibrations than smaller eye movements, the team found.

"The fact that these eardrum movements are encoding spatial information about eye movements means that they may be useful for helping our brains merge visual and auditory space," said David Murphy, a doctoral student in Groh's lab and co-first author on the paper. "It could also signify a marker of a healthy interaction between the auditory and visual systems."

The team, which included Christopher Shera at the University of Southern California and David W. Smith of the University of Florida, is still investigating how these eardrum vibrations impact what we hear, and what role they may play in hearing disorders. In future experiments, they will look at whether up and down eye movements also cause unique signatures in eardrum vibrations.

"The eardrum movements literally contain information about what the eyes are doing," Groh said. "This demonstrates that these two sensory pathways are coupled, and they are coupled at the earliest points."

Story Source:

Materials provided by Duke University. Note: Content may be edited for style and length.

In the spring of 1995, a patient with a bizarre set of symptoms entered the office of Lloyd Minor, MD, an expert on inner-ear disorders at Johns Hopkins.

The 50-year-old gentleman told Minor that when he sang in the shower, the items in the shower — the shampoo bottle, the loofah, the shower head — began to move about. And it was always in a specific pattern, as if the items were following one another around the face of a clock. The patient told the doctor that he had also noticed that if he hummed a similar tone or heard certain loud noises while looking in the mirror, he saw his eyes move in response.

“And in fact he said, ‘Look, I can show you,’ ” says Minor, now dean of the Stanford University School of Medicine, “if you just give me something so I can put a loud noise in my right ear.” 

So Minor asked the patient to hum the particular tone. He recorded a tone of a similar frequency on a Dictaphone, played the sound in the patient’s right ear and looked into his eyes. Just as the patient had said, his eyes moved. Minor also noticed that they moved in a specific pattern.

“It wasn’t a random eye movement,” Minor says. The eyeballs, he says, move in three dimensions — vertical, horizontal and torsional (rotation about the line of sight, when described from the patient’s frame of reference) — and as he watched this patient, he paid attention to all three. The patient’s eyes moved upward and counterclockwise. The pattern never varied, and was tightly linked to the sound.

That’s essentially all it took for Minor to solve the mystery. Upon seeing the direction of the eye movement in response to this particular sound, he suspected that the source of the problem was a hole in the superior semicircular canal — one of the three tiny canals hidden deep within the inner ear. These canals serve as part of the vestibular system, a set of inner-ear structures that provides input to the brain on motion, equilibrium and spatial orientation. When just a few weeks later a second patient came to see him with similar symptoms and similar eye movements, Minor was convinced he was right.

“Both of them had very, very large eye movements evoked by sound following a similar set pattern,” Minor says. “It’s partly by chance that these two patients both had very prominent eye movements that were very easy to see.”

He had discovered a disorder that he named superior canal dehiscence syndrome — and went on to develop a surgery to treat it.

Minor was far from the only physician to see patients with bizarre sets of symptoms involving hearing, vision and perceptions of motion. At about the same time Minor was examining the eyeballs of his first patient at Johns Hopkins, a French horn player in Germany was telling his doctors that his voice echoed like a kazoo in his brain, that eating anything crunchy sounded like a gun going off. And an audiologist in Atlanta told her doctors that she could hear a loud scratching sound whenever her eyeballs moved. Both would eventually make their way, years later, into Minor’s office.

Symptoms described by these patients ranged from relatively mundane (though unpleasant) nausea and dizziness to superhero-like abilities to hear the inner workings of their own bodies — their pulse, their chewing, their digestive systems. They got misdiagnosed, underwent unnecessary surgeries, fell into depression, withdrew from the world.

“Doctors had no answers,” says the audiologist, Cindy Hirsch, AuD. “I had an eye specialist tell me this was a psychiatric case because I could hear my eyes move.”

“There was this whole bucket of patients, and we really didn’t understand what was wrong with them,” says Robert Jackler, MD, chair of otolaryngology at Stanford. “A lot of physicians thought they sounded mentally ill; they had such peculiar complaints. No one could figure out what was wrong.”

Minor first began studying the vestibular system in a bioengineering course as an undergraduate at Brown University. Immediately, he was hooked. He was fascinated by the mathematical symmetry involved; he loved the elegant way the system worked to maintain the senses of motion and balance.

“The course used mathematical and engineering models to understand physiological systems,” Minor says. “And the professor used the balance system, and the eye movements associated with it, as an example of how you could not only describe the way the system worked, but you could learn mechanistically about how the brain was working.”

Like many scientists, Minor really likes to figure out how things work — the more complex the better. And the vestibular system is complex. Take what Minor refers to as “vestibular illusions.” Why, when you step onto an escalator that isn’t moving, does your brain tell your body that it is? Or why, when you’re sitting on a stationary train and the train next to you starts to move, does it feel like you’re moving even though you know you’re not? Unlike most of us, Minor knows exactly how complicated the answers to these questions can be.

“It was during that undergraduate course that I read the papers of the person who later became my mentor,” Minor says. That person was Jay Goldberg, PhD, now a professor emeritus of pharmacological and physiological sciences at the University of Chicago, who wrote a seminal series of scientific papers in the 1970s that captured the imagination of the young Minor. Goldberg had described for the first time the dynamics governing the responses of sensory neurons carrying information from the vestibular receptors in the inner ear to the brainstem, setting the stage for future studies in the field of vestibular neurophysiology.

Minor later wrote to Goldberg, and then traveled to Chicago to meet with him. They stayed in touch throughout Minor’s medical school years. “We made plans that I would come to work with him after I graduated from medical school.”

In between his surgical residency and a residency in otolaryngology, Minor spent four years working in Goldberg’s lab, conducting experiments in animal models that further explored vestibular neurophysiology. By the mid-1990s, as both a surgeon and an expert on the science of the vestibular system, Minor was unusually well-equipped to solve the mystery of the patients who could hear their eyeballs scratching as they moved back and forth.

‘Doctors had no answers. I had an eye specialist tell me this was a psychiatric case because I could hear my eyes move.’

The vestibular system controls how we move through the world. It works with our senses to give the brain information about where we are in space, whether we are moving, and the direction and rate of our movements. It keeps us from stumbling when we get out of bed in the middle of the night; it maintains balance and spatial orientation and keeps us from falling.

The sensory information about motion, equilibrium and spatial orientation is provided by the vestibular apparatus, which in each ear includes the utricle, saccule, and those three semicircular canals, bones so small that together they can fit on the surface of a dime. The utricle and the saccule, two sacs located just below the semicircular canals, contain small stones and viscous fluid that enable hair cells to detect linear motion and orientation relative to gravity. The saccule and utricle detect vertical linear motion, like when you drop in an elevator, and horizontal linear movement, such as zooming forward in a car. The fluid-filled semicircular canals detect rotational movement and inform the brain about angular head movements.

Each of the canals lies along a different plane, perpendicular to one another, and sends messages to the balance center in the brain for head rotation in its plane. When the head rotates in a direction sensed by a particular canal, the fluid within it lags behind because of inertia and exerts pressure against a specialized structure — the canal’s sensory receptor. The receptor then sends nerve impulses to the brain about movement from the specific canal that is stimulated.

One of the most important functions of the vestibular system is to keep the eyes focused on objects of interest during head movements, like when you’re driving down a bumpy road. Rotatory motion upward and downward is where the superior semicircular canal comes in. As Minor knew from studying late-19th-century experiments on the vestibular system in pigeons, pressure on the superior semicircular canal causes the eyes to move in the plane of that canal. It was this motion that Minor saw when he watched his two patients’ eyes move in response to sound, and suspected that it must be the superior canal that was damaged.

“The specific pattern of the eye movements, that was a smoking gun pointing to the superior semicircular canal being the source of the problem,” Minor says.

Normally, the inner ear is a closed capsule with only two openings — the oval and round windows of the cochlea. Having a hole in one of the canals — a third opening — can lead to a number of auditory and vestibular disturbances. Among the most dramatic: Sounds from inside the body can enter directly into the inner ear through bone conduction.

“Some of the sounds that are already in our body, our pulse, our neck creaking, our own voice, those get into the inner ear through that hole much more readily than normal, so people report these crazy symptoms like hearing their eyes move, hearing their blood,” says John Carey, MD, one of Minor’s colleagues at Johns Hopkins who assisted in the later surgeries and research. “It may be too loud or distorted because they are hearing their voice come through their bones directly into their ear. Their voices sound loud, uncomfortable, distorted. Many patients resort to whispering.”

To test his theory, Minor and colleagues collaborated with a neuroradiologist to develop a more sensitive version of a CT scan to search for a tiny hole in the canal.

Within months, they were able to scan the gentleman who liked to sing in the shower. Sure enough, there was a hole in his right superior semicircular canal.

Finally, an answer.

“In addition to being sent to a psychiatrist and told that he was imagining these things, which he clearly wasn’t, the patient was concerned that maybe he had multiple sclerosis or a neurological disease,” says Minor. “For him it was just a real frustration. Once we figured out what it was, he felt reassured and did not feel he needed the problem to be corrected. He just stopped singing in the shower.”

About two-thirds of patients with the syndrome choose to live with it; others have symptoms that are just too disabling, Minor says. They want a cure badly.

His second patient, also at Johns Hopkins, fit into this category. Like the first patient, she had sound-induced wobbling vision known as oscillopsia, but she also had disequilibrium.

Minor and his colleagues at Johns Hopkins developed an operation to correct the disorder. The surgery entails making an incision above the ear and then gently elevating the temporal lobe of the brain to reveal the superior canal, using fascia and bone to plug the canal hole, securing the opening in the skull with titanium plates and sewing the scalp back up. Other surgical approaches to correct the disorder have also been developed in the intervening 20 years.

In 1996, he operated on his second patient and her symptoms immediately disappeared. In 1998, Minor and colleagues at Johns Hopkins published their first paper on the disorder, in the Archives of Otolaryngology Head and Neck Surgery, describing eight patients with the syndrome. A series of additional publications followed.

“We showed that there were specific hearing abnormalities associated with the syndrome,” Minor says. “We also showed that there were other vestibular abnormalities that could be evaluated by clinical tests. We established that the surgery was selective in its effects on the superior canal. That the sound-induced eye movements went away. That the hearing often returned to its normal range. Most of the severe symptoms were gone. Patients were much better than before. In making these discoveries, we also extended our understanding of vestibular physiology. Our work on this syndrome has been a wonderful synthesis of bench to bedside and back to bench.”

Exactly how many people suffer from this syndrome remains unclear, Minor says. At Johns Hopkins, surgeons have performed about 240 procedures, and they are often done at Stanford as well. What is known: Many patients are diagnosing themselves online. Both the audiologist from Atlanta and the horn player from Germany found out about Minor’s research and discoveries online, then contacted him at Johns Hopkins by email. Minor eventually operated on both. Some have suggested the disorder be renamed Minor’s syndrome.

For the horn player, surgery ended 22 years of suffering. He was able to return to his music. Hirsch, the audiologist, had endured the syndrome for seven years.

“My symptoms kept getting worse,” she says. “I stopped attending weddings, bar mitzvahs and my children’s sporting events. I became a social recluse. In November 2004, I went searching for answers online, found Dr. Minor and emailed him. He called me that night at 5 p.m. on a Friday. I was overwhelmed and honored to hear directly from him.”

On Feb. 10, 2006, at Johns Hopkins, she became the 34th patient with superior canal dehiscence syndrome to have canal-plugging surgery. After waking up from surgery, the surgeons asked if she was OK. She motioned with her hand for them to wait, then closed her eyes and moved them back and forth. There was no sound. Her eyeballs had been silenced.