Giving Gaze Instability a New Look
By the time Mary Wisniewski came to Johns Hopkins for treatment, she’d already been through the medical wringer. Five years earlier, she had surgery to remove a tumor growing on her acoustic nerve, which was affecting her hearing. That was followed by another operation to repair leaking cerebrospinal fluid. Later, she had to have a shunt inserted to relieve fluid accumulating around her brain. Through all of this, she complained to her doctors many times that she was having problems with balance and dizziness, but her symptoms were continually discounted.
“My vision continued to get worse,” she says. “My world bounced and vibrated.”
Eventually, when Wisniewski headed to Johns Hopkins’ Hydrocephalus Center for additional care for fluid buildup around her brain, she says that the doctors there truly listened to her complaints. They referred her to see Michael Schubert, a vestibular physiologist and physical therapist who treats patients with vestibular problems, those that affect the system responsible for balance.
“Mary’s original surgery damaged the part of her ear that detects head motion,” Schubert explains, “so when the head is moving, the world isn’t stable.” It’s the same effect as trying to walk while looking through a pair of binoculars, he says. The world bounces and sways, making any motion very disorienting.
This problem, called gaze instability, can be disabling. For example, people with this condition might not be able to recognize faces while they’re walking, Schubert says, or read street signs while driving.
The typical treatment for gaze instability involves a series of exercises to train the brain to compensate for this problem by keeping the eyes still during motion. One common exercise is staring at a target while turning the head; as patients get better at keeping the image in focus, they try moving their heads faster.
However, Schubert says, these exercises have several drawbacks. Although they help the brain compensate, they train both vestibular systems at once, when often only one ear’s vestibular system is affected. Additionally, they can take many weeks to work, and compliance can be difficult.
Schubert and his colleagues from Neuroscience Research Australia are working on developing a better solution. They’re creating a device that retrains the vestibular system only on the affected side for those patients with damage to a single vestibular system. The device is also appropriate for those with damage to both vestibular systems.
The researchers’ device consists of a headband with an embedded sensor that detects head speed. A laser on the headband projects a target that moves at a tiny fraction of the head speed. By watching the laser, patients can retrain their vestibular system to once again keep the eyes still when the head moves. The device also helps evaluate the extent of patients’ vestibular problems.
When Wisniewski met Schubert, he diagnosed her problem and prescribed the usual exercises—the best therapy that conventional medicine has to offer. But he also asked her if she’d be interested in participating in research to develop his new device.
“She was eager to help,” Schubert recalls, “and eager to learn about her own problem.”
Participating in his study wasn’t particularly easy, Schubert explains. Testing the device’s early prototype involved wearing a donut-shaped contact lens to evaluate eye movement, which could be uncomfortable.
But Wisniewski wasn’t deterred and enthusiastically volunteered as a subject. Weeks later, she aided Schubert’s research even further. Wisniewski was so impressed by the promise of his work that she secured a $10,000 gift from an anonymous donor. The funds will help Schubert and his colleagues construct two new devices that can be used for further testing.
“Great minds like his,” Wisniewski says, “cannot overcome adversities like mine without the necessary research. My desire through all of the adversities I have encountered medically is that someone, somewhere will benefit from this.”