An eye movement test that can diagnose Parkinson’s disease 10 years before a patient exhibits the classic symptoms is gathering attention as a major breakthrough in the treatment of the chronic, progressive movement disorder. The test, which is noninvasive and nearly 100 percent accurate, can confirm the presence of Parkinson’s prior to the onset of bradykinesia (slow movement), rigidity, balance impairment and tremors in the hand or foot. During the test, the manner in which a patient’s eyes follow a prompt is recorded and the data interpreted to confirm a tremor behind the eyes. “Every person with Parkinson’s disease has a tremor behind the eyes.” says Virginia Commonwealth University neurologist Mark Baron.
Baron, who is a clinical neurologist and a professor of neurology at the VCU School of Medicine, has collaborated for the past decade with Paul Wetzel, an associate professor in VCU’s Department of Biomedical Engineering, who has researched eye movement behavior for more than 30 years. “The ability to properly control our eyes is vital and involves many areas of the brain and common pathways,” Wetzel says. “If any of these areas or structures are affected by disease and/or injury, we hypothesize that we should be able to observe these changes in the eye-movement behavior.”
When he came to VCU more than 15 years ago, Wetzel became interested in Parkinson’s after he was introduced to a neurosurgeon and two neurologists who were involved in treating patients who had the disease. His interest led him to Baron, who is also director of the Southeast/Richmond Veterans Affairs Parkinson’s Disease Research, Education, and Clinical Center at the McGuire Veterans Affairs Medical Center. While the majority of those tested are patients at McGuire, Baron often sends unusual cases and those who require confirmation from his office at the
VCU Parkinson’s Disease and Movement Disorders Center to McGuire.
Five years ago, VCU Biomedical Engineering doctoral candidate George Gitchel joined the McGuire team. Gitchel administers and interprets the eye-movement test, and has expanded the team’s research to include other movement disorders, such as Huntington’s disease, ataxia and dystonia. “This led us to the development of a tool that can differentiate approximately 30 different disorders,” Gitchel says.
Parkinson’s disease is the result of the death of neurons in the brain, some of which produce dopamine, a chemical that sends messages to the part of the brain that controls movement and coordination. As the disease progresses, the amount of dopamine produced in the brain decreases. Currently, there is no cure for the disease; its progress cannot be arrested, and symptoms can only be treated, not eliminated.
Unlike other neurological conditions, such as multiple sclerosis, there are no imaging, blood or other laboratory tests available to confirm a Parkinson’s diagnosis. Instead, health care professionals rely on information provided by the patient and the observation of a patient’s movement. Drug therapy can point to a Parkinson’s diagnosis if symptoms improve drastically when the patient is medicated.
To date, the McGuire team has tested more than 3,000 patients and has submitted an application to patent the eye-movement test. “We now have data to show that we can diagnose [the disease] at least 10 years prior to the first tremor or gait slowing,” Baron says. Early detection of Parkinson’s would not only allow for treatment of the disease in its beginning stages, but also for planning and lifestyle adjustments, such as regular exercise. “One day, which hopefully is not far away, when we have treatments to actually slow the disease down, this, I am certain, will have a major impact on lives.”
