The Goals of Our Research
The focus of our research continues to be on disorders that affect balance, vision and eye movements with emphasis on two major problems:
How does the brain coordinate the movements of the two eyes? If the eyes don’t work together, we see double. If they are not help still, producing nystagmus or jumping of the eyes, vision is blurred. These are common problems among children (called strabismus) and adults who have diseases that also affect balance.
How can we better diagnose and treat patients with symptoms of dizziness, vertigo, ataxia and loss of balance? Disease of the balance apparatus occurs with both inner ear (vestibular) problems, including Ménière’s disease, tumors and viral infections, and with many diseases of the brain. These include stroke, trauma, cerebellar degeneration, Arnold-Chiari malformation, and Parkinson’s disease and related conditions, such as progressive supranuclear palsy (PSP). Disorders of both the inner ear and the brain commonly lead to double and blurred vision, especially when our heads or bodies move. This can happen, for example, when riding in a car, walking or running, or even when reading or watching television. These disorders often lead to serious falls. In order to understand how these symptoms can be treated, we are investigating the vestibular reflexes associated with the types of movement of the head that occur with walking and running. Therapeutically, we are developing ways to speed recovery of balance, and so prevent falls, and relief from dizziness and vertigo. Accordingly, a major research emphasis is on how the brain learns to compensate for disease and trauma, and how we can promote this compensation through drug treatment and better programs of physical therapy.
Our Research Progress and Latest Discoveries
2009 was an extraordinarily productive year for us. A number of important papers have appeared related to stroke, ataxia, eye movements, vertigo and the cerebellum. We especially thank the patients and friends who made generous contributions in support of our research. This private funding has been critical to the recent expansion of our effort and our overall success.
- Diagnosing and Treating Balance Disorders
- Cerebellar Ataxia, Arnold-Chiari malformation and PSP
- Eliminating Double Vision – Keeping the Eyes Aligned
- Dizziness in the Emergency Room
Our work on the eye movement response to the front and back and side to side motion of the head when we walk and turn has been published this year. We have discovered that this largely unconscious reflex response is not only capable of undergoing motor learning, but also that it is under some degree of higher level, voluntary, mental control. This finding has important implications for rehabilitation techniques after trauma, stroke, and other types of damage to the inner ear. Will, attitude, mood, and paying attention may all be critical for speeding up recovery or preventing decline in patients with balance disorders from both inner ear and brain disease. Last year we reported an unexpected but potentially major advance in accelerating recovery after damage to the inner ear and brain. Simply having subjects rest for a minute between five minute training sessions, permitted faster and more powerful learning (by a process called consolidation) than training without the rest periods.
This year, one of our junior colleagues has received funding to explore this strategy in detail and to learn how it might be applied to patients. By developing an optimal strategy to promote learning by the brain, patients will recover more quickly and completely after they suffer an inner ear disorder r other disturbances within the brain.
We are also continuing our collaborative projects with NASA to study how astronauts might better adapt to different gravity environments. Last year we showed that double vision could develop in normal humans in space flight and this year we will relate these findings to new tests of inner ear function in patients.
We have published a major new finding from cerebellar patients that we discovered last year. Patients with cerebellar ataxia do not process information from the inner ear correctly and this leads to blurred vision during very rapid head movements. In fact, we discovered that our patients’ eyes move up instead of going straight to the side when they shake their head horizontally. With a new MRI approach we are investigating how individual differences in the anatomical orientation of the inner ear organs within our skull lead to different patterns of disability. This information will allow us to adjust the balance therapy programs individually for patients with ataxia and cerebellar disease. After promising pilot studies which we previewed for you last year, we are now embarking on an extensive study of patients with cerebellar ataxia using a variety of new MRI techniques including diffusion tensor imaging (largely developed here at Johns Hopkins), high resolution MRI, and functional MRI. We have published our first papers from this work correlating disability with specific changes in the brain.
Patients with cerebellar disturbances often have disabling nystagmus (jumping of the eyes) and visual blurring. We have an outstanding new postdoctoral trainee here this year who will pursue drug treatment of patients with a specific form of ataxia called ataxia telangiectasia, and we hope the results can help patients with other types of ataxia.
We continue to study the treatment of strabismus or ‘crossed eyes’, which produces double vision. By recording eye movements before and after eye muscle surgery, we are investigating how the brain keeps the images seen by both eyes together so objects do not appear double. We have now studied ten patients with sophisticated, high-resolution, magnetic resonance imaging (MRI) of the eye muscles and quantitative eye movement recordings before and after surgery. We have also developed a sophisticated experimental model of eye muscle palsy which is revealing unexpected and potentially ‘paradigm shifting’ ideas about how we analyze and treat strabismus. We hope to determine exactly how patching and prisms can be used to treat double vision. This material will be presented at the premier eye research meeting in Florida next year with a special symposium at which we will report our results.
Dr. David Newman-Toker in our group has performed a landmark study of patients who come to the emergency department because of dizziness. He developed new bedside clinical testing criteria for diagnosing stroke in dizzy patients that are even better than the initial MRI scan!
We have a number of research and clinical collaborations with colleagues in Ophthalmology, Otolaryngology, Radiology. Biomedical Engineering and Physical Therapy, with all of us studying impaired vision, vertigo and imbalance.