New technique might improve diagnosis of movement disorders
Published: Friday, June 21, 2013 at 11:00 a.m.
Last Modified: Friday, June 21, 2013 at 11:00 a.m.
If you shoot dye into a bowl of water and the dye is unable to flow freely in the water, you have some sense of what a disease such as Parkinson's looks like inside the brain.
The restricted spread of colored water is known as “constrained diffusion,” which in physiological terms can signal the onset of neurodegenerative diseases.
Scientists are now able to visualize these patterns of diffusion using a technique called diffusion tensor imaging, or DTI, which helps them classify correctly and avoid misdiagnosing a group of movement disorders that resemble each other.
A University of Florida study on the technique measured water molecular diffusion in the cerebellum and basal ganglia in patients and specifically identified damage to the gray and white matter in the brain.
UF researcher David Vaillancourt, an associate professor in the department of applied physiology and kinesiology and the study's lead researcher, explained that gray areas are where neurons are firing to induce thoughts, behaviors and movements.
“White matter connects the gray matter — like roads connect to cities,” Vaillancourt said.
The study examined the diffusion patterns in 72 patients with a movement disorder such as Parkinson's disease, essential tremor or multiple system atrophy, in order to identify markers of distinction between them.
“No other imaging, cerebrospinal fluid or blood marker has been this successful at differentiating these disorders,” Vaillancourt said in a news release. “The results are very promising.”
The researchers were able to correctly identify all the patients' diseases. They looked specifically at the cerebellum and basal ganglia because those areas are affected differently depending on the disease. Essential tremor, for example, has changes in the cerebellum but not the basal ganglia.
Although the patients already had been diagnosed with diseases, the ultimate goal is to use DTI at the outset of diagnosis so that patients aren't treated unnecessarily for disorders they don't actually have.
“This is not at a point where we are going to start diagnosing patients based on this, but it shows significant promise in that direction,” Vaillancourt said.
Accurate diagnoses for these diseases can be helpful for patients and caregivers alike, he continued. “I think people generally want to know what they have. It helps people plan and know what to put in place.”
For example, people with Parkinson's disease and essential tremor can live a long time, whereas those with multiple systems atrophy pass away quickly, he said, adding that between 10 percent and 15 percent of patients are misdiagnosed.
Dr. Michael Okun, a neurologist and co-director of the Center for Movement Disorders at UF, called the study, which was published in the journal Movement Disorders, “a critical contribution to the field.”
“Early and accurate diagnosis will be essential for testing new therapies and especially those that can meaningfully alter the disease course,” Okun said. “The field has been hoping that such technology would begin to solve a problem that has plagued the field and threatened to slow new therapies to the bedside.”
Previously, drugs and other therapies might have been tested in patients with the wrong diagnosis, Vaillancourt added.
He said that future studies would look at larger patient cohorts. In the future, they also might examine the cortex because it is less affected in Parkinson's and essential tremor compared with multiple systems atrophy.
Apart from its use in neurodegenerative diseases, DTI also has been used to diagnose traumatic brain injury, multiple sclerosis and certain cancers.
“It's definitely a technique that has a lot of appeal clinically. It fits within the MRI systems and health care infrastructure,” Vaillancourt said. “It's fairly easy to implement.”
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