Eye tremor could be early sign of Parkinson's Disease

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Eye tremor could be early sign of Parkinson's Disease
Tue, 04-10-2012 - 11:34pm

I think this is me....


Eye tremors are pervasive in Parkinson's disease and could be an early warning sign of the neurodegenerative movement disorder, according to a case-control study.

All 112 Parkinson's patients tested, including newly diagnosed cases not yet on medication, showed constant small rhythmic movements of their eyes when attempting to fix their gaze on an object, Mark S. Baron, MD, of the VA Medical Center in Richmond, Va., and colleagues found.

By comparison, the same fixation instability was seen in just two of 60 age-matched controls, one of whom apparently had presymptomatic Parkinson's disease based on symptoms that developed over 2 years of follow up, the group reported online in the Archives of Neurology.

"The pervasiveness and specificity of this feature suggest that modern, precise oculomotor testing could provide a valuable early physiological biomarker for diagnosing Parkinson's disease," the group wrote.

As a simple screening test, it could be nearly 100% accurate, whereas even specialists are wrong in diagnosing Parkinson's about 15% of the time with when they first see someone with tremor, Baron said in an interview.

That will be key to identifying who could benefit from treatment as new options are developed that can slow progression of the disease, he told MedPage Today.

The movements are too small to notice clinically and require specialty equipment to measure, Baron noted.

However, 63% of the Parkinson's patients had fixation instability that moved their focus enough on occasion to reach the 0.5° threshold thought to create problems with vision.

"We do know that people often complain of blurred vision with Parkinson's disease, but no one's been able to explain why," Baron told MedPage Today. "We believe this is probably a major reason."

In the study, the researchers used a video-based system that rests on the head and tracks the center of the pupil with infrared lights and cameras.

Among the 112 Parkinson's patients recruited from the Richmond VA's center for Parkinson's research and treatment, 94 were on dopaminergic medications and had shown benefit. The rest were de novo untreated.

Altogether, this group had persistent problems with fixation stability. The oscillations had:

  • A mean frequency of 5.7 Hz (ranging from 4.3 to 10.9 Hz)
  • A mean amplitude of 0.27° horizontally and 0.33° vertically (range from 0.14° to 1.63°)