Early Parkinson's diagnosis aided by new technology - East Valley Tribune: Health

Early Parkinson's diagnosis aided by new technology

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Posted: Monday, October 3, 2011 2:30 pm

To diagnose Parkinson's disease, physicians for decades have had to rely largely on a keen eye and experience.

Now the pairing of a new drug and a high-tech nuclear brain scan is offering long-awaited help in recognizing the progressive movement disorder, which has neither a specific diagnostic test nor a cure.

Researchers hope that by finding Parkinson's earlier, it may be possible someday to halt the disease's progress.

The telltale signs of Parkinson's -- among them trembling of the head, hands, legs or face, rigid posture, lack of facial expression -- can range from severe to very subtle, especially at the early stages. Adding to the difficulty, other neurological conditions can be mistaken for Parkinson's, but require different treatments. Some prescription medications have side effects that can cause Parkinson's-like symptoms, further complicating a diagnosis.

Research has shown that about 10 percent of patients suspected of having Parkinson's do not have it. That figure may be 15 or even 25 percent in practices that don't specialize in the condition, said Dr. Robert Hauser, director of the University of South Florida's Health's Parkinson's Disease and Movement Disorders Center.

End result: The proper diagnosis and treatment can be delayed for years. The delay is frustrating at best, and dangerous at worst.

The Food and Drug Administration in January approved a procedure called DaTscan from GE Healthcare, and it's becoming more widely available. Available in Europe for the past decade, the procedure uses an injected drug, Ioflupane I 123, and a type of brain imaging known as single photon emission computed tomography (SPECT) to look for dopamine, a brain chemical that Parkinson's patients lack. As the disease progresses, dopamine levels decline. The scan checks that.

"A normal image looks like you have two fat commas in the brain," Hauser said of the brain area where dopamine is concentrated. "But because you lose dopamine neurons from the back forward ... one of those commas looks more like a period."

Early diagnosis is important because there's evidence that at least one Parkinson's medication, Azilect, may both reduce symptoms and slow the disease's progression.

"Normally when you have (obvious) symptoms, you have already lost 80 to 90 percent of cells that produce dopamine in the brain. You want to diagnose (the disease) at 30 percent" and treat patients earlier, said Saleem Khamisani, a neurologist at St. Anthony's Hospital in St. Petersburg, Fla. He specializes in Parkinson's and recently started offering the test.

In the summer of 2010, Tampa reading teacher Vicky Greer noticed she was extremely fatigued, had trouble walking and was developing a slight tremor in her right hand. Her family doctor dismissed the notion of Parkinson's. When her symptoms worsened, she sought out Hauser.

By the time Greer had a DaTscan at Tampa General Hospital in December as part of a clinical trial, her dopamine level was 60 percent depleted.

"He looked at me and watched me walk and said he was about 98 percent sure that it was Parkinson's," Greer recalled about Hauser.

The scan confirmed the diagnosis. "It was hard," said Greer."I'm an active, young 59-year-old. It has really impacted my lifestyle."

Grim as the news was, Greer said it was a relief to have an explanation for her symptoms: "It was better to know what was going on, to have a diagnosis."

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