For decades physicians have had to rely largely on a keen eye and experience to diagnose Parkinson's disease.
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.
Any patient who has sought an elusive diagnosis knows the value of being certain of what you're dealing with. Plus, 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 USF 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.
In January the Food and Drug Administration approved a procedure called DaTscan from GE Healthcare, and it now is becoming more widely available. The procedure, which has been done in Europe for the past decade, 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, and that's what the scan shows.
"A normal image looks like you have two fat commas in the brain," said Hauser, speaking of the part of the brain where dopamine is concentrated.
"But because you lose dopamine neurons from the back forward, what happens is one of those commas looks more like a period," he explained.
Dr. Saleem Khamisani, a neurologist at St. Anthony's Hospital in St. Petersburg who specializes in Parkinson's, recently started offering the test. "DaTscan will help us make the diagnosis early and differentiate some other diseases that can be confused with Parkinson's," he said.
Early diagnosis is important because there's evidence that at least one Parkinson's medication, Azilect, may not only reduce symptoms but may also slow progression of the disease.
"Normally when you have (obvious) symptoms, you have already lost 80 to 90 percent of cells that produce dopamine in the brain," Khamisani said. "You want to diagnose it at 30 percent and treat them earlier."
By the time Vicky Greer had a DaTscan at Tampa General Hospital in December as part of a clinical trial, her dopamine level was 60 percent depleted.
It was just last summer that the St. Petersburg teacher 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, but when her symptoms worsened in the fall, she sought out Hauser.
"He looked at me and watched me walk and said he was about 98 percent sure that it was Parkinson's," recalls Greer.
The scan confirmed the diagnosis. "It was hard," said Greer, a reading teacher at Tomlinson Adult Learning Center.
"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,'' she said. "To have a diagnosis."
Irene Maher can be contacted at [email protected]