What If It Isn’t Parkinson’s?

HYANNIS – In treatment for Parkinson’s disease, “Roy” attended lectures on the subject and joined a Parkinson’s support group to help deal with his anxiety and depression.  But, neurologist Karen Lynch, MD, wasn’t so sure he had the condition. She suggested a new imaging procedure at Cape Cod Hospital (CCH) that could help settle the question.

The test revealed he did not, in fact, have Parkinson’s disease.

“He no longer had the weight of progressive degenerative condition, which turned out to be a big thing for him,” Dr. Lynch said.

Since being introduced at CCH in the last year, more than 50 people have been evaluated using the nuclear medicine test DaTscan. It is first FDA-approved imaging system to help confirm the diagnosis, which is especially useful in cases where the indicators aren’t clear-cut.

“This type of technology is usually found only in academic medical centers. We expect to see an increase in the numbers of local patients diagnosed with Parkinson’s disease in the future as our population ages. We are lucky to be able to offer it here on the Cape,” said  Salvatore Viscomi, MD, chairman of the Department of Radiology at Cape Cod Healthcare.

DaTscan uses a MRI-like SPECT (single photon emission computed tomography) camera to trace a small amount of an injected radioactive substance as it travels to the part of the brain where dopamine is produced. Dopamine is a protein necessary for control of body movement and coordination.

Dopamine deficiency is a hallmark of Parkinson’s disease and can distinguish it from other movement disorders like essential tremor.

“There is no single test for Parkinson’s disease,” said Dr. Viscomi. “Diagnosing it requires a composite of information. The test results from DaTscan, in addition to the findings on the patient exam and the clinical history, give a pretty accurate picture.”

What to Expect

 “DaTscan is not difficult or painful, however it does take a bit more time than other imaging tests,” said Vicky Jelley, radiology technician at Cape Cod Hospital. She explains the sequence of events involved in this test:

  • An injection of Lugol’s solution to protect the thyroid from absorbing any radiation, with a one-hour period of observation in the nuclear medicine department afterwards
  • An IV injection of radiopharmaceutical agent phenyltropane
  • Three-hour wait for the full absorption of phenyltropane, which can be done at home
  • A 45-minute scan of the brain, where the patient lies prone on the table with eyes closed

“Patients with a history of claustrophobia or who are unable to remain still may require mild sedation. This should be discussed with their neurologist advance,” advised Jelley.

Results are generally available within 48 hours.

What is Parkinson ’s disease?

 Parkinson’s disease is a chronic neurodegenerative brain disorder that gets progressively worse over time. It is incurable, but there are medications and surgical treatments to help lessen the symptoms.

According to the Parkinson’s Disease Foundation, the main symptoms of the condition are:

  • tremor of the hands, arms, legs, jaw and face
  • bradykinesia or slowness of movement
  • rigidity or stiffness of the limbs and trunk
  • postural instability or impaired balance and coordination

More than 60,000 Americans are newly diagnosed each year. It affects over 10 million people worldwide. The biggest risk factor is age, as most cases are diagnosed after 60. However, there are rare cases of diagnosis as early as age 18.

The cause of Parkinson’s disease is unknown.

Parkinson’s disease is the most common form of one of three conditions included in a group of Parkinsonian Syndromes. The others are:

“While essential tremor is the most common tremor disorder around, telling it apart from Parkinsonian syndrome diseases isn’t always straight forward,” said Dr. Lynch. “While DaTscan can tell the difference between Parkinson’s disease and essential tremor, it cannot differentiate one Parkinsonian syndrome from another.”

Essential tremor is not caused by dopamine deficiency.

 How Does DaTscan Work?

 DaTscan is able to highlight the very small area in the brain where the dopamine receptors are located. The radiotracer shows if these cells exist in normal numbers and if they are fully functioning.

Since essential tremor is not caused by dopamine insufficiency, DaTscan can be helpful in ruling out Parkinson’s disease in these cases.

“DaTscan will be negative in those cases that have just tremor. That’s probably the main reason why I order the test,” said Dr. Lynch.

The test is also helpful in investigating disease progression, especially when medications stop being effective.

“I don’t use a DaTscan for every single Parkinson’s patient.  A good clinical examination by a neurologist is often sufficient. Most of the time, I tend to use it for patients who have an indistinguishable tremor disorder, patients with mild/early symptoms or one where there has been a change in responsiveness to medications, i.e. those previously labeled as Parkinson’s disease but with atypical features where I question the diagnosis,” she said.

And in some cases, DaTscan is ordered to relieve a patient’s worry, as in Roy’s case.

For anyone experiencing worrisome symptoms, early diagnosis is the key.

“It’s another tool in our kit to be confident  and ensure a reliable and accurate diagnosis.   Early detection with the help of clinical exam and DaT scan is key because there are very effective treatments out there,” said Dr. Lynch. “And if you can slow down disability and improve quality of life as early as possible, that’s the primary goal of care.”

By CLAUDIA DOLPHIN, Cape Cod Health News

 

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