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Monday, August 8, 2022
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What Is A Dat Test For Parkinson’s

Is Early Diagnosis Possible

The DaTscan Can’t Indicate MS Or Parkinson’s. It’s A Pharmaceutical Con.

Experts are becoming more aware of symptoms of Parkinsons that precede physical manifestations. Clues to the disease that sometimes show up before motor symptoms and before a formal diagnosis are called prodromal symptoms. These include the loss of sense of smell, a sleep disturbance called REM behavior disorder, ongoing constipation thats not otherwise explained and mood disorders, such as anxiety and depression.

Research into these and other early symptoms holds promise for even more sensitive testing and diagnosis.

For example, biomarker research is trying to answer the question of who gets Parkinsons disease. Researchers hope that once doctors can predict that a person with very early symptoms will eventually get Parkinsons disease, those patients can be appropriately treated. At the very least, these advances could greatly delay progression.

Parkinson’s Disease and Movement Disorders Center

Our center provides compassionate and timely treatment to patients with movement disorders, such as dystonia, ataxia, essential tremor and similar conditions. But our mission goes beyond patient care excellence. By offering educational events and support groups, we empower patients and caregivers to become better partners in their health.

New Diagnostic Standards For Parkinsons

Until recently, the gold-standard checklist for diagnosis came from the U.K.s Parkinsons Disease Society Brain Bank. It was a checklist that doctors followed to determine if the symptoms they saw fit the disease. But thats now considered outdated. Recently, new criteria from the International Parkinson and Movement Disorder Society have come into use. This list reflects the most current understanding of the condition. It allows doctors to reach a more accurate diagnosis so patients can begin treatment at earlier stages.

Why Would My Doctor Order A Datscan

Your doctor may order a DaTSCAN to confirm or rule out a diagnosis, or to see how a medication is affecting your brain or internal organs. SPECT scans may also be ordered to help diagnose or monitor conditions affecting the bones and the internal organs, especially the heart and the brain, and even to manage and stage cancer.

DaTSCAN allows physicians to see which areas of the brain are responding to various stimuli, making it particularly helpful in confirming diagnoses as movement disorders such as Parkinsons Disease, Parkinsonian Syndrome, and Essential Tremor. DaTSCAN can also be helpful in diagnosing and treating traumatic brain injury , attention deficit disorder , attention deficit hyperactivity disorder , and more.

Also Check: Parkinson’s Disease Life Expectancy

Tests To Rule Out Other Conditions

Blood tests can help rule out other possible causes of the symptoms, such as abnormal thyroid hormone levels or liver damage.

An MRI or CT scan can check for signs of a stroke or brain tumor, which may cause similar symptoms.

Hydrocephalus due to atrophy can occur with some types of dementia and would be visible with one of these imaging tests. If the person has neurologic symptoms but a normal scan result, Parkinsons disease may be present.

The doctor a lumbar puncture to rule out inflammation or a brain infection.

Tests Used In Establishing The Cause Of Parkinsonism

DaTscan testing for Parkinson

PET is a radiotracer-based method that can assess the in vivo function of the dopaminergic and other neurotransmitter systems. DOPA PET is a reliable tool to establish nigrostriatal cell loss but not very practical in clinical practice because the technique is only available in a limited number of centers, is expensive, and expertise in cerebral PET imaging is essential .

DAT SPECT imaging – a practical, less expensive, and more widely available technique than DOPA PET – has been incorporated in most centers as diagnostic tool . DAT tracers like FP-CIT are typically used. Recent studies have shown that DAT SPECT imaging might be a sensitive method to establish nigrostriatal dopaminergic degeneration . For example, people with subclinical and even preclinical PD already have clear deficits of the nigrostriatal pathway . Also, if the scan does not show a nigrostriatal deficit, it is highly unlikely that the patient suffers from symptoms caused by nigrostriatal cell loss . SPECT with tracers labeling postsynaptic dopamine D2/3 receptors shows a relatively low diagnostic accuracy, 59 to 80% sensitivity and 46 to 50% specificity in differentiating PD from non-neurodegenerative diseases .

Hyperechogenicity in the area of the midbrain has been consistently found in 79 to 90% of patients with PD using TCS . However, in 6 to 12% of healthy volunteers, hyperechogenicity of the substantia nigra is also found . This is even higher in patients with essential tremor .

Also Check: What Is The Life Expectancy Of Someone With Parkinson’s Disease

On The Day Of The Exam

  • Drink plenty of fluids and go to the bathroom frequently
  • Wear loose comfortable clothing, since you will need to lie still for a period of time.
  • Please bring a list of all medications that you are taking name and dosage.
  • We want to make your waiting time as pleasant as possible. Consider bringing your favorite magazine, book or music player to help you pass the time.
  • Please leave your jewelry and valuables at home.

Referral To A Specialist

If your GP suspects Parkinson’s disease, you’ll be referred to a specialist.

This will usually be:

  • a neurologist, a specialist in conditions affecting the brain and nervous system
  • a geriatrician, a specialist in problems affecting elderly people

The specialist will most likely ask you to perform a number of physical exercises so they can assess whether you have any problems with movement.

A diagnosis of Parkinson’s disease is likely if you have at least 2 of the 3 following symptoms:

  • shaking or tremor in a part of your body that usually only occurs at rest
  • slowness of movement
  • muscle stiffness

If your symptoms improve after taking a medication called levodopa, it’s more likely you have Parkinson’s disease.

Special brain scans, such as a single photon emission computed tomography scan, may also be carried out in some cases to try to rule out other causes of your symptoms.

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Would I Still Have Gotten A Datscan

DaTscan Diagnoses Parkinson’s Early

It was important for me to have confirmation other than my symptoms of abnormalities in my brain. I think this scan can be used as a baseline to follow my disease progression.

So, yes, I would have still gotten this test, although the $2,000 out-of-pocket cost upfront may have given me pause.

Note: Parkinsons News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or another qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website. The opinions expressed in this column are not those of Parkinsons News Today or its parent company, BioNews Services, and are intended to spark discussion about issues pertaining to Parkinsons disease.

Recommended Reading: Parkinson’s Disease Epidemiology

What Doctors Look For When Diagnosing Parkinsons

Certain physical signs and symptoms noticed by the patient or his or her loved ones are usually what prompt a person to see the doctor. These are the symptoms most often noticed by patients or their families:

  • Shaking or tremor: Called resting tremor, a trembling of a hand or foot that happens when the patient is at rest and typically stops when he or she is active or moving

  • Bradykinesia: Slowness of movement in the limbs, face, walking or overall body

  • Rigidity: Stiffness in the arms, legs or trunk

  • Posture instability: Trouble with balance and possible falls

Once the patient is at the doctors office, the physician:

  • Takes a medical history and does a physical examination.

  • Asks about current and past medications. Some medications may cause symptoms that mimic Parkinsons disease.

  • Performs a neurological examination, testing agility, muscle tone, gait and balance.

What Happens During A Datscan

During a DaTSCAN, a very small amount of tracer, specific for the organ or tissue to be scanned, is injected into a vein by a nuclear medicine technologist. Images may be taken during the injection, immediately after the injection, or following a delayed period to allow the tracer to distribute to the organ or tissue of interest. The gamma rays emitted by the tracer are detected by a special camera that is positioned near the organ or part of the body being imaged.

You will need to remain very still for the camera, but it will not touch you. The radiation from a nuclear medicine procedure is comparable to that received during a routine X-ray. The tracer only remains in the body for a short period of time before being eliminated in the urine or stool.

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Am I Convinced That I Have Pd

Three years after my diagnosis, I am still struggling to find relief from my symptoms and slow the progression of this disease. I exercise, eating a mostly vegan and gluten-free diet, take Sinemet , and use the Neupro transdermal patch. I am working with my current neurologist to fine-tune my medication cocktail.

I had wondered whether I did have PD since Ive never had an aha moment in which I feel somewhat normal after taking medications. People tell me I look fine and they dont observe any external signs of the disease. However, my tremors are internal and I feel horrible and constantly fatigued.

What Is A Datscan

Parkinson

A DaTscan is an imaging drug, also called Ioflupane I 123 or phenyltropane, that acts as a radioactive tracer for dopamine transporters within the brain. This drug was approved by the FDA in 2011. It may help distinguish the diagnosis of essential tremor from Parkinson’s syndromes, like Parkinsons disease or Parkinsons disease dementia.

The drug is administered during the SPECT scan. This scanning technique gathers images of a particular area in the brain called the striatum, a cluster of neurons in the subcortical basal ganglia of the forebrain. The striatum helps facilitate the transportation of dopamine.

DaTscan is injected into the patients bloodstream and eventually circulates to the brain. The tracer attaches itself to a molecule found on dopamine neurons in the striatum called the dopamine transporter . The patient then undergoes a SPECT scan which will produce an image of the dopaminergic neuron terminals that remain available in the striatum.

In patients with a diagnosis of Parkinsons disease, or parkinsonism , this area of the brain will show dark. This indicates the loss of dopamine-containing nerve cells within the brain, a hallmark of the disease.

Recommended Reading: What Is The Life Expectancy Of Someone With Parkinson’s Disease

Datscan: A Test To Help In The Diagnosis Of Parkinsons

In 2011, the Food and Drug Administration approved an imaging test to help diagnose PD. In this test, a radioactive tracer, Ioflupane 123I, also known as DaTscan, is injected into the blood, where it circulates around the body and makes its way into the brain. It attaches itself to the dopamine transporter, a molecule found on dopamine neurons. Several hours after the tracer has been injected, special imaging equipment scans the head to detect the presence of DaTscan.

People with PD will typically have a smaller signal in a part of the brain called the striatum, where the ends of the dopamine neurons are meant to be. Here is a normal scan on the left, which would indicate a healthy dopamine system, next to an abnormal scan on the right, which would indicate an unhealthy dopamine system.

It is important to note that conventional MRI imaging will appear normal in PD and is therefore not helpful in confirming the diagnosis. Other atypical parkinsonian conditions, such as vascular parkinsonism however, can have abnormalities on MRI, so the test may be done to rule out other diagnoses.

What Are The Pitfalls Of Datscan

DaTscan will appear abnormal in any disease in which there is a loss of dopamine nerve endings in the striatum. Therefore, Parkinson-plus syndromes, discussed in a prior blog, such as Progressive supranuclear palsy , Corticobasal ganglionic degeneration and Multiple system atrophy all typically demonstrate abnormal DaTscans. DaTscan therefore cannot be used to distinguish between these syndromes.

Every medical test has a false positive and a false negative rate. This means, that it is inevitable that in a certain percentage of people who have PD, the DaTscan will be read as normal and in a certain percentage of people without PD, the DaTscan will be read as abnormal. Results of any medical test that is performed, must therefore be considered within the entire clinical context.

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What Are The Limitations Of The Test

Currently, DaTscan that is in clinical use is not quantitative, which means that the test is not designed to determine how impaired the dopamine system is just whether it is or not. This means that the test is not used to tell you whether the disease has progressed over time and is not used to follow a patients disease. It also is not used currently as a clinical test to screen for the disease before motor symptoms are evident. Because of these limitations, the search continues for additional measurable indicators, known as biomarkers, to help diagnosis and manage PD.

Tips and Takeaways

  • DaTscan is a test that can help in the diagnosis of PD, although in most situations a clinical exam done by a neurologist offers the same information.
  • Neurologists are skilled to diagnose PD through a clinical exam. While the exam to some may seem very basic and thus a PD diagnosis subjective or questionable, neurologists are well-trained to assess and diagnose with confidence.
  • DaTscan may be useful in distinguishing PD from certain conditions, but not from others, so talk with your neurologist about whether DaTscan would be useful in your specific situation.
  • DaTscan is not a test used for monitoring PD progression. It can be used to help clarify a PD diagnosis, but it is not a test you would undergo multiple times during the course of your disease.

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Dr. Rebecca Gilbert

Passive Manipulation Of Limbs

What tests are used to differentiate Parkinson’s disease from other similar conditions?

To test for the presence of rigidity, we need to passively manipulate the limbs of the patient. However, If the disease is in its early stage or the symptoms are well controlled with medications, we may not be able to see rigidity. We will need to use some activation maneuvers, that basically consist in performing repetitive movements with the limb contralateral to the one that is being tested.

Also, there are two types of rigidity:

– Lead-pipe rigidity: where the tone is uniformly and smoothly increased throughout the entire range of movement

– Cogwheel rigidity: where a tremor is superimposed on the hypertonia, making the movement irregular due to intermittent increase and reduction of tone

Upper Extremity Testing

For the upper extremity the most sensitive joint where to check for rigidity is the wrist. To uncover rigidity, passively rotate the wrist and feel for a resistance to the movement. It is very important that the arm of the patient is fully relaxed when rotating the wrist. To do this, place your proximal hand under the patients forearm, while your distal hand grabs and rotates the wrist of the patient. When rigidity is present, the range of motion will be preserved but you will feel a resistance in performing the movement.

Wrist rotation with activation maneuver.

It is also possible to test for rigidity in the elbow by passively flexing and extending the forearm.

Elbow flexion-extension with activation maneuver.

Lower Extremity Testing

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Important Risk And Safety Information About Datscan

What is the most important information you should know about DaTscan?

  • Serious allergic and injection-site reactions could occur following a DaTscan injection. If you have any symptoms of a serious allergic nature, including low blood pressure trouble breathing throat tightness swelling of your face, lips, or tongue or rash and itching, inform your doctor or go to your nearest emergency room right away
  • To help decrease the amount of thyroid accumulation of iodine: Your doctor will give you a medication at least one hour before giving you DaTscan. The purpose of this medication is to minimize the amount of radioactive iodine going into your thyroid gland
  • Pregnancy: Clinical studies have not been conducted with DaTscan on pregnant women. Any radioactive drug, including DaTscan, may cause harm to the fetus. If you are pregnant, your doctor will decide if a DaTscan test is appropriate
  • If your are a nursing mother, your doctor will decide whether you should interrupt nursing and pump and discard breast milk for six days after DaTscan administration to reduce the risks to your nursing infant
  • If you have kidney and/or liver problems: The effects of kidney and /or liver damage from the use of DaTscan are not certain. DaTscan is removed by the kidney, and patients with severe kidney problems may have increased radiation exposure that could change DaTscan images
  • Children: DaTscan should not be given to children

When Is Datscan Helpful

There are situations in which DaTscan can be very helpful in securing a diagnosis when neurologic exam findings are not clear-cut. Although DaTscan cannot distinguish PSP, CBGD, and MSA from PD, studies suggest that it may be able to distinguish drug-induced parkinsonism and vascular parkinsonism from PD.

The FDA indication for DaTscan is for distinguishing between PD and essential tremor . Usually it is quite straightforward for a neurologist to distinguish between the tremors of ET and the tremors of PD. PD tremors occur at rest and are accompanied by slowness and stiffness of the limb, whereas ET tremors occur with action and are not accompanied by slowness and stiffness of the limb. However, some people may have mixed tremor features making the diagnosis more difficult. In those cases, a DaTscan can be very useful.

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