Diagnosing Parkinson’s disease

How will a doctor diagnose Parkinson’s disease?

It can prove a little tricky to make an accurate diagnosis for Parkinson’s disease. Tests are generally recommended to rule out a variety of other illness and conditions which may show similar symptoms. There is no specific diagnostic test for Parkinson’s as yet.

A doctor will generally make a diagnosis through careful and thorough evaluations, assessing medical health history, physical examinations and neurological examinations. These will assess the functions of the brain, nervous system, muscle strength, level of coordination and reflexes, fine motor skills (especially the hands), walking ability and mental function.

A doctor will also request as much detail as possible regarding use of medications and supplements (including those of a herbal nature), other existing conditions, family medical history and the possibility of chemical exposure.

As many as 40% of Parkinson’s disease cases may not be diagnosed during the early stages of the disease, and 25% of occurrences may be misdiagnosed due to disease symptom similarities. Many symptoms mirror other medical conditions, such as osteoporosis. As many as a third of Parkinson’s disease sufferers may not even develop tremor.

There is no single symptom which can distinguish Parkinson’s disease from any other known medical condition. Doctors will use their thorough evaluations, including a chosen rating system to assess the combination of symptoms before making a diagnosis. Tests will likely be recommended to start narrowing down possibilities and eliminating conditions which are usually easily diagnosed using specific methods.

Recommended tests will include:

• Computerised tomography (CT scan): The use of X-rays and computer imaging technology can assist doctors with gaining a clear view of the inside of the body, especially the brain. A dye (contrast material) injected intravenously helps to highlight internal structures. A scanner will then be used to take a series of images. A scan can take between 15 and 60 minutes to complete.
• Magnetic resonance imaging (MRI scan): This scanner makes use of a large magnet, radio waves and computerised technology in order to produce highly detailed images (several dozen) of the body’s internal structures. Used to make a diagnosis, this scan is safe to use for testing (provided there are no other existing conditions or devices such as a heart pacemaker or cerebral aneurysm clip, which prohibit the use of this imaging test). If already being treated for Parkinson’s and using a brain stimulator, additional care will need to be taken beforehand. In most instances, an MRI scan can take between 45 and 60 minutes, or up to an hour and a half.
• Positron emission topography (PET scan): This will be used to assess how the body’s cells are functioning. A small amount of radioactive material (a tracer) is injected into a vein in the arm (intravenously) and sends out positively charged particles (positrons) which interact with negatively charged ones (electrons). An image is then produced using a doughnut-shaped scanner (moving in circles around the body), showing every angle of the body and its organs to assist the doctor in detecting possible abnormalities and problems. Of specific interest will be regions in the brain responsible for movement and the spinal cord (where Parkinson’s disease is concerned). The scanning process usually takes between 45 and 60 minutes.
• Other imaging tests: An ultrasound of the brain or SPECT scan (single-photon emission computerized tomography) using radioactive substances and a camera to analyse the function of certain bodily organs.
• Blood tests: These may be recommended according to specific symptoms as a means to potentially rule out other possible conditions.

As tricky as it may be, making an accurate diagnosis as early as possible can have a profound effect on the progression of the condition. Early intervention can be the most effective treatment in the long-term and potentially prevent (slow down) more advanced stages during a person’s lifetime. A primary care physician (general practitioner or GP) may refer a person to a neurologist if they suspect Parkinson’s disease following a thorough evaluation process (which can sometimes take multiple consultations). A specialist with more experience in diagnosing Parkinson’s disease can implement treatment quicker and more effectively, but it may take several follow-up appointments, tests and evaluations before a diagnosis is made.

A diagnosis of Parkinson’s disease is typically made if:

• Between two and three major symptoms of Parkinson’s disease are present
• Onset of these major symptoms began on one side of the body
• No secondary causes appear to have brought on the symptoms (such as medication side-effects or the effects of a stroke and other medical conditions)
• A short period of using levodopa medication (L-DOPA) shows improvement of symptoms