Parkinson's disease can be difficult to diagnose. Previously and typically the most common tool utilized to confirm a Parkinson's diagnosis has been a DaTSCAN (a brain SPECT assessing dopamine transporter levels in the brain) which is used to help measure dopamine levels that can lead to a PD diagnosis. However, in most cases, the diagnosis of PD becomes clear on clinical signs and symptoms of tremor, bradykinesia (slowness or small size movements,) and rigidity.
But at times, this can be confused for other conditions. For example, if a person has arthritis or back pain, they may have slowness or fast finger movements and shuffling, even without a neurodegenerative cause for their symptoms.
Fortunately, a new leading edge diagnostic technology has been developed to improve diagnostic accuracy for PD. By performing a simple skin biopsy known as the Syn-One test, physicians and diagnostic teams can now look for an abnormal form of the protein alpha-synuclein in the nerves of the skin. Alpha-synuclein is a protein who's abnormal (toxic) form causes clumping in the nerve cells, eventually causing the brain cells that create dopamine to start dying off, resulting in the symptoms of PD. This abnormal form of alpha-synuclein is known as phosphorylated alpha-synuclein.
The skin biopsy is typically performed in three locations: in the skin over the upper back, lower thigh, and lower leg above the ankle. This procedure is done under local anesthesia, meaning the skin is numbed, and the biopsy areas heal on their own without stitches. The biopsy specimens are then sent to a laboratory for review and confirmation for the presence of phosphorylated alpha-synuclein presence. After three weeks, a report is sent back notifying clinicians if any phosphorylated alpha-synuclein was found, as well as other information about peripheral nerve health.
The accuracy of the Syn-One test for detecting phosphorylated alpha-synuclein is 95-99% accurate, ensuring confidence in the results of the test and the diagnosis. However, there are five conditions that carry this abnormal alpha-synuclein, known as the synucleinopathies. Thus, if the Syn-One test is positive, the laboratory report will say there is evidence of synucleinopathy. It falls to the clinician to differentiate between the synucleinopathies based on clinical information.
The synucleinopathies (conditions that will test positive with the Syn-One test) are:
Dementia with Lewy Bodies
Multiple System Atrophy (MSA)
Pure autonomic failure
REM sleep behavior disorder
The Syn-One test can thus be useful in differentiating between tremor due to Parkinson's disease versus other causes of tremor (most commonly essential tremor or medication-related). It can also help in cases of slowing and stiffness to differentiate between normal aging or arthritis versus PD. The test can also be used to rule out any symptoms that may be caused by diabetic autonomic neuropathy, medications, or irritable bowel syndrome, among other causes.
Ensuring accurate diagnosis can be especially challenging when patients are in the early stages of their PD condition. Early accurate diagnosis is key for the development of preventative treatment options to slow progression. In addition, symptomatic treatment options will differ based on the diagnosis, and patients deserve an answer as soon as possible when facing a potential PD diagnosis. Patients who have an obvious or well-established diagnosis do not need further testing, but for those whose diagnosis is unclear, the use of the Syn-One test can be extremely useful.
Advances such as the Syn-One test as well as the DaTSCAN are just two of the ways that Parkinson's can be diagnosed. If you are seeking a Parkinson's diagnosis, ask your neurologist or movement disorder specialist if the Syn-One test may be an accurate option for you.
Source: Melita Petrossian, Pacific Movement Disorders Center. New Diagnostic Test for Parkinson's Disease available at Pacific Neuroscience Institute. Accessed 9/16/2022.