New Diagnostic Test for Parkinson’s Disease available at Pacific Neuroscience Institute
by Melita Petrossian
In most cases, the diagnosis of Parkinson’s disease (PD) is clear based on clinical signs of rest tremor, bradykinesia (slowness or small size of movements), and rigidity. However, too frequently, aspects of the clinical symptoms and signs can be equivocal, and the diagnosis may be unclear. For example, if a person has arthritis or back pain, they may have slowness of fast finger movements and shuffling, even without a neurodegenerative cause for their symptoms.
Leading-edge diagnostic technology for Parkinson’s disease
Fortunately, your team at the Pacific Movement Disorders Center at Pacific Neuroscience Institute (PNI) has access to leading edge diagnostic technology to improve diagnostic accuracy when faced with a possible PD diagnosis. Specifically, we are performing a simple skin biopsy known as the Syn-One test to look for an abnormal form of the protein alpha-synuclein in the nerves of the skin. Alpha-synuclein is a protein whose 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.
Syn-One skin biopsy test
The skin biopsy is performed in three locations: in the skin over the upper back, lower thigh, and lower leg above the ankle. This is done under local anesthesia, meaning the skin is numbed, and the biopsy areas heal on their own without stitches and in the majority of cases without scarring. The biopsy specimens are then sent to a company in Arizona called CND Life Sciences which was founded by neurologists at Harvard Medical School. After three weeks, we receive a report which notifies us if any phosphorylated alpha-synuclein was found, as well as other information about peripheral nerve health.
5 conditions have abnormal alpha-synuclein
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:
- Parkinson’s disease (PD) – i.e., idiopathic PD, typical PD
- Dementia with Lewy bodies (DLB) – a.k.a. Lewy body dementia
- Multiple system atrophy (MSA)
- Pure autonomic failure
- REM sleep behavior disorder – considered a precursor to PD, DLB, or MSA
The Syn-One test can thus be useful in differentiating between tremor due to Parkinson’s disease vs 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 vs PD.
Syn-One can differentiate between conditions
Dementia with Lewy bodies is a form of cognitive decline (dementia) associated with Parkinson’s-like tremor, slowness, and/or gait issues, often with hallucinations or other behavioral changes. The Syn-One test can differentiate between DLB and other causes of dementia such as Alzheimer’s disease and vascular dementia. However, it cannot differentiate between PD and DLB, as both will show positive results on the Syn-One test.
Patients with dizziness upon standing due to blood pressure drops (orthostatic hypotension), constipation, abnormal sweatiness, and urinary dysfunction may be experiencing reduced function of the autonomic nervous system, meaning the nerves which control the visceral organs. Autonomic dysfunction can be seen in PD, multiple system atrophy, and pure autonomic failure (PAF). All three of these conditions will show a positive Syn-One test. However, the Syn-One test will be negative if the symptoms are caused by diabetic autonomic neuropathy, medications, or irritable bowel syndrome, among other causes.
Multiple system atrophy (MSA) is a neurodegenerative condition which is entirely unrelated to the similar sounding multiple sclerosis (MS). MSA can manifest as autonomic dysfunction with ataxia (problems with coordination, stumbling, slurred speech) and/or with atypical parkinsonism (slowness, stiffness, tremor, and/or shuffling gait which does not respond to treatment). The Syn-One test can be useful to differentiate between MSA and other causes of ataxia such as spinocerebellar ataxia. It can also differentiate between MSA and other causes of atypical parkinsonism such as progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS).
Diagnosing Parkinson’s disease accurately
Ensuring accurate diagnoses can be especially challenging when patients are in early stages of their conditions. Early accurate diagnosis is key for the development of preventative treatment options to slow progression of PD, DLB, and MSA. In addition, symptomatic treatment options will differ based on the diagnosis, and patients deserve an answer as soon as possible when facing these potential diagnoses. 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 use of the Syn-One test as well as the DaTSCAN (a brain SPECT assessing dopamine transporter levels in the brain) are just two of the ways that our work at PNI is helping improve the quality of life of our patients and our community.
Pacific Movement Disorders Center | 310-582-7433
About the Author
Melita Petrossian, MD, is Director of Pacific Movement Disorders Center and is a fellowship-trained neurologist with clinical interests and expertise in movement disorders such as Parkinson’s disease, essential tremor, dystonia, gait disorders, ataxia, myoclonus, blepharospasm, hemifacial spasm, Meige syndrome, spasticity, tics, and Tourette’s syndrome. She also specializes in Parkinson’s-related conditions such as Dementia with Lewy Bodies, progressive supranuclear palsy, multiple system atrophy, corticobasal degeneration, primary freezing of gait, and Parkinson’s disease dementia.
Last updated: February 19th, 2021