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Salivary Gland Biopsy Shows Promise to Helping to Diagnose Parkinsonís
- Mar 20 2014
A simple outpatient procedure that involves obtaining a tissue sample may help diagnose Parkinson’s disease (PD) in the future, according to a new study in the journal Neurology. Using the technique, researchers diagnosed the disease correctly in a small group of people with PD about 75 percent of the time.
Currently, there is no objective biological test (such as a blood test) to diagnose PD. Instead, doctors diagnose the disease clinically by observing people’s symptoms. The accuracy of such a diagnosis depends on the training of the diagnosing physician (better if diagnosed by a trained neurologist than an internist) and the duration of the clinical follow up when the diagnosis is made (the longer, the more accurate).
The only way to definitively identify Parkinson’s is to demonstrate the presence of Lewy bodies, abnormal clumps of alpha-synuclein protein, in the brains of people with PD at autopsy. But autopsies have also shown that people with advanced PD have Lewy bodies in other areas of the body, for example, in the nerve cells of a salivary gland below the floor of the mouth, called the submandibular gland.
Researcher Charles Adler, M.D., Ph.D., at the Mayo Clinic in Scottsdale, AZ, and his colleagues wondered whether people living with PD also have Lewy bodies in their submandibular glands, and if doctors could perhaps diagnose the disease by testing tissue from the gland. He and his team performed a procedure called a needle core biopsy of the submandibular glands in 15 people who had PD for five or more years. The researchers numbed an area on the neck (just under the lower jaw) with local anesthetic, and then removed small pieces of salivary gland tissue through a hollow needle inserted into the skin. They examined the tissue sections with a microscope for signs of Lewy bodies.
- Twelve biopsies (12 out of 15) included tissue from the submandibular gland.
- 75 percent (nine out of 12) of the biopsies from the submandibular gland had Lewy bodies, consistent with PD.
- Side effects of the procedure were minimal. Five people reported a swollen cheek, sore throat, excess fluid at the biopsy site, swelling under the chin, or slight bleeding/swelling/bruising under the jaw.
What Does It Mean?
This small pilot study suggests that a needle core biopsy of the submandibular gland may one day help to definitively diagnose PD in living people. The noninvasive technique confirmed the diagnosis of PD based on clinical symptoms 75 percent of the time (when a submandibular tissue was indeed sampled), with minimal side effects.
The ability to diagnose Parkinson’s with a test that goes beyond clinical observation would be a significant achievement in the fight against PD. It could improve diagnosis and clinical care, and advance research.
For example, before a person decides to undergo an invasive treatment such as deep brain stimulation, a biopsy could confirm that they actually have PD and could therefore benefit from the procedure. Also, the test could help to ensure that people who don’t actually have PD, would not be selected for PD clinical studies since they could skew results.
This study has several limitations. First, only people who had PD for five or more years were included. At that stage, the physician’s clinical diagnosis is often correct. Future study should focus on people with shorter disease duration to see whether this test may help establish a diagnosis of PD early, or maybe even identify people at risk for PD. Second, this study did not include healthy control subjects or people with PD-like diseases for comparison to the people with clinically diagnosed PD, but this data was available from a previous study. And finally, as a pilot study, only 15 people with PD were included.
Now that the researchers have obtained some promising results in this small group, they can expand their study to include controls, people with PD-like diseases, and larger numbers of people with early and advanced PD. Hopefully, pushing the needle further in our efforts to diagnose and cure Parkinson’s.
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Reference: Submandibular gland needle biopsy for the diagnosis of Parkinson disease. Charles H. Adler, Brittany N. Dugger, Michael L. Hinni, et al. Neurology published online February 5, 2014. DOI 10.1212/WNL.0000000000000204 http://dx.doi.org/10.1212/WNL.0000000000000204
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Source Date: Mar 20 2014