Ultrasonography is a noninvasive, inexpensive technique for evaluating the salivary glands in patients with suspected Sjögren's syndrome, according to a recent study.
Other methods of assessing salivary gland involvement—sialography, for one, or scintigraphy of the salivary glands– are invasive and have low specificity, respectively, wrote the researchers.
Dr. Dirk Wernicke of the Clinic for Rheumatology Berlin-Buch, Berlin, and colleagues looked at 316 consecutive patients with rheumatic diseases. Overall, 57 had primary Sjögren's syndrome (SS); 33 had secondary SS due to the presence of other inflammatory diseases; 78 had sicca syndrome involving symptoms of dry mouth and eyes in the absence of other evidence of SS; and 148 were asymptomatic controls who had other inflammatory conditions, including rheumatoid arthritis, lupus, or undifferentiated connective tissue disease. In all groups, the majority was female, and the mean ages were 51, 53, 48, and 45, respectively (J. Rheumatol. 2008 Jan. 15 [Epub ahead of print]).
“In comparison with asymptomatic controls, the mean volume of the submandibular glands in the women with primary and secondary SS was reduced by 33% and 40%, respectively” on ultrasound, wrote the authors, from 4.8 mL in the controls to 3.2 mL and 2.9 mL in primary and secondary SS patients, respectively. There was also a significant difference in men with primary SS—the mean volume was reduced by 28%, compared with controls—but, likely due to the small number of men in the cohort, no significance was seen between controls and secondary SS.
The researchers also looked at parenchymal inhomogenicity. In this study, a diagnosis of SS was made when “at least two major salivary glands showed evident grade II parenchymal inhomogenicity,” wrote the researchers. In an interview, Dr. Wernicke said grade II parenchymal inhomogenicity refers to “diffuse hypoechoic areolae larger than 2 mm.” (Grade 0 is normal homogenous parenchyma, and grade I mild parenchymal inhomogenicity is seen on ultrasound as diffuse hypoechoic areolae smaller than 2 mm.) This yielded a specificity of 96.1% in sicca symptom patients and 100% in the asymptomatic controls. “SS was diagnosed in our cohort with a sensitivity of 63%” (in both primary and secondary groups), they added.
“The use of imaging techniques is very different in [various] countries,” said Dr. Wernicke. In the U.S., he said, it is “so far, not widely used by rheumatologists. The experience is good in Germany and Italy, less in the U.K. and in North America.” He believes ultrasound should be included in the diagnostic criteria of the disease.
Dr. Wernicke and his associates disclosed no conflicts of interest.