The investigation of the relationship of ultrasonographic median nerve crosssectional area with electrophysiological studies and disease activity in patients with rheumatoid arthritis

ABSTRACT THE INVESTIGATION OF THE RELATIONSHIP OF ULTRASONOGRAPHIC MEDIAN NERVE CROSS-SECTIONAL AREA WITH ELECTROPHYSIOLOGICAL STUDIES AND DISEASE ACTIVITY IN PATIENTS WITH RHEUMATOID ARTHRITIS Objectives: In this study, we aimed to investigate the relationship of median nerve cross-sectional area with electrophysiological studies and disease activity in rheumatoid arthritis patients. Material and Methods: Sixty rheumatoid arthritis (RA) patients diagnosed with carpal tunnel syndrome (CTS) by clinical and electrophysiological examinations, 60 RA patients without CTS and 46 idiopathic CTS control groups were included in the study. Age, gender, smoking and alcohol use, education level, presence of active wrist arthritis, BMI, disease duration, medications, RF, anti CCP, ESR and CRP values of the patients were recorded. Disease activity in patients with RA was evaluated with DAS-28. The Boston CTS questionnaire was used for the symptom severity and functional evaluation of the patients. Health Assessment Questionnaire (HAQ) was used to measure the health-related quality of life. Ultrasonographic median nerve cross-sectional area (MSCA) was measured at the level of the proximal carpal tunnel of all participants. The patients were evaluated electrophysiologically no later than one week after they were evaluated with USG. Results: The mean age, proportion of female gender, and BMI in the group with CTS+RA were significantly higher compared to the other two groups, whereas the education level and smoking rate were lower (p<0.001, p=0.010, p<0.001, p=0.023, p<0.001, respectively). There were no differences between the groups in terms of other sociodemographic data. While the RA medications used, RA disease duration, seropositivity rates, and DAS-28 scores were similar between the CTS+ and CTS− groups with RA, the median nerve cross-sectional area (10.33 vs. 7.66, p<0.001) and HAQ scores (0.69 vs. 0.25, p<0.001) were found to be significantly higher in RA patients with CTS. When the CTS groups were compared with each other, there was no difference between the groups in terms of CTS duration and HAQ scores. However, idiopathic CTS patients had significantly higher median nerve cross-sectional area (11.83 vs. 10.33, p=0.002), VAS score (7 vs. 4, p<0.001), Boston symptom severity score (2.9 vs. 2, p<0.001), and Boston functional status score (2.8 vs. 2.12, p=0.005) compared to CTS+RA patients. Regarding CTS provocation tests, there was no difference between the CTS groups in the Flick test; however, Tinel, Phalen, and Reverse Phalen tests were found to be significantly higher in the idiopathic CTS group compared to the RA+CTS group (p<0.001, p=0.002, p=0.002, respectively). In terms of electrophysiological findings, motor latency was longer in the idiopathic CTS group (4.21 vs. 3.58 ms, p<0.001), while motor amplitude and motor conduction velocities did not differ between the two groups. For sensory conduction findings, latency was longer (p=0.002) and velocity slower (p<0.001) in the idiopathic CTS group, whereas there was no significant difference in amplitude between the groups. Conclusion: The results of our study indicate that the median nerve cross-sectional area has weak diagnostic potential in CTS among patients with RA and is not correlated with disease activity. In these patients, the use of ultrasound (US) appears to be more appropriate for elucidating the pathophysiology and evaluating the anatomical structure of the region. Keywords: rheumatoid arthritis, carpal tunnel syndrome, ultrasonography, electromyography