The aim of the study was to evaluate the ultrasonographic (United States) alterations of the median nerve, the performance of the Kamath screening questionnaire and the clinical examination (Tinel and Phanel test) in patients with rheumatoid arthritis (RA) and psoriatic arthritis (PsA) with previous or present inflammatory involvement of the radio-ulno-carpal joint. A cross-sectional study was carried out. Patients with RA and PsA and clinical symptoms suggestive of CTS were consecutively recruited. The main clinical-demographic characteristics were collected in all patients. The Kamath questionnaire was administered to all patients during the clinic visit. The US examination was used as a 'gold-standard' for the diagnosis of CTS (transverse nerve area >12mm2 and morpho-structural alterations) and was used to assess the sensitivity and specificity of the Kamath questionnaire and the Tinel and Phanel clinical tests. 44 patients, 34 patients with RA and 10 patients with PsA were evaluated. 7 (16%) patients had a median nerve cross-sectional area >12mm2, associated with US abnormalities of the nerve. The Kamath questionnaire showed moderate sensitivity values (71.4%) but low specificity (56.7%) for ultrasonographic diagnosis of CTS with a negative predictive value of 91.3%. Clinical tests show low sensitivity but high specificity. No statistically significant correlations were found with the main clinical variables. The screening questionnaire showed moderate sensitivity but low specificity compared to the ultrasound 'gold standard'. Clinical tests may support the diagnosis of CTS in these conditions.
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