Ultrasonographic assessment of mild and moderate idiopathic carpal tunnel syndrome.

AIM: To investigate the diagnostic value of ultrasonography in mild and moderate idiopathic carpal tunnel syndrome (CTS).
MATERIALS AND METHODS: Cross-sectional areas (CSA), flattening ratios at three different levels, swelling ratio, and palmar displacement were analysed in 26 patients (14 with bilateral and 12 with unilateral disease, 40 wrists in total) for the presence and the severity of CTS. Twenty had normal nerve conduction studies (NCS) defined as "mild", and 20 of them had abnormal NCS defined as "moderate". The control group consisted of 20 healthy participants.
RESULTS: All parameters were significantly different between patient and control groups. Palmar displacement, swelling ratio, CSA at all levels and distal flattening ratio had the highest significance (p < 0.0001). The criterion with the highest sensitivity was the swelling ratio > or = 1.3 (72.5%), followed by the middle CSA > 9 mm2 and the palmar displacement > 2.5 mm. All of these criteria had a higher sensitivity in diagnosing moderate cases (85-100%) than diagnosing mild cases (30-55%). There was a significant difference between normal and mild CTS groups regarding palmar displacement, distal flattening ratio, middle CSA and swelling ratio (p < 0.0001 for all) and between normal and moderate groups regarding all parameters (p < 0.01 - 0.0001) When combined middle CSA, palmar displacement and swelling ratio had an overall discriminatory accuracy of 83.8%.
CONCLUSION: Additional diagnostic confirmation can be provided by ultrasonography and may be preferred as the initial step instead of electrophysiological studies. Detection of at least two of the three criteria (median nerve CSA > 9 mm2 at pisiform level, swelling ratio > or = 1.3, and palmar displacement > 2.5 mm) may be helpful for the verification of the diagnosis.