Plast Reconstr Surg. 2022 Aug 24. doi: 10.1097/PRS.0000000000009622. Online ahead of print.
BACKGROUND: Confirmatory methods such as nerve conduction studies (NCS) are often performed to support a clinical carpal tunnel syndrome diagnosis and to rule out other upper extremity pathologies. Ultrasonography (US) provides another diagnostic option, especially when NCS are discordant with history and physical examination. This study seeks to explore the correlation of US findings with clinical CTS diagnosis in patients with normal NCS.
METHODS: A database of 220 CTS patients was retrospectively analyzed to reveal 24 patients (28 hands) with clinically diagnosed CTS and normal NCS. Patient demographics and NCS and US findings were compared to those of a control group of non-CTS patients (42 patients, 52 hands). Median nerve cross-sectional area (CSA) was recorded, with values ≥ 10mm2 considered positive for CTS. Statistical and correlation analyses were performed between control and CTS groups comparing key parameters of interest.
RESULTS: Mean CSA was significantly increased in CTS patients with normal NCS than in controls. Similarly, the proportion of CTS positive, NCS negative patients with CSA measurements greater than 10mm2 was significantly greater than the proportion for control patients. Neither age nor BMI correlated with CSA measurements. NCS latencies and amplitudes did not correlate with ultrasound abnormalities.
CONCLUSIONS: Clinically diagnosed CTS patients with normal NCS were found to have clinically significant median nerve CSA on ultrasound (10.1 ± 2.1 mm2, p<0.001). Furthermore, CSA measurements on ultrasound do not correlate with NCS parameters. These results suggest that ultrasound holds a unique diagnostic utility in the evaluation of CTS, especially when NCS are negative.