Exploring Use Of Ultrasonography (Us) To Distinguish Symptom Dominance For Patients With Carpal Tunnel Syndrome (Cts) And Implications For Different Neuroplastic Pattern Secondary To CTS
Xue Deng, PhD Candidate (HK), MscOT(US), BscOT(HK) 1; Lai-Heung Chau, B.Sc.Nursing(HK) 2; Suk-Yee Chiu, B.Sc.Nursing(HK) 2; Kwok-Pui Leung, MBChB (HK) 2, Sheung-Wai Li, MBBS (NSW) 2; Josephine Wing-Yuk Ip, MBBS(HK)1
1The University of Hong Kong, Pokfulam Road, Hong Kong; 2Tung Wah Hospital, Sheung Wan, Hong Kong
Introduction: Ultrasonography (US) is validated as an alternative tool for Nerve Conduction Studies(NCS), a prevalent standard approach to confirm the diagnosis and grade the severity of carpal tunnel syndrome (CTS). However, NCS is constraint in associating with CTS symptomatology, correlating more with paresthesia-dominant CTS. Recently, a study (Maeda et al., 2016) consisting of 59 women diagnosed with CTS (48.9 ± 9.6 years) indicated significant sensory velocity difference (t(46)=1.99, p=0.05) of ipsilateral median-ulnar nerves between pain-dominant (-19.5 ~ -9 m/s) and paresthesia-dominant (-26.7 ~ -11.9 m/s) groups. It is unknown if US can be alternatively used to differentiate CTS symptom dominance, with validated cut-off values for differentiating CTS symptom dominance.
Methods: Subjects with both NCS and US recordings admitted from Jan 2014 to June 2017 were reviewed in a demographics-matched manner. The range of ipsilateral median-ulnar sensory velocity differences were redefined to guarantee the enrolled hands were within absolute range of corresponding symptom dominance (Absolute pain-dominant group: -11.9 ~ -9 m/s; absolute paresthesia-dominant group: -26.7 ~ -19.5m/s). Independent t-tests were performed to examine differences of cross-sectional area (CSA) and perimeter(P) at the wrist (CSA-W and P-W, respectively) and mid-forearm (CSA-MF and P-MF respectively) of median nerve measured by US. The ratio of CSA (R-CSA) and perimeter (R-P) was calcuated according to standard format, followed by independent t-test performed. (Format: R-CSA=CSA-W/CSA-MF; R-P=P-W/P-MF).
Results: 56 out of 252 reviewed cases (59.4 ± 11.4 years) with 68 eligible hands were enrolled. There was a significant difference in CSA-W (t=-2.141, p=.037, p<0.05) between pain-dominant (N1=39, CSA-W= 10.69 ± 2.72 mm2) and paresthesia-dominant group (N2=29, CSA-W=12.24 ± 3.11 mm2). P-W, R-CSA and R-P were descriptively different (Pain-dominant group (N1=37 for P-W & R-P while N1=39 for R-CSA): P-W= 15.55±2.63 mm, R-P=1.57±0.34, R-CSA=2.04±0.59; Paresthesia-dominant group: N2=29, P-W=16.46±2.0 mm, R-P=1.62±.34, R-CSA=2.28±0.94) while no significant difference in CSA-MF (t=-.87, p=.39, p>0.05) and P-MF (t=-.93, p=.36, p>0.05) between groups.
Conclusions: The overall results may suggest a potential role of US in dissociating symptom dominance for CTS subjects. A more robust result with statistical significance in P-W, R-CSA and R-P would be promising with more cases recruited. Further study might prospectively examine the hypothesis with the cut-off values validated and explore the association with neuroplastic changing pattern regarding different symptom dominance.
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