Arch Hand Microsurg.  2020 Mar;25(1):8-16. 10.12790/ahm.19.0062.

Analysis of Sonographic Measurement by Anatomical Area in Carpal Tunnel Syndrome and Correlation the Measurement with Electrodiagnostic Study

• Park J

• KMID: 2501102
• DOI: http://doi.org/10.12790/ahm.19.0062

Abstract

Purpose
To evaluate effectiveness of ultrasonographic measurement of carpal tunnel by anatomical area and correlation with electrodiagnostic study in diagnosis of carpal tunnel syndrome.
Methods
From September 2018 to March 2019, we performed the ultrasonography for 30 cases with carpal tunnel syndrome diagnosed with electrodiagnosis and 30 cases as control group. We measured median nerve diameter, cross-sectional area (CSA), and flattening ratio (FR) by area of carpal tunnel. We analyzed the difference of measurement between two groups and correlate the measurement with electrodiagnosis findings.
Results
There was significant statistically differences in sonographic measurement between two groups by independent t-test (CSA zone 1, p=0.01; FR zone 2, p=0.000; FR zone 3; p=0.001). With Pearson correlation test, there was correlation between sonographic measurement and electrodiagnostic findings (terminal latency and nerve conduction velocity) statistically, but the Pearson coefficient was low (r<0.4).
Conclusion
By anatomical area, the available value of sonographic measurement was different. But, as the values were has low power to diagnose the carpal tunnel syndrome, ultrasonography is proper to use as a complementary tool in diagnosis of carpal tunnel syndrome.

Keyword

Carpal tunnel syndrome; Ultrasonography; Electrodiagnosis

Figure

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  Fig. 1. Demonstration of zone of carpal tunnel. Zone 1 is proximal area to true carpal tunnel. Zone 2 is proximal carpal tunnel between scaphoid distal pole (S) and pisiform (P). Zone 3 is distal carpal tunnel between hamate (H) and trapezium (T).

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  Fig. 2. The measurement of median nerve. D1 and D2 are horizontal and vertical diameter of median nerve. C is circumference and A is cross-sectional area.

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  Fig. 3. There was significant statistical difference between two groups in cross-sectional area of Zone 1 (A), flattening ratio of Zone 2 (B) and Zone 3 (C).

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  Fig. 4. Receiver operating characteristic (ROC) curve of cross-sectional area of Zone 1 (Z1A) and flattening ratio of Zone 2, Zone 3 (Flattening R(Z2), Flattening R(Z3)). Each area under the curve (AUC) was 0.69, 0.75, and 0.75.

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  Fig. 5. There was statistical difference between ultrasonography measurement and electrodiagnostic study. But they had low coefficient of correlation and ultrasonography measurement could not represent electrodiagnostic severity. (A) Pearson correlation test between CSA of Zone 1 and EDS (terminal latency [TL], nerve conduction velocity [NCV]). (B) Pearson correlation test between cross-sectional area ratio and TL.

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  Fig. 6. Swelling of median nerve proximal to the carpal tunnel (arrow demonstrate the compression of median nerve and the right side of figure is proximal area). So-called by "notching sign". Generally, the median nerve in carpal tunnel syndrome is thickened, especially in proximal entrance of carpal tunnel.

Reference

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