A Novel Ultrasonographic Anthropometric-Independent Measurement of Median Nerve Swelling in Carpal Tunnel Syndrome: The "Nerve/Tendon Ratio" (NTR)

Paolo Falsetti, Edoardo Conticini, Caterina Baldi, Emilio D'Ignazio, Suhel Gabriele Al Khayyat, Marco Bardelli, Stefano Gentileschi, Roberto D'Alessandro, Miriana D'Alessandro, Caterina Acciai, Federica Ginanneschi, Luca Cantarini, Bruno Frediani, Paolo Falsetti, Edoardo Conticini, Caterina Baldi, Emilio D'Ignazio, Suhel Gabriele Al Khayyat, Marco Bardelli, Stefano Gentileschi, Roberto D'Alessandro, Miriana D'Alessandro, Caterina Acciai, Federica Ginanneschi, Luca Cantarini, Bruno Frediani

Abstract

Background: There is little consensus on ultrasound (US) normative values of cross-sectional area of median nerve (MN-CSA) in carpal tunnel syndrome (CTS) because of its dependency on anthropometric parameters. We aim to propose a novel anthropometric-independent US parameter: MN-CSA/flexor radialis carpi CSA (FCR-CSA) ratio (“Nerve Tendon Ratio”, NTR), in the diagnosis of clinically and electrodiagnostic (EDS)-defined CTS. Methods: 74 wrists of 49 patients with clinically defined CTS underwent EDS (scored by the 1−5 Padua Scale of electrophysiological severity, PS) and US of carpal tunnel with measurement of MN-CSA (at the carpal tunnel inlet), FCR-CSA (over scaphoid tubercle) and its ratio (NTR, expressed as a percentage). US normality values and intra-operator agreement were assessed in 33 healthy volunteers. Results: In controls, the mean MN-CSA was 5.81 mm2, NTR 64.2%. In 74 clinical CTS, the mean MN-CSA was 12.1 mm2, NTR 117%. In severe CTS (PS > 3), the mean MN-CSA was 15.9 mm2, NTR 148%. In CTS, both MN-CSA and NTR correlated with sensitive conduction velocity (SCV) (p < 0.001), distal motor latency (DML) (p < 0.001) and PS (p < 0.001), with a slight superiority of NTR vs. MN-CSA when controlled for height, wrist circumference and weight. In CTS filtered for anthropometric extremes, only NTR maintained a correlation with SCV (p = 0.023), DML (p = 0.016) and PS (p = 0.009). Diagnostic cut-offs were obtained with a binomial regression analysis. In those patients with a clinical diagnosis of CTS, the cut-off of MN-CSA (AUROC: 0.983) was 8 mm2 (9 mm2 with highest positive predictive value, PPV), while for NTR (AUROC: 0.987), the cut-off was 83% (100% with highest PPV). In patients with EDS findings of severe CTS (PS > 3), the MN-CSA (AUROC: 0.876) cut-off was 12.3 mm2 (15.3 mm2 with highest PPV), while for NTR (AUROC: 0.858) it was 116.2% (146.0% with highest PPV). Conclusions: NTR can be simply and quickly calculated, and it can be used in anthropometric extremes.

Keywords: carpal tunnel syndrome; electrodiagnostics; median nerve; neuropathy; ultrasound.

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Transverse scan over left carpal tunnel of a tall male, asymptomatic for CTS in left hand (180 cm × 85 kg, 19 cm of wrist circumference). Linear 6–18 MHz probe. The MN-CSA (area 1) results of 11 mm2 are suggestive of pathologic swelling, but EDS was normal (PS = 0, performed as control side, for CTS in the right side). The flexor carpi radialis (FCR) shows a CSA (area 2) of 14 mm2. MN = median nerve, FPL = flexor pollicis longus, * = transverse ligament, FDS = flexor digitorum superficialis.
Figure 2
Figure 2
Transverse scan over left and right carpal tunnels in male patient (172 cm × 82 kg, 18.5 cm of wrist circumference) affected with extremely severe CTS (Padua Scale 5 bilaterally). Linear 4–15 MHz probe. Both MN-CSA show frankly pathologic values (Area 1, left: 17 mm2, Area 3, right: 14 mm2). NTR is calculated as the ratio between MN-CSA and FCR-CSA (expressed as a percentage), and shows bilaterally pathologic values (left 143%, right 119%) indicative for severe CTS. MN = median nerve, FCR = flexor carpi radialis.
Figure 3
Figure 3
ROC curves obtained comparing each US parameter (MN-CSA and NTR) in the clinical diagnosis of CTS (as gold standard).
Figure 4
Figure 4
ROC curves obtained comparing each US parameter (MN-CSA and NTR) in severe EDS-defined (PS > 3) diagnosis of CTS (as gold standard).
Figure 5
Figure 5
Transverse scan over right carpal tunnel in a small female patient (150 cm × 50 kg, 13.7 cm of wrist circumference) affected with medium-grade CTS (Padua Scale 3, SCV 37.1 m/sec, DML 4.8 ms). Linear 8–24 MHz probe. Both areas of median nerve (MN) and flexor carpi radialis (FCR) were manually traced. A MN-CSA of 12 mm2 is not always considered pathologic (cut-off for MN neuropathy until 14–15 mm2 in some studies on CTS) and the severity is often underestimated because of the anthropometric characteristics of the patient. The NTR shows values unequivocally pathologic (124%), as MN-CSA is compared with an anatomic structure (FCR-CSA) that maintains small dimensions in CTS, following the anthropometric characteristics of the patient.

References

    1. Pelosi L., Arányi Z., Beekman R., Bland J., Coraci D., Hobson-Webb L.D., Padua L., Podnar S., Simon N., van Alfen N., et al. Expert consensus on the combined investigation of carpal tunnel syndrome with electrodiagnostic tests and neuromuscular ultrasound. Clin. Neurophysiol. 2022;135:107–116. doi: 10.1016/j.clinph.2021.12.012.
    1. Yoshii Y., Zhao C., Amadio P.C. Recent Advances in Ultrasound Diagnosis of Carpal Tunnel Syndrome. Diagnostics. 2020;10:596. doi: 10.3390/diagnostics10080596.
    1. Steimle J., Gabriel S., Tarr R., Kohrs B., Johnston P., Martineau D. Comparing Diagnostic and Treatment Recommendations of Carpal Tunnel Syndrome Available on the Internet With AAOS Clinical Practice Guidelines. Hand. 2020;15:514–520. doi: 10.1177/1558944718821417.
    1. Erickson M., Lawrence M., Lucado A. The role of diagnostic ultrasound in the examination of carpal tunnel syndrome: An update and systematic review. J. Hand Ther. 2022;35:215–225. doi: 10.1016/j.jht.2021.04.014.
    1. Beekman R., Visser L.H. Sonography in the diagnosis of carpal tunnel syndrome: A critical review of the literature. Muscle Nerve. 2003;27:26–33. doi: 10.1002/mus.10227.
    1. Mondelli M., Filippou G., Gallo A., Frediani B. Diagnostic utility of ultrasonography versus nerve conduction studies in mild carpal tunnel syndrome. Arthritis Rheum. 2008;59:357–366. doi: 10.1002/art.23317.
    1. Moon H.I., Kwon H.K., Lee A., Lee S.K., Pyun S.B. Sonography of Carpal Tunnel Syndrome According to Pathophysiologic Type: Conduction Block Versus Axonal Degeneration. J. Ultrasound Med. 2017;36:993–998. doi: 10.7863/ultra.16.05019.
    1. Tai T.W., Wu C.Y., Su F.C., Chern T.C., Jou I.M. Ultrasonography for diagnosing carpal tunnel syndrome: A meta-analysis of diagnostic test accuracy. Ultrasound Med. Biol. 2012;38:1121–1128. doi: 10.1016/j.ultrasmedbio.2012.02.026.
    1. Buchberger W., Judmaier W., Birbamer G., Lener M., Schmidauer C. Carpal tunnel syndrome: Diagnosis with high-resolution sonography. AJR Am. J. Roentgenol. 1992;159:793–798. doi: 10.2214/ajr.159.4.1529845.
    1. Billakota S., Hobson-Webb L.D. Standard median nerve ultrasound in carpal tunnel syndrome: A retrospective review of 1,021 cases. Clin. Neurophysiol. Pract. 2017;2:188–191. doi: 10.1016/j.cnp.2017.07.004. Published 15 September 2017.
    1. De Kleermaeker F.G.C.M., Meulstee J., Verhagen W.I.M. The controversy of the normal values of ultrasonography in carpal tunnel syndrome: Diagnostic accuracy of wrist-dependent CSA revisited. Neurol. Sci. 2019;40:1041–1047. doi: 10.1007/s10072-019-03756-z.
    1. Won S.J., Kim B.J., Park K.S., Yoon J.S., Choi H. Reference values for nerve ultrasonography in the upper extremity. Muscle Nerve. 2013;47:864–871. doi: 10.1002/mus.23691.
    1. Bathala L., Kumar P., Kumar K., Shaik A., Visser L.H. Normal values of median nerve cross-sectional area obtained by ultrasound along its course in the arm with electrophysiological correlations, in 100 Asian subjects. Muscle Nerve. 2014;49:284–286. doi: 10.1002/mus.23912.
    1. Fowler J.R., Gaughan J.P., Ilyas A.M. The sensitivity and specificity of ultrasound for the diagnosis of carpal tunnel syndrome: A meta-analysis. Clin. Orthop. Relat. Res. 2011;469:1089–1094. doi: 10.1007/s11999-010-1637-5.
    1. Torres-Costoso A., Martínez-Vizcaíno V., Álvarez-Bueno C., Ferri-Morales A., Cavero-Redondo I. Accuracy of Ultrasonography for the Diagnosis of Carpal Tunnel Syndrome: A Systematic Review and Meta-Analysis. Arch. Phys. Med. Rehabil. 2018;99 doi: 10.1016/j.apmr.2017.08.489.
    1. Fowler J.R., Byrne K., Pan T., Goitz R.J. False-Positive Rates for Nerve Conduction Studies and Ultrasound in Patients Without Clinical Signs and Symptoms of Carpal Tunnel Syndrome. J. Hand Surg. Am. 2019;44:181–185. doi: 10.1016/j.jhsa.2018.11.010.
    1. Olde Dubbelink T.B.G., De Kleermaeker F.G.C.M., Meulstee J., Bartels R.H.M.A., Claes F., Verhagen W.I.M. Augmented Diagnostic Accuracy of Ultrasonography for Diagnosing Carpal Tunnel Syndrome Using an Optimised Wrist Circumference-Dependent Cross-Sectional Area Equation. Front. Neurol. 2020;11:577052. doi: 10.3389/fneur.2020.577052.
    1. Olde Dubbelink T.B., De Kleermaeker F.G., Beekman R., Wijntjes J., Bartels R.H., Meulstee J., Verhagen W.I. Wrist Circumference-Dependent Upper Limit of Normal for the Cross-Sectional Area Is Superior Over a Fixed Cut-Off Value in Confirming the Clinical Diagnosis of Carpal Tunnel Syndrome. Front. Neurol. 2021;12:625565. doi: 10.3389/fneur.2021.625565.
    1. Hobson-Webb L.D., Massey J.M., Juel V.C., Sanders D.B. The ultrasonographic wrist-to-forearm median nerve area ratio in carpal tunnel syndrome. Clin. Neurophysiol. 2008;119:1353–1357. doi: 10.1016/j.clinph.2008.01.101.
    1. Practice parameter for carpal tunnel syndrome (summary statement). Report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology. 1993;43:2406–2409. doi: 10.1212/WNL.43.11.2406.
    1. Rempel D., Evanoff B., Amadio P.C., de Krom M., Franklin G., Franzblau A., Gray R., Gerr F., Hagberg M., Hales T., et al. Consensus criteria for the classification of carpal tunnel syndrome in epidemiologic studies. Am. J. Public Health. 1998;88:1447–1451. doi: 10.2105/AJPH.88.10.1447.
    1. American Association of Electrodiagnostic Medicine. American Academy of Neurology. American Academy of Physical Medicine and Rehabilitation Practice parameter for electrodiagnostic studies in carpal tunnel syndrome: Summary statement. Muscle Nerve. 2002;25:918–922. doi: 10.1002/mus.10185.
    1. Ginanneschi F., Dominici F., Milani P., Biasella A., Rossi A. Evidence of altered motor axon properties of the ulnar nerve in carpal tunnel syndrome. Clin. Neurophysiol. 2007;118:1569–1576. doi: 10.1016/j.clinph.2007.03.024.
    1. Padua L., LoMonaco M., Gregori B., Valente E.M., Padua R., Tonali P. Neurophysiological classification and sensitivity in 500 carpal tunnel syndrome hands. Acta Neurol. Scand. 1997;96:211–217. doi: 10.1111/j.1600-0404.1997.tb00271.x.
    1. Falsetti P., Conticini E., Gaggiano C., Baldi C., Tarsia M., Bardelli M., Frediani B. Doppler and Spectral Ultrasound of Sacroiliac Joints in Pediatric Patients with Suspected Juvenile Spondyloarthritis. Diagnostics. 2022;12:992. doi: 10.3390/diagnostics12040992.
    1. Fu T., Cao M., Liu F., Zhu J., Ye D., Feng X., Bai Y. Carpal tunnel syndrome assessment with ultrasonography: Value of inlet-to-outlet median nerve area ratio in patients versus healthy volunteers. PLoS ONE. 2015;10:e0116777. doi: 10.1371/journal.pone.0116777.
    1. Tagliafico A.S. Peripheral nerve imaging: Not only cross-sectional area. World J. Radiol. 2016;8:726–728. doi: 10.4329/wjr.v8.i8.726.
    1. Gonzalez-Suarez C.B., Fidel B.C., Cabrera JT C., Dela Cruz F.C., Gesmundo MV T., Regala CF G., Grimmer K. Diagnostic Accuracy of Ultrasound Parameters in Carpal Tunnel Syndrome: Additional Criteria for Diagnosis. J. Ultrasound Med. 2019;38:3043–3052. doi: 10.1002/jum.15012.
    1. Yoshii Y., Villarraga H.R., Henderson J., Zhao C., An K.N., Amadio P.C. Ultrasound assessment of the displacement and deformation of the median nerve in the human carpal tunnel with active finger motion. J. Bone Jt. Surg. Am. 2009;91:2922–2930. doi: 10.2106/JBJS.H.01653.
    1. Wee T.C., Simon N.G. Ultrasound elastography for the evaluation of peripheral nerves: A systematic review. Muscle Nerve. 2019;60:501–512. doi: 10.1002/mus.26624.
    1. Lin C.P., Chen I.J., Chang K.V., Wu W.T., Özçakar L. Utility of Ultrasound Elastography in Evaluation of Carpal Tunnel Syndrome: A Systematic Review and Meta-analysis. Ultrasound Med. Biol. 2019;45:2855–2865. doi: 10.1016/j.ultrasmedbio.2019.07.409.
    1. Charles S., Oommen K., Ong J., Fowler J.R. Use of Ultrasound in Patients With Carpal Tunnel Syndrome: A Cost-Effective Solution to Reduce Delays in Surgical Care. J. Hand Surg. Am. 2021;47 doi: 10.1016/j.jhsa.2021.08.008.

Source: PubMed

Sponsoren und Mitarbeiter

Krankheiten

Drogeninterventionen

3
Abonnieren