Research Article| Volume 35, ISSUE 2, P215-225, April 2022

Download started.


The role of diagnostic ultrasound in the examination of carpal tunnel syndrome: an update and systematic review

Published:April 14, 2021DOI:


      • Intra- and interrater reliability and known-group validity of cross-sectional area (CSA) measurements of the median nerve taken at the carpal tunnel inlet are consistently well-supported in the literature.
      • There is conflicting evidence on the concurrent validity of measures of median nerve CSA taken at the carpal tunnel inlet when electrodiagnostic studies are used as the reference standard.
      • The findings of this scoping review indicate a 3.1%-37% false negative rate and a 0-32.1% false positive rate when diagnosing carpal tunnel syndrome, using inlet CSA cutoff values between 8.5 mm2 to 12.6 mm2.
      • In comparing data on inlet and outlet CSA measurements, there is more evidence to support the use of measuring CSA at the carpal tunnel inlet. The diagnostic utility values including sensitivity, specificity, and positive and negative likelihood ratios were consistently less for outlet CSA when compared to inlet CSA.
      • There is conflicting evidence on known-group validity of the flattening ratio when measured at the level of the hamate.



      Diagnostic ultrasound is becoming more available and has potential for identifying carpal tunnel syndrome (CTS), but there is a lack of consensus on optimal measurement parameters and interpretation.


      The purpose of this systematic review was to analyze and summarize recent published data evaluating measurement properties of diagnostic ultrasound for use in individuals with CTS.


      Five databases were searched to identify studies reporting on diagnostic measurement in individuals ≥18 years of age. Thirty-four studies underwent critical appraisal using Center for Evidence Based Medicine guidelines for diagnostic study accuracy. Each team member independently reviewed and scored the studies and consensus was reached through discussion.


      Seventeen studies evaluating 21 unique nerve or tunnel measurements and 9 measurement ratios were included. Measurements of median nerve cross sectional area (CSA) taken at the carpal tunnel inlet consistently demonstrated good to excellent interrater reliability (ICC=0.83-0.93) and good intrarater reliability (r>0.81). All studies supported inlet CSA in differentiating between individuals with and without CTS. Carpal tunnel inlet CSA measurements demonstrated a moderate correlation to the Padua severity classification (r = 0.71), but this varied between studies. Diagnostic accuracy of CSA measured at the carpal tunnel inlet using diagnostic cutoff values ranging from 8.5 mm2 to 12.6 mm2 resulted in a range sensitivity (63%-96.9%) and specificity (67.9%-100%).


      The US measurement most supported was the median nerve CSA measured at the carpal tunnel inlet. There was no evidence supporting the routine use of diagnostic US for individuals with suspected CTS, and no additional evidence to support replacement of electrodiagnostic studies by US. More research is needed to determine use of US for classifying CTS severity or as a differential diagnostic tool for conditions that mimic CTS.

      Level of Evidence



      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to Journal of Hand Therapy
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Dale A.
        • Harris-Adamson C.
        • Rempel D.
        Prevalence and incidence of carpal tunnel syndrome in US working populations: pooled analysis of six prospective studies.
        Scand J Work Environ Health. 2013; 39: 495-505
        • Goldberg G.J.M.Z.
        • Mummaneni R.
        • Tucker J.D.
        Electrosonodiagnosis in carpal tunnel syndrome: a proposed diagnostic algorithm based on an analytic literature review.
        Phys Med Rehabil. 2016; 8: 463-475
        • Drakopoulos D.
        • Mitsiokapa E.
        • Karamanis E.
        • Kontogeorgakos V.
        • Mavrogenis A.F.
        Ultrasonography provides a diagnosis similar to that of nerve conduction studies for carpal tunnel syndrome.
        Orthopedics. 2019; 42 (e460-e464)
        • Zaidman C.
        • Al-Lozi M.
        • Pestronk A.
        Peripheral nerve size in normals and patients with polyneuropathy: an ultrasound study.
        Muscle Nerve. 2009; 40: 960-966
        • Cartwright M.S.
        • Shin H.W.
        • Passmore L.V.
        • Walker F.O.
        Ultrasonographic reference values for assessing the normal median nerve in adults.
        J Neuroimaging. 2009; 19: 47-51
        • 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
      1. American Academy of Orthopaedic Surgeons. Management of carpal tunnel syndrome evidence-based clinical practice guideline. Published 2016. Accessed December 28, 2017.

      2. Center of Evidence Based Medicine. Critical appraisal form for diagnsotic accuracy studies. Accessed February 27, 2019.

      3. Bruyère Research Institute. AMSTAR: a measurement tool to assess systematic reviews. Accessed March 3, 2020.

        • Shea B.J.
        • Hamel C.
        • Wells G.A.
        AMSTAR is a reliable and valid measurement tool to assess the methodological quality of systematic reviews.
        J Clin Epidemiol. 2009; 62: 1013-1020
        • Jiwa N.
        • Abraham A.
        • Bril V.
        The median to ulnar cross-sectional surface area ratio in carpal tunnel syndrome.
        Clin Neurophysiol. 2018; 129: 2239-2244
        • Lee K.M.
        • Kim H.J.
        Relationship between electrodiagnosis and various ultrasonographic findings for diagnosis of carpal tunnel syndrome.
        Ann Rehabil Med. 2016; 40: 1040-1047
        • Phongamwong C.
        • Soponprapakorn N.
        • Kumnerddee W.
        Determination of electrophysiologically moderate and severe carpal tunnel syndrome: ultrasonographic measurement of median nerve at the wrist.
        Ann Rehabil Med. 2017; 41: 604-609
        • Junck A.D.
        • Escobedo E.M.
        • Lipa B.M.
        Reliability assessment of various sonographic techniques for evaluating carpal tunnel syndrome.
        J Ultrasound Med. 2015; 34: 2077-2088
        • Portney L.G.
        • Watkins M.P.
        Foundations of Clinical Research: Applications to Practice.
        F.A. Davis Company, Philadelphia, PA2015 (3rd ed.)
        • Atan T.
        • Günendi Z.
        Diagnostic utility of the sonographic median to ulnar nerve cross-sectional area ratio in carpal tunnel syndrome.
        Turkish J Med Sci. 2018; 48: 110-116
        • Ažman D.
        • Hrabač P.
        • Demarin V.
        Use of multiple ultrasonographic parameters in confirmation of carpal tunnel syndrome.
        J Ultrasound Med. 2018; 37: 879-889
        • El Habashy H.R.
        • El Hadidy R.A.
        • Ahmed S.M.
        • Sayed B.B.E.
        • Ahmed A.S.
        Carpal tunnel syndrome gading using high-resolution ultrasonography.
        J Clin Neurophysiol. 2017; 34: 353-358
        • Kutlar N.
        • Bayrak A.O.
        • Bayrak İ.K.
        • Canbaz S.
        • Türker H.
        Diagnosing carpal tunnel syndrome with Doppler ultrasonography: a comparison of ultrasonographic measurements and electrophysiological severity.
        Neurol Res. 2017; 39: 126-132
        • Gonzalez-Suarez C.B.
        • Fidel B.C.
        • Cabrera J.T.C.
        Diagnostic accuracy of ultrasound parameters in carpal tunnel sndrome: additional criteria for diagnosis.
        J Ultrasound Med. 2019; 38: 3043-3052
        • Köroğlu Ö.
        • Kesikburun S.
        • Adıgüzel E.
        • Taşkaynatan M.A.
        • Özgül A.
        Estimating the most accurate sonographic measurement in the diagnosis of carpal tunnel syndrome: Which is the best?.
        Turkish J Phys Med Rehabil. 2019; 65: 177-183
        • Chang Y.W.
        • Hsieh T.C.
        • Tzeng I.S.
        • Chiu V.
        • Huang P.J.
        • Horng Y.S.
        Ratio and difference of the cross-sectional area of median nerve to ulnar nerve in diagnosing carpal tunnel syndrome: a case control study.
        BMC Med Imaging. 2019; 19: 1-9
        • El-Shintenawy A.A.
        • Kassem E.M.
        • El-Saadany H.M.
        • Alashkar D.S.
        Diagnostic potential of high resolution ultrasound and nerve conduction study in patients with idiopathic carpal tunnel syndrome.
        Egypt Rheumatol. 2019; 41: 71-75
        • Ha D.S.
        • Kim H.S.
        • Kim J.M.
        • Lee K.H.
        The correlation between electrodiagnostic results and ultrasonographic findings in the severity of carpal tunnel syndrome in females.
        Ann Rehabil Med. 2017; 41: 595-603
        • Wessel L.E.
        • Marshall D.C.
        • Stepan J.G.H.
        Sonographic findings associated with carpal tunnel syndrome.
        J Hand Surg Am. 2019; 44: 374-381
        • Pimentel B.F.R.
        • Faloppa F.
        • Tamaoki M.J.S.
        • Belloti J.C.
        Effectiveness of ultrasonography and nerve conduction studies in the diagnosing of carpal tunnel syndrome: Clinical trial on accuracy.
        BMC Musculoskelet Disord. 2018; 19: 1-11
        • Roghani R.S.
        • Hashemi S.E.
        • Holisaz M.T.
        • Gohari F.
        • Delbari A.
        • Lokk J.
        The diagnostic accuracy of median nerve ultrasonography in elderly patients with carpal tunnel syndrome: Sensitivity and specificity assessment.
        Clin Interv Aging. 2018; 13: 1953-1962
        • 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 (e10): 758-765
        • Guyatt G.
        User's Guides to the Medical Literature: A Manual for Evidence-Based Clinical Practice.
        McGraw-Hill Education/Medical, New York, NY2014 (3rd ed.)
        • Alemán L.
        • Berná J.D.
        • Reus M.
        • Martinez F.
        • Doménech-Ratto G.
        • Campos M.
        Reproducability of sonographic measurments of the median nerve.
        J Ultrasound Med. 2008; 27: 193-197
        • Mhoon J.T.
        • Juel V.C.
        • Hobson-Webb L.D.
        Median nerve ultrasound as a screening tool in carpal tunnel syndrome: Correlation of cross-sectional area measures with electrodiagnostic abnormality.
        Muscle and Nerve. 2012; 46: 871-878
        • Moran L.
        • Perez M.
        • Esteban A.
        • Bellon J.
        • Arranz B.
        • Del Cerro M.
        Sonographic measurement of cross-sectional area of the median nerve in the diagnosis of carpal tunnel syndrome: correlation with nerve conduction studies.
        J Clin Ultrasound. 2009; 37: 125-131
        • Ooi C.C.
        • Wong S.K.
        • Tan A.B.H.
        Diagnostic criteria of carpal tunnel syndrome using high-resolution ultrasonography: correlation with nerve conduction studies.
        Skeletal Radiol. 2014; 43: 1387-1394
        • Wang L.Y.
        • Leong C.P.
        • Huang Y.C.
        • Hung J.W.
        • Cheung S.M.
        • Pong Y.P.
        Best diagnostic criterion in high-resolution ultrasonography for carpal tunnel syndrome.
        Chang Gung Med J. 2008; 31: 469-476
        • Kim J.Y.
        • Yoon J.S.
        • Kim S.J.
        • Won S.J.
        • Jeong J.S.
        Carpal tunnel syndrome: clinical, electrophysiological, and ultrasonographic ratio after surgery.
        Muscle and Nerve. 2012; 45: 183-188
        • 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 dagnostic test accuracy.
        Ultrasound Med Biol. 2012; 38: 1121-1128
        • Roll S.C.
        • Volz K.R.
        • Fahy C.M.
        • Evans K.D.
        Carpal tunnel syndrome severity staging using sonographic and clinical measures.
        Muscle Nerve. 2015; 51 (New): 838-845
        • Azami A.
        • Maleki N.
        • Anari H.
        • Iranparvar Alamdari M.
        • Kalantarhormozi M.
        • Tavosi Z.
        The diagnostic value of ultrasound compared with nerve conduction velocity in carpal tunnel syndrome.
        Int J Rheum Dis. 2014; 17: 612-620
        • Buchberger W.
        • Schön G.
        • Strasser K.
        • Jungwirth W.
        High-resolution ultrasonography of the carpal tunnel.
        J Ultrasound Med. 1991; 10: 531-537
        • Mackinnon S.E.
        Pathophysiology of nerve compression.
        Hand Clin. 2002; 18: 231-241

      JHT Read for Credit

      Quiz: # 844

      Record your answers on the Return Answer Form found on the tear-out coupon at the back of this issue or to complete online and use a credit card, go to There is only one best answer for each question.
      • # 1.
        The design of the study is.
        • a.
          prospective cohort
        • b.
          case series
        • c.
          systematic review
        • d.
      • # 2.
        Study scores were
        • a.
          reached through a consensus of the team after discussion
        • b.
          validated by computer analysis
        • c.
          randomly reviewed by team members
        • d.
          dictated by pre-established norms
      • # 3.
        CSA of the median nerve was shown to have
        • a.
          excellent sensitivity, but poor specificity
        • b.
          little clinical value
        • c.
          excellent correlation to the CSA of the ulnar nerve
        • d.
          good intrarater reliability and excellent interrater reliability
      • # 4.
        CSA measures were taken at the
        • a.
          midpalmar level
        • b.
          the level of the distal wrist crease
        • c.
          carpal tunnel inlet
        • d.
          carpal tunnel outlet
      • # 5.
        The evidence is that ultrasound should replace EMG & NCV in the evaluation of CTS
        • a.
        • b.
      When submitting to the HTCC for re-certification, please batch your JHT RFC certificates in groups of 3 or more to get full credit.