DOI: http://dx.doi.org/10.18203/2320-6012.ijrms20164183

Ultrasound evaluation of carpal tunnel syndrome in patients with bifid median nerve

Smiti Sripathi, Anurag Ayachit, Rebin Bos

Abstract


Background: Patients with high division of the median nerve proximal to carpal tunnel, or bifid median nerve, may present with carpal tunnel syndrome (CTS). Ultrasound (US) measurements indicative of CTS in this subset of patients differ from those in patients with non-bifid median nerve.   The objectives were to evaluate the parameter ∆CSA [difference between the maximum cross-sectional area of bifid median nerve within carpal tunnel (CSAc) and outside tunnel (CSAp)] in the diagnosis of CTS, to compare sensitivity and specificity of ∆CSA with nerve conduction velocity studies (NCS), and to compare the cross-sectional area (CSAc, CSAp & ∆CSA) of bifid median nerve in CTS patients with that in asymptomatic controls.

Methods: 20 wrists with bifid median nerves and symptoms suggestive of CTS were included in the study group. Nerve conduction velocity studies (NCS) were performed in all cases. 4 wrists of asymptomatic age-matched subjects had bifid median nerves and normal NCS and were included in the control group. High resolution ultrasonography was performed for all wrists and findings documented. Statistical Analysis: Receiver Operating Characteristics curves were used to obtain the level of significance (p-value) and assessment of correlation between ∆CSA and NCS findings.

Results: There was significant correlation between ∆CSA and NCS. A cut-off value of 2.3mm2 gave the best calculated sensitivity (76.9 %) and specificity (100%).

Conclusions: CSA criteria for diagnosing CTS in patients with bifid median nerves are different from those in patients with non-bifid median nerve. ∆CSA is a sensitive and specific parameter for confirming the diagnosis of CTS in patients with bifid median nerve with sensitivity approaching that of NCS.


Keywords


Bifid median nerve, Carpal tunnel syndrome, Ultrasound

Full Text:

PDF

References


Sripathi S, Bansal D, Ayachit A, Kadavigere R. High resolution ultrasound in evaluation of bifid median nerve in carpal tunnel syndrome in Indian population. Poster presented at: European Congress of Radiology. 2015 March 4-8; Vienna, Austria.

Lanz U. Anatomical variations of the median nerve in the carpal tunnel. J Hand Surg Am. 1977;2:44-53.

Roll SC, Evans KD. Sonographic representation of Bifid Median Nerve and Persistent Median Artery. J Diagnostic Medical Sonography. 2011;27:89-94.

Gassner EM, Peer S, Jaschke W. Persistent Median Artery in the Carpal Tunnel. Color Doppler Ultrasonographic Findings. J Ultrasound Med. 2002;21:455-61.

Chammas M, Boretto J, Burmann LM, Ramos RM, dos Santos Neto FC, Silva JB. Carpal tunnel syndrome – Part I (anatomy, physiology, etiology and diagnosis). Rev Bras Ortop. 2014;49:429-36.

Klauser AS, Halpern EJ, DeZordo T, Feuchtner GM, Arora R, et al. Carpal Tunnel Syndrome Assessment with US: Value of Additional Cross-sectional Area Measurements of the Median Nerve in Patients versus Healthy Volunteers. Radiology. 2009;250:171-7.

Klauser AS, Halpern EJ, Faschingbauer R, Guerra F, Martinoli C, et al. Bifid Median Nerve in Carpal Tunnel Syndrome: Assessment with US Cross-sectional Area Measurement. Radiology. 2011;259:808-15.

Jarvik JG, Comstock BA, Kliot M, Turner JA, Chan L, Heagerty PJ. Surgery versus non-surgical therapy for carpal tunnel syndrome: a randomised parallel-group trial. Lancet. 2009;374:1074-81.

Eiken O, Carstam N, Eddeland A. Anomalous distal branching of the median nerve: case reports. Scand J Plast Reconstr Surg. 1971;5:149-52.

Tountas CP, Bihrle DM, MacDonald CJ, Bergman RA.Variations of the median nerve in the carpal canal. J Hand Surg. 1987;12:708-12.

Ahn DS, Yoon ES, Koo SH, Park SH. A prospective study of the anatomic variations of the median nerve in the carpal tunnel in Asians. Ann Plast Surg. 2000;44:282-7.

Propeck T, Quinn TJ, Jacobson JA, Paulino AF, Habra G, Darian VB. Sonography and MR imaging of bifid median nerve with anatomic and histologic correlation. AJR Am J Roentgenol. 2000;175:1721-5.

Iannicelli E, Chianta GA, Salvini V, Almberger M, Monacelli G, Passariello R. Evaluation of bifid median nerve with sonography and MR imaging. J Ultrasound Med. 2000;19:481-5.

Bayrak IK, Bayrak AO, Kale M, Turker H, Diren B. Bifid median nerve in patients with carpal tunnel syndrome. J Ultrasound Med. 2008;27:1129-36.

Mohammadi A, Afshar A, Etemadi A, Masoudi S. Comparison of high resolution ultrasonography and nerve conduction study in the diagnosis of carpal tunnel syndrome: diagnostic value of median nerve cross-sectional area. Iran J Radiol. 2009;6:147-52.

Mondelli M, Filippou G, Gallo A, Frediani B. Diagnostic utility of ultrasonography versus nerve conduction studies in mild carpal tunnel syndrome. Arthritis Rheum. 2008;59:357-66.

Padua L, Pazzaglia C, Caliandro P, Granata G, Foschini M, Briani C, et al. Carpal tunnel syndrome: ultrasound, neurophysiology, clinical, and patient-oriented assessment. Clin Neurophysiol. 2008;119: 2064-9.

Chan KU, George J, Goh KJ, Ahmad TS. Ultrasonography in the evaluation of carpal tunnel syndrome: Diagnostic criteria and comparison with nerve conduction studies. Neurology Asia. 2011;16:57-64.

Elwakil TF, Elazzazi A, Shokeir H. Treatment of carpal tunnel syndrome by low-level laser versus open carpal tunnel release. Lasers Med Sci. 2007;22:265-70.

Akcar N, Özkan S, Mehmetoglu Ö, Calisir C, Adapinar B. Value of power Doppler and gray-scale US in the diagnosis of carpal tunnel syndrome: contribution of cross-sectional area just before the tunnel inlet as compared with the cross-sectional area at the tunnel. Korean J Radiology. 2010;11:632-9.

Mallouhi A, Pülzl P, Trieb T, Piza H, Bodner G. Predictors of carpal tunnel syndrome: accuracy of gray-scale and color Doppler sonography. AJR Am J Roentgenol. 2006;186:1240-5.