Ultrasound imaging of anconeus epitrochlearis muscle as a cause of cubital tunnel syndrome

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1 Ultrasound imaging of anconeus epitrochlearis muscle as a cause of cubital tunnel syndrome Poster No.: C-3371 Congress: ECR 2010 Type: Scientific Exhibit Topic: Musculoskeletal Authors: A. Karatasiou, E. Andipa, D. Papoutsi, I. Paianidi, K. Limberopoulos, M. Tsouroulas; Athens/GR Keywords: anconeus epitrochlearis muscle, ultrasound imaging, cubital tunnel syndrome DOI: /ecr2010/C-3371 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 15

2 Purpose Anconeus epitrochlearis muscle is a known but infrequently documented cause of cubital tunnel syndrome. The purpose of this study is to evaluate the efficiency of ultrasonography in demonstrating the presence of anconeus epitrochlearis muscle and to establish the prevalence of this finding in cases with cubital tunnel syndrome. Methods and Materials 58 patients with symptoms of ulnar nerve entrapment at the elbow underwent ultrasound examination. Clinical symptoms included medial elbow pain, numbness and paresthesias of the fourth and fifth digits and weakness of the hand. Physical examination was consistent with sensory and motor dysfunction of the ulnar nerve proximal to the wrist and distal to the brachial plexus. The entire study population underwent electrodiagnostic evaluation of the ulnar nerve including sensory and motor conduction velocities and electromyography of the muscles innervated by the ulnar nerve. Ulnar neuropathy with localization to the elbow region was confirmed in all cases. Ultrasound imaging of the elbow was obtained with a high frequency (5-17MHz), lineararray transducer. The posterior aspect of the elbow was examined with the elbow flexed o at 90 and the palm resting on the table. Page 2 of 15

3 In this position, the cubital tunnel and the ulnar nerve were evaluated and the triceps muscle and tendon, the olecranon recess and bursa were depicted. Longitudinal and transverse images of the ulnar nerve were obtained and measurements of its anteroposterior diameter were made. 25 patients were further studied with MRI. T1, T2-weighted and STIR sequences were used and 3-mm slices through the radio-humeral joint, using an 1,5T magnetic resonance imager were obtained. In 14 of the patients who underwent MRI, surgical decompression of the ulnar nerve was performed. Post-operative follow-up was obtained in 6 patients at 3 and 6 months. Results In all patients the ulnar nerve was depicted hypoechoic and enlarged. Its anteroposterior diameter ranged from 2,5-4,5mm and was greater than that of the asymptomatic contra-lateral elbow. Page 3 of 15

4 Fig.: Longitudinal image of the ulnar nerve which was found hypoechoic and enlarged with an anteroposterior diameter of 4,4 mm. Despite nerve edema suggestive of neuropathy, color doppler ultrasonography did not reveal increased vascularity. Page 4 of 15

5 Fig.: Color doppler ultrasound of an edematous ulnar nerve revealing absence of increased vascularity In 19/58 patients (32%), ultrasound revealed the presence of an aberrant muscle known as the anconeus epitrochlearis, to be the cause of neuropathy. The muscle was depicted as a small triangular hypo-echoic muscular band with a fibrous fascia, transversing the cubital tunnel. The muscle fibers crossed from the medial humeral epicondyle and inserted on the olecranon. Page 5 of 15

6 Fig.: Transverse image of the elbow's posterior aspect depicting anconeus epitrochlearis muscle as a hypoechoic triangular band transversing the cubital tunnel above the ulnar nerve. 12 of the 19 patients who displayed anconeus epitrochlearis as the cause of cubital tunnel syndrome, underwent MRI. In all cases MRI revealed increased signal intensity and enlargement of the ulnar nerve. Page 6 of 15

7 Fig.: An axial STIR image through the elbow joint depicting an enlarged ulnar nerve with high signal intensity and a band of muscle fibers superior to the nerve, representing the anconeus epitrochlearis muscle. Page 7 of 15

8 Fig.: Axial T1WI of the same patient showing the ulnar nerve with low signal intensity, as well as the anconeus epitrochlearis muscle transversing the cubital tunnel The presence of the aberrant muscle was confirmed in all cases but one in which the cause of ulnar nerve compression proved to be a thickened retinaculum known as the Osborne fascia which delimits the cubital tunnel and continues distally with the aponeurotic arch between the ulnar and humeral heads of the flexor carpi ulnaris muscle [1]. Page 8 of 15

9 Fig.: Elbow ultrasound of a patient with cubital tunnel syndrome showing an anlarged ulnar nerve and an adjacent hypoechoic band which was perceived as an anconeus epitrochlearis muscle. Page 9 of 15

10 Fig.: Axial STIR image of the same elbow joint showing an enlarged, high signal intensity ulnar nerve compressed by a thickened cubital tunnel retinaculum All 12 patients with ultrasonographic evidence of anconeus epitrochlearis that underwent MRI were treated with local surgical excision of the space-occupying muscle or in one case the fibrous fascia. Of the 6 patients that were followed-up after surgery, 3 were markedly improved, whereas nerve edema persisted after 6 months in 3 cases. Page 10 of 15

11 Fig.: Transverse post-operative image of the cubital tunnel showing persistent ulnar nerve edema, despite surgical excision of the anconeus epitrochlearis muscle. Page 11 of 15

12 Fig.: Longitudinal post-operative color doppler image of the same patient with ulnar nerve edema and no signs of increased vascularity Page 12 of 15

13 Conclusion Many possible causes of ulnar nerve compression have been reported including osteophytes, ectopic bone, ganglia, dislocation of the ulnar nerve, cubitus valgus deformity and the presence of the aberrant anconeus epitrochlearis muscle [2,3,4,5,6]. This muscle which covers the ulnar nerve, has been noted to be present in 1% to 30% of cadavers and it renders the nerve more susceptible to compression [2,3,7,8]. As shown in this study, the prevalence of anconeus epitrochlearis in patients with clinical and electromyographic evidence of cubital tunnel syndrome, is significant. Ultrasound can clearly visualize the site of nerve constriction and detect space-occupying lesions in the cubital tunnel [9]. Although ultrasound of the elbow is operator dependent and requires experience, it offers advantages including time and cost-effectiveness, dynamic study and the possibility of performing the examination in a comfortable position for the patient [1]. It can therefore provide clinically useful information in assessing patients with medial elbow pain and aid in pre and post-operative planning. In rare cases MRI proves to be a valuable imaging supplement in the diagnosis of ulnar nerve entrapment at the elbow, since it is both sensitive and specific and correlates well with intraoperative findings [10,11]. References Page 13 of 15

14 1. Martinoli C, Bianchi S, Giovagnorio F, Pugliese F. Ultrasound of the elbow. Skeletal Radiol 2001;30: Husarik DB, Saupe N, Pfirrmann CWA, Jost B, Hodler J, Zanetti M. Elbow Nerves: MR Findings in 60 Asymptomatic Subjects-Normal Anatomy, Variants, and Pitfalls. Radiology 2009;252:(1) 3. Dellon AL. Musculotendinous Variations about the Medial Humeral Epicondyle. J Hand Surgery 1986;11-B:(2) 4. O'Driscoll SW, Horii E, Carmichael SW, Morrey BF. The cubital channel and ulnar neuropathy. J Bone Joint Surg [Br] 1991;73-B: Nakamichi K, Tachibana S, Kitajima I. Ultrasonography in the diagnosis of ulnar tunnel syndrome caused by an occult ganglion. J Hand Surgery 2000;25B(5): Puig S, Turkof E, Sedivy R, Ciovica R, Lang S, Kainberger F. Sonographic Diagnosis of Recurrent Ulnar Nerve Compression by Ganglion Cysts. J Ultrasound Med 1999;18: Dahners LE, Wood FM. Anconeus epitrochlearis, a rare cause of cubital tunnel syndrome. J Hand Surg 1984;9A: Masear VR, Hill JJ, Cohen SM. Ulnar compression neuropathy secondary to the anconeus epitrochlearis muscle. J Hand Surg 1988;13A: Okamoto M, Abe M, Shirai H, Ueda N. Diagnostic ultrasonography of the ulnar nerve in cubital tunnel syndrome. J Hand Surg 2000;25B(5): Jeon I, Fairbairn KJ, Neumann L, Wallace WA. MR imaging of edematous anconeus epitrochlearis: another cause of medial elbow pain? Skeletal Radiol 2005;34: Britz GW, Haynor DR, Kntz C, Goodkin R, Gitter A, Maravilla K, Kliot M. Ulnar Nerve Entrapment at the Elbow: Correlation of Magnetic Resonance Imaging, Clinical, Electrodiagnostic, and Intraoperative Findings. Neurosurgery 1996;38: Page 14 of 15

15 Personal Information Page 15 of 15

Diagnosis of ulnar neuropathy in the elbow: value of ultrasonography and MRI

Diagnosis of ulnar neuropathy in the elbow: value of ultrasonography and MRI Poster No.: C-2216 Congress: ECR 2013 Type: Educational Exhibit Authors: P. L. Pegado, C. A. Santos Ruano, J. Raposo, P. Alves,