Cubital Tunnel

Cumulative trauma disorders (CTDs), also referred to as repetitive-motion injuries, result from excessive use of the hand, wrist, or forearm. As with overexertion injuries, the frequency and costs of CTDs are growing to epidemic proportions. Some of the most common cumulative trauma disorders are carpal tunnel syndrome, cubital tunnel syndrome, tendinitis, and tenosynovitis. 

Cubital Tunnel Syndrome is compression of the ulnar nerve in the elbow, thought to be caused by resting the elbow on a hard surface or sharp edge. Symptoms include tingling in the ring finger and little finger. 

Dynamic US of the elbow can be used to help demonstrate abnormal dislocation of the ulnar nerve, with or without snapping triceps syndrome. This finding typically occurs in the cubital tunnel, an osteofibrous tunnel formed by a groove between the olecranon and the medial epicondyle and bridged by the Osborn retinaculum. As described in Chapter 8, dynamic scanning during full elbow flexion can allow continual depiction of the intermittent dislo-... 

Chiou HJ, Chou YH, Cheng SP et al (1998) Cubital tunnel syndrome diagnosis by high-resolution ultrasonography. J Ultrasound Med 17 643-648... 

Nakamichi K, Tachibana S, Kitajima I (2000) Ultrasonography in the diagnosis of ulnar tunnel syndrome caused by an occult ganglion. J Hand Surg [Br] 25 503-504 Okamoto M, Abe M, Shirai H et al (2000) Diagnostic ultrasonography of the ulnar nerve in cubital tunnel syndrome. J Hand Surg [Br] 5 499-502... 

Karakurt L, Ozdemir H, Yilmaz E et al (2005) Morphology and dynamics of the ulnar nerve in the cubital tunnel after percutaneous cross-pinning of supracondylar fractures in children s elbows an ultrasonographic study. J Pediatr Orthop B 14 189-193... 

Essentials of Clinical History and Physical Examination 358 Tendon Abnormalities 358 Ligament Instability 358 Cubital Tunnel Syndrome 358... 

The anconeus epitrochlearis is a small accessory muscle (prevalence ranging from 1% to 34%) that forms the roof of the cubital tunnel, replacing the Osborne retinaculum and joins the posterior aspect of the medial epicondyle with the medial aspect of the olecranon.. This muscle is often bilateral and can cause ulnar neuropathy by occupying space within the cubital tunnel and decreasing its free volume during full elbow flexion. Somewhat equivalent to the anconeus epitrochlearis, an anomalous myotendinous junction of the triceps may also be prominent over the posteromedial side of the cubital tunnel (see Sect. 8.5.4.S). 

The elbow is traversed by the ulnar, median and radial nerves that cross through its posteromedial, anterior and lateral aspects respectively. In the elbow area, the median nerve is accompanied by the brachial artery, the radial nerve gives off a main motor branch, the posterior interosseous nerve, and the ulnar nerve travels across an osteofibrous tunnel, the cubital tunnel. 

A useful clinical maneuver to assess the state of the ulnar nerve is the Froment s test . The patient is asked to pinch a sheet of paper between thumb and index finger. In case of overt ulnar neuropathy, the patient grasps the paper by flexing the thumb (activation of the median-innervated flexor pollicis longus as a compensation for the weakness of dorsal interosseous muscles) (see Sect. 8.5.4.3). In patients with cubital tunnel syndrome, palpation of the ulnar nerve at the cubital tunnel may be painful and may reproduce symptoms. 

For evaluation of the posteromedial aspect of the joint, including the cubital tunnel and the ulnar nerve, the patient s elbow should be placed in forceful external rotation to enable visualization and palpation of the medial epicondyle and olecranon (Fig. 8.7a). This can be obtained either with the patient seated and the elbow extended and hyper-pronated with its dorsal aspect facing the exam-ineror, at least for the right side, with the patient... 

Fig. 8.23. Normal ulnar nerve. Long-axis 12-5 MHz US image of the normal ulnar nerve obtained over the cubital tunnel with extended elbow. The relationships of the nerve (arrows) with the medial epicondyle (ME) and the flexor carpi ulnaris muscle (feu) are shown. The ulnar nerve exhibits a hypoechoic appearance and a fairly uniform thickness throughout the tunnel. The insert at the upper left side of the figure indicates probe positioning...

Fig. 8.57a-d. Cubital tunnel syndrome in a patient with anconeus epitrochlearis muscle, a Short-axis and b long-axis 12-5 MHz US images of the cubital tunnel reveal the anconeus epitrochlearis muscle (straight arrows) that lies between the medial epicondyle (ME) and the olecranon (0) in close relation with a swollen ulnar nerve (curved arrow). Correlative transverse c Tlw SE and d fat-suppressed T2w SE MR images demonstrate the aberrant muscle (straight arrows) within the cubital tunnel. In d, the ulnar nerve (curved arrow) appears markedly hyperintense as a result of compression neuropathy. ME, medial epicondyle 0, olecranon... 

Fig. 8.61a-d. Postoperative patient with recurrence of symptoms after decompressive surgery of the ulnar nerve at the cubital tunnel for a ganglion cyst. a,b Transverse 12-5 MHz US images obtained a at the cubital tunnel level and b at the proximal forearm with c,d Tlw SB MR imaging correlation show a relapsed cyst (asterisks) which constricts the transposed ulnar nerve (arrow). The patient underwent surgery again and the postoperative course was finally uneventful. ME, medial epicon-dyle... 

Fig. 8.62a-f. Dynamic study of the cubital tunnel in ulnar nerve dislocation. a-c Schematic drawings and d-f respective series of transverse 12-5 MHz US images obtained a,d with extended elbow and during progressive degrees of elbow flexion (b,e and c,f). When the elbow is extended, the ulnar nerve (arrow) is contained within the tunnel. Elbow flexion gradually pushes the nerve over the medial epicondyle (ME) until it snaps completely out of the cubital tunnel to lie superficial to the common flexor tendon origin (ft). 0, olecranon... 

Fig. 8.63a-d. Dynamic study of the cubital tunnel in a patient with recurrent ulnar nerve dislocation and clinical symptoms of ulnar neuropathy, a-d Series of transverse 13-8 MHz US images acquired a with extended elbow and b-d throughout elbow flexion show a markedly swollen and hypoechoic nerve (arrow) that flattens and dislocates over the medial epicondyle (ME) during elbow flexion. In the symptomatic patient, this finding is suggestive of ulnar neuropathy based on a friction mechanism... 

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