Summary Cubital Tunnel Syndrome is a compressive neuropathy of the ulnar nerve caused by anatomic compression in the medial elbow. Diagnosis is made clinically with presence of sensory changes to the ring and little finger, intrinsic muscle weakness and a positive tinel's sign over the cubital tunnel. Treatment may be nonoperative modalities such as bracing or surgical decompression depending on the severity and duration of symptoms, and success of nonoperative treatment. Epidemiology Incidence common ~30 per 100,000 person annually second most common compression neuropathy of upper extremity Demographics males > females females more likely to present at earlier age incidence increases with age in both men and women Etiology Pathophysiology Cubital tunnel syndrome results from compression and traction on the ulnar nerve Sites of entrapment most common between the two heads of FCU/aponeurosis (most common site) within arcade of Struthers (hiatus in medial intermuscular septum) between Osborne's ligament and MCL less common sites of compression include medial head of triceps medial intermuscular septum medial epicondyle fascial bands within FCU anconeus epitrochlearis (anomalous muscle from the medial olecranon to the medial epicondyle) aponeurosis of FDS proximal edge external sources of compression fractures and medial epicondyle nonunions osteophytes heterotopic ossification tumors and ganglion cysts post-traumatic Associated conditions cubitus varus or valgus deformities medial epicondylitis burns elbow contracture release Anatomy Ulnar nerve arises from the medial cord of the brachial plexus (C8-T1) lies posteromedial to brachial artery in anterior compartment of upper arm pierces IM septum at arcade of Struthers 8 cm proximal to the medial epicondyle runs behind medial epicondyle within the cubital tunnel enters forearm between 2 heads (humeral and ulnar heads) of FCU runs between FCU and FDP passes superficial to the transverse carpal ligament at the wrist Cubital tunnel roof formed by FCU fascia and Osborne's ligament (travels from the medial epicondyle to the olecranon) floor formed by posterior oblique and transverse bands of MCL and elbow joint capsule walls formed by medial epicondyle and olecranon Classification McGowan and Dellon Type 1 Subjective sensory symptoms without objective loss of two-point sensibility or muscular atrophy Type 2A Sensory symptoms + weakness on pinch and grip without atrophy Type 2B Sensory symptoms + atrophy and intrinsic muscle strength ≤ 3 Type 3 Profound muscular atrophy and sensory disturbance Presentation Symptoms paresthesias of small finger, ulnar half of ring finger, and ulnar dorsal hand exacerbating activities include cell phone use (excessive flexion) occupational or athletic activities requiring repetitive elbow flexion and valgus stress night symptoms caused by sleeping with arm in flexion Physical exam inspection and palpation interosseous and first web space atrophy ring and small finger clawing observe ulnar nerve subluxation over the medial epicondyle as the elbow moves through a flexion-extension arc sensory decreased sensation in ulnar 1-1/2 digits motor loss of the ulnar nerve results in paralysis of intrinsic muscles (adductor pollicis, deep head FPB, interossei, and lumbricals 3 and 4) which leads to weakened grasp from loss of MP joint flexion power weak pinch from loss of thumb adduction (as much as 70% of pinch strength is lost) Froment sign compensatory thumb IP flexion by FPL (AIN) during key pinch compensates for the loss of metacarpal adduction by adductor pollicis (ulna n.) adductor pollicis muscle normally acts as a MCP flexor, first metacarpal adductor, and IP extensor Jeanne sign compensatory thumb MCP hyperextension and thumb adduction by EPL (radial n.) with key pinch compensates for loss of IP extension and thumb adduction by adductor pollicis (ulna n.) Wartenberg sign persistent small finger abduction and extension during attempted adduction secondary to weak 3rd palmar interosseous and small finger lumbrical Masse sign palmar arch flattening and loss of ulnar hand elevation secondary to weak opponens digiti quinti and decreased small finger MCP flexion extrinsic weakness Pollock's sign inability to flex DIPJ of ring and small fingers (weak FDP) provocative tests Tinel sign positive over cubital tunnel elbow flexion test positive when flexion of the elbow for > 60 seconds reproduces symptoms direct cubital tunnel compression exacerbates symptoms Studies EMG / NCS helpful in establishing diagnosis and prognosis threshold for diagnosis conduction velocity <50 m/sec across elbow low amplitudes of sensory nerve action potentials and compound muscle action potentials Differential Ulnar Tunnel Syndrome key findings that differentiate cubital tunnel syndrome from ulnar tunnel syndrome found with cubital tunnel syndrome less clawing sensory deficit to dorsum of the hand motor deficit to ulnar-innervated extrinsic muscles Tinel sign at the elbow positive elbow flexion test C8 radiculopathy key finding that differentiate cubital tunnel syndrome from a C8 radiculpathy cubital tunnel syndrome weakness to distal phalanx flexion of middle and index finger (difficulty with fine motor function) paresthesias in ring and little finger C8 radiculopathy symptoms improve with shoulder abduction Treatment Nonoperative NSAIDs, activity modification, and nighttime elbow extension splinting indications first line of treatment with mild symptoms outcomes management is effective in ~50% of cases Operative in situ ulnar nerve decompression without transposition indications when nonoperative management fails before motor denervation occurs outcomes meta-analyses have shown similar clinical results with significantly fewer complications compared to decompression with transposition 80-90% good results when symptoms are intermittent and denervation has not yet occurred poor prognosis correlates most with intrinsic muscle atrophy ulnar nerve decompression and anterior transposition indications failed in situ release throwing athlete patient with poor ulnar nerve bed from tumor, osteophyte, or heterotopic bone outcomes similar outcomes to in situ release but increased risk of creating a new point of compression Improved outcomes with unstable nerves in the pediatric population medial epicondylectomy indications visible and symptomatic subluxating ulnar nerve thin patients with inadequate subcutaneous tissue to perform a transposition outcomes risk of destabilizing the medial elbow by damaging the medial ulnar collateral ligament Techniques NSAIDs, activity modification, and nighttime elbow extension splinting technique night bracing in 45° extension with forearm in neutral rotation In situ ulnar nerve decompression releasing the fascial structures superficial to the ulnar nerve along the medial aspect of the elbow 4-cm incision midway between the olecranon and medial epicondyle distally release Osborne ligament and the superficial and deep fascia of FCU proximally release the fascia between the medial triceps and medial intermuscular septum avoid circumferential dissection of the nerve to minimize devascularization and to avoid creating hypermobility of the nerve endoscopically-assisted cubital tunnel release is an option favorable early results but lacks long-term data Decompression and transposition (submuscular, intramuscular, or subcutaneous) decompress the nerve and circumferentially dissect the nerve to allow for transposition excise the medial intermuscular septum anteriorly transpose the nerve secured with subcutaneous tissue, placed anterior to a fascial sling, or placed within or beneath the flexor pronator mass Medial Epicondylectomy decompress the nerve and then perform an oblique osteotomy of the medial epicondyle preserve the insertion of the MCL + repair the periosteum Complications Recurrence secondary to inadequate decompression, perineural scarring, or tethering at the intermuscular septum or FCU fascia higher rate of recurrence than after carpal tunnel release Neuroma formation iatrogenic injury to a branch of the medial antebrachial cutaneous nerve may cause persistent posteromedial elbow pain crosses field 3cm distal to medial epicondyle