Involves compression of the ulnar nerve at the elbow behind the medial epicondyle ('funny bone' area)
Aetiology
Compression can be due to a tight band of fascia forming the roof of the tunnel (known as Osborne’s fascia) or due to tightness at the intermuscular septum as the nerve passes through or between the two heads at the origin of flexor carpi ulnaris
Clinical features
Symptoms
Paraesthesiae in the ulnar 1½ fingers
Night symptoms - caused by sleeping with the arm in flexion
Signs
Tinel’s test over the cubital tunnel is usually positive
Weakness of ulnar nerve innervated muscles may be present including the 1st dorsal interosseous (abduction index finger) and adductor pollicis
Weakness of adductor pollicis can be assessed with Froment’s test - thumb flexes at the IPJ joint while pinching a piece of paper to compensate for a weak adductor pollicis muscle
