Describe the etiology of cubital tunnel syndrome.
Leaning on the elbow or prolonged elbow flexion during occupational activities (e.g., leaning on a desk), athletic activities, or surgical procedures (e.g., during general anesthesia)
Masses (e.g., tumors, hematomas)
Metabolic abnormalities (e.g., diabetes)
List clinical features (muscles)
Atrophy of the hypothenar muscles
Inability to flex the ring finger and little finger when asked to make a fist
Results in a hand position that is similar to the “OK sign” (proximal nerve lesions)
Claw hand deformity (ulnar claw) 
Mainly in distal nerve injuries
Palsy of the 3rd and 4th lumbricals with preserved function of extrinsic flexors
Hyperextension at MCP joints and flexion at PIP and DIP joints of the ring finger and little finger
Present at rest, increases when the patient is asked to extend the fingers
Wartenberg sign: little finger in persistent abduction due to weak third palmar interosseous muscle
Froment sign: The thumb flexes at the interphalangeal joint while pinching a piece of paper to compensate for a weak adductor pollicis muscle.
Caused by the loss of function of the adductor pollicis and the predominance of the extensor pollicis longus and the abductor pollicis brevis
Leads to hyperextension of the thumb's metacarpophalangeal joint
List clinical features (sensory).
Lesions at the elbow
Positive Tinel test: marked paresthesias can be reproduced in the ulnar portion of the hand by tapping on the medial epicondyle of the humerus.
Elbow lesions typically present with referred pain in the forearm.
Lesions at the ulnar canal (located in the wrist)
The ulnar canal is divided into three zones
Zone I: proximal to the bifurcation of the ulnar nerve
Motor and sensory symptoms (i.e., sensory loss in the palmar surface of the small finger and medial aspect of the ring finger) possible
Sensory features similar to those caused by proximal lesions at the elbow
Zone II: lesions at the deep motor branch cause motor symptoms only
Zone III: lesions at the distal sensory branch cause sensory symptoms only
Describe the diagnostics.
Typically involves nerve conduction studies and EMG
Identifies the level of nerve compression
Ultrasound and MRI: used to support the EMG findings and to detect possible causes of compression (e.g., space-occupying lesions)
X-ray: Consider cervical spine, chest, elbow, and wrist films to rule out other possible causes of symptoms.
Describe the treatment.
Modify behavior (e.g., avoid prolonged resting on elbow, repeated flexion of elbow)
Bracing at night
Analgesia (e.g., NSAIDs)
Surgical decompression: if clinical features are severe, persistent (i.e., lasting more than 6 to 12 weeks), or progressively worsen despite conservative therapy.