Most commonly from compression near medial apsect of elbow (cubital tunnel)
A second site of compression is Guyon' canal, which is at medial aspect of wrist, palmar side
Risk Factors
Men > Women
Age > 35
Repetitive motion or prolonged wrist extension, cycling from gripping handle bar (Guyon canal), compression at elbow; trauma or osteophytes can contribute
Symptoms
Weakness w/grip
Chronic pain, which radiate down to 1/2 ring and pinky fingers, often worse at night/in AM
Physical Exam Findings
Paresthesias in pinky and ring fingers reproduced when tap over ulnar groove of elbow → "funny bone" sensation
If related to compression at Guyon canal, numbness or paresthesias in ring and pinky fingers reproduced by tapping over the canal or with phelan's maneuver (holding wrist in extreme flexion)
Weakness can occur with extreme compression→atrophy of lumbricals (intrinsics), claw fingers