Froment sign

Froment sign is a special test of the wrist for palsy of the ulnar nerve, specifically, the action of adductor pollicis.^[1]

Froment sign
Positive Froment sign (below)
Differential diagnosis	palsy of the ulnar nerve

Process of examination

To perform the test, a patient is asked to hold an object, usually a flat object such as a piece of paper, between the thumb and index finger (pinch grip). The examiner then attempts to pull the object out of the subject's hands.^[2]

• A normal individual will be able to maintain a hold on the object without difficulty.
• However, with ulnar nerve palsy, the patient will experience difficulty maintaining a hold using the adductor pollicis. They will instead use the flexor pollicis longus of the thumb to grip the paper causing a flexion of the interphalangeal joint.^[3]
• Froment sign is the flexion of the interphalangeal joint of the thumb rather than adduction of the entire thumb.
• Note that the flexor pollicis longus is nearly always innervated by the anterior interosseous branch of the median nerve.
• Simultaneous hyperextension of the thumb MCP joint is indicative of ulnar nerve compromise. This is also known as Jeanne's sign.^[2]

Eponym

It is named after French neurologist Jules Froment.^[4][5]