Historical Overview
- Ulnar nerve palsy is a typically progressive condition that can result in complex and multifaceted disabilities if not managed properly.1,2
- Several eponymous signs have been described to assist with the diagnosis and management of ulnar nerve palsy. Although many of these signs are primarily of academic interest, some may be used to indicate the severity of the palsy.1
- One of these diagnostic tools is Pollock’s sign, which was initially described in 1919 and involves flexion capabilities of the distal interphalangeal (DIP) joints of the ring and little fingers.1,3
Description
- Pollock’s sign is a diagnostic test used to determine the extent of ulnar nerve palsy by evaluating a patient’s ability to flex the DIP joints of the ring and little fingers.1,3
Pathophysiology
- The ulnar nerve is the terminal branch of the medial cord of the brachial plexus. It largely consists of nerve fibers from C8 and T1 nerve roots, but may have contributions from C7 or higher.4
- Most ulnar nerve palsies are the result of trauma in the developed world, while systemic neurologic conditions are more dominant in developing countries. Other possible causes include neuromuscular dysfunction (hereditary sensory-motor neuropathy or poliomyelitis), infection (leprosy), and chronic ulnar nerve compression.2,4
- With classic low ulnar nerve palsy, there is complete loss of function of the interossei and 2 ulnar lumbricals, resulting in a loss of the primary flexors of the metacarpophalangeal (MP) joints and extensors of the interphalangeal (IP) joints.
- The extrinsic flexors can compensate for this loss, but the flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP) tendons only flex the MP joint once the IP joints have reached maximum flexion.
- High ulnar nerve palsy adds the loss of the ulnar half of the FDP, which further weakens grip strength and grasp.5
Instructions
- Obtain a complete and accurate patient history that includes any associated trauma.
- Evaluate the skin and soft tissues for any trophic ulcers.
- Ask the patient to place their hand in a supinated position on a flat surface, with all fingers extended
- Isolate the DIP joint of the little finger by restricting motion to the MP and proximal interphalangeal (PIP) joints.
- Ask the patient to flex the little finger while applying a resistive force.
- Observe the patient’s ability to flex the DIP joint of the little finger against resistance.
- Repeat steps 4-6 with the ring finger.
Related Signs and Tests1
- Andre-Thomas’ sign
- Bouvier’s sign
- Bunnell’s sign
- Duchenne’s sign
- Earlee-Vlastou’s sign
- Egawa’s sign
- Froment’s sign
- Jeanne’s sign
- Masse’s sign
- Mumenthaler’s sign
- Pitres-Testut sign
- Sunderland’s sign
- Wartenberg’s sign
Diagnostic Performance Characteristics
- A patient’s inability to flex the DIP joints can be explained by a weakened FDP muscle to the ring and little fingers, as the FDP is an important contributor to power grip. This is typically more marked in the little than in the ring finger.1,3
- Slight flexion of the proximal phalanx of the ring finger may be obtained from the contraction of the FDP pulling on the lumbrical, since part of its origin comes from the FDP tendon.3
