Abstract

Plastic bag palsy is an entrapment neuropathy of the digital nerves caused by compression of the nerves against the bony phalanges by the handles of a plastic bag. The common digital nerves arise from fibers of the median and ulnar nerves. The thumb also has contributions from superficial branches of the radial nerve. The common digital nerves pass along the metacarpal bones and divide as they reach the distal palm. The volar digital nerves supply the majority of sensory innervation to the fingers and run along the ventrolateral aspect of the finger beside the digital vein and artery. The smaller dorsal digital nerves contain fibers from the ulnar and radial nerves and supply the dorsum of the fingers as far as the proximal joints.

Plastic bag palsy has increased in frequency as stores have switched from paper to plastic bags. Compression by the handles of a heavy plastic bag is the inciting cause, and the most common clinical feature is the presence of painful digital nerves at the point of compression. Plastic bag palsy may present in either an acute or a chronic form. Pain may develop from an acute injury to the nerves after carrying a heavy bag on too few fingers, or it may occur from direct trauma to the soft tissues overlying the digital nerves if the fingers become caught in a bag handle twisted around them. Plastic bag palsy is occasionally seen in homeless people who carry their possessions around in bags and who use the same hand day after day. The affected nerves may be thickened, and inflammation of the nerve and overlying soft tissues may be seen. In addition to pain, patients may complain of paresthesias and numbness just below the point of nerve compromise.