Digital Nerve Block of the Fingers

Indications and Clinical Considerations

Digital nerve block of the fingers is used primarily in 2 clinical situations: (1) to provide surgical anesthesia in the distribution of the digital nerves for laceration, tendon, and fracture repair; and (2) to provide postoperative pain relief after joint replacement or major surgical procedures on the hand. The technique can also be used to palliate the pain associated with traumatic neuropathy of the digital nerves of the fingers caused by overuse of scissors and pliers, entrapment neuropathies including plastic bag palsy, or tumors of the digital nerve ( Fig. 102.1 ).

Electromyography helps distinguish other causes of hand numbness from neuropathy of the digital nerve. Plain radiographs are indicated for all patients with digital neuropathies to rule out occult bony disease such as bone spurs or cysts that may be compressing the digital nerve. On the basis of the patient’s clinical presentation, additional testing may be indicated, including complete blood cell count, uric acid, sedimentation rate, and antinuclear antibody testing. Magnetic resonance imaging and ultrasound imaging of the hand can be done to rule out soft-tissue tumors such as ganglia that may be compressing the digital nerve ( Fig. 102.2 ). The injection technique described later serves as both a diagnostic and a therapeutic maneuver.

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. Occurring with increasing frequency as stores have switched from paper bags to smaller plastic bags, plastic bag palsy may present in either an acute or chronic form. In plastic bag palsy, compression by the handle of a heavy plastic bag is the inciting cause ( Fig. 102.3 ). The common clinical feature of plastic bag palsy is the presence of painful digital nerves at the point at which the plastic bag handles compress the nerves. Occasionally seen in the homeless who carry the same plastic bag of their possessions in the same hand each day, the affected nerves may be thickened and inflammation of the nerve and overlying soft tissues may be seen. In addition to pain, the patient suffering from plastic bag palsy may also complain of paresthesias and numbness just below the point of nerve compromise. Pain may also increase with exposure to cold.