Ultrasound-guided metacarpal and digital nerve block is useful in the management of the pain subserved by the metacarpal and digital nerves. This technique serves as an excellent adjunct to brachial plexus block and for general anesthesia when performing surgery on the fingers and is seeing increased utilization to provide anesthesia for reduction of fractures and dislocations of the metacarpals and phalanges as well as to provide surgical anesthesia for tendon repairs and plastic surgery repairs of complex finger injuries. Ultrasound-guided metacarpal and digital nerve block can also be used to provide postoperative pain relief following total joint arthroplasties of the joints of the fingers.

Ultrasound-guided metacarpal and digital nerve block can also be used as a diagnostic tool when performing differential neural blockade on an anatomic basis in the evaluation of hand and finger pain as well as in a prognostic manner to determine the degree of neurologic impairment the patient will suffer when destruction of a metacarpal or digital nerve is being considered or when there is a possibility that the nerve may be sacrificed during surgeries in this anatomic region. This technique may also be useful in those patients suffering symptoms from compression of the metacarpal and digital nerves including patients suffering from bowler’s thumb or plastic bag palsy (Fig. 81.1).

Patients suffering from dysfunction of the metacarpal or digital nerve may suffer from pain with pressure on the nerve when using scissors or jewelry pliers. Dysesthesias are common as is sleep disturbance. On physical examination, pain can be elicited by compression over the affected nerve. Continued compression of the affected nerve may cause numbness distal to the point of compression. Coexistent arthritis, sesamoiditis, gout, other crystal arthropathies, and synovitis of the metacarpal and interphalangeal joints may predispose the patient to the development of entrapment of the metacarpal and digital nerves (Fig. 81.2).

Plain radiographs of the hand are indicated in all patients suspected of suffering from metacarpal and digital nerve dysfunction to rule out occult bony pathology (Fig. 81.3). Based on 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 (MRI) or ultrasound imaging of the hand is indicated to assess the status of the affected nerves as well as to identify other occult pathology including arthritis, sesamoiditis, and synovitis.

The common palmar 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 (Fig. 81.4). 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.