Intraoperative testing of selectivity of spiral nerve cuff electrodes

Nerve cuff electrodes were used intraoperatively to stimulate peripheral nerves to test electrode selectivity in the human upper extremity. Subjects were recruited from patients undergoing upper extremity nerve repair procedures. The nerves were stimulated through different contacts in the cuff and with varying parameters. Estimates of threshold and selectivity data were recorded. The stimulation thresholds found were an order of magnitude higher than prior animal studies using the spiral nerve cuff electrode. Preliminary selectivity was found on the ulnar nerve and the upper trunk of the brachial plexus of one subject. The biceps and pectoralis major were selectively activated by a single cuff placed proximally, on the upper trunk; the flexor carpi ulnaris and first dorsal interosseous were selectively activated by a single cuff placed on the ulnar nerve.