Reconstruction of tonic vibration reflex in the biceps brachii reinnervated by transferred intercostal nerves in patients with brachial plexus injury

Abstract

The transfer of intercostal nerves to musculocutaneous nerves has been performed to reconstruct elbow flexion in patients with brachial plexus injury. In nine of 15 such patients, 2–3 Hz tapping of the distal tendon of the biceps muscle reinnervated by the transferred intercostal nerves (IC-biceps) induced a mode in the correlogram between tap and EMG pulse of IC-biceps. In five of the mode-positive patients, tapping of various frequencies induced gradual augmentation of integrated EMG of IC-biceps. This reflex was consistent with the tonic vibration reflex (TVR) in normal controls. Conduction velocity and frequency property of the reflex were compatible with the speculation that rapid-conducting muscle afferents (group Ia or II or both) reinnervate mechanoreceptors, such as muscle spindles. The clinical significance of muscle sensory reinnervation is not clear; however, the reconstruction of TVR following this operation is worthy in that it confirms the specific sensory reinnervation of denervated muscle in humans.