Does Steal Phenomenon Exist in Multiple Neurotization?-An Experimental Rat Study.

BACKGROUND:  Nerve transfers from one common donor nerve to recipient nerves with multiple target branches can yield slower and unpredictable recovery in the target nerves. Our hypothesis is that steal phenomenon exists when multiple nerve neurotization comes from one donor nerve.

METHODS:  In 30 Sprague-Dawley rats, the left ulnar nerve (UN) was selected as the donor nerve, and the musculocutaneous nerve (MCN) and median nerve (MN) as the recipient target nerves. The rats were separated into three groups (10 rats in each): group A, UN-to-MCN (one-target); group B, UN-to-MN (one-target); and group C, UN-to-MCN and MN (two-target). The right upper limbs were nonoperative as the control group. Outcome obtained at 20 weeks after surgery included grooming test, muscle weight, compound muscle action potential, tetanic muscle contraction force, axon counts, and retrograde labeling of the involved donor and target nerves.

RESULTS:  At 20 weeks after surgery, muscles innervated by neurotization resulted in significant worse outcomes than the control side. This was especially true in two-target neurotization in the parameter of muscle weight and forearm flexor muscle contraction force outcome when compared to one-target neurotization. Steal phenomenon does exist because flexor muscle contraction force was significantly worse during two-target neurotization.

CONCLUSION:  This study proves the existence of steal phenomenon in multiple target neurotization but does not significantly affect the functional results. Postoperative rehabilitative measures (including electrical stimulation, induction exercise) and patient compliance (ambition and persistence) are other crucial factors that hold equivalent importance to long-term successful recovery.