[Secondary nerve reconstruction in the upper extremity in children--results with respect to number of motor units].

After nerve injury, the therapy of choice is primary suture. If this, however, is not possible or inadequate, a secondary reconstruction must be carried out within a suitable period of time. This study shows results after nerve transplantation within a timeframe of six weeks. Seventeen children with peripheral nerve injuries of the upper extremity were treated. Secondary nerve reconstruction was accomplished by sural nerve transplantation. Eight children, aged from 5 to 13 years, were examined. The median nerve was affected in three and the ulnar nerve in five cases. The examination included clinical and electrophysiological assessments. The length of grafts was correlated with the clinical result. Besides the calculation of sensitive and motor nerve conduction velocity the number of motor units from the flexor pollicis brevis muscle or abductor digiti minimi muscle were determined by motor-unit-estimation (MUE) on both sides. The observation time period was on an average 2.9 years. Results were good to excellent. A persisting Hoffmann-Tinel's sign was found only once in median nerve lesion. Loss of sensitivity following harvesting of sural nerve was not noted as a problem by any of these children. Length of grafts did not affect the results. Standard values were reached in every case in the electrophysiological examination. The number of motor units of the abductor pollicis brevis muscle and abductor digiti minimi muscle decreased to approximately 50% compared to the healthy side. Sural nerve grafting resulted in good motor and sensory function. We recommend grafting within six weeks, as Wallerian degeneration is completed and regeneration from the proximal nerve stump is optimal. Although children have a very good regeneration potential, the examined cases did not achieve a complete restoration of all motor units of the muscles.