Regeneration through a long nerve graft used in the correction of facial palsy

A surgical technique has been developed for the correction of established unilateral palsy in man. A long (20 cm or more) sural nerve graft is anastomosed to a facial nerve branch on the unaffected side and its distal end left lying free in the cheek of the affected side. After regeneration times of 5.5-14.5 months, the distal end of the graft is joined to a free (pectoralis minor) muscle graft. In due course the muscle graft contracts in unison with the unaffected side giving near normal symmetry to facial movements. In 30 cases (ages 6-52 years) qualitative and quantitative examination was made of the distal end of grafts taken at the time of joining the graft to the muscle. Total axon counts, myelinated plus non-myelinated, confirmed abundant regeneration when compared with total axons in the supplying facial nerve; myelinated fibres remained small (mean diameter 2.5 micrometers) over the range of regeneration times. Quantitation included non-myelinated axons because they probably have the potential to become myelinated once the nerve is functional. Numbers of regenerating axons were not correlated with age, nor with regeneration time. Lack of a distal connection did not appear to lead to secondary degeneration of the regenerated myelinated fibres. These were maintained in an 'immature' state for many months. This observation is of practical interest since it has been suggested that delayed connection to the distal target may have a deleterious effect on the outcome of the procedure.