[Nerve-plasty interventions on the facial nerve in the elderly patient--morphological evaluation of disappointing functional results].

BACKGROUND

Nerve sutures such as facial-facial anastomosis are helpful methods for recovery of facial movements after peripheral nerve lesions. Most of the results on neuronal regeneration were based on experiments with young or young adult animals. In contrary the vast majority of the diseases (cholesteatoma or tumors of the parotid gland) causing facial nerve lesions are in aged patients.

METHODS

Therefore, we compared the original data from two recently published articles concerning the axonal outgrowing process after facial-facial-anastomosis in young-adult and aged rats. In additional, we tried to explain the clinically observed postparalytic syndrome (synkinesia, autoparalytic syndrome,...) after surgical interventions on the facial nerve with the experimental results in the rat.

RESULTS

As an important result, we could not find spontaneous loss of facial motoneurons on the control side in the aged rats. On the operated side, two results have to be emphasized. The initial regeneration (10-42 days after the operation) showed a significant faster reinnervation in the group of young rats. The aged rats showed an apparent hyperinnervation after axonal outgrow to the mimic muscles has been accomplished.

CONCLUSION

Both experimental observations are in agreement with our clinical experiences. After facial nerve surgery, aged patients show a delayed recovery of the mimic functions and a more pronounced postparalytic syndrome. A morphological explanation one can bear is that the delayed reinnervation causes the extreme hyerinnervation, which leads to a simultaneous innervation of different muscles by same facial motoneurons.