Facial nerve surgery inevitably leads to partial pareses, abnormally associated movements and pathologically altered reflexes. The reason for this "post-paralytic syndrome" is the misdirected reinnervation of targets, which consists of two major components. First, due to malfunctioning axonal guidance, a muscle gets reinnervated by a "foreign" axon, that has been misrouted along a "wrong" fascicle. Second, the supernumerary collateral branches emerging from all transected axons simultaneously innervate antagonistic muscles and cause severe impairment of their coordinated activity. Since it is hardly possible to influence the first major component and improve the guidance of several thousands axons, the authors concentrated on the second major component and tried to reduce the collateral axonal branching.

<p>Outline of the General Neurobiological Problem

The Perikarya Which Support Axonal Regrowth are Hyperexcitable
Axonal Regrowth is Compromised by Ephaptic Cross-Talk Between the Branches
Biological Significance of Axonal Branching
Role of Cytoskeleton Reorganization During Axonal Branching
The Individual Guidance Cues Promoting Reinnervation of Original Targets are Still Unknown
Conclusion
Outline of the Clinical Problem
Questions Still Open
Methodological Approach
Materials and Methods
First Set of Experiments: Attempts to Reduce Collateral Axonal Branching by Alterations of the Trigeminal Input to the Facial Perikarya
Second Set of Experiments: Attempts to Reduce Collateral Axonal Branching at the Lesion Site
Results
First Set of Experiments: Influence of the Altered Afferent Input to Axotomized Facial Perikarya on the Quality of Reinnervation
Second set of Experiments: Attempts to Reduce Collateral Axonal Branching at the Lesion Site
Discussion
The Combined Approach to Evaluate the Quality of Peripheral Nerve Regeneration
Sensory-Motor Integrity as A Factor for Motor Regeneration
Collateral Branching Versus Terminal Sprouting of Axons
Prospects for the Future
References
Subject index.</p>