Manual stimulation, but not acute electrical stimulation prior to reconstructive surgery, improves functional recovery after facial nerve injury in rats

Article type: Research Article

Authors: Skouras, Emmanouil | Merkel, Daniel | Grosheva, Maria | Angelova, Srebrina K. | Schiffer, Gereon | Thelen, Ulrich | Kaidoglou, Katerina | Sinis, Nektarios | Igelmund, Peter | Dunlop, Sarah A. | Pavlov, Stoyan | Irintchev, Andrey | Angelov, Doychin N.

Affiliations: Department of Trauma, Hand and Reconstructive Surgery, University of Cologne, Cologne, Germany | Anatomical Institute I, University of Cologne, Cologne, Germany | Department of Oto-Rhino-Laryngology, University of Cologne, Cologne, Germany | Department of Histology and Embryology, Aristotle University Thessaloniki, Thessaloniki, Greece | Department of Hand-, Plastic-, and Reconstructive Surgery with Burn Unit, BG-Trauma Centre, University of Tuebingen, Tuebingen, Germany | School of Animal Biology and Western Australian Institute for Medical Research, The University of Western Australia, Perth, WA, Australia | Department of Anatomy, Histology, Embryology, Medical University Varna, Varna, Bulgaria | Department of Oto-Rhino-Laryngology, Friedrich-Schiller University Jena, Jena, Germany

Note: [] Corresponding author: Prof. Dr. Doychin N. Angelov, M.D., Ph.D., Institut für Anatomie der Universität zu Köln, Joseph-Stelzmann-Strasse 9, D-50924 Köln, Germany. Tel.: +49 221 478 5654; Fax: +49 221 478 6711; E-mail: [email protected]

Abstract: The outcome of peripheral nerve injuries requiring surgical repair is poor. Recent work suggested that electrical stimulation (ES) of the proximal nerve stump to produce repeated discharges of the parent motoneurons for one hour could be a beneficial therapy if delivered immediately prior to reconstructive surgery of mixed peripheral nerves. Purpose: We tested whether ES has a positive influence on functional recovery after repair of a purely motor nerve, the facial nerve. Methods: Electrical stimulation (20 Hz) was delivered to the proximal nerve stump of the transected facial nerve for 1 hour prior to nerve reconstruction by end-to-end suture (facial-facial anastomosis, FFA). For manual stimulation (MS), animals received daily rhythmic stroking of the whisker pads. Restoration of vibrissal motor performance following ES or MS was evaluated using video-based motion analysis. We also assessed the degree of collateral axonal branching at the lesion site, by counting motoneuronal perikarya after triple retrograde labeling, and estimated the quality of motor end-plate reinnervation in the target musculature. Outcomes at 4 months were compared to animals receiving sham stimulation (SS) or MS. Results: Neither protocol reduced the degree of collateral sprouting. ES did not improve functional outcome and failed to reduce the proportion of polyinnervated motor end-plates. By contrast, MS restored normal whisking function and reduced polyinnervation. Conclusion: Whereas acute ES is not beneficial for facial nerve repair, MS provides long-term benefits.

Keywords: Electrical stimulation, facial nerve, functional recovery, motoneuron, nerve repair

DOI: 10.3233/RNN-2009-0474

Journal: Restorative Neurology and Neuroscience, vol. 27, no. 3, pp. 237-251, 2009