[Light and electron microscopy of human vocal muscle in recurrent laryngeal nerve paresis (author's transl)].

In longstanding recurrent laryngeal nerve paresis with parmedian fixation of the vocal cord the fine structure of the vocal muscle is surprisingly well preserved. Though there are in part bundles of atrophic muscle fibers and increased connective tissue, the normal ultrastructure of the remaining muscle and of the myelinated nerves remains always intact. It is assumed that the vocal cord is prevented from regaining its motility both by the increased connective tissue which misdirects the nerve fibers and by irreverisble changes of the cricoarytaenoid joint. The results are discussed in relation to attempts of reconstructive surgery of the recurrent laryngeal nerve as well as various problems in the neurophysiology of the laryngeal muscles.