Which End is Up? Terminology for Terminolateral (End-to-Side) Nerve Repair: A Review A. Lee Dellon, M.D., Ph.D., 1 Marcus Castro Ferreira, M.D., Ph.D., 2 Eric H. Williams, M.D., 1 and Gedge D. Rosson, M.D. 1 ABSTRACT By convention, we ‘‘come from’’ and ‘‘go to.’’ A flap has a donor site and goes to a recipient site. A transplant comes from a donor and goes to a recipient. Neural regeneration proceeds from proximal to distal. It seems most appropriate then for a nerve repair description to follow this logical order. Therefore an ‘‘end-to-side’’ repair would mean that the donor nerve, the nerve that is providing the axons with which to neurotize the recipient nerve, should be the nerve named first. An end-to-side repair would therefore require that the nerve whose end is sutured into the side of the recipient nerve be the nerve that is bringing the proximal axons to regenerate distally, for whatever that purpose may be, sensory or motor. A side-to-end repair would therefore require that the nerve whose side is sutured to the end of the recipient nerve be the nerve that is bringing the proximal axons to regenerate distally, for whatever that purpose may be, sensory or motor. The full descriptive phrase must include whether the intent is to reinnervate a skin target and is, therefore, a sensory repair, or to reinnervate a motor target. The names of both the donor and the recipient nerves must be specified. Illustrations of these logical possibilities are shown in this review of the modern history of ‘‘end-to-side’’ or ‘‘side-to-end’’ nerve coaptations. KEYWORDS: Neurorrhaphy, neurotization, end-to-side As the field of reconstructive microsurgery en- tered the world stage, it became necessary to define the meaning of words that were being used to describe not only operative details but also research techniques and outcomes. Indeed, there was no phrase for this field itself (Terzis JK, personal communication, February 12, 2009). The term for this new field was coined when Rollin Daniel and I published the first book ever on microsurgery titled, ‘‘Reconstructive Microsurgery’’ in 1976 by Little and Brown Co. ... Later on Bernie O’Brien and Wayne Morrison [in Australia] used the same title for their book that came out in the 80s. In 1979 and in 1984, when the ISRM [International Society for Reconstructive Microsurgery] and the ASRM [American Society for Reconstructive Micro- surgery] became organized as formal societies, they adopted this terminology. In a landmark publication, Millesi and Terzis 1 reported the considerations of a committee of the 1 Division of Plastic Surgery, Johns Hopkins University, Baltimore, Maryland; 2 Department of Plastic Surgery, University of Sao Paolo, Sao Paolo, Brazil. Address for correspondence and reprint requests: Gedge D. Rosson, M.D., Division of Plastic, Reconstructive, and Maxillofacial Surgery, The Johns Hopkins Hospital Outpatient Center, 601 North Caroline Street, McElderry 8161, Baltimore, MD 21287 (e-mail: gedge@jhmi.edu). J Reconstr Microsurg 2010;26:295–301. Copyright # 2010 by Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York, NY 10001, USA. Tel: +1(212) 584-4662. Received: October 13, 2009. Accepted: December 3, 2009. Published online: February 8, 2010. DOI: http://dx.doi.org/10.1055/s-0030-1248240. ISSN 0743-684X. 295