title: Quantification of Trapezius Muscle Innervation During Neck Dissections: Cervical Plexus Versus the Spinal Accessory Nerve.
abstract: OBJECTIVE
  Despite increasing use of selective, nerve-sparing surgical techniques during neck dissections, the reported rate of postoperative paralysis of the trapezius muscle is still high. The aim of the study is to measure and compare motor inflow to the trapezius muscle, in order to better understand the peripheral neuroanatomy.
  
  
  METHODS
  Intraoperative nerve monitoring (electroneurography) in patients undergoing routine neck dissection (n=18). The innervation of the 3 functional parts of the trapezius muscle was mapped and quantified through compound muscle action potentials.
  
  
  RESULTS
  In 18/18 (100%) of the patients, the spinal accessory nerve (SAN) innervated all parts of the trapezius muscle. In 7/18 (39%) of the patients, an active motor branch from the cervical plexus was detected, equally distributed to all functional parts of the trapezius muscle, at levels comparable to the SAN.
  
  
  CONCLUSIONS
  Compared to the SAN, branches from cervical plexus provide a significant amount of neural input to all parts of the trapezius muscle. Intraoperative nerve monitoring can be used in routine neck dissections to detect these branches, which may be important following surgical injury to the SAN.
authors.affiliation: Karolinska Institutet, Stockholm, Sweden Karolinska University Hospital, Stockholm, Sweden clara.svenberg-lind@karolinska.se.
authors.forename: Clara
authors.initials: C
authors.lastname: Svenberg Lind
authors.affiliation: Karolinska Institutet, Stockholm, Sweden Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Bertil
authors.initials: B
authors.lastname: Lundberg
authors.affiliation: Karolinska Institutet, Stockholm, Sweden Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Lalle
authors.initials: L
authors.lastname: Hammarstedt Nordenvall
authors.affiliation: Karolinska Institutet, Stockholm, Sweden.
authors.forename: Susanne
authors.initials: S
authors.lastname: Heiwe
authors.affiliation: Karolinska Institutet, Stockholm, Sweden Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Jonas K E
authors.initials: JK
authors.lastname: Persson
authors.affiliation: Karolinska Institutet, Stockholm, Sweden Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Jonas
authors.initials: J
authors.lastname: Hydman
mesh_terms: D000055:Accessory Nerve / Q000473:pathology*; D000368:Aged; D002572:Cervical Plexus / Q000473:pathology*; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D016343:Monitoring, Intraoperative / Q000379:methods; D037981:Neck Dissection / Q000009:adverse effects / Q000379:methods; D017063:Outcome Assessment, Health Care; D010243:Paralysis / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D011183:Postoperative Complications / Q000175:diagnosis / Q000503:physiopathology / Q000517:prevention & control*; D064171:Superficial Back Muscles / Q000294:innervation*
keywords: cervical plexus; neck dissection; shoulder syndrome; spinal accessory nerve; trapezius muscle