title: The impact of different degrees of injured c7 nerve transfer: an experimental rat study.
abstract: BACKGROUND
  Ipsilateral C7 nerve transfer is an available procedure in C5C6 2-root avulsion injury of the brachial plexus. However, concomitant injury of a normal-looking C7 cannot be ruled out. The efficiency of a concomitant injury of C7 transfer was investigated.
  
  
  METHODS
  Forty-two Sprague-Dawley rats were randomly assigned to 5 groups. They all underwent a 2-stage procedure. In the first stage from dorsal spine approach, left C5 and C6 roots were avulsed and C7 was crushed with jeweler's forceps with different degrees: group A (n = 6), C7 not injured; group B (n = 10), C7 crushed for 10 seconds; group C (n = 10), C7 crushed for 30 seconds; group D (n = 10), C7 doubly crushed for 60 seconds; and group E (n = 6), C7 transected and not repaired. Four weeks later in the second stage, the C7 was reexplored via volar approach, transected, and coapted to the musculocutaneous nerve. At 12 weeks following the nerve transfer, functional outcomes were assessed.
  
  
  RESULTS
  Grooming test, muscle weight, electromyography, and muscle tetanic contraction force all showed that the biceps muscles were significantly worse in group C (moderate crush) and group D (severe crush). Group B (mild crush) and group A (uninjured) showed no difference. Group E (C7 cut and not repaired) was the worst.
  
  
  CONCLUSIONS
  An injured but grossly normal-looking ipsilateral C7 can be used as a motor source but with variable results. The result is directly proportional to the severity of injury, potentially implying that better results will be achieved when longer regeneration time is allowed.
authors.affiliation: Division of Plastic and Reconstructive Surgery, Department of Surgery, Medical University of Vienna, Vienna, Austria; and Division of Reconstructive Microsurgery, Department of Plastic Surgery, Chang Gung Memorial Hospital, Taoyuan, Taiwan.
authors.forename: Chieh-Han John
authors.initials: CH
authors.lastname: Tzou
authors.affiliation: Division of Plastic and Reconstructive Surgery, Department of Surgery, Medical University of Vienna, Vienna, Austria; and Division of Reconstructive Microsurgery, Department of Plastic Surgery, Chang Gung Memorial Hospital, Taoyuan, Taiwan.
authors.forename: David Chwei-Chin
authors.initials: DC
authors.lastname: Chuang
authors.affiliation: Division of Plastic and Reconstructive Surgery, Department of Surgery, Medical University of Vienna, Vienna, Austria; and Division of Reconstructive Microsurgery, Department of Plastic Surgery, Chang Gung Memorial Hospital, Taoyuan, Taiwan.
authors.forename: Tommy Nai-Jen
authors.initials: TN
authors.lastname: Chang
authors.affiliation: Division of Plastic and Reconstructive Surgery, Department of Surgery, Medical University of Vienna, Vienna, Austria; and Division of Reconstructive Microsurgery, Department of Plastic Surgery, Chang Gung Memorial Hospital, Taoyuan, Taiwan.
authors.forename: Johnny Chuieng-Yi
authors.initials: JC
authors.lastname: Lu