title: Facial Nerve Axonal Analysis and Anatomical Localization in Donor Nerve: Optimizing Axonal Load for Cross-Facial Nerve Grafting in Facial Reanimation.
abstract: BACKGROUND
  Donor nerve axonal count over 900 in two-stage reconstructions using cross-facial nerve grafts is possibly associated with improved outcomes in facial reanimation. Facial nerve axonal analysis was performed to determine the ideal location for optimizing axonal load. Correlation of axonal number, branch diameter, and age was also assessed.
  
  
  METHODS
  Twenty-eight fresh unpreserved cadaveric hemifaces were dissected exposing the extracranial facial nerve branches. Axonal counts at 2-cm intervals from the pes anserinus along branches inserting into the zygomaticus major muscle were taken, noting position relative to the zygomatic arch, posterior ramus border, lateral border of the zygomaticus muscle, and anterior parotid gland border. Nerves were fixed, sectioned, and stained with SMI-31 antineurofilament stain for digital axonal analysis.
  
  
  RESULTS
  All specimens had one or more intraparotid zygomatic branches with over 900 axons, and 96 percent had an extraparotid branch with over 900 axons. The likelihood that a zygomatic branch would have over 900 axons at its last intraparotid point (mean, 6 mm posterior to the parotid border) was 92 percent (range, 67 to 100 percent) in contrast to 61 percent (range, 25 to 100 percent) when sampled at the first extraparotid point (mean, 14 mm anterior to the parotid border). Nerve cross-sectional area was positively correlated to its axonal count (R° = 78 percent; p < 0.0001), with nerve diameter over 0.6 mm predicting over 900 axons. Age did not correlate with axonal counts.
  
  
  CONCLUSIONS
  Branches with adequate axonal load were found in all specimens. The likelihood of adequate branch selection improved from 61 percent to 92 percent with short retrograde intraparotid dissection. Nerve diameter correlated with axonal load.
authors.affiliation: Dallas, Texas; Beirut, Lebanon; and Bethesda, Md.|From the Department of Plastic Surgery, Department of Otolaryngology, and Department of Pathology, Division of Neuropathology, University of Texas Southwestern Medical Center; the Division of Plastic and Reconstructive Surgery, American University of Beirut; and Otology/Neurotology, Walter Reed National Military Medical Center.
authors.forename: Austin
authors.initials: A
authors.lastname: Hembd
authors.affiliation: Dallas, Texas; Beirut, Lebanon; and Bethesda, Md.|From the Department of Plastic Surgery, Department of Otolaryngology, and Department of Pathology, Division of Neuropathology, University of Texas Southwestern Medical Center; the Division of Plastic and Reconstructive Surgery, American University of Beirut; and Otology/Neurotology, Walter Reed National Military Medical Center.
authors.forename: Purushottam A
authors.initials: PA
authors.lastname: Nagarkar
authors.affiliation: Dallas, Texas; Beirut, Lebanon; and Bethesda, Md.|From the Department of Plastic Surgery, Department of Otolaryngology, and Department of Pathology, Division of Neuropathology, University of Texas Southwestern Medical Center; the Division of Plastic and Reconstructive Surgery, American University of Beirut; and Otology/Neurotology, Walter Reed National Military Medical Center.
authors.forename: Salim
authors.initials: S
authors.lastname: Saba
authors.affiliation: Dallas, Texas; Beirut, Lebanon; and Bethesda, Md.|From the Department of Plastic Surgery, Department of Otolaryngology, and Department of Pathology, Division of Neuropathology, University of Texas Southwestern Medical Center; the Division of Plastic and Reconstructive Surgery, American University of Beirut; and Otology/Neurotology, Walter Reed National Military Medical Center.
authors.forename: Dinah
authors.initials: D
authors.lastname: Wan
authors.affiliation: Dallas, Texas; Beirut, Lebanon; and Bethesda, Md.|From the Department of Plastic Surgery, Department of Otolaryngology, and Department of Pathology, Division of Neuropathology, University of Texas Southwestern Medical Center; the Division of Plastic and Reconstructive Surgery, American University of Beirut; and Otology/Neurotology, Walter Reed National Military Medical Center.
authors.forename: J Walter
authors.initials: JW
authors.lastname: Kutz
authors.affiliation: Dallas, Texas; Beirut, Lebanon; and Bethesda, Md.|From the Department of Plastic Surgery, Department of Otolaryngology, and Department of Pathology, Division of Neuropathology, University of Texas Southwestern Medical Center; the Division of Plastic and Reconstructive Surgery, American University of Beirut; and Otology/Neurotology, Walter Reed National Military Medical Center.
authors.forename: Brandon
authors.initials: B
authors.lastname: Isaacson
authors.affiliation: Dallas, Texas; Beirut, Lebanon; and Bethesda, Md.|From the Department of Plastic Surgery, Department of Otolaryngology, and Department of Pathology, Division of Neuropathology, University of Texas Southwestern Medical Center; the Division of Plastic and Reconstructive Surgery, American University of Beirut; and Otology/Neurotology, Walter Reed National Military Medical Center.
authors.forename: Sachin
authors.initials: S
authors.lastname: Gupta
authors.affiliation: Dallas, Texas; Beirut, Lebanon; and Bethesda, Md.|From the Department of Plastic Surgery, Department of Otolaryngology, and Department of Pathology, Division of Neuropathology, University of Texas Southwestern Medical Center; the Division of Plastic and Reconstructive Surgery, American University of Beirut; and Otology/Neurotology, Walter Reed National Military Medical Center.
authors.forename: Charles L
authors.initials: CL
authors.lastname: White
authors.affiliation: Dallas, Texas; Beirut, Lebanon; and Bethesda, Md.|From the Department of Plastic Surgery, Department of Otolaryngology, and Department of Pathology, Division of Neuropathology, University of Texas Southwestern Medical Center; the Division of Plastic and Reconstructive Surgery, American University of Beirut; and Otology/Neurotology, Walter Reed National Military Medical Center.
authors.forename: Rod J
authors.initials: RJ
authors.lastname: Rohrich
authors.affiliation: Dallas, Texas; Beirut, Lebanon; and Bethesda, Md.|From the Department of Plastic Surgery, Department of Otolaryngology, and Department of Pathology, Division of Neuropathology, University of Texas Southwestern Medical Center; the Division of Plastic and Reconstructive Surgery, American University of Beirut; and Otology/Neurotology, Walter Reed National Military Medical Center.
authors.forename: Shai M
authors.initials: SM
authors.lastname: Rozen
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001369:Axons; D005152:Facial Muscles / Q000294:innervation*; D005154:Facial Nerve / Q000033:anatomy & histology* / Q000637:transplantation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010306:Parotid Gland / Q000294:innervation; D015050:Zygoma / Q000294:innervation