Laryngeal abductor muscle reinnervation in a pig model.
OBJECTIVE
To develop a large animal model for studies of laryngeal abductor reinnervation.


METHODS
Six minipigs underwent unilateral anastomosis of the phrenic nerve-abductor branch of the recurrent laryngeal nerve (RLN). Polyhydroxybutyrate (PHB) conduits were used for repair. At each of 30, 60 and 120 days, 2 animals underwent video laryngeal endoscopy (VLE) and were then killed. VLE was also performed in the 120-day pair at 60 days. Nerve-conduit-nerve-muscle samples were fixed for light and immunofluorescence (pan-neurofilaments, S-100) microscopy. Laryngeal muscles were harvested (myosin heavy chain analysis).


RESULTS
VLE showed recovery of abductor function in 1 animal at 60 days and in 1 at 120 days. Haematoxylin-eosin staining demonstrated a complex inflammatory response. Eosinophil recruitment was observed. Stepwise regeneration and reorganization of the distal nerve between 30 and 120 days was observed with pan-NF staining. The mean minimum diameter in the reinnervated posterior crico-arytenoids tended to increase for up to 120 days.


CONCLUSIONS
Anastomosis of the phrenic nerve-abductor branch of the RLN with a PHB conduit in a pig can result in functional and histological recovery within 2-4 months and appears to at least sustain abductor muscle fibre morphology. Recovery occurs despite a complex inflammatory response, which may be an essential part of healing rather than inhibitory.
Birchall
Martin
M
Laryngeal Research Group, University of Bristol, Bristol, UK. martin.birchall@bristol.ac.uk
Idowu
Bernadine
B
Murison
Pamela
P
Jones
Alan
A
Burt
Rachel
R
Ayling
Sarah
S
Stokes
Chris
C
Pope
Laysan
L
Terenghi
Giorgio
G
D000714:Anastomosis, Surgical; D000818:Animals; D004724:Endoscopy; D005260:Female; D007821:Laryngeal Muscles / Q000033:anatomy & histology / Q000166:cytology / Q000294:innervation*; D009413:Nerve Fibers, Myelinated / Q000502:physiology; D010791:Phrenic Nerve / Q000601:surgery; D010865:Pilot Projects; D020127:Recovery of Function; D012009:Recurrent Laryngeal Nerve / Q000033:anatomy & histology / Q000166:cytology / Q000601:surgery*; D012038:Regeneration / Q000502:physiology; D012129:Respiratory Function Tests; D013552:Swine; D013997:Time Factors; D014743:Videotape Recording