Comparison of Myelin-Associated Glycoprotein With Vincristine for Facial Nerve Inhibition After Bilateral Axotomy in a Transgenic Thy1-Gfp Rat Model.
JAMA Facial Plast Surg
; 21(5): 426-433, 2019 Sep 01.
Article
em En
| MEDLINE
| ID: mdl-31219545
ABSTRACT
IMPORTANCE Aberrant synkinetic movement after facial nerve injury can lead to prominent facial asymmetry and resultant psychological distress. The current practices of neuroinhibition to promote greater facial symmetry are often temporary in nature and require repeated procedures. OBJECTIVE:
To determine whether myelin-associated glycoprotein (MAG), a specific neuroinhibitor, can prevent neuroregeneration with efficacy comparable with that of vincristine, a well-established neurotoxin. DESIGN, SETTING, ANDPARTICIPANTS:
Rats transgenic for Thy-1 cell surface antigen-green fluorescent protein (Thy1-Gfp) were randomized into 3 groups. Each rat received bilateral crush axotomy injuries to the buccal and marginal mandibular branches of the facial nerves. The animals received intraneural injection of saline, MAG, or vincristine. MAIN OUTCOMES ANDMEASURES:
The animals were imaged via fluorescent microscopy at weeks 1, 3, 4, and 5 after surgery. Quantitative fluorescent data were generated as mean intensities of nerve segments proximal and distal to the axotomy site. Electrophysiological analysis, via measurement of compound muscle action potentials, was performed at weeks 0, 3, 4, and 5 after surgery.RESULTS:
A total of 12 rats were included in the study. Administration of MAG significantly reduced fluorescent intensity of the distal nerve in comparison with the control group at week 3 (mean [SD], MAG group 94 [11] intensity units vs control group 130 [11] intensity units; P < .001), week 4 (MAG group 81 [19] intensity units vs control group 103 [9] intensity units; P = .004), and week 5 (MAG group 76 [10] intensity units vs control group 94 [10] intensity units; P < .001). In addition, rats treated with MAG had greater fluorescent intensity than those treated with vincristine at week 3 (mean [SD], MAG group 94 [11] intensity units vs vincristine group 76 [6] intensity units; P = .03), although there was no significant difference for weeks 4 and 5. At week 5, both MAG and vincristine demonstrated lower distal nerve to proximal nerve intensity ratios than the control group (control group, 0.94; vs MAG group, 0.82; P = .01; vs vincristine group; 0.77; P < .001). There was no significant difference in amplitude between the experimental groups at week 5 of electrophysiological testing. CONCLUSIONS AND RELEVANCE Lower facial asymmetry and synkinesis are common persistent concerns to patients after facial nerve injury. Using the Thy1-Gfp rat, this study demonstrates effective inhibition of neuroregeneration via intraneural application of MAG in a crush axotomy model, comparable with results with vincristine. By potentially avoiding systemic toxic effects of vincristine, MAG demonstrates potential as an inhibitor of neural regeneration for patients with synkinesis. LEVEL OF EVIDENCE NA.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Vincristina
/
Glicoproteína Associada a Mielina
/
Sincinesia
/
Nervo Facial
Idioma:
En
Ano de publicação:
2019
Tipo de documento:
Article