Microneurovascular allotransplantation of the canine tongue.
BACKGROUND
Reconstruction of the tongue with existing methods of tissue transfer often leaves glossectomy patients with significant deficits in speech and swallowing. The critical role of the tongue is implied by its unique structure and function. This paper reports the development of an animal model of hemitongue allotransplantation and documents functional and anatomic outcomes of this procedure.


METHODS
Ten pairs of unmatched dogs underwent reciprocal exchange of the left hemitongue with microneurovascular replantation. The unoperated hemitongue acted as the control. Under cyclosporine immunosuppression, animals surviving long term underwent clinical observation, before electromyography, force transduction studies, and histological evaluation being euthanized.


RESULTS
Five animals survived between 6 and 13 months for long-term evaluation. The remaining group were euthanized because of or died of overwhelming infection or uncontrollable transplant rejection. The latter sometimes resulted from difficulty in the delivery of the cyclosporine. Clinical recovery of tongue function was observed, as well as resumption of motor unit potential activity on electromyography. Contractile force recovery of the transplanted tongue averaged 68% of control (range, 47%-97%), and histological study of the hypoglossal and lingual nerves demonstrated anatomic evidence of reinnervation. Preservation of muscle, mucosal, and stromal ultrastructure was seen with light microscopy of the transplanted tongue.


CONCLUSIONS
Allotransplantation of the hemitongue and associated neurovascular apparatus is possible in a large mammalian model, with long-term survival of tissue being accompanied by partial recovery of contractile properties. Anatomical and clinical evidence also points to sensory recovery. These data support the future possibility of employing a similar technique in glossectomy patients.
Haughey
B H
BH
Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, St. Louis, MO 63110, USA.
Beggs
J C
JC
Bong
J
J
Genden
E M
EM
Buckner
A
A
D000818:Animals; D016572:Cyclosporine / Q000627:therapeutic use; D004285:Dogs; D004576:Electromyography; D005260:Female; D006084:Graft Rejection; D006085:Graft Survival; D007002:Hypoglossal Nerve / Q000502:physiology / Q000601:surgery; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D008036:Lingual Nerve / Q000502:physiology / Q000601:surgery; D008297:Male; D009416:Nerve Regeneration / Q000502:physiology; D014059:Tongue / Q000503:physiopathology / Q000637:transplantation*; D014184:Transplantation, Homologous
D007166:Immunosuppressive Agents; D016572:Cyclosporine