Tongue replantation in an animal model

A novel flap design technique for subtotal tongue reconstruction with an "Individualized and Convenient Tongue Model"

BACKGROUND

To achieve improved functional outcomes in subtotal tongue reconstruction, a flap design with sufficient volume and appropriate shape is necessary. In this study, we introduce an "Individualized and Convenient Tongue Model" (ICTM) for flap design in subtotal tongue reconstruction.

METHODS

By studying the anatomical morphology of the tongue, we found a similar geometry within the dorsum and body of the tongue as well as the mouth floor. This can be used to create an ICTM through folding and splicing. We can simulate tongue defects in the ICTM and transform defect shapes into guide plates for flap design. In this study, fifty-eight patients requiring subtotal tongue reconstruction were randomly divided into two groups: an ICTM group (35 patients) and a conventional group (31 patients). In the ICTM group, we individually designed profunda artery perforator flaps (PAPFs) or anterolateral thigh flaps (ALTFs) using the ICTM method. In the conventional group, the flap was designed according to the surgeon's clinical experience. Patient demographics, operative and follow-up data were recorded. Swallowing, speech intelligibility, and cosmetic results were assessed using appropriate scales.

RESULTS

All flaps survived, although there were no significant differences in tumor size, operation time, flap size, and complication rate compared to the conventional group. Patients in the ICTM group had significantly improved speech intelligibility (p = 0.019), cosmetic appearance (p = 0.009), and swallowing ability (p = 0.003).

CONCLUSIONS

The ICTM technique is an effective and convenient solution for subtotal tongue reconstruction that provides an individualized flap design and improves functional outcomes compared to the conventional design.

Hemi-tongue Allograft Transplantation in Dogs

Background

When complete recovery of tongue function following tumor excision is desired, reestablishment of the complex movements of the tongue is necessary. However, currently available methods for recovery of tongue function, such as flap surgery or prosthesis insertion, are inadequate. In the current study, we investigated the effects of transplantations of tongue allografts.

Methods

Hemi-tongue allotransplantation procedures were performed with 8 pairs of sex-blind and unrelated beagle dogs. In each donor, the right side of the tongue, including the lingual and hypoglossal nerves, extrinsic muscles of the tongue, mucous membrane of the oral floor, lingual artery, and vein were exposed. A vascularized transplantation method was used with manual anastomosis of the blood vessels and nerves.

Results

Survival of the grafted tongue was only noted in 1 dog that died 5 days after transplantation. We suspected that the death was due to nutritional deficiency or dehydration, rather than hyperacute rejection of the transplant or technical failure of the microsurgical anastomosis. The grafted tongue was partially connected to the side of the recipient tongue, and lymphocyte infiltration was observed in this dog.

Conclusions

Postoperative management is difficult in dogs. Even if tongue allograft including nerves and extrinsic muscles is performed, it seems to take a long time before the tongue recovers its functions. Furthermore, expansive tongue allograft was too invasive a treatment for animals. If we want to adapt this procedure to humans, the first trial in a human will be done without animal experiments, as was the case with face transplantations.

"Five-point eight-line" anatomic flap design for precise hemitongue reconstruction

BACKGROUND

Reconstruction of hemiglossectomy defects requires careful flap design to avoid adverse functional and aesthetic outcomes.

METHODS

Hemitongue specimens were obtained from minipigs to study the three-dimensional anatomy and to define anatomic landmarks for precise measurements of flap requirement. The concept developed in animal models was then applied to hemiglossectomy reconstruction in clinical practice. Sixty-one patients were randomly enrolled into the following two groups: a "five-point eight-line segment" (FIPELS) flap design group (28 patients) and a conventional group (33 patients). Functional and aesthetic outcomes were compared between the two groups.

RESULTS

All flaps designed with the FIPELS technique matched the hemiglossectomy defects without the need for flap trimming, thus reducing the operating time (P = .03). Swallowing functions, speech intelligibility, and aesthetic outcomes were superior in the FIPELS group than that in the conventional group (P < .05).

CONCLUSIONS

The FIPELS flap design for hemiglossectomy reconstruction yields improved functional and aesthetic outcomes compared to a conventional flap design.

Rat model of laryngeal transplantation with normal circulation maintained by combination with the tongue

Recent research on laryngeal transplantation used a rat model with physiologically abnormal circulation, because the common carotid artery was used for venous drainage. Since a model with normal circulation is better for accurate assessment, we developed a vascularized laryngeal graft, using the common carotid artery as the arterial supply and the external jugular vein as the venous drainage. The transplant included other tributaries from the tongue and the pharynx by combination with the tongue, because the tributaries from the larynx were very small. Ten transplants were performed. The transplanted organs were examined daily. Seven days after transplantation, the composite grafts were evaluated histologically. The mortality rate was 10%. All composite grafts were fully viable, and their structure was maintained in the remaining nine rats. Our model is appropriate for experiments on laryngeal transplantation.