Free radial forearm flap transplantations for reconstruction of the oral cavity and oropharynx. Clinical and morphological findings with special attention paid to sensory reinnervation

It remains a controversial question whether or not the anastomosis of sensory nerves is necessary in free transplants of microvasculary re-anastomosed radial forearm flaps in the oral cavity and oropharynx. Some authors perform this routinely because they expect fewer complications in a skin with a sensory nerve supply. We carried out clinical and morphological examinations in 20 patients in order to determine the sensory innervation of the transplanted tissue. All patients received free transplants of microvasculary reanastomosed radial forearm flaps during a tumor operation in the oral cavity or oropharynx. Postoperative wound healing proceeded without complications in all but three cases, but these disturbances were insufficient to explain any deficit in sensation in the operated areas. Following surgery, sensation was determined clinically by two-point discrimination. Morphological studies of 20 flap biopsies using conventional colored light microscopy demonstrated nerve fibers in 14 of the biopsies. Immunohistochemical investigations also showed the presence of small nerve fibers by proving S-100 positive Schwann cells. We could not find a correlation between the demonstration of nerve fibers and the use of radiation (or an increased radiation dosage) following surgery. These findings suggest that nerve regeneration was completed just before the 6(th) postoperative month, which was the earliest time recorded in this study. Perivascular (vegetative) nerves showed a delayed regeneration and could be demonstrated only 36 months after operation. Histological investigations of the transplanted tissue showed a decrease in keratin with a partial increase in parakeratosis, a loss of skin structures and nearly always chronic inflammation. Our findings verify that a sensory innervation is possible in free transplanted radial forearm flaps by the regeneration of nerves coming from the transplantation bed and/or adjacent (oral) mucosa. This leads to a sensation comparable to that of healthy mucosa. These findings also indicate that there is no need for the anastomosis of sensory nerves during transplant surgery.