A comparison of donor and recipient site sensation in free tissue reconstruction of the oral cavity

In patients who undergo oral cavity reconstruction, loss of sensation plays a vital role in producing disturbances in postoperative oral function. Microsurgical techniques have provided a method of addressing this deficit through the use of sensate cutaneous free flaps in which microneural anastomoses are performed between a sensory nerve supplying the flap, and a recipient nerve in the head and neck. The purpose of this study was to compare the cutaneous sensation of the radial forearm flap and lateral arm flap donor sites, the two most commonly used intraoral sensate flaps. For comparison, sensation was also determined in five intraoral sites: the tip of tongue, lateral tongue, cheek, gingiva, and hard palate. Sensation was evaluated at the two potential donor sites in 66 random subjects using static and moving two-point discrimination, thermal sensation differences, and Semmes-Weinstein monofilament pressures. In the same subjects Semmes- Weinstein monofilament pressures were used to evaluate intraoral sensation. Information was recorded on age, sex, smoking and denture status. All four sensory evaluations demonstrated that the lateral arm flap donor site was mum sensitive than the radial forearm donor site. Thermal sensitivity differentials (0.52 vs. 0.40°C, p <: 0.001), static two-point discrimination (15.4 vs. 15.0 mm, p < 0.2), moving two-point discrimination (5.8 vs. 4.8 mm, p < 0.03), and Semmes-Weinstein monofilament pressures (5.10 vs. 4.08 g per square millimeter, p < 0.001) all indicated a more sensitive lateral arm flap donor site. Older subjects had significantly decreased sensation at both donor rites based on static two-point discrimination and Semmes-Weinstein monofilament testing. No sex differences were noted. Based on Semmes- Weinstein monofilament testing in the mouth, the tip of the tongue is the most sensitive area (2.26 g per square millimeter), followed by the hard palate (3.60 g per square millimeter), the lateral tongue (4.08 g per square millimeter), the cheek (4.77 g per square millimeter), and the gingiva (8.06 g per square millimeter). Smokers had significantly decreased sensation at the tip of tongue and hard palate. Denture wearers had significantly diminished sensation in all intraoral locations except the lateral tongue. Older patients had significantly diminished sensation at all intraoral sites. No sex differences were noted. The lateral arm flap donor site is a more sensitive region than the radial forearm flap donor site. However, the lateral arm flap donor site is less sensitive than the tip of tongue and hard palate, while the radial forearm flap donor site is less sensitive than the tip of tongue, hard palate, lateral tongue, and cheek. This suggests that for certain locations, intraoral sensate flaps may require measures such as sensory reeducation protocols to approach normal recipient site sensation.