Evaluation of Sensibility of Noninnervated, Intraoral, Microsurgically Transferred Flaps.

BACKGROUND

This study investigated sensory recovery of microvascular free flaps in the oral cavity with functional magnetic resonance imaging to assess activation in the primary sensory cortex (S1).

METHODS

The study included 20 patients with sensory recovery at the flap site in the tongue or floor of mouth after ablative cancer surgery that involved unilateral resection of the lingual nerve and reconstruction with a radial free forearm flap, anterolateral thigh flap, or lower leg perforator flap without nerve readaptation between 2012 and 2019. Control nonflap and contralateral flap sites were electrically stimulated with a patient-specific, sensation-inducing voltage for 10 minutes with 30-second on/off intervals. During this process, functional magnetic resonance imaging was conducted simultaneously to assess the signal area and level in S1.

RESULTS

The stimulation voltage was higher at the flap site than at the control nonflap site (6.0 versus 3.0 V; P < 0.001). The signal area activated upon stimulation of the flap and control nonflap site was located in the cortical area representing the lingual nerve. The signal level in S1 upon stimulation of the flap site was similar to that upon stimulation of the control nonflap site (3.2 versus 3.5 T; P = 0.751).

CONCLUSION

Activation of the cortical area representing the lingual nerve upon stimulation of the flap site implies that sensory recovery of microvascular free flaps in the tongue and floor of mouth region involves nerve ingrowth from the remaining lingual nerve into the flap tissue.