Cross-Face Nerve Grafting with Infraorbital Nerve Pathway Protection: Anatomic and Histomorphometric Feasibility Study

Abstract

Smiling is an important aspect of emotional expression and social interaction, leaving facial palsy patients with impaired social functioning and decreased overall quality of life. Although there are several techniques available for facial reanimation, staged facial reanimation using donor nerve branches from the contralateral, functioning facial nerve connected to a cross-face nerve graft (CFNG) is the only technique that can reliably reproduce an emotionally spontaneous smile. Although CFNGs provide spontaneity, they typically produce less smile excursion than when the subsequent free functioning muscle flap is innervated with the motor nerve to the masseter muscle. This may be explained in part by the larger number of donor motor axons when using the masseter nerve, as studies have shown that only 20% to 50% of facial nerve donor axons successfully cross the nerve graft to innervate their targets. As demonstrated in our animal studies, increasing the number of donor axons that grow into and traverse the CFNG to innervate the free muscle transfer increases muscle movement, and this phenomenon may provide patients with the benefit of improved smile excursion. We have previously shown in animal studies that sensory nerves, when coapted to a nerve graft, improve axonal growth through the nerve graft and improve muscle excursion. Here, we describe the feasibility of and our experience in translating these results clinically by coapting the distal portion of the CFNG to branches of the infraorbital nerve.

Supercharge End-to-Side Motor Transfer to a Long Nerve Graft to Enhance Motor Regeneration — An Experimental Rat Study

“…17 Using SETS transfers of nearby sensory nerves to long nerve grafts can keep the denervated Schwann cells in a growth-supporting state, counteract chronic denervation in long nerve grafts, and improve nerve regeneration and functional outcomes. This concept was clinically applied by Catapano et al, 36 who coapted a contralateral infraorbital nerve branch to the end of a cross-facial nerve graft to improve axonal growth and thus muscle excursion in a facial paralysis cohort of patients.…”

Selective Denervation of the Facial Dermato-Muscular Complex in the Rat: Experimental Model and Anatomical Basis

“…In line, we performed a detailed surgical dissection of the cutaneous branch of the mylohyoid nerve and quantified its total axon composition, which has not been conducted in the rat. Overall, this data may be helpful in various experimental models for surgical nerve reconstruction models: the supraorbital and infraorbital nerves may be used for corneal neurotization (Catapano et al, 2018 ; Rosenblatt et al, 2020 ) as well as for sensory protection of cross-face nerve grafts for facial reanimation (Placheta et al, 2015b ; Catapano et al, 2016 ) and the mylohyoid nerve has been proposed as a donor nerve for facial nerve reconstruction (Tubbs et al, 2007 ). A better understanding of the neurophysiological processes occurring as a result of the reconstructive procedures may optimize surgical outcomes in clinical practice.…”

Corneal Neurotization—Indications, Surgical Techniques and Outcomes

“…The infraorbital nerve has been studied to a far less significant degree. Catapano et al found that the infraorbital nerve used to contain 975 myelinated fibres in an anatomic and histomorphometric feasibility study [ 81 ]. The authors commented that this number is expected to provide a sufficient number of donor axons to protect the sural nerve graft.…”