Masseteric-facial nerve anastomosis associated with cross face nerve graft: a reliable solution for incomplete facial palsy

Introduction: One of the most common causes of incomplete facial palsy is Bell\u2019s palsy. Although in most cases this idiopathic condition evolves towards complete restoration, almost 30% of these patients report some degree of functional and morphological sequelae, including, but not limited to, facial synkinesis and paresis. Different surgical techniques have been proposed to reanimate complete facial palsy this kind of facial weakness: neural neurorrhaphy between the hypoglossus nerve and the injured facial nerve, cross face nerve grafting, mini -temporalis flap rotation and free muscle transfer to restore facial symmetry and mimic movements. Others prefer to symmetries the face by injecting botulin toxin on the healthy side. Materials and Methods: Between 2011 and 2016, twenty -four patients (17 females; 7 males) affected by an incomplete unilateral facial palsy underwent surgical treatment in the Maxillofacial Surgery Department of the San Paolo Hospital of Milan (Italy) to restore the symmetry of the face at rest and during smiling. 20 patients were affected by an incom plete facial palsy of the middle third of the face. In these patients, a neural anastomosis between the masseteric nerve and a branch of the injured facial nerve directed to the zygomatic muscle was created to give new contractile strength to the midface mimic muscles. 4 patients were affected by an incomplete facial palsy of the lower third of the face. In these patients, a neural neurorrhaphy between the masseteric nerve and the marginalis mandibulae nerve was created. Furthermore, all patients received a cross face sural nerve graft to restore the spontaneity of smile: nerve graft was directed to the middle third of the face in 20 patients, while in 4 patients to the lower third, according to the paresis localization. Results: Surgery was uneventful in all cases. Follow up time ranged from 3 months to 5 years (only 4 patients, operated during the current year, have a follow up time lower than 18 months). A significant improvement of facial movement was achieved in all evaluated patients. Facial recovery began within 2 and 12 months after surgery with the restoration of facial symmetry at rest. All patients had to clench their teeth while smiling in the beginning. After 2 to 4 months of exercising with a physiotherapist, the patients had to think about smiling if they wanted to do it, but clenching was no longer necessary. From 6 to 12 months after the onset of paralysis, smiling became automatic. Spontaneous smile was restored through the use of the contralateral facial nerve. Conclusions: The nervous anastomosis between the masseteric nerve and a branch of the facial nerve represents a valid choice for the reanimation of the incomplete facial palsy; in addition, its association with a cross face nerve grafting allows not only to achieve an excellent symmetry during the voluntary movement but also to restore the emotional smile