Overview of Facial Nerve: Injury, Repair and Regeneration

Abstract

Facial nerve injury is a common clinical entity; it may arise from congenital, infectious, idiopathic, traumatic, neoplastic, endocrine, neurologic, and systemic causes. It is also not uncommon for nerve to be deliberately sacrificed at time of surgery in order to completely remove malignancy. Consequences of this injury can be devastating and include exposure keratosis and blindness, facial asymmetry, poor nasal airflow, oral incompetence, psychological stress and synkinesis, in which miswiring of nerves results in synchronous involuntary muscle movement with expressions. The main drawback of nerve repair is its inability to guarantee complete functional recovery. For example, axonal misalignment can cause partially reversible neuronal atrophy, which can interfere with the production of neurotrophic factors for accelerated regeneration. Management of facial nerve injuries continues to be one of the most difficult issues faced by the surgeons. It follows a complicated algorithm depending on the mechanism and the location of the injury, the time course of the paralysis, the medical condition and prognosis of the patient. Although many techniques have been developed to rehabilitate patients with facial paralysis (FP), the outcome of all of these procedures lacks the symmetry or spontaneity of an intact facial nerve. Therefore, the aim of the present study was to review facial nerve injury, facial nerve repair and regeneration.