Intraneural topography of the extratemporal facial nerve: microsurgical nerve reconstruction

The fascicular pattern is the most important component of a nerve when a microsurgical reconstruction is made. The intraneural topography of the extratemporal facial nerve does not have a reliable fascicular pattern, although our study in 25 extratemporal facial nerves showed a definite fascicular pattern in the different studied levels. The microanatomic intraneural investigation was made in four different levels; we studied the diameter of the trunk, number and diameter of each fascicle, fascicular pattern, characteristics of the epineurium, perineurium, and interfascicular connective tissue, and extra- and intraneural blood supply. In the proximal and distal facial trunk, most axons are included in one to three big funiculus surrounded by a small amount of connective, interfascicular tissue; both epineurium and perineurium are thin and slender. The principal arteries are placed between funiculus and epineurium. Either epineurial or interfascicular neurorrhaphy could be produced and mono- or polyfascicular nerve grafts can be used. In both temporofacial and cervicofacial primary branches, the fascicular distribution was from four to five fascicles in 64% of cases with abundant connective interfascicular tissue involving the principal arteries. The interfascicular surgical technique is of election, but the epineurial suture must not be discarded. Nerve graft must be polyfascicular. The goal of nerve repair is to obtain the restoration of anatomic continuity of the most of axons by means of a complete fascicular alignment, in which detailed knowledge of the intraneural topography of the facial nerve must be required for reliable microsurgical reparation.