Aberrant Facial Nerve

Litton et al used radiologie studies to document the variable relationship of the facial nerve to the tympanic annulus.1 Nager and Proctor described aberrant coursing of the vertical portion of the facial nerve, further underscoring the potential for injury during a transcanal approach.2 Adad et al drilled 37 temporal bones to directly examine the relationship of the facial nerve to the tympanic annulus, proving that the nerve runs lateral to the annulus in the posteroinferior quadrant in more than 70% of specimens.3 Therefore, the tympanic annulus is not a reliable landmark to predict the course of the facial nerve. Given the aberrant anatomy of the facial nerve in the external auditory canal, the transcanul approach used in many otologic procedures carries a rare but inherent risk of facial nerve injury.