Transtympanic Facial Nerve Paralysis: A Review of the Literature.

Even though the facial nerve is the most commonly injured cranial nerve, penetrating trauma through the external auditory canal leading to facial nerve paralysis is extremely rare. Transtympanic facial nerve paralysis is well known to otolaryngologists as “slag injuries” in which molten metal or hot sparks enter the ear during welding.1 Iatrogenic injuries to the facial nerve are also well documented and can occur during otologic surgery and when removing a foreign body from the ear.2–4 However, only a few cases of nonthermal, noniatrogenic transtympanic damage to the facial nerve have been reported. We present a rare case of facial nerve paresis caused by accidental penetrating trauma and review the literature on this uncommon mechanism of injury.