Temporal bone findings in a patient with Möbius syndrome.

Temporal bone findings in a case of Möbius syndrome are presented. The most striking pathological feature of the case is that the facial nerves ended in the horizontal segment in the temporal bones on both sides. This finding gives direct evidence that the site of nerve lesion in Möbius syndrome is in the peripheral nerve. Despite the disappearance of facial nerve in the horizontal segment, a neural element reappeared in the vertical segment of the fallopian canal, and moreover, the chorda tympani was found to cross the tympanic cavity in the normal position. This finding suggests that fibers of the chorda tympani sometimes take an alternative pathway via Arnold's nerve.