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FIG 1. Dumbbell facial nerve schwannoma. The facial nerve schwannoma (FNS) dumbbells through an enlarged labyrinthine facial canal to involve the geniculate ganglion (GG). Minimal extension of the schwannoma may be present along the greater superficial petrosal nerve (GSPN). The tympanic segment of the facial nerve (TS) is usually not involved. The cisternal portion of the facial nerve (FN) is seen as it courses toward the IAC through the porus acusticus (PA), the entrance to the IAC. Used by permission (37).FIG 2. Transmodiolar dumbbell schwannoma. The transmodiolar schwannoma (TMS) extends through the cochlear aperture (CA) and modiolus into the cochlea. The schwannoma involves the cochlear nerve (CN). The normal superior vestibular nerve (SVN) and inferior vestibular nerve (IVN) are present within the IAC. V: Vestibule. Used by permission (37)
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