Nervus intermedius schwannoma, also known as intermediate nerve schwannoma, is a schwannoma arising from the nervus intermedius (contributing sensory and visceral motor fibers to the facial nerve).
They are rare tumors, probably often misdiagnosed as facial nerve schwannomas (motor root) or vestibular schwannomas.
Given how small the nervus intermedius is and how closely it travels with the large motor root (facial nerve) before joining it laterally in the internal acoustic meatus, distinguishing between the two on imaging is difficult, if not impossible when the tumor is confined to the internal acoustic meatus. If, however, tumor can be seen growing along the greater superficial petrosal nerve or chorda tympani, then it is likely that the tumor represents a nervus intermedius schwannoma rather than a facial nerve schwannoma, as this is the distribution of its fibers 1.
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