Large facial nerve schwannomas without facial palsy: case reports and review of the literature

Abstract

Although approximately 30% of facial nerve schwannoma cases present with no facial palsy, a large facial nerve schwannoma extending to the middle and posterior cranial fossa quite rarely presents without facial palsy. The authors encountered two patients with large facial nerve schwannoma who presented with only hearing impairment and no facial palsy. The first patient was a 64-year-old woman who presented with right auditory impairment without facial palsy. MR images demonstrated a dumbbell-shaped tumor in the cerebellopontine angle. Another patient, a 40-year-old woman, also presented with vertigo and right tinnitus without facial palsy. MR images demonstrated a huge tumor expanding into both the posterior cranial fossa and middle cranial fossa. In both cases, intraoperative findings confirmed that the tumors had grown from the facial nerve. Facial nerve schwannoma can be easily diagnosed if detailed neurological evaluations and appropriate neuroimagings are conducted. However, in spite of such huge tumoral size and expanding pattern, the facial nerve function was relatively preserved. Anatomical features of the facial schwannoma are discussed. A tumor extending to the middle and posterior cranial fossa should remind neurosurgeons to consider facial nerve schwannomas even in the absence of facial palsy.

Magnetic resonance imaging of facial nerve schwannoma

“…Our results are similar to the series by McMonagle, who reported 51% with facial nerve dysfunction 10. However, large FNS can occur without facial nerve dysfunction 27–29. In our series, patients with facial nerve dysfunction presented at a significantly earlier age than those without.…”

Large Cystic Hypoglossal Schwannoma with Fluid-Fluid Level: A Case Report

“…The extremely slow growth of benign schwannoma may allow for a higher degree of tolerance of the nerve. 12 The abundant tumor blood flow supports not only the schwannoma itself but also helps preserve hypoglossal nerve integrity. 13 Finally, the formation and expansion of a cyst lead to rapid neurological deterioration, which makes the patient seek medical assistance prior to the onset of hypoglossal nerve palsy.…”

Pathology of the Facial Nerve

“…Tinnitus, conductive or sensorineural hearing loss, and vertigo may be the only clinical signs in patients with a facial nerve schwannoma 15 . CT and MR are then initially performed to find more frequent causes of the above-mentioned clinical signs, but will depict the facial nerve schwannoma.…”