Facial nerve schwannoma
Facial nerve schwannoma may arise in any portion of the facial nerve, with a predilection for the geniculate ganglion 1) 2).
They can occur anywhere from the internal auditory canal to the parotid gland. Schwannomas arising from the greater superficial petrosal nerve are exceedingly rare 3).
Even in these tumors, hearing loss tends to precede facial paresis. Hearing loss may be sensorineural from VIII cranial nerve compression from tumors arising in the proximal portion of VII cranial nerve (cisternal or internal auditory canal (IAC) segment), or it may be conductive from erosion of the ossicles by tumors arising in the second (tympanic, or horizontal) segment of VII. Facial palsy (peripheral) may also develop, usually late 4).
Computed tomography (CT) of the temporal bone is important for evaluating the impact on the surrounding structures 5).
Treatment for intracranial facial nerve schwannomas depends on clinical presentation, tumor size, preoperative facial, and hearing function.
Conservative management is recommended for asymptomatic patients with small tumors. Stereotactic radiosurgery may be an option for smaller and symptomatic tumors with good facial function. If tumor is large or the patient has facial paralysis, surgical resection should be indicated. If preservation of the facial nerve is not possible, total resection with nerve grafting should be performed for those patients with facial paralysis, whereas subtotal resection is best for those patients with good facial function 6).
see Middle Fossa Approach for Facial Nerve Schwannoma.
These tumors must be assessed with imaging studies, incisional biopsy is not recommended. The treatment is surgical resection in symptomatic patients with facial paralysis greater than grade III of House-Brackmann, with immediate reconstruction of the nerve 7).
Facial nerve schwannoma case series.
Facial nerve schwannoma case reports.