Intracranial and intratemporal facial nerve schwannoma. (Imaging Clinic).Facial nerve schwannomas have a predilection for the area of the geniculate ganglion, although they can occur at any point along the nerve between its origin in the pons and its exit in the stylomastoid foramen and parotid segment. (1) A weakness of the facial nerve that progresses slowly is most likely the result of a neoplasm; such palsies account for less than 5% of all facial palsies. By contrast, Bell's palsy has a strikingly rapid onset. Trauma, herpes zoster infection, and complications of otitis media are all more common causes of facial nerve palsy facial nerve palsy Facial palsy, see there than is facial nerve schwannoma. (2) A facial nerve schwannoma can cause a sensorineural hearing loss Sensorineural hearing loss Hearing loss caused by damage to the nerves or parts of the inner ear governing the sense of hearing. Mentioned in: Tinnitus sensorineural hearing loss when it extends into the internal acoustic canal and a conductive hearing loss Conductive hearing loss A type of medically treatable hearing loss in which the inner ear is usually normal, but there are specific problems in the middle or outer ears that prevent sound from getting to the inner ear in a normal way. when it extends into the middle ear. Although facial palsy is the most common clinical symptom of a facial schwannoma, some patients do not experience facial paralysis. In such cases, the lesion is discovered on imaging as a large mass in the middle ear or middle cranial fossa (figure). Computed tomography (CT) might not be able to differentiate a schwannoma from a cholesteatoma unless there is an obvious fusiform fusiform /fu·si·form/ (-form) shaped like a spindle; tapered at each end. fu·si·form adj. Tapering at each end; spindle-shaped. fusiform spindle-shaped. enlargement of the more distal or proximal facial nerve canal. Contrast-enhanced magnetic resonance imaging magnetic resonance imaging (MRI), noninvasive diagnostic technique that uses nuclear magnetic resonance to produce cross-sectional images of organs and other internal body structures. (MRI) can be more sensitive in differentiating an enhancing schwannoma from a cholesteatoma, which does not enhance. (3,4) References (1.) Pulec JL. Facial nerve neuroma neuroma /neu·ro·ma/ (ndbobr-ro´mah) a tumor growing from a nerve or made up largely of nerve cells and nerve fibers.neurom´atous acoustic neuroma . Ear Nose Throat J 1994;73: 721-2, 725-39, 743-52. (2.) Swartz JD, Harnsberger HR. The facial nerve. In: Swartz JD, Harnsberger HR. Imaging of the Temporal Bone. 2nd ed. New York: Thieme Medical Publishers, 1992:268-96. (3.) Martin N, Sterkers O, Mompoint D, Nahum H. Facial nerve neuromas: MR imaging. Report of four cases. Neuroradiology 1992;34:62-7. (4.) Parnes LS, Lee DH, Peerless SJ. Magnetic resonance imaging of facial nerve neuromas. Laryngoscope 1991; 101:31-5. From the Neuroradiology Service, University Hospital Ramon y Cajal Ra·mòn y Ca·jal , Santiago 1852-1934. Spanish histologist. He shared a 1906 Nobel Prize for research on the nervous system. . Madrid, Spain (Dr. Trujillo), and the Department of Radiology, Louisiana State University Health Science Center, New Orleans (Dr. Palacios). |
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