Clinical Presentation:
Schwannoma, a benign tumor of Schwann cells, can be inherited through a deletion on chromosome 22, but is more commonly sporadic. Individuals, especially females, between the ages of 40 and 60 are the most commonly affected. Symptoms for this abnormality vary with the location of the tumor. If the tumor is located around cranial nerve VIII, the patient might experience hearing loss. or tinnitus. If the location is cranial nerve V, the patient will experience facial pain, numbness, and muscle weakness. If the tumor is surrounding cranial nerve VII, the patient may suffer from gradual facial paralysis or a hemifacial spasm.
Pathology:
Schwannoma is commonly located at the transition between central and peripheral segments of a nerve. The two most common locations for this benign tumor are intracranial or intraspinal. If the location of the schwannoma is intracranial, it will most likely be located around sensory nerves, VIII and V. They are rarely intraventricular or intraparenchymal. If intraspinal, the tumor is typically found in the lumbosacral area or cauda equina. The schwannoma may compress the surrounding nerves, but does not invade the nerve.
Imaging Findings:
Lesions on MRI images are hypointense on T1WI and hyperintense on T2WI. Tumors of the vestibular nerve have an "ice-cream cone" shape due to a larger round cisternal portion with small pointed extension into the internal auditory canal.
Differential Diagnosis:
Differential diagnosis includes meningioma, metastasis, sarcoidosis, paraganglioma. Meningioma frequently exhibit dural spread or a "dural tail" and usually do not extend into the internal auditory canal.
Treatment:
Treatment is primarily surgical resection, but radiation or radiosurgery have also been used.