Diagnosis: Zoster sine herpete
In this case, MRI demonstrated a linear, nonmasslike enhancement without much expansion of the nerve in the middle ear or internal auditory canal, findings that made a tumor unlikely. The differential diagnosis should include Bell palsy, meningitis, sarcoidosis, and a metastatic or perineural tumor. Because our patient had an episode of vertigo but lacked systemic symptoms such as fever, headache, neck stiffness, and lung or heart problems, the former 3 diseases were excluded. Therefore, perineural spread from a malignant neoplasm in the head and neck was the only serious consideration. Its criteria on MRI included replacement of normal perineural fat with tumor, enhancement with gadolinium, and increased size of the nerve in question.1Because there was no history of tumor (especially squamous cell carcinoma of the skin) to suggest that perineural tumor was the diagnosis, and physiologic testing indicated that 3 nerve bundles in the internal auditory canal, ie, facial, superior, and inferior vestibular nerves, were affected, an inflammatory process rather than a tumor lesion was suspected. Finally, zoster sine herpete was diagnosed.