Background: For acoustic neuromas, stereotactic radiotherapy (radiosurgery or stereotactic fractionated radiotherapy) has been established as an important alternative to microsurgery. In most cases initial symptoms are slow progression of unilateral hearing loss, tinnitus or vertigo or acute hearing loss with vertigo. MRI scan shows a contrast-enhancing tumor within the inner auditory channel. If the patient undergoes primary radiotherapy, diagnosis is usually not verified histologically. Therefore, careful evaluation of the medical history is mandatory despite a typical appearance on the MRI scan. If medical history does not match with acoustic neuroma, further diagnostics are necessary to rule out infectious disease or carcinomatous meningitis.
Case report: Two patients with hearing loss, vertigo and the diagnosis of acoustic neuromas by MRI scan were referred for radiotherapy. In both cases the symptoms progressed very rapidly, not typical of acoustic neuromas, and in both patients repeated liquor puncture finally revealed carcinomatous meningitis. One patient died during therapy; in the second patient intrathecal chemotherapy and additional radiotherapy of the skull base led to partial remission continuing for several months.
Conclusion: Before primary radiotherapy of small intrameatal lesions diagnosis must be reassessed carefully. This is especially true for bilateral lesions suspicious for acoustic neuromas and rapid progression and persistence of clinical symptoms where carcinomatous meningitis has to be taken into account.