Internal auditory canal metastasis

Metastasis of the inner auditory canal is a really rare event. Clinically, it usually presents with rapid worsening cranial nerve palsy. Authors present a review of the literature reporting clinical features, radiological findings, intraoperative aspects of an illustrative case. A 56-year-old female patient presented with a peripheral facial nerve palsy. MRI showed two left p-fossa tumors whose one into the inner canal. Rapid worsening of facial damage despite corticosteroid treatment and the possibility to remove both tumors in the same surgical step suggested authors to operated on the patient. Intraoperatively, inner canal tumor looked totally involving the VII-VIII nerve complex so surgical extirpation was only partially feasible. Posterior wall drilling of the meatus was performed which improved facial palsy. Leptomeningeal spinal seeding occurred and spinal irradiation was performed. The case highlights the importance of maintaining a high degree of awareness of the auditory canal metastasis in patients with a previous history of malignancy who develop a rapid progressive peripheral VII nerve palsy. Furthermore, our case and literature data suggest that inner canal metastasis is a distinct entity from temporal bone and ponto-cerebellar angle metastasis on the base of the peculiarity of clinical features, prognosis, therapeutic strategies. In fact, inner canal metastases usually arise in patients apparently cured, and they imply a better prognosis even if with an higher risk of leptomeningeal seeding. Moreover, surgery rarely allows the removal of the lesion, also if symptoms relief may be achieved, as in our case.