Sixth nerve palsy as a presenting sign of intracranial plasmacytoma and multiple myeloma

Multiple myeloma and plasmacytoma are rare causes of mass lesions at the sk ull base and cavernous sinus. Sixth nerve palsy, in isolation or in combina tion with other cranial neuropathies, may occur rarely as the initial prese nting feature of multiple myeloma. We report the neuro-ophthalmologic radio logic, and pathologic findings for two patients who developed sixth nerve p alsies as an initial manifestation of intracranial plasmacytoma and multipl e myeloma. One patient presented with an isolated sixth nerve palsy in the setting of multiple vasculopathic risk factors. Treatable skull base lesion s, including plasmacytoma and multiple myeloma, must be considered in patie nts with sixth nerve palsies, especially among those who demonstrate a prog ressive course or multiple cranial neuropathies.