Isolated Abducens Nerve Palsy: A Rare Manifestation of Recurrent Extramedullary Myeloma

Multiple myeloma is a plasma cell neoplasm, which may present as a solitary plasmacytoma and, uncommonly, as an extramedullary plasmacytoma. Intracranial plasmacytomas may manifest in central nervous system involvement as cranial nerve palsies. Cranial nerve six palsy is the most common in cases of malignancy. However, isolated abducens palsy presenting as multiple myeloma recurrence is very uncommon. Here, we detail two cases in which intracranial plasmacytoma lesions were present within the region of the Dorello canal, resulting in acute isolated unilateral diplopia from disease recurrence in the absence of systemic marrow involvement.