Summary

Painful ophthalmoplegia due to extramedullary plasmacytoma is a rare initial manifestation of multiple myeloma. The present report describes a 48-year-old man who suffered an acute onset of retro-orbital pain, left abducens palsy and left facial hypoesthesia. In addition, he exhibited an elevated erythrocyte sedimentation rate and partial responsiveness to corticosteroid treatment, all of which resemble the features of Tolosa–Hunt syndrome. Imaging studies revealed a multilobulated tumour invading the left sphenoid bone and sphenoid sinus, later confirmed as a plasmacytoma at pathology. Multiple myeloma was also diagnosed by bone marrow examination. After completion of chemotherapy and radiotherapy, the patient has been free of symptoms for 10 months. Although cranial neuropathies with any combination of oculomotor, abducens, trochlear, ophthalmic and maxillary nerves may indicate a cavernous sinus lesion, neuropathies exclusive to the abducens and maxillary nerves may raise the possibility of extracavernous sinus origin. Cranial imaging is crucial in diagnosing painful ophthalmoplegia with additional minimal cranial nerve signs.