Isolated trigeminal nerve metastases from breast cancer: An unusual cause of trigeminal mononeuropathy

BACKGROUND Mononeuropathy of a cranial nerve caused by brain metastases rarely occurs in patients with a malignant neoplasm. Even after the development of computed tomography (CT) and magnetic resonance imaging (MRI), few cases of brain metastases resulting in trigeminal mononeuropathy have been reported. We report a case of trigeminal mononeuropathy caused by a brain metastases that was detected on CT and MRI preoperatively, and was successfully treated by microsurgery and radiation. CASE DESCRIPTION A 49-year-old woman with a history of breast cancer complained of right facial pain. CT and MRI revealed a brain tumor in the right Meckel's cave and cerebellopontine angle. She underwent surgery, and the diagnosis was metastatic breast cancer. No recurrence was detected on MRI performed 2 years after the resection and radiation of the tumor. CONCLUSIONS Most of the reported cases of brain metastases causing a mononeuropathy occurred before the availability of CT; the mononeuropathy was diagnosed by neurologic or postmortem examination. Even after the development of CT and MRI, few cases of brain metastases resulting in trigeminal mononeuropathy have been reported. If such patients do not manifest symptoms of brain metastases other than the mononeuropathy, it is difficult to make the correct diagnosis without CT and MRI. Physicians must be aware of mononeuropathy as an uncommon presenting symptom of brain metastases. (C) 1998 by Elsevier Science Inc.