Abducens (sixth) nerve palsy presenting as a rare case of isolated brainstem metastasis from a primary breast carcinoma

Reyes KB, Lee HY, Ng I, Goh KY
Correspondence: Dr Reyes Karen Bulan, kurr_b_reyes@yahoo.com

ABSTRACT
Most isolated abducens (sixth) nerve palsies are ischaemic in nature. However, there are other causes that can mimic an abducens nerve palsy, which requires aggressive diagnostic management. A 56-year-old hypertensive woman presented with a right abduction deficit. Her past history revealed that she had undergone a mastectomy and completed a course of chemo and radiation therapy for breast carcinoma. She was well until she developed binocular diplopia five months later. Magnetic resonance imaging showed a right pontine mass. Stereotactic biopsy was performed, and histopathology revealed a metastatic carcinoma that was compatible with an origin from the breast primary. We conclude that identifying and managing patients with metastatic lesions involves a multidisciplinary approach. Thorough history-taking and neuroophthalmologic evaluation would help physicians in establishing the primary differentials, which could not only be sight-saving but life-saving as well.

Keywords: abducens (sixth) nerve palsy, brainstem metastasis, breast carcinoma, lateral rectus palsy
Singapore Med J 2011; 52(11): e220-e222