Isolated inferior rectus palsy caused by a metastasis to the oculomotor nucleus

Abstract

Purpose: To report a case of isolated inferior rectus palsy secondary to a metastasis to the oculomotor nucleus.

Methods: Case report. A 41-year-old woman with a history of breast cancer presented with acute onset of left hypotropia and exotropia.

Results: Forced generation testing confirmed weakness of the right inferior rectus muscle that was not reversed by intravenous edrophonium infusion. Magnetic resonance imaging disclosed numerous metastatic lesions to the cerebral hemispheres and brainstem. One lesion in the right midbrain was adjacent to the cerebral aqueduct in the right oculomotor nucleus.

Conclusion: Metastasis to the oculomotor nucleus is a rare cause of isolated inferior rectus palsy; however, this entity should be considered in the differential diagnosis of an isolated inferior rectus palsy because of the life-threatening consequences of a brainstem lesion.