Bilateral adduction palsy with a paramedian midbrain lesion is most likely wall-eyed bilateral oculomotor subnuclear ophthalmoplegia: a case report of a brainstem infarction.

A 73-year-old female was hospitalized in our Department of Neurology for diplopia due to multiple infarctions in the midbrain and pons. A neurological examination revealed bilateral adduction palsy during horizontal gaze with nystagmus of the contralateral abducting eye. Exotropia and impaired convergence were also noticed. The distinctive symptoms indicated wall-eyed bilateral internuclear ophthalmoplegia (WEBINO). We speculate that the cause of WEBINO in our case was bilateral medial rectus palsy via bilateral damage to the medial rectus subnuclei (MRSN) due to the paramedian midbrain infarction. We propose that bilateral adduction palsy with impaired convergence due to bilateral MRSN impairment, such as in our case, should be given a more appropriate name because we speculate that it is not 'internuclear ophthalmoplegia'. 'WEBOSO' (wall-eyed bilateral oculomotor subnuclear ophthalmoplegia) may be a more appropriate name.