Case Report: Bilateral Horizontal Gaze Palsy (1 + 1 Syndrome): A Supranuclear Gaze Palsy

A rare case of bilateral horizontal gaze palsy with intact vertical gaze eye movements and largely intact vestibulo-ocular reflex is presented owing to demyelinating lesions of the patient's bilateral paramedian pontine reticular formations and left infranuclear abducens nerve from the patient's recently diagnosed multiple sclerosis.

The purpose of this study was to report on a rare case of bilateral horizontal gaze palsy from a supranuclear lesion in a patient with a recent diagnosis of multiple sclerosis.

A 43-year-old African American woman presented urgently for evaluation of her inability to move her eyes into either horizontal gaze. Vertical conjugate movements remained intact, as did three of four extraocular muscles with horizontal vestibulo-ocular reflex testing, suggesting a supranuclear palsy. Magnetic resonance imaging revealed two demyelinating lesions in her inferior pons, which spared her nuclear and internuclear horizontal gaze pathways, as well as three of four extraocular muscles of her infranuclear horizontal gaze pathway as evidenced by her largely intact vestibulo-ocular reflex. This suggested bilateral paramedian pontine reticular formation lesions (supranuclear) and a mild left abducens nerve palsy (infranuclear).

Close evaluation of extraocular motilities and a solid understanding of the supranuclear, nuclear, internuclear, and infranuclear components of the horizontal gaze pathway can help identify challenging gaze palsies when encountered in a clinical setting. Appropriate neuroimaging can then be performed with an emphasis on the suspected location of the lesion(s) based on the patient's clinical findings.