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VOLUME 8 , ISSUE 3 ( September-December, 2021 ) > List of Articles

Pictorial CME

Eight-and-a-half Syndrome—A Rare Pontine Neuro-ophthalmological Syndrome

Kamatchi Sundaramoorthy, Murali Kamalakannan, Swamy Kondapalli, Sakthivelayutham Saravanan, Sowmini Padmaja Raman, Malcolm Jeyaraj Krishnamoorthy, Sathish Kumar Mallikarjuna, Viveka Saravanan Raju

Keywords : Eight-and-half syndrome, Internuclear ophthalmoplegia, Paramedian pontine reticular formation

Citation Information : Sundaramoorthy K, Kamalakannan M, Kondapalli S, Saravanan S, Raman SP, Krishnamoorthy MJ, Mallikarjuna SK, Raju VS. Eight-and-a-half Syndrome—A Rare Pontine Neuro-ophthalmological Syndrome. Bengal Physician Journal 2021; 8 (3):81-83.

DOI: 10.5005/jp-journals-10070-7062

License: CC BY-NC 4.0

Published Online: 23-12-2021

Copyright Statement:  Copyright © 2021; The Author(s).


The combination of one-and-a-half syndrome and facial nerve palsy is a rare neurological syndrome called eight-and-a-half syndrome, described first by Eggenberger in 1998. The one-and-a-half syndrome is characterized by ipsilateral conjugate horizontal gaze palsy (the “one”) and an ipsilateral internuclear ophthalmoplegia (the “one-half”). A single unilateral lesion involving the paramedian pontine reticular formation or the abducens nucleus (causing the conjugate gaze palsy) with the interruption of internuclear fibers of the ipsilateral medial longitudinal fasciculus along with the region of facial colliculus results in eight-and-a-half syndrome. The occlusion of perforating artery to the pons resulting in pontine infarction is the commonest cause of this syndrome. The rare causes include demyelination, tumor, infection, and brainstem vasculitis. We describe here a case of eight-and-a half syndrome in a 50-year old gentleman due to pontine infarct, who also had cerebrovascular disease risk factors.

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