BRIEF RESEARCH REPORT article
Front. Neurol.
Sec. Neuro-Ophthalmology
This article is part of the Research TopicEye Movement Abnormalities in Brain DiseasesView all 5 articles
Downbeat Nystagmus in Association with the Dorsal Midbrain Syndrome: Proposed Mechanisms, Literature Review, and Case series
Provisionally accepted
- 1NYU Langone Health, New York, United States
- 2Mayo Clinic in Florida, Jacksonville, United States
- 3Universitat Ulm, Ulm, Germany
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Introduction: Downbeat nystagmus (DBN) is classically attributed to cerebellar pathology. Far less often, DBN arises from brainstem disease, with midbrain etiologies being exceptionally rare and poorly characterized. In particular, DBN with the dorsal midbrain syndrome has been sporadically reported and its mechanism is unclear. Methods/Results: We analyzed non-human primate and human literature on vertical gaze and brainstem-related DBN in the context of three patients with DBN and dorsal midbrain syndrome. Upgaze paresis was universal, skew deviation present in two, and parkinsonism developed in two after shunt-related complications. We reviewed the literature using strict criteria requiring DBN in central gaze and at least two definitive features of the dorsal midbrain syndrome, identifying two additional patients. Discussion: In five patients with DBN and dorsal midbrain syndrome, aqueductal stenosis or compression with upgaze paresis were unifying features. Potential mechanisms for DBN include involvement of the interstitial nucleus of Cajal, disruption of descending midbrain projections to paramedian tracts, or unstable cerebellar outflow, but clinical and experimental evidence makes these explanations less compelling. Converging evidence from our series, prior reports, and non-human primate studies suggests bilateral posterior commissural dysfunction related to aqueductal pathology as the most plausible mechanism for DBN with the dorsal midbrain syndrome.
Keywords: Downbeat nystagmus, Interstitial nucleus of Cajal, dorsal midbrain, Parinaud syndrome, posterior commissure
Received: 30 Sep 2025; Accepted: 11 Nov 2025.
Copyright: © 2025 Saab, Eggenberger, Cho, Friedrich and Rucker. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Janet C Rucker, janet.rucker@nyulangone.org
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