Epidemiology of Adult-Onset Nystagmus and Saccadic Intrusions of Central Etiologies: A Population-Based Study in Olmsted County

Abstract

Background: – The incidence and clinical characteristics of adult-onset abnormal spontaneous eye movements of central origin remain poorly defined.Methods: – We conducted a retrospective, population-based study using the Rochester Epidemiology Project to identify all adults (age ≥18 years) in Olmsted County, MN, diagnosed with nystagmus or saccadic intrusions between 1970 and 2019. Cases involving childhood-onset nystagmus, physiologic, or peripheral vestibular nystagmus, as well as those with insufficient diagnostic information, were excluded. Demographics, clinical, and imaging data were collected, including nystagmus types, characteristics, and outcomes.Results: – A total of 208 patients were identified for the 50-year period, yielding a median annual incidence of 4.65 per 100, 000 adults. The mean age at diagnosis was 56.2 ± 19.2 years and 43.3% were female. Gaze-evoked nystagmus (46.2%) was the most frequent subtype, followed by torsional (25.0%), downbeat (11.5%), and upbeat nystagmus (8.7%). The cerebellum was the most commonly affected region on neuroimaging, and strokes/transient ischemic attacks were the leading etiology. Specific lesion–nystagmus correlations included pendular and abducting nystagmus with pontine lesions (P = 0.009 and <0.001, respectively), convergence–retraction nystagmus with midbrain (P = 0.036), and thalamic lesions (P = 0.007). Torsional nystagmus was most frequently associated with ischemic strokes (P = 0.045), downbeat nystagmus (DBN) with central nervous system malformations (P = 0.008), and abducting nystagmus with demyelinating diseases (P < 0.001). At follow-up visits, approximately 60% of cases showed complete or partial improvement. Factors independently associated with nystagmus recovery included skew deviation (adjusted hazard ratio [aHR] 2.667 [95% confidence interval [CI], 1.234–5.768])), toxic-metabolic cause (aHR 3.378 [95% CI, 1.816–6.284]), absence of DBN (aHR 0.142 [95% CI, 0.050–0.407]), and absence of neurodegeneration (aHR 0.050 [95% CI, 0.007–0.372]).Conclusions: – This is the first population-based study describing the incidence and characteristics of adult-onset central nystagmus and saccadic intrusions in North America. Distinct anatomical and etiologic associations were identified across nystagmus subtypes. Poorer recovery was linked to neurodegenerative diseases, and DBN, whereas nystagmus improvement was associated with toxic-metabolic cause and presence of skew deviation.