Superior oblique myokymia: diagnostic criteria and long-term outcome

Superior oblique myokymia (SOM) is a rare disorder characterized by brief episodes of high-frequency, low-amplitude monocular nystagmus frequently caused by vascular contact with the trochlear nerve. Comprehensive analyses of SOM symptomatology and long-term progression are limited. No diagnostic criteria are available.

Adult patients who were diagnosed with SOM between 2008 and 2024 were asked to complete a detailed questionnaire on disease symptomatology, time course, and medication. The impact of the disease on patient-reported functioning was assessed using a Likert scale. In addition, medical records were screened in all patients.

A total of 35 patients with SOM were identified (21 females; mean age at symptom onset 42.8 ± 15.0 years). 30 patients experienced visuo-perceptual symptoms (i.e., diplopia or oscillopsia, 85.7%), 22 patients ocular motor symptoms (i.e., noticeable "eye-twitching", 62.9%), and 15 patients dizziness or gait instability (42.9%). Of 22 patients analyzed for their long-term therapeutic outcome, 13 described symptom improvement with pharmacotherapy, and six without pharmacotherapy. Patients experienced a moderate to high impact of the disease on their daily private and professional lives. Based on these findings, specific diagnostic criteria for SOM were proposed.

SOM can substantially impair patients' quality of life and daily functioning. The long-term course appears favorable, with most patients experiencing either complete remission or significant symptom reduction over time. Pharmaceutical treatment proved effective in nearly 90% of patients, and spontaneous remission was also observed. Further research should focus on larger patient cohorts defined by clear diagnostic criteria to enhance understanding of SOM's natural history and treatment outcomes.