To assess: (1) the prevalence of blepharoclonus in patients with idiopathic Parkinson’s Disease (iPD) in a single-center cohort; (2) the association of blepharoclonus with disease stage, tremor severity, and various nonmotor symptoms; and (3) the prevalence of blepharoclonus in synucleinopathy vs. nonsynucleinopathy-associated parkinsonism

In our clinical practice, we have observed that patients with iPD often have blepharoclonus, but its prevalence is not well described in the literature.  Understanding the relative frequencies of blepharoclonus in iPD and atypical parkinsonism syndromes will shed light on the diagnostic utility of this clinical sign

We prospectively enrolled 75 iPD and 10 atypical PD patients, and recorded age, sex, disease duration and Hoehn & Yahr stage. Diagnosis was based on Movement Disorders Society (MDS) criteria. Blepharoclonus was considered present if eyelid fluttering was sustained for > 5 seconds after gentle eye closure. For each patient, we completed selected questions from the MDS-UPDRS (Unified Parkinson’s Disease Rating Scale) part 2, REM Sleep Behavior Disorder Questionnaire, MDS-UPDRS part 3 tremor assessments, and recorded the presence/absence of dyskinesia.

63/75 (84%) of iPD patients had blepharoclonus. Presence of blepharoclonus was not significantly associated with presence of REM-sleep behavior disorder or higher tremor score. Among the 10 atypical PD patients, 5 had synucleinopathy-related syndromes. Blepharoclonus was present in 3/5 synucleinopathy patients and in 0/5 patients with non-synucleinopathy-associated PD. The atypical PD sample was too small for meaningful analysis.

Blepharoclonus is highly prevalent in our clinical population. This suggests its possible utility as an additional clinical marker for PD. Moreover, the absence of blepharoclonus may suggest an alternative diagnosis to iPD. Its presence, perhaps, may suggest a synucleinopathy rather than a tauopathy. An analysis of a larger cohort, including many more with atypical PD, is necessary to establish whether blepharoclonus best distinguishes idiopathic from atypical PD, or synucleinopathy from non-synucleinopathy.