Lesion-Induced Blepharospasm: Epidemiology and Clinical Characteristics

Abstract

<p><strong>Background: </strong>Lesion-induced blepharospasm is considered rare. However, this information is based on a small number of heterogenous retrospective cohorts without routine neuroimaging.</p><p><strong>Objectives: </strong>To study the epidemiology and clinical characteristics of lesion-induced blepharospasm.</p><p><strong>Methods: </strong>Patients with blepharospasm with uncertain etiology prior to brain imaging were systematically searched from the electronic medical records of Turku University Hospital (1996-2022). Clinical information and imaging data were extracted from the patients' records and re-evaluated by the investigators. Etiology of blepharospasm was evaluated by an in-depth review of the clinical information in the context of available literature on lesion-induced dystonias. The prevalence and annual incidence of blepharospasm were calculated based on the annual population count in the area.</p><p><strong>Results: </strong>The search identified 57 patients, of whom four (7.0%) were considered to have lesion-induced blepharospasm, corresponding to a population-based prevalence of 2.5 per million and annual incidence of 0.3 per million. All patients with lesion-induced blepharospasm had atypical features, which were all significantly more common than in patients with idiopathic blepharospasm (<em>P</em> < 0.05).</p><p><strong>Conclusions: </strong>Lesion-induced blepharospasm is more common than thought previously. However, all these patients showed atypical features, suggesting that brain imaging in blepharospasm can be limited to patients with atypical features only.</p><p><strong>Highlights: </strong>This study investigated the epidemiology of lesion-induced blepharospasm by systematically re-evaluating all patients with blepharospasm with uncertain etiology prior to structural brain imaging from a university hospital (1996-2022).Our results show that lesion-induced blepharospasm is more common that thought previously (7.0% of included patients, prevalence 2.5 per million, annual incidence 0.3 per million).All patients with lesion-induced blepharospasm showed clinical features that were considered atypical for idiopathic blepharospasm, indicating that routine brain imaging is not needed in patients with typical symptoms.</p>