Risk factors for spread of primary adult onset blepharospasm: a multicentre investigation of the Italian movement disorders study group

Objectives-Little is known about factors influencing the spread of blepharo spasm to other body parts, An investigation was carried out to determine wh ether demographic features (sex, age at blepharospasm onset), putative risk , or protective factors for blepharospasm (family history of dystonia or tr emor, previous head or face trauma with loss of consciousness, ocular disea ses, and cigarette smoking), age related diseases (diabetes, hypertension), edentulousness, and neck or trunk trauma preceding the onset of blepharosp asm could distinguish patients with blepharospasm who had spread of dystoni a from those who did not. Methods-159 outpatients presenting initially with blepharospasm were select ed in 16 Italian Institutions. There were 104 patients with focal blepharos pasm (mean duration of disease 5.3 (SD 1.9) years) and 55 patients in whom segmental or multifocal dystonia developed (mainly in the cranial cervical area) 1.5 (1.2) years after the onset of blepharospasm. Information was obt ained from a standardised questionnaire administered by medical interviewer s. A Cox regression model was used to examine the relation between the inve stigated variables and spread. Results-Previous head or face trauma with loss of consciousness, age at the onset of blepharospasm, and female sex were independently associated with an increased risk of spread. A significant association was not found betwee n spread of dystonia and previous ocular diseases, hypertension, diabetes, neck or trunk trauma, edentulousness, cigarette smoking, and family history of dystonia or tremor. An unsatisfactory study power negatively influenced the validity and accuracy of the negative findings relative to diabetes, n eck or trunk trauma, and cigarette smoking. Conclusions-The results of this exploratory study confirm that patients pre senting initially with blepharospasm are most likely to experience some spr ead of dystonia within a few years of the onset of blepharospasm and sugges t that head or face trauma with loss of consciousness preceding the onset, age at onset, and female sex may be relevant to spread. The suggested assoc iation between edentulousness and cranial cervical dystonia may be apparent because of the confounding effect of both age at onset and head or face tr auma with loss of consciousness. The lack of influence of family history of dystonia on spread is consistent with previous findings indicating that th e inheritance pattern is the same for focal and segmental blepharospasm.