title: Young onset hemifacial spasm.
abstract: BACKGROUND
  Hemifacial spasm (HFS) frequently affects middle aged individuals and the clinical features and etiology have been well reported. However, there is limited data on the exact pathogenesis in young-onset HFS. If age is a major determinant of the etiology or influences the presentation of HFS, there may be clinical differences between the young and elderly HFS patients.
  
  
  OBJECTIVE
  We determined the prevalence, clinical and imaging features of young-onset HFS (age of onset<or=30 years) in a tertiary referral center. These data were compared with old onset (age of onset>or=65 years) HFS patients.
  
  
  METHODS
  We examined consecutive patients clinically diagnosed with HFS in a tertiary referral center. The clinical (demographics, clinical presentation, severity of HFS, associated medical conditions and other variables) and imaging findings of young onset patients and old onset patients were tabulated and compared.
  
  
  RESULTS
  Amongst 230 consecutive HFS patients, 15 (6.5%) were young-onset HFS and 50 (21.7%) were old-onset HFS. In the young-onset HFS, the mean age of onset of symptoms was 26.5+/-6.5 (6-30) years, with 80% women and 75.0% of young onset HFS having neurovascular compression (NVC) of the root exit zone (REZ) of the facial nerve on the ipsilateral side; 86.7% had initial onset of twitching in the upper eyelids that later progressed to the lower facial muscles. While the prevalence of hypertension, diabetes mellitus and other associated vascular disorders in late onset HFS was higher than in young onset groups, the clinical features and frequency of NVC of the facial REZ between the two groups were similar.
  
  
  CONCLUSIONS
  We demonstrated a 6.5% frequency of young-onset HFS in our cohort of HFS and their clinical presentation was similar to the old onset patients. Genetic, anatomic or other unidentified factors may contribute to NVC in young-onset HFS.
authors.affiliation: Department of Neurology, Singapore General Hospital, Singapore. gnrtek@sgh.com.sg
authors.forename: E K
authors.initials: EK
authors.lastname: Tan
authors.forename: L L
authors.initials: LL
authors.lastname: Chan
mesh_terms: D000328:Adult; D017677:Age Distribution; D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001488:Basilar Artery / Q000473:pathology / Q000503:physiopathology; D015897:Comorbidity; D003920:Diabetes Mellitus / Q000453:epidemiology; D018450:Disease Progression; D005152:Facial Muscles / Q000294:innervation / Q000503:physiopathology; D005154:Facial Nerve / Q000473:pathology / Q000503:physiopathology; D005155:Facial Nerve Diseases / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D005260:Female; D019569:Hemifacial Spasm / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D006801:Humans; D006973:Hypertension / Q000453:epidemiology; D018810:Magnetic Resonance Angiography; D008297:Male; D015995:Prevalence; D017678:Sex Distribution