• orolingual tremor;
  • facial tremor;
  • task-specific tremor;
  • smiling


Facial tremor occurring on smiling is a rare phenomenon and has been described (to the best of our knowledge) in the literature only once. We describe two patients who presented with a bilateral facial tremor that occurred only on smiling and other activation of therisorii muscles and had a high frequency of 9 Hz. One patient additionally suffered from young-onset Parkinson's disease, whereas the other had no further neurological symptoms or signs apart from this tremor. Anti-parkinsonian medication was unhelpful for the facial tremor in the patient with Parkinson's disease. Tremor on smiling may be a discrete entity or may be associated in some cases of Parkinson's disease. © 2009 Movement Disorder Society