• Oromandibular dystonia;
  • lateral pterygoid muscle;
  • botulinum toxin;
  • hormonal factors

Summary  Oromandibular dystonia (OMD) is a focal neurological movement disorder characterized by involuntary sustained and often painful muscle contraction, usually producing repetitive movements or abnormal positions of the mouth, jaw and/or tongue. We report on a 30-year-old woman affected with OMD with a 12-year follow-up. Focal dystonia involved an involuntary activity of the lateral pterygoid muscles causing forceful jaw displacement in the maximal protrusive position. These episodes initially occurred during jaw function and increased up to an open-lock with bilateral pre-auricular pain. Dystonic spasms were absent during sleep and were reduced temporarily by sensory tricks. Treatment with botulinum toxin type A (BTX) was performed during three different sessions over a 1-year period. Electromyographic-guided BTX injections into the lateral pterygoid muscles were given with cannula electrodes. Botox reduced the involuntary activity of the muscles. Recurrence and exacerbation of dystonic symptoms occurred during the two pregnancies and completely disappeared immediately after both deliveries with prolonged symptom-free periods. During the last 8 years, the patient had a slight relapse of symptoms during flu attacks, periods of stress and during menses. The temporal pattern of these symptoms indicates a possible relationship between OMD and hormonal factors.