INTRODUCTION Oromandibular dystonia (OMD) is a focal dystonic movement disorder affecting the mid and lower face, particularly the jaw and tongue. It is characterized by spasms along the sides of the nose, the cheek, mouth, and chin. Uncontrolled spasms make opening and closing of the mouth difficult and can have a profound influence on eating and speaking. Meige's syndrome is a term used for a regional dystonia consisting of the two adjacent focal dystonias, benign essential blepharospasm, and oromandibular dystonia. It is not uncommon for clinical manifestations to begin with orbicularis muscle spasm, later spreading to the lower face and even the neck after months to a few years. The condition can spread further to other focal areas including spastic dysphonia, and cervical dystonia. The etiology is unknown but in the idiopathic form is believed to be related to a neurotransmitter defect possible in the basal ganglia. About 20% of patients with brain injuries develop new onset cervical or oromandibular dystonias. OMD can also result from facial injury and surgery.
CLINICAL PRESENTATION Symptoms usually begin between the ages of 40 and 70 years and are more common in females. Symptoms begin with mild difficulties opening or closing the mouth and progress to more forceful spasms. Symptoms are often exacerbated by specific activities such as speaking or chewing. Difficulty in swallowing is a common complaint. Spasms of the mid and lower facial muscles occur in an uncontrolled fashion lasting from momentary twitches to sustained forceful and sometimes painful contractions. Occasionally the masseter muscles can be involved with jaw clenching as a major component. Sensory tricks such as humming, singing, or touching the side of the face, chin, or lips, can sometimes reduce the frequency or intensity of spasms.
TREATMENT Botulinum toxin has become the primary treatment of choice for oromandibular dystonia and essential blepharospasm. More than 90% of patients obtain some relieve of spasms that can last
Oromandibular Dystonia (Contd.)
for an average of three months. One to two unit injections of botulinum toxin type A (Botox® or Dysport®) are placed into the involved facial muscles. For patients who become refractory to type A, toxin type B (Myobloc®) can offer some benefit. Complications of botulinum toxin when used in the mid and lower face include bruising, mouth droop, chewing and speaking problems, and dry mouth. Pharmacologic therapy may be useful as an adjunct but is rarely useful as a primary treatment modality. About 20% to 30% of patients will report some benefit from one drug or another. The most important drugs are Clonazepam (Klonopin), trihexyphenidyl (Artane), and baclofen (Lioresal). Unlike blepharospasm, there is no good surgical procedure for oromandibular dystonia.
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