Oromandibular Dystonia, better known as TMJ Dysfunction
Oromandibular Dystonia - dystonia affecting the muscles of the mouth and jaw.
What is dystonia?
Dystonia is a neurological disorder. It causes involuntary muscle contractions which force the affected parts of the body into abnormal movements or postures.
Oromandibular dystonia (OMD) is a focal dystonia of the mouth and jaw and, while it can affect people of any age, typically occurs in older adults. By causing affected muscles to contract involuntarily, it produces abnormal movements of the mouth and tongue, often impairing speech. When it starts in adults, it rarely spreads to any other region of the body.
The movements can work to clamp the jaw shut or suddenly to open the mouth. The jaw may move up and down or deviate to one side and the spasms may affect the tongue. Symptoms may vary from mild to severe, and there may be associated pain or physical discomfort. The condition may start with occasional slight difficulty in opening or closing the mouth in certain situations, such as when speaking or eating. Gradually the symptoms become more severe, more prolonged and occur in other situations. Sometimes, the condition may be partially relieved by humming, singing, yawning, deliberately moving the mouth or by touching the chin and lips.
Though oromandibular dystonia progresses in this way, it is not life threatening. Neither the mind nor the senses are affected.
The condition varies from one individual to another. Jaw-closing OMD is likely to interfere with speech and eating. Jaw-opening OMD, probably causing more embarrassment to the individual who has it, can have a detrimental effect on social interaction.
What causes oromandibular dystonia?
OMD is believed to be the result of abnormal functioning of the basal ganglia, deep brain structures involved in the control of movement.
Occasionally, the onset of OMD may be brought on by drugs used to treat psychiatric disease. In the past, this has led to the condition being wrongly perceived by some to be a psychiatric illness.
How is the oromandibular dystonia treated?
Up to now, no cure has been found. Various drug treatments have been tried in the treatment of oromandibular dystonia, but, while certain of these may provide benefit for some individuals, none is universally effective. The drugs may also produce side effects in some people.
Botulinum toxin injections, which weaken the muscles affected by spasms, are the most effective treatment. Carefully targeted injections need to be repeated every three months or so, as the effects are only temporary. In cases where little improvement results from the injections, it may be because they have not been accurately targeted, or the dose needs adjusting, or a different type of botulinum toxin is required.
Sometimes electromyography (EMG) is used to identify the appropriate muscles. Which muscles require injection will vary from one individual to another, and may vary from one occasion to another.
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