Oromandibular Dystonia - Types, Causes, Symptoms, and Diagnosis

Introduction:

Involuntary (automatic) and rhythmic contractions of the tongue, facial muscles, and muscles involved in chewing are called oromandibular dystonia. It has been reported in about 6.9 individuals in every 100,000 population. It is more common among females and occurs between 40 to 70 years.

What Is Oromandibular Dystonia?

Oromandibular dystonia is a neurological disorder characterized by severe contractions of muscles of the lower face, leading to repetitive and uncontrolled movements of the tongue, jaw, and facial muscles. It is also referred to as cranial dystonia, orofacial buccal dystonia, lingual dystonia, etc. When the lip and facial muscles are affected in musicians who play wind instruments, it is called embouchure dystonia.

What Are the Types of Oromandibular Dystonia?

Oromandibular dystonia is a focal type (affecting a particular part or two) of muscle contraction and is further classified as follows:

• Jaw opening.

• Jaw closing.

• Jaw deviating.

• Combination of the above.

What Causes Oromandibular Dystonia?

The main causative factor of oromandibular dystonia remains unknown. However, certain factors like:

• Neurological disorders that are already present due to hereditary or other causes can predispose to oromandibular dystonia.

• Specific drugs like neuroleptics used to treat psychological conditions are also found to cause dystonia of the facial muscles.

• Trauma or injury to the brain and its structures.

• Abnormal functioning of structures of the brain (basal ganglia) leads to the production of extra signals leading to uncontrolled movements of the jaw, tongue, and face.

• Generalized (affecting multiple muscles) dystonia occurring due to genetic changes in the DYT1 gene also causes dystonia of the jaw.

• After some dental procedures like tooth removal, implant placements, fitting of dentures, and other surgeries, jaw dystonia can occur.

• Wilson's disease is a rare disorder characterized by the accumulation of copper in the brain, liver, and other parts.

• Parkinson's disease causes difficulty in walking, balance, and coordination, and it is also found to cause the jaw-closing type of oromandibular dystonia.

• Infections or any injury also rarely cause dystonia of the jaw.

What Are the Symptoms of Oromandibular Dystonia?

The involuntary movements of the jaw, face, and tongue are triggered mainly by speaking, chewing, or stress. The symptoms of oromandibular dystonia are as follows:

• Difficulty in chewing and swallowing.

• Spasmodic dysphonia (strange and whispering voice).

• Decreased secretion of saliva.

• Uncontrolled and repetitive movements of the tongue.

• Grinding or clenching of teeth (Bruxism).

• Pursing of lips.

• Unconscious opening and closing of the jaw.

• Twisting of the lower jaw in front or sideways.

• Open locks (the mouth remains wide open and unable to close) and other temporomandibular joint disorders.

• Retraction of the corners of the lips.

• Rapid blinking of eyes.

• Tightening of muscles of nose and face.

• Breathing difficulties.

• Involuntary movements of muscles (platysma) of the neck.

• Headache, facial muscle pain, and fatigue.

• Jaw closure oromandibular dystonia causes damage to the teeth (fracture, wear, and loss), lips, gums, and tongue.

• It usually leads to stress, depression, social withdrawal, and other psychological issues.

• Difficulty in performing daily activities.

How to Diagnose Oromandibular Dystonia?

The methods involved in the diagnosis of oromandibular dystonia are:

• Physical Examination of the patient is essential, along with complete dental and medical history. It aids in the evaluation of the actual cause of dystonia.

• Electromyography (EMG) is performed to assess and record the activity of muscles and nerve cells. It aids in diagnosing any muscle and nerve dysfunction.

• Magnetic Resonance Imaging (MRI) of the brain is done to detect any lesions, injuries, or tumors in brain structures.

What Is the Differential Diagnosis?

Oromandibular dystonia should not be misinterpreted with the following:

• The temporomandibular joint disorder affects the joint that connects the lower jaw to the skull and is characterized by pain, locking of jaws, and difficulty chewing.

• Hemifacial spasm is a nerve disorder in which involuntary movements and twitching of muscles on one side of the face occur.

• Certain psychological disorders can cause muscular pain and uncontrolled movements.

How to Manage Oromandibular Dystonia?

1) Pharmaceutical Management:

• Drugs like Clonazepam, Baclofen, Carbamazepine, and antiparkinson drugs are suggested to control muscle movements. The drugs act on chemical substances that aid the transmission of signals from the brain to muscles.

• Botulinum injections act by blocking the release of a substance called acetylcholine at the junction of nerve and muscle. Thereby, the signals to the muscle are temporarily blocked. It prevents the repetitive movements of muscles. However, its side effects include muscle weakness, difficulty in swallowing, and the patient may become resistant to the therapy, depending on the dose provided.

• Muscle afferent block (MAB) hinders the signals from the muscle to the spinal cord. It is found highly effective in patients with oromandibular dystonia, and the side effects are low.

2) Surgical Management:

• There is no specific surgical treatment available. However, removal of the coronoid process of the temporomandibular joint showed increased mouth opening in severe cases of jaw-closing dystonia.

• Selective peripheral denervation removes the nerve when they enter the overactive muscle. It is considered the last option if no other treatment is found effective.

• Deep brain stimulation is a procedure of placing an element (electrode) inside the brain, and it is connected to a small device (generator) embedded in the chest. The generator sends signals to the brain, thereby controlling the involuntary movements.

3) Therapeutic Management:

Physical and occupational therapies are followed to improve the movement and functioning of muscles and prevent the worsening of spasms.

What Are the Lifestyle Modifications Needed?

• Bite guards are also suggested in case of tongue biting in a few patients.

• Use electric toothbrushes to maintain oral hygiene.

• Know your sensory tricks: Gently touching specific areas of lips, under eyes, chin, etc., prevents irregular movements of the jaw and face temporarily.

• Physical exercises and yoga are done to manage stress.

Conclusion:

Oromandibular dystonia occurs rarely and may cause symptoms that affect daily activities. However, it is not a disorder to get stressed off as various treatment options are available to improve the quality of life. The group effort of health professionals aids in proper diagnosis and making decisions on the best treatment.