Introduction
Dystonia is a neurological movement disorder that causes involuntary muscle contractures. Dystonia musculorum deformans is a rare disorder with many other names, like:
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Early-onset torsion dystonia.
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Early-onset isolated dystonia.
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Early-onset generalized torsion dystonia.
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Idiopathic torsion dystonia.
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Early-onset generalized limb-onset dystonia.
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Early-onset primary dystonia.
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Oppenheim dystonia.
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EOTD.
Dystonia musculorum deformans are more prevalent among the Ashkenazi Jewish population.
What Is Dystonia Musculorum Deformans?
Dystonia musculorum deformans is a rare movement disorder characterized by repetitive, sustained, and involuntary muscle contractions resulting in twisted postures or movements. These muscle contractions usually begin in one limb and progress to other limbs and the trunk. The cervical and cranial regions are usually not involved.
What Causes Dystonia Musculorum Deformans?
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Dystonia musculorum deformans are caused by genetic mutations that are inherited in an autosomal dominant inheritance pattern. Dystonia musculorum deformans are due to mutations in the DYT1 gene, which is responsible for encoding the torsin A protein.
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The genetic penetrance of this condition is 30 to 40 percent. Therefore, it is known that genetic factors and other environmental factors contribute to the development of the disease.
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Not all cases are inherited, and some individuals may develop the condition spontaneously without any family history of the disorder.
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The exact cause of this condition is unknown. Another possible cause is the abnormal functioning of the basal ganglia, a group of structures in the brain that help control movement.
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Other factors contributing to the development of dystonia musculorum deformans include exposure to toxins and trauma and alterations in the neurotransmitters, which are chemicals in the brain that transmit signals between nerve cells.
What Are the Symptoms of Dystonia Musculorum Deformans?
The severity of symptoms can vary widely between individuals and even within the same individual over time. Some individuals affected by dystonia musculorum deformans may experience only mild symptoms, while others may be severely affected and experience severe disability. The severity and the distribution of symptoms differ widely, even between individuals of the same family. Symptoms start developing from childhood or adolescence and progress in the majority of cases. Some of the common symptoms include
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Involuntary muscle contractions, which start in one leg or arm, often progress to the other limbs and the trunk region.
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Abnormal movements like tremors, jerks, or spasms may occur along with muscle contractions.
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Muscle stiffness or rigidity (hypertonia) is present in some individuals.
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Abnormal postures due to the twisting movements (torsion) in the trunk.
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Difficulty in performing fine motor tasks such as writing or typing.
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Some people affected by this condition may have abnormal gait or walking patterns.
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This condition rarely affects the muscles in the head and neck.
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Affected persons are intellectually normal with no other neurological symptoms.
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Abnormality in the voice occurs in rare cases.
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When it progresses to the craniocervical muscles, in rare cases, it may cause difficulties in speech and swallowing and also cause vision problems.
How Is Dystonia Musculorum Deformans Diagnosed?
There is no specific diagnostic test for dystonia musculorum deformans. Diagnosis is usually made through medical history, physical examination, and other diagnostic tests.
Some of the common diagnostic tests done are listed below.
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Clinical examination of the affected individual reveals involuntary muscle contractions, abnormal movements, and postures. The doctor also evaluates the person’s gait, fine motor skills, and speech.
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MRI of the brain can help identify any structural abnormalities or changes in the brain that may be causing the symptoms.
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Molecular genetic testing is done to confirm the diagnosis and is recommended for individuals with a family history of the condition.
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Electromyography (EMG) measures the electrical activity of the muscles and can help identify the presence of muscle spasms and abnormal muscle contractions.
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Blood tests may be performed to rule out other conditions that can cause similar symptoms, such as infections, autoimmune disorders, or metabolic disorders.
What Are the Other Conditions That Are Similar to Dystonia Musculorum Deformans?
Many other isolated dystonia forms have similar features to that of dystonia musculorum deformans. Some of them include
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Dopa-responsive dystonia.
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Primary dystonia - in this, there is more prominent involvement of the head, neck, and laryngeal muscles.
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Autosomal dominant focal dystonia, which is usually adult-onset.
How Is Dystonia Musculorum Deformans Managed?
There is no cure for dystonia musculorum deformans, but there are several treatment options available that can be done to manage the symptoms and improve the quality of life. The treatment approach varies for each affected individual. Common treatments that can be done are listed below.
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Medications: Several medications can be used to manage the symptoms of dystonia musculorum deformans. Medications used are anticholinergic drugs, benzodiazepines, Tetrabenazine, muscle relaxants, dopamine-depleting agents, and Baclofen. Most of these medications focus on the neurotransmitters that control muscle movement.
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Physical Therapy and Occupational Therapy: Physical therapy helps by strengthening the muscles and helps in gaining control over the affected area. It also helps in improving posture. Occupational therapy helps the affected individuals to manage daily tasks such as writing, etc.
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Site-Specific Injections: Botulinum toxin injections, when injected directly into the affected muscle, help control the symptoms. However, this is not a cure for the condition, and it works by temporarily paralyzing the affected muscles. Botulinum injections are now considered first-line treatment options for focal dystonias.
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Surgery: A surgical approach is recommended when the other treatment options do not improve the symptoms. Surgery may be recommended to remove or immobilize affected muscles and tendons. Intrathecal Baclofen application is also done in some cases. Baclofen is a muscle relaxant.
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Deep Brain Stimulation: Deep brain stimulation involves implanting electrodes in the brain and using a device to deliver electrical impulses to certain areas in the brain. Deep brain stimulation of the internal globus pallidus (a basal ganglia component) has been an essential treatment in recent years.
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Psychological Counseling: Psychological counseling can help individuals with dystonia musculorum deformans cope with the emotional impact of the condition, such as depression and anxiety.
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Genetic Counseling: Genetic counseling is given to affected individuals and their families to educate them about the inheritance pattern and the risks for the offspring.
Conclusion
Dystonia musculorum deformans, characterized by sustained muscle contractions leading to abnormal postures, poses significant challenges to affected individuals. Patients with dystonia musculorum deformans have normal cognitive function. Current treatment options aim to help with the symptoms. With modern treatment options, most affected patients can maintain an independent and comparatively good quality of life. Ongoing research into the underlying mechanisms holds promise for future therapeutic advancements in managing this disorder.
